Research on supercontinuum sources on silicon has made significant progress in the past few decades.However,conventional approaches to broaden the spectral bandwidth often rely on complex and critical dispersion engin...Research on supercontinuum sources on silicon has made significant progress in the past few decades.However,conventional approaches to broaden the spectral bandwidth often rely on complex and critical dispersion engineering by optimizing the core thickness or introducing the cladding with special materials and structures.We propose and demonstrate supercontinuum generation using long-periodgrating(LPG)waveguides on silicon with a C-band pump.The LPG waveguide is introduced for quasi-phase matching,and the generated supercontinuum spectrum is improved greatly with grating-induced dispersive waves.In addition,the demonstrated LPG waveguide shows a low propagation loss comparable with regular silicon photonic waveguides without gratings.In experiments,when using a 1550-nm 75-fs pulse pump with a pulse energy of 200 pJ,the supercontinuum spectrum generated with the present LPG waveguide shows an ultrabroad extent from 1150 to 2300 nm,which is much wider by 200 nm than that achieved by dispersionengineered uniform silicon photonic waveguides on the same chip.This provides a promising option for on-chip broadband light source for silicon photonic systems.展开更多
Chip-scale programmable optical signal processors are often used to flexibly manipulate the optical signals for satisfying the demands in various applications,such as lidar,radar,and artificial intelligence.Silicon ph...Chip-scale programmable optical signal processors are often used to flexibly manipulate the optical signals for satisfying the demands in various applications,such as lidar,radar,and artificial intelligence.Silicon photonics has unique advantages of ultra-high integration density as well as CMOS compatibility,and thus makes it possible to develop large-scale programmable optical signal processors.The challenge is the high silicon waveguides propagation losses and the high calibration complexity for all tuning elements due to the random phase errors.In this paper,we propose and demonstrate a programmable silicon photonic processor for the first time by introducing low-loss multimode photonic waveguide spirals and low-random-phase-error Mach-Zehnder switches.The present chip-scale programmable silicon photonic processor comprises a 1×4 variable power splitter based on cascaded Mach-Zehnder couplers(MZCs),four Ge/Si photodetectors,four channels of thermally-tunable optical delaylines.Each channel consists of a continuously-tuning phase shifter based on a waveguide spiral with a micro-heater and a digitally-tuning delayline realized with cascaded waveguide-spiral delaylines and MZSs for 5.68 ps time-delay step.Particularly,these waveguide spirals used here are designed to be as wide as 2μm,enabling an ultralow propagation loss of 0.28 dB/cm.Meanwhile,these MZCs and MZSs are designed with 2-μm-wide arm waveguides,and thus the random phase errors in the MZC/MZS arms are negligible,in which case the calibration for these MZSs/MZCs becomes easy and furthermore the power consumption for compensating the phase errors can be reduced greatly.Finally,this programmable silicon photonic processor is demonstrated successfully to verify a number of distinctively different functionalities,including tunable time-delay,microwave photonic beamforming,arbitrary optical signal filtering,and arbitrary waveform generation.展开更多
A compact spectrometer on silicon is proposed and demonstrated with an ultrahigh resolution.It consists of a thermally-tunable ultra-high-Q resonator aiming at ultrahigh resolution and an array of wideband resonators ...A compact spectrometer on silicon is proposed and demonstrated with an ultrahigh resolution.It consists of a thermally-tunable ultra-high-Q resonator aiming at ultrahigh resolution and an array of wideband resonators for achieving a broadened working window.The present on-chip spectrometer has a footprint as compact as 0.35 mm^(2),and is realized with standard multi-project-wafer foundry processes.The measurement results show that the on-chip spectrometer has an ultra-high resolution Δλ of 5 pm and a wide working window of 10 nm.The dynamic range defined as the ratio of the working window and the wavelength resolution is as large as 1940,which is the largest for on-chip dispersive spectro-meters to the best of our knowledge.The present high-performance on-chip spectrometer has great potential for high-resolution spectrum measurement in the applications of gas sensing,food monitoring,health analysis,etc.展开更多
Multi-lane integrated transmitter chips are key components in future compact optical modules to realize high-speed optical interconnects.Thin-film lithium niobate(TFLN)photonics have emerged as a promising platform fo...Multi-lane integrated transmitter chips are key components in future compact optical modules to realize high-speed optical interconnects.Thin-film lithium niobate(TFLN)photonics have emerged as a promising platform for achieving high-performance chip-scale optical systems.Combining a coarse wavelength-division multiplexing(CWDM)devices using fabrication-tolerant angled multimode interferometer structure and high-performance electro-optical modulators,we demonstrate monolithic on-chip four-channel CWDM transmitter on the TFLN platform for the first time.The four-channel CWDM transmitter enables high-speed transmissions of 100 Gb/s data rate per wavelength channel(i.e.,an aggregated date rate of 400 Gb/s).展开更多
The field of silicon nanophotonics has attracted considerable attention in the past decade because of its unique advantages,including complementary metal–oxide–semiconductor（CMOS） compatibility and the ability to ...The field of silicon nanophotonics has attracted considerable attention in the past decade because of its unique advantages,including complementary metal–oxide–semiconductor（CMOS） compatibility and the ability to achieve an ultra-high integration density. In particular, silicon nanophotonic integrated devices for on-chip light manipulation have been developed successfully and have played very import roles in various applications. In this paper, we review the recent progress of silicon nanophotonic devices for on-chip light manipulation, including the static type and the dynamic type. Static onchip light manipulation focuses on polarization/mode manipulation, as well as light nanofocusing, while dynamic on-chip light manipulation focuses on optical modulation/switching. The challenges and prospects of high-performance silicon nanophotonic integrated devices for on-chip light manipulation are discussed.展开更多
Compact passive silicon photonic devices with high performance are always desired for future largescale photonic integration.Inverse design provides a promising approach to realize new-generation photonic devices,whil...Compact passive silicon photonic devices with high performance are always desired for future largescale photonic integration.Inverse design provides a promising approach to realize new-generation photonic devices,while it is still very challenging to realize complex photonic devices for most inverse designs reported previously due to the limits of computational resources.Here,we present the realization of several representative advanced passive silicon photonic devices with complex optimization,including a sixchannel mode(de)multiplexer,a broadband 90 deg hybrid,and a flat-top wavelength demultiplexer.These devices are designed inversely by optimizing a subwavelength grating(SWG)region and the multimode excitation and the multimode interference are manipulated.Particularly,such SWG structures are more fabrication-friendly than those random nanostructures introduced in previous inverse designs.The realized photonic devices have decent performances in a broad bandwidth with a low excess loss of<1 dB,which is much lower than that of previous inverse-designed devices.The present inverse design strategy shows great effectiveness for designing advanced photonic devices with complex requirements(which is beyond the capability of previous inverse designs)by using affordable computational resources.展开更多
Waveguide-integrated optical modulators are indispensable for on-chip optical interconnects and optical computing.To cope with the ever-increasing amount of data being generated and consumed,ultrafast waveguide-integr...Waveguide-integrated optical modulators are indispensable for on-chip optical interconnects and optical computing.To cope with the ever-increasing amount of data being generated and consumed,ultrafast waveguide-integrated optical modulators with low energy consumption are highly demanded.In recent years,two-dimensional(2D)materials have attracted a lot of attention and have provided tremendous opportunities for the development of high-performance waveguide-integrated optical modulators because of their extraordinary optoelectronic properties and versatile compatibility.This paper reviews the state-of-the-art waveguide-integrated optical modulators with 2D materials,providing researchers with the developing trends in the field and allowing them to identify existing challenges and promising potential solutions.First,the concept and fundamental mechanisms of optical modulation with 2D materials are summarized.Second,a review of waveguide-integrated optical modulators employing electro-optic,all-optic,and thermo-optic effects is provided.Finally,the challenges and perspectives of waveguide-integrated modulators with 2D materials are discussed.展开更多
Photonic waveguides are the most fundamental element for photonic integrated circuits(PICs).Waveguide properties,such as propagation loss,modal areas,nonlinear coefficients,etc.,directly determine the functionalities ...Photonic waveguides are the most fundamental element for photonic integrated circuits(PICs).Waveguide properties,such as propagation loss,modal areas,nonlinear coefficients,etc.,directly determine the functionalities and performance of PICs.Recently,the emerging waveguides with bound states in the continuum(BICs)have opened new opportunities for PICs because of their special properties in resonance and radiation.Here,we review the recent progress of PICs composed of waveguides with BICs.First,fundamentals including background physics and design rules of a BIC-based waveguide will be introduced.Next,two types of BIC-based waveguide structures,including shallowly etched dielectric and hybrid waveguides,will be presented.Lastly,the challenges and opportunities of PICs with BICs will be discussed.展开更多
Dealing with the increase in data workloads and network complexity requires efficient selective manipulation of any channels in hybrid mode-/wavelength-division multiplexing(MDM/WDM)systems.A reconfigurable optical ad...Dealing with the increase in data workloads and network complexity requires efficient selective manipulation of any channels in hybrid mode-/wavelength-division multiplexing(MDM/WDM)systems.A reconfigurable optical add-drop multiplexer(ROADM)using special modal field redistribution is proposed and demonstrated to enable the selective access of any mode-/wavelength-channels.With the assistance of the subwavelength grating structures,the launched modes are redistributed to be the supermodes localized at different regions of the multimode bus waveguide.Microring resonators are placed at the corresponding side of the bus waveguide to have specific evanescent coupling of the redistributed supermodes,so that any mode-/wavelength-channel can be added/dropped by thermally tuning the resonant wavelength.As an example,a ROADM for the case with three mode-channels is designed with low excess losses of<0.6,0.7,and 1.3 dB as well as low cross talks of<−26.3,−28.5,and−39.3 dB for the TE0,TE1,and TE2 modes,respectively,around the central wavelength of 1550 nm.The data transmission of 30 Gbps∕channel is also demonstrated successfully.The present ROADM provides a promising route for data switching/routing in hybrid MDM/WDM systems.展开更多
A high-performance silicon arrayed-waveguide grating(AWG)with 0.4-nm channel spacing for dense wavelength-division multiplexing systems is designed and realized successfully.The device design involves broadening the a...A high-performance silicon arrayed-waveguide grating(AWG)with 0.4-nm channel spacing for dense wavelength-division multiplexing systems is designed and realized successfully.The device design involves broadening the arrayed waveguides far beyond the single-mode regime,which minimizes random phase errors and propagation loss without requiring any additional fabrication steps.To further enhance performance,Euler bends have been incorporated into the arrayed waveguides to reduce the device’s physical footprint and suppress the excitation of higher modes.In addition,shallowly etched transition regions are introduced at the junctions between the free-propagation regions and the arrayed waveguides to minimize mode mismatch losses.As an example,a 32×32 AWG(de)multiplexer with a compact size of 900μm×2200μm is designed and demonstrated with a narrow channel spacing of 0.4 nm by utilizing 220-nm-thick silicon photonic waveguides.The measured excess loss for the central channel is∼0.65 dB,the channel nonuniformity is around 2.5 dB,while the adjacent-channel crosstalk of the central output port is−21.4 dB.To the best of our knowledge,this AWG(de)multiplexer is the best one among silicon-based implementations currently available,offering both dense channel spacing and a large number of channels.展开更多
Integrated optical delay lines have become imperative to meet the growing demand as large aperture antennas and high number of subarrays required for microwave beamforming,high-speed optical communication,and integrat...Integrated optical delay lines have become imperative to meet the growing demand as large aperture antennas and high number of subarrays required for microwave beamforming,high-speed optical communication,and integrated quantum photonics.It is very challenging to achieve large delay ranges,small footprints,and broad bandwidths simultaneously due to the strong trade-off between the propagation loss and the group refractive index of optical waveguides.In this paper,we propose and experimentally demonstrate multimode-enabled silicon photonic delay line for the first time,which breaks the delay-density limit of singlemode waveguide spirals,towards a broadband,mm^(2)-scale,and ultra-large time delay.By demonstrating low-loss-propagation possibilities for different polarizations and modes,we introduce a novel multimode delay unit by integrating the mode(de)multiplexers and the ultralowloss multimode waveguide spiral supporting the TE_(0),TE_(1),and TE_(2)modes propagating in parallel.The measured propagation losses for the TE_(0),TE_(1),and TE_(2)modes are 0.2 dB/cm,0.31 dB/cm,and 0.49 dB/cm,respectively.In this way,the highest line delay-density of 376.9 ps/cm and low delay loss of 0.004 dB/ps are achieved.Furthermore,we implement a 7-bit tunable multimode photonic delay line and experimentally demonstrate an ultra-large delay range of 12.7 ns with a delay resolution of 100 ps and within an ultra-compact footprint of 3.85mm^(2),enabling a delay density over 3299 ps/mm^(2),showing the largest delay range and the highest delay density among on-chip delay lines reported to date,to the best of our knowledge.展开更多
Structured light carrying angular momentum,such as spin angular momentum(SAM)and orbital angular momentum(OAM),has been at the core of new science and applications,driving the need for compact on-chip sources.While ma...Structured light carrying angular momentum,such as spin angular momentum(SAM)and orbital angular momentum(OAM),has been at the core of new science and applications,driving the need for compact on-chip sources.While many static on-chip solutions have been demonstrated,as well as on-chip sources of free-space modes,no architecture that is fully reconfigurable in all angular momentum states and all on-chip has so far been possible.Here we report the first all-on-chip structured light generator for the creation of both scalar and vectorial angular momentum beams,facilitated through a silicon-on-insulator(SOI)chip with a silica mode multiplexer(silica chip).We selectively stimulate six linearly-polarized(LP)modes of the silica multimode bus waveguide,precisely controlling the modal powers and phases with the SOI chip.This allows us to tailor arbitrary superpositions of the mode set thus synthesizing common cylindrical vector vortex beams as well as OAM beams of controlled spin and topological charge.Our compact structured light generator exhibits high switching speed and operates across the telecom band,paving the way for applications such as optical communication and integrated quantum technologies.展开更多
Reconfigurable silicon microrings have garnered significant interest for addressing challenges in artificial intelligence,the Internet of Things,and telecommunications due to their versatile capabilities.Compared to e...Reconfigurable silicon microrings have garnered significant interest for addressing challenges in artificial intelligence,the Internet of Things,and telecommunications due to their versatile capabilities.Compared to electrooptic(EO)and thermo-optic(TO)devices,emerging micro-electromechanical systems(MEMS)-based reconfigurable silicon photonic devices actuated by electrostatic forces offer near-zero static power consumption.This study proposes and implements novel designs for fully reconfigurable silicon photonic MEMS microrings for high-speed dense wavelength division multiplexing(DWDM)elastic networks.The designs include an all-pass microring with a 7 nm free spectral range(FSR)and full-FSR resonance tuning range,an add-drop microring with a 3.5 nm FSR and full-FSR tuning range,and an add-drop double-microring with a 34 nm FSR,wide-range discrete resonance tunability,and flat-top tunability.These advancements hold promise for practical applications.展开更多
Sharing the hardware platform between diverse information systems to establish full cooperation among different functionalities has attracted substantial attention.However,broadband multifunctional integrated systems ...Sharing the hardware platform between diverse information systems to establish full cooperation among different functionalities has attracted substantial attention.However,broadband multifunctional integrated systems with large operating frequency ranges are challenging due to the bandwidth and computing speed restrictions of electronic circuitry.Here,we report an analog parallel processor(APP)based on the silicon photonic platform that directly discretizes and parallelizes the broadband signal in the analog domain.The APP first discretizes the signal with the optical frequency comb and then adopts optical dynamic phase interference to reassign the analog signal into 2N parallel sequences.Via photonic analog parallelism,data rate and data volume in each sequence are simultaneously compressed,which mitigates the requirement on each parallel computing core.Moreover,the fusion of the outputs from each computing core is equivalent to directly processing broadband signals.In the proof-of-concept experiment,two-channel analog parallel processing of broadband radar signals and high-speed communication signals is implemented on the single photonic integrated circuit.The bandwidth of broadband radar signal is 6 GHz and the range resolution of 2.69 cm is achieved.The wireless communication rate of 8 Gbit/s is also validated.Breaking the bandwidth and speed limitations of the single-computing core along with further exploring the multichannel potential of this architecture,we anticipate that the proposed APP will accelerate the development of powerful optoelectronic processors as critical support for applications such as satellite networks and intelligent driving.展开更多
High-capacity on-chip optical transmitters and receivers are crucial for data transmissions.Currently,advanced multiplexing technologies,including wavelength division multiplexing(WDM),mode-division multiplexing(MDM),...High-capacity on-chip optical transmitters and receivers are crucial for data transmissions.Currently,advanced multiplexing technologies,including wavelength division multiplexing(WDM),mode-division multiplexing(MDM),and polarization-divisionmultiplexing(PDM)have been developed to greatly enhance the link capacity.In this paper,monolithically integrated silicon photonic transmitter and receiver with an ultra-high-capacity density of 37.0 Tbps/cm^(2) were proposed and demonstrated by introducing hybrid multiplexers and arrayed modulators/photodetectors.For the demonstrated transmitter/receiver chips,there are five wavelength channels and four mode channels with dual polarizations involved,while all these channels have low excess losses of 1 to 2 dB and low crosstalk less than−15 dB.Finally,all 20 channels are able to work with 50 Gbps on–off keying(OOK)signals per channel,achieving a total capacity of 1T-bps within an ultra-compact chip size of 0.032 cm^(2) for transmitters and 0.022 cm^(2) for receivers.展开更多
Silicon-based large-scale photonic integrated circuits are becoming important,due to the need for higher complexity and lower cost for optical transmitters,receivers and optical buffers.In this paper,passive technolog...Silicon-based large-scale photonic integrated circuits are becoming important,due to the need for higher complexity and lower cost for optical transmitters,receivers and optical buffers.In this paper,passive technologies for large-scale photonic integrated circuits are described,including polarization handling,light non-reciprocity and loss reduction.The design rule for polarization beam splitters based on asymmetrical directional couplers is summarized and several novel designs for ultra-short polarization beam splitters are reviewed.A novel concept for realizing a polarization splitter–rotator is presented with a very simple fabrication process.Realization of silicon-based light non-reciprocity devices(e.g.,optical isolator),which is very important for transmitters to avoid sensitivity to reflections,is also demonstrated with the help of magneto-optical material by the bonding technology.Low-loss waveguides are another important technology for large-scale photonic integrated circuits.Ultra-low loss optical waveguides are achieved by designing a Si3N4 core with a very high aspect ratio.The loss is reduced further to,0.1 dB m21 with an improved fabrication process incorporating a high-quality thermal oxide upper cladding by means of wafer bonding.With the developed ultra-low loss Si3N4 optical waveguides,some devices are also demonstrated,including ultra-high-Q ring resonators,low-loss arrayed-waveguide grating(de)multiplexers,and high-extinction-ratio polarizers.展开更多
Graphene has attracted much attention for the realization of high-speed photodetection for silicon photonics over a wide wavelength range.However,the reported fast graphene photodetectors mainly operate in the 1.55μm...Graphene has attracted much attention for the realization of high-speed photodetection for silicon photonics over a wide wavelength range.However,the reported fast graphene photodetectors mainly operate in the 1.55μm wavelength band.In this work,we propose and realize high-performance waveguide photodetectors based on bolometric/photoconductive effects by introducing an ultrathin wide silicon−graphene hybrid plasmonic waveguide,which enables efficient light absorption in graphene at 1.55μm and beyond.When operating at 2μm,the present photodetector has a responsivity of ~70 mA/W and a setup-limited 3 dB bandwidth of >20 GHz.When operating at 1.55μm,the present photodetector also works very well with a broad 3 dB bandwidth of >40 GHz(setup-limited)and a high responsivity of ~0.4 A/W even with a low bias voltage of−0.3 V.This work paves the way for achieving highresponsivity and high-speed silicon-graphene waveguide photodetection in the near/mid-infrared ranges,which has applications in optical communications,nonlinear photonics,and on-chip sensing.展开更多
Two-dimensional materials(2DMs)have been used widely in constructing photodetectors(PDs)because of their advantages in flexible integration and ultrabroad operation wavelength range.Specifically,2DM PDs on silicon hav...Two-dimensional materials(2DMs)have been used widely in constructing photodetectors(PDs)because of their advantages in flexible integration and ultrabroad operation wavelength range.Specifically,2DM PDs on silicon have attracted much attention because silicon microelectronics and silicon photonics have been developed successfully for many applications.2DM PDs meet the imperious demand of silicon photonics on low-cost,high-performance,and broadband photodetection.In this work,a review is given for the recent progresses of Si/2DM PDs working in the wavelength band from near-infrared to mid-infrared,which are attractive for many applications.The operation mechanisms and the device configurations are summarized in the first part.The waveguide-integrated PDs and the surface-illuminated PDs are then reviewed in details,respectively.The discussion and outlook for 2DM PDs on silicon are finally given.展开更多
An ultrahigh-Q silicon racetrack resonator is proposed and demonstrated with uniform multimode silicon photonic waveguides.It consists of two multimode straight waveguides connected by two multimode waveguide bends(MW...An ultrahigh-Q silicon racetrack resonator is proposed and demonstrated with uniform multimode silicon photonic waveguides.It consists of two multimode straight waveguides connected by two multimode waveguide bends(MWBs).In particular,the MWBs are based on modified Euler curves,and a bent directional coupler is used to achieve the selective mode coupling for the fundamental mode and not exciting the higher-order mode in the racetrack.In this way,the fundamental mode is excited and propagates in the multimode racetrack resonator with ultralow loss and low intermode coupling.Meanwhile,it helps achieve a compact 180°bend to make a compact resonator with a maximized free spectral range(FSR).In this paper,for the chosen 1.6μm wide silicon photonic waveguide,the effective radius Reffof the designed 180°bend is as small as 29μm.The corresponding FSR is about 0.9 nm when choosing 260μm long straight waveguides in the racetrack.The present high-Q resonator is realized with a simple standard single-etching process provided by a multiproject wafer foundry.The fabricated device,which has a measured intrinsic Q-factor as high as 2.3×10~6,is the smallest silicon resonator with a>106Q-factor.展开更多
基金supported by the UK’s Engineering and Physical Sciences Research Council(Grant Nos.EP/V000624/1,EP/X03495X/1,EP/X041166/1,and EP/T02643X/1)the Royal Society(Grant No.RG\R2\232531).
文摘Research on supercontinuum sources on silicon has made significant progress in the past few decades.However,conventional approaches to broaden the spectral bandwidth often rely on complex and critical dispersion engineering by optimizing the core thickness or introducing the cladding with special materials and structures.We propose and demonstrate supercontinuum generation using long-periodgrating(LPG)waveguides on silicon with a C-band pump.The LPG waveguide is introduced for quasi-phase matching,and the generated supercontinuum spectrum is improved greatly with grating-induced dispersive waves.In addition,the demonstrated LPG waveguide shows a low propagation loss comparable with regular silicon photonic waveguides without gratings.In experiments,when using a 1550-nm 75-fs pulse pump with a pulse energy of 200 pJ,the supercontinuum spectrum generated with the present LPG waveguide shows an ultrabroad extent from 1150 to 2300 nm,which is much wider by 200 nm than that achieved by dispersionengineered uniform silicon photonic waveguides on the same chip.This provides a promising option for on-chip broadband light source for silicon photonic systems.
基金We are grateful for financial supports from National Major Research and Development Program(No.2018YFB2200200)National Science Fund for Distinguished Young Scholars(61725503)+1 种基金Zhejiang Provincial Natural Science Foundation(LZ18F050001,LGF21F050003)National Natural Science Foundation of China(NSFC)(91950205,6191101294,11861121002,61905209,62175214,62111530147).
文摘Chip-scale programmable optical signal processors are often used to flexibly manipulate the optical signals for satisfying the demands in various applications,such as lidar,radar,and artificial intelligence.Silicon photonics has unique advantages of ultra-high integration density as well as CMOS compatibility,and thus makes it possible to develop large-scale programmable optical signal processors.The challenge is the high silicon waveguides propagation losses and the high calibration complexity for all tuning elements due to the random phase errors.In this paper,we propose and demonstrate a programmable silicon photonic processor for the first time by introducing low-loss multimode photonic waveguide spirals and low-random-phase-error Mach-Zehnder switches.The present chip-scale programmable silicon photonic processor comprises a 1×4 variable power splitter based on cascaded Mach-Zehnder couplers(MZCs),four Ge/Si photodetectors,four channels of thermally-tunable optical delaylines.Each channel consists of a continuously-tuning phase shifter based on a waveguide spiral with a micro-heater and a digitally-tuning delayline realized with cascaded waveguide-spiral delaylines and MZSs for 5.68 ps time-delay step.Particularly,these waveguide spirals used here are designed to be as wide as 2μm,enabling an ultralow propagation loss of 0.28 dB/cm.Meanwhile,these MZCs and MZSs are designed with 2-μm-wide arm waveguides,and thus the random phase errors in the MZC/MZS arms are negligible,in which case the calibration for these MZSs/MZCs becomes easy and furthermore the power consumption for compensating the phase errors can be reduced greatly.Finally,this programmable silicon photonic processor is demonstrated successfully to verify a number of distinctively different functionalities,including tunable time-delay,microwave photonic beamforming,arbitrary optical signal filtering,and arbitrary waveform generation.
基金financial supports from National Major Research and Development Program(No.2018YFB2200200)National Science Fund for Distinguished Young Scholars(61725503)+2 种基金National Natural Science Foundation of China(NSFC)(6191101294,91950205)Zhejiang Provincial Natural Science Foundation(LZ18F050001,LD19F050001)The Fundamental Research Funds for the Central Universities.Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001).
文摘A compact spectrometer on silicon is proposed and demonstrated with an ultrahigh resolution.It consists of a thermally-tunable ultra-high-Q resonator aiming at ultrahigh resolution and an array of wideband resonators for achieving a broadened working window.The present on-chip spectrometer has a footprint as compact as 0.35 mm^(2),and is realized with standard multi-project-wafer foundry processes.The measurement results show that the on-chip spectrometer has an ultra-high resolution Δλ of 5 pm and a wide working window of 10 nm.The dynamic range defined as the ratio of the working window and the wavelength resolution is as large as 1940,which is the largest for on-chip dispersive spectro-meters to the best of our knowledge.The present high-performance on-chip spectrometer has great potential for high-resolution spectrum measurement in the applications of gas sensing,food monitoring,health analysis,etc.
基金This work is supported partially by the National Major Research and Development Program(2019YFB1803902)National Natural Science Foundation of China(NSFC)(62135012,62105107)+3 种基金Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001)Guangdong Basic and Applied Basic Research Foundation(2021A 1515012215,2021B1515120057)Science and Technology Planning Project of Guangdong Province(2019A050510039)Fundamental Research Funds for the Central Universities(2021QNA5001).
文摘Multi-lane integrated transmitter chips are key components in future compact optical modules to realize high-speed optical interconnects.Thin-film lithium niobate(TFLN)photonics have emerged as a promising platform for achieving high-performance chip-scale optical systems.Combining a coarse wavelength-division multiplexing(CWDM)devices using fabrication-tolerant angled multimode interferometer structure and high-performance electro-optical modulators,we demonstrate monolithic on-chip four-channel CWDM transmitter on the TFLN platform for the first time.The four-channel CWDM transmitter enables high-speed transmissions of 100 Gb/s data rate per wavelength channel(i.e.,an aggregated date rate of 400 Gb/s).
基金Project supported by the National Natural Science Foundation for Distinguished Young Scholars(Grant No.61725503)Zhejiang Provincial Natural Science Foundation(Grant No.Z18F050002)+1 种基金the National Natural Science Foundation of China(Grant Nos.61431166001 and 11861121002)the National Major Research and Development Program of China(Grant No.2016YFB0402502)
文摘The field of silicon nanophotonics has attracted considerable attention in the past decade because of its unique advantages,including complementary metal–oxide–semiconductor（CMOS） compatibility and the ability to achieve an ultra-high integration density. In particular, silicon nanophotonic integrated devices for on-chip light manipulation have been developed successfully and have played very import roles in various applications. In this paper, we review the recent progress of silicon nanophotonic devices for on-chip light manipulation, including the static type and the dynamic type. Static onchip light manipulation focuses on polarization/mode manipulation, as well as light nanofocusing, while dynamic on-chip light manipulation focuses on optical modulation/switching. The challenges and prospects of high-performance silicon nanophotonic integrated devices for on-chip light manipulation are discussed.
基金supported by the National Major Research and Development Program(Grant No.2018YFB2200200)the National Science Fund for Distinguished Young Scholars(Grant No.61725503)+3 种基金the National Natural Science Foundation of China(Grant Nos.62175216,61961146003,91950205)Zhejiang Provincial Natural Science Foundation(Grant No.LR22F050001)The Fundamental Research Funds for the Central UniversitiesThe Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(Grant No.2021R01001).
文摘Compact passive silicon photonic devices with high performance are always desired for future largescale photonic integration.Inverse design provides a promising approach to realize new-generation photonic devices,while it is still very challenging to realize complex photonic devices for most inverse designs reported previously due to the limits of computational resources.Here,we present the realization of several representative advanced passive silicon photonic devices with complex optimization,including a sixchannel mode(de)multiplexer,a broadband 90 deg hybrid,and a flat-top wavelength demultiplexer.These devices are designed inversely by optimizing a subwavelength grating(SWG)region and the multimode excitation and the multimode interference are manipulated.Particularly,such SWG structures are more fabrication-friendly than those random nanostructures introduced in previous inverse designs.The realized photonic devices have decent performances in a broad bandwidth with a low excess loss of<1 dB,which is much lower than that of previous inverse-designed devices.The present inverse design strategy shows great effectiveness for designing advanced photonic devices with complex requirements(which is beyond the capability of previous inverse designs)by using affordable computational resources.
基金funding support from the National Major Research and Development Program(2019YFB2203603)the National Science Fund for Distinguished Young Scholars(61725503)+2 种基金the National Natural Science Foundation of China(NSFC)(62275273,11804387,and 91950205)the China Postdoctoral Science Foundation(2020M681847)the Zhejiang Provincial Natural Science Foundation(LZ18F050001).
文摘Waveguide-integrated optical modulators are indispensable for on-chip optical interconnects and optical computing.To cope with the ever-increasing amount of data being generated and consumed,ultrafast waveguide-integrated optical modulators with low energy consumption are highly demanded.In recent years,two-dimensional(2D)materials have attracted a lot of attention and have provided tremendous opportunities for the development of high-performance waveguide-integrated optical modulators because of their extraordinary optoelectronic properties and versatile compatibility.This paper reviews the state-of-the-art waveguide-integrated optical modulators with 2D materials,providing researchers with the developing trends in the field and allowing them to identify existing challenges and promising potential solutions.First,the concept and fundamental mechanisms of optical modulation with 2D materials are summarized.Second,a review of waveguide-integrated optical modulators employing electro-optic,all-optic,and thermo-optic effects is provided.Finally,the challenges and perspectives of waveguide-integrated modulators with 2D materials are discussed.
基金Project supported by the National Key Research and Development Program of China (2021YFB2800404)National Natural Science Foundation of China (62105283)+1 种基金Zhejiang Provincial Natural Science Foundation of China (LDT23F04012F05)Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang (2021R01001)
文摘Photonic waveguides are the most fundamental element for photonic integrated circuits(PICs).Waveguide properties,such as propagation loss,modal areas,nonlinear coefficients,etc.,directly determine the functionalities and performance of PICs.Recently,the emerging waveguides with bound states in the continuum(BICs)have opened new opportunities for PICs because of their special properties in resonance and radiation.Here,we review the recent progress of PICs composed of waveguides with BICs.First,fundamentals including background physics and design rules of a BIC-based waveguide will be introduced.Next,two types of BIC-based waveguide structures,including shallowly etched dielectric and hybrid waveguides,will be presented.Lastly,the challenges and opportunities of PICs with BICs will be discussed.
基金supported by the National Major Research and Development Program(Grant No.2019YFB2203600)the National Science Fund for Distinguished Young Scholars(Grant No.61725503)+3 种基金the National Natural Science Foundation of China(Grant Nos.62125503,91950205,61961146003,and 62005238)the Zhejiang Provincial Natural Science Foundation(Grant No.LD19F050001)The Fundamental Research Funds for the Central UniversitiesThe Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(Grant No.2021R01001).
文摘Dealing with the increase in data workloads and network complexity requires efficient selective manipulation of any channels in hybrid mode-/wavelength-division multiplexing(MDM/WDM)systems.A reconfigurable optical add-drop multiplexer(ROADM)using special modal field redistribution is proposed and demonstrated to enable the selective access of any mode-/wavelength-channels.With the assistance of the subwavelength grating structures,the launched modes are redistributed to be the supermodes localized at different regions of the multimode bus waveguide.Microring resonators are placed at the corresponding side of the bus waveguide to have specific evanescent coupling of the redistributed supermodes,so that any mode-/wavelength-channel can be added/dropped by thermally tuning the resonant wavelength.As an example,a ROADM for the case with three mode-channels is designed with low excess losses of<0.6,0.7,and 1.3 dB as well as low cross talks of<−26.3,−28.5,and−39.3 dB for the TE0,TE1,and TE2 modes,respectively,around the central wavelength of 1550 nm.The data transmission of 30 Gbps∕channel is also demonstrated successfully.The present ROADM provides a promising route for data switching/routing in hybrid MDM/WDM systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.U23B2047,62321166651,62205292,and 92150302)the Zhejiang Major Research and Development Program(Grant No.2021C01199)+1 种基金the Zhejiang Provincial Natural Science Foundation(Grant Nos.LZ18F050001,LD19F050001,LQ21F050006,and LD22F040004)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(Grant No.2021R01001)。
文摘A high-performance silicon arrayed-waveguide grating(AWG)with 0.4-nm channel spacing for dense wavelength-division multiplexing systems is designed and realized successfully.The device design involves broadening the arrayed waveguides far beyond the single-mode regime,which minimizes random phase errors and propagation loss without requiring any additional fabrication steps.To further enhance performance,Euler bends have been incorporated into the arrayed waveguides to reduce the device’s physical footprint and suppress the excitation of higher modes.In addition,shallowly etched transition regions are introduced at the junctions between the free-propagation regions and the arrayed waveguides to minimize mode mismatch losses.As an example,a 32×32 AWG(de)multiplexer with a compact size of 900μm×2200μm is designed and demonstrated with a narrow channel spacing of 0.4 nm by utilizing 220-nm-thick silicon photonic waveguides.The measured excess loss for the central channel is∼0.65 dB,the channel nonuniformity is around 2.5 dB,while the adjacent-channel crosstalk of the central output port is−21.4 dB.To the best of our knowledge,this AWG(de)multiplexer is the best one among silicon-based implementations currently available,offering both dense channel spacing and a large number of channels.
基金supported by National Natural Science Foundation of China(U23B2047,62321166651,62305294,62175214,and 92150302)Natural Science Foundation of Zhejiang Province(LD19F050001)+2 种基金Zhejiang Provincial Major Research and Development Program(2022C01103)Fundamental Research Funds for the Central Universities(226202400171)Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001).
文摘Integrated optical delay lines have become imperative to meet the growing demand as large aperture antennas and high number of subarrays required for microwave beamforming,high-speed optical communication,and integrated quantum photonics.It is very challenging to achieve large delay ranges,small footprints,and broad bandwidths simultaneously due to the strong trade-off between the propagation loss and the group refractive index of optical waveguides.In this paper,we propose and experimentally demonstrate multimode-enabled silicon photonic delay line for the first time,which breaks the delay-density limit of singlemode waveguide spirals,towards a broadband,mm^(2)-scale,and ultra-large time delay.By demonstrating low-loss-propagation possibilities for different polarizations and modes,we introduce a novel multimode delay unit by integrating the mode(de)multiplexers and the ultralowloss multimode waveguide spiral supporting the TE_(0),TE_(1),and TE_(2)modes propagating in parallel.The measured propagation losses for the TE_(0),TE_(1),and TE_(2)modes are 0.2 dB/cm,0.31 dB/cm,and 0.49 dB/cm,respectively.In this way,the highest line delay-density of 376.9 ps/cm and low delay loss of 0.004 dB/ps are achieved.Furthermore,we implement a 7-bit tunable multimode photonic delay line and experimentally demonstrate an ultra-large delay range of 12.7 ns with a delay resolution of 100 ps and within an ultra-compact footprint of 3.85mm^(2),enabling a delay density over 3299 ps/mm^(2),showing the largest delay range and the highest delay density among on-chip delay lines reported to date,to the best of our knowledge.
基金supported by National Natural Science Foundation of China(NSFC)(62375238,92150302,U23B2047,and 62321166651)Zhejiang Provincial Major Research and Development Program under Grant 2021C01199The Fundamental Research Funds for the Central Universities,The Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001).
文摘Structured light carrying angular momentum,such as spin angular momentum(SAM)and orbital angular momentum(OAM),has been at the core of new science and applications,driving the need for compact on-chip sources.While many static on-chip solutions have been demonstrated,as well as on-chip sources of free-space modes,no architecture that is fully reconfigurable in all angular momentum states and all on-chip has so far been possible.Here we report the first all-on-chip structured light generator for the creation of both scalar and vectorial angular momentum beams,facilitated through a silicon-on-insulator(SOI)chip with a silica mode multiplexer(silica chip).We selectively stimulate six linearly-polarized(LP)modes of the silica multimode bus waveguide,precisely controlling the modal powers and phases with the SOI chip.This allows us to tailor arbitrary superpositions of the mode set thus synthesizing common cylindrical vector vortex beams as well as OAM beams of controlled spin and topological charge.Our compact structured light generator exhibits high switching speed and operates across the telecom band,paving the way for applications such as optical communication and integrated quantum technologies.
基金National Key Research and Development Program of China(2024YFB2908302)National Science Fund for Distinguished Young Scholars(61725503)+5 种基金National Natural Science Foundation of China(U23B2047,62321166651,92150302,62375240)Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001)Zhejiang Provincial Major Research and Development Program(2021C01199)Natural Science Foundation of Zhejiang Province(LZ22F050006)Fundamental Research Funds for the Central UniversitiesStartup Foundation for Hundred-Talent Program of Zhejiang University。
文摘Reconfigurable silicon microrings have garnered significant interest for addressing challenges in artificial intelligence,the Internet of Things,and telecommunications due to their versatile capabilities.Compared to electrooptic(EO)and thermo-optic(TO)devices,emerging micro-electromechanical systems(MEMS)-based reconfigurable silicon photonic devices actuated by electrostatic forces offer near-zero static power consumption.This study proposes and implements novel designs for fully reconfigurable silicon photonic MEMS microrings for high-speed dense wavelength division multiplexing(DWDM)elastic networks.The designs include an all-pass microring with a 7 nm free spectral range(FSR)and full-FSR resonance tuning range,an add-drop microring with a 3.5 nm FSR and full-FSR tuning range,and an add-drop double-microring with a 34 nm FSR,wide-range discrete resonance tunability,and flat-top tunability.These advancements hold promise for practical applications.
基金supported in part by the National Natural Science Foundation of China(T2225023,62205202)the Shanghai Sailing Program(No.22YF1420200)。
文摘Sharing the hardware platform between diverse information systems to establish full cooperation among different functionalities has attracted substantial attention.However,broadband multifunctional integrated systems with large operating frequency ranges are challenging due to the bandwidth and computing speed restrictions of electronic circuitry.Here,we report an analog parallel processor(APP)based on the silicon photonic platform that directly discretizes and parallelizes the broadband signal in the analog domain.The APP first discretizes the signal with the optical frequency comb and then adopts optical dynamic phase interference to reassign the analog signal into 2N parallel sequences.Via photonic analog parallelism,data rate and data volume in each sequence are simultaneously compressed,which mitigates the requirement on each parallel computing core.Moreover,the fusion of the outputs from each computing core is equivalent to directly processing broadband signals.In the proof-of-concept experiment,two-channel analog parallel processing of broadband radar signals and high-speed communication signals is implemented on the single photonic integrated circuit.The bandwidth of broadband radar signal is 6 GHz and the range resolution of 2.69 cm is achieved.The wireless communication rate of 8 Gbit/s is also validated.Breaking the bandwidth and speed limitations of the single-computing core along with further exploring the multichannel potential of this architecture,we anticipate that the proposed APP will accelerate the development of powerful optoelectronic processors as critical support for applications such as satellite networks and intelligent driving.
基金National Major Research and Development Program(2021YFB2800404)National Natural Science Foundation of China(U23B2047,62321166651,62305294,and 92150302)+2 种基金Natural Science Foundation of Zhejiang Province(LDT23F04012F05)Fundamental Research Funds for the Central Universitiesand The Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001).
文摘High-capacity on-chip optical transmitters and receivers are crucial for data transmissions.Currently,advanced multiplexing technologies,including wavelength division multiplexing(WDM),mode-division multiplexing(MDM),and polarization-divisionmultiplexing(PDM)have been developed to greatly enhance the link capacity.In this paper,monolithically integrated silicon photonic transmitter and receiver with an ultra-high-capacity density of 37.0 Tbps/cm^(2) were proposed and demonstrated by introducing hybrid multiplexers and arrayed modulators/photodetectors.For the demonstrated transmitter/receiver chips,there are five wavelength channels and four mode channels with dual polarizations involved,while all these channels have low excess losses of 1 to 2 dB and low crosstalk less than−15 dB.Finally,all 20 channels are able to work with 50 Gbps on–off keying(OOK)signals per channel,achieving a total capacity of 1T-bps within an ultra-compact chip size of 0.032 cm^(2) for transmitters and 0.022 cm^(2) for receivers.
基金This research is supported by DARPA MTO under the CIPhER contract no.HR0011-10-1-0079 and iPHOD contract no.HR0011-09-C-0123The authors thank S Rodgers,D Blumenthal,MJR Heck,M-C Tien,CM Bruinink,A Leinse and RG Heideman for their useful discussions and expertise.
文摘Silicon-based large-scale photonic integrated circuits are becoming important,due to the need for higher complexity and lower cost for optical transmitters,receivers and optical buffers.In this paper,passive technologies for large-scale photonic integrated circuits are described,including polarization handling,light non-reciprocity and loss reduction.The design rule for polarization beam splitters based on asymmetrical directional couplers is summarized and several novel designs for ultra-short polarization beam splitters are reviewed.A novel concept for realizing a polarization splitter–rotator is presented with a very simple fabrication process.Realization of silicon-based light non-reciprocity devices(e.g.,optical isolator),which is very important for transmitters to avoid sensitivity to reflections,is also demonstrated with the help of magneto-optical material by the bonding technology.Low-loss waveguides are another important technology for large-scale photonic integrated circuits.Ultra-low loss optical waveguides are achieved by designing a Si3N4 core with a very high aspect ratio.The loss is reduced further to,0.1 dB m21 with an improved fabrication process incorporating a high-quality thermal oxide upper cladding by means of wafer bonding.With the developed ultra-low loss Si3N4 optical waveguides,some devices are also demonstrated,including ultra-high-Q ring resonators,low-loss arrayed-waveguide grating(de)multiplexers,and high-extinction-ratio polarizers.
基金supported by the National Major Research and Development Program(No.2018YFB2200200)National Science Fund for Distinguished Young Scholars(61725503)+2 种基金National Natural Science Foundation of China(NSFC)(61905210 and 91950205)China Postdoctoral Science Foundation(2019M662041)Zhejiang Provincial Natural Science Foundation(LZ18F050001 and LD19F050001).
文摘Graphene has attracted much attention for the realization of high-speed photodetection for silicon photonics over a wide wavelength range.However,the reported fast graphene photodetectors mainly operate in the 1.55μm wavelength band.In this work,we propose and realize high-performance waveguide photodetectors based on bolometric/photoconductive effects by introducing an ultrathin wide silicon−graphene hybrid plasmonic waveguide,which enables efficient light absorption in graphene at 1.55μm and beyond.When operating at 2μm,the present photodetector has a responsivity of ~70 mA/W and a setup-limited 3 dB bandwidth of >20 GHz.When operating at 1.55μm,the present photodetector also works very well with a broad 3 dB bandwidth of >40 GHz(setup-limited)and a high responsivity of ~0.4 A/W even with a low bias voltage of−0.3 V.This work paves the way for achieving highresponsivity and high-speed silicon-graphene waveguide photodetection in the near/mid-infrared ranges,which has applications in optical communications,nonlinear photonics,and on-chip sensing.
基金supported by National Major Research and Development Program(No.2018YFB2200200/2018YFB2200201)National Science Fund for Distinguished Young Scholars(61725503)+3 种基金National Natural Science Foundation of China(NSFC)(61905210,61961146003,91950205)China Postdoctoral Science Foundation(2020T130575,2019M662041)Zhejiang Provincial Natural Science Foundation(LZ18F050001,LD19F050001)The Fundamental Research Funds for the Central Universities.
文摘Two-dimensional materials(2DMs)have been used widely in constructing photodetectors(PDs)because of their advantages in flexible integration and ultrabroad operation wavelength range.Specifically,2DM PDs on silicon have attracted much attention because silicon microelectronics and silicon photonics have been developed successfully for many applications.2DM PDs meet the imperious demand of silicon photonics on low-cost,high-performance,and broadband photodetection.In this work,a review is given for the recent progresses of Si/2DM PDs working in the wavelength band from near-infrared to mid-infrared,which are attractive for many applications.The operation mechanisms and the device configurations are summarized in the first part.The waveguide-integrated PDs and the surface-illuminated PDs are then reviewed in details,respectively.The discussion and outlook for 2DM PDs on silicon are finally given.
基金National Major Research and Development Program(2018YFB2200200)China National Funds for Distinguished Young Scientists(61725503)+1 种基金National Natural Science Foundation of China(6191101294,91950205)Natural Science Foundation of Zhejiang Province(LD19F050001,LZ18F050001)。
文摘An ultrahigh-Q silicon racetrack resonator is proposed and demonstrated with uniform multimode silicon photonic waveguides.It consists of two multimode straight waveguides connected by two multimode waveguide bends(MWBs).In particular,the MWBs are based on modified Euler curves,and a bent directional coupler is used to achieve the selective mode coupling for the fundamental mode and not exciting the higher-order mode in the racetrack.In this way,the fundamental mode is excited and propagates in the multimode racetrack resonator with ultralow loss and low intermode coupling.Meanwhile,it helps achieve a compact 180°bend to make a compact resonator with a maximized free spectral range(FSR).In this paper,for the chosen 1.6μm wide silicon photonic waveguide,the effective radius Reffof the designed 180°bend is as small as 29μm.The corresponding FSR is about 0.9 nm when choosing 260μm long straight waveguides in the racetrack.The present high-Q resonator is realized with a simple standard single-etching process provided by a multiproject wafer foundry.The fabricated device,which has a measured intrinsic Q-factor as high as 2.3×10~6,is the smallest silicon resonator with a>106Q-factor.
