Frequency conversion is pivotal in nonlinear optics and quantum optics for manipulating and translating light signals across different wavelength regimes.Achieving frequency conversion between two light beams with a s...Frequency conversion is pivotal in nonlinear optics and quantum optics for manipulating and translating light signals across different wavelength regimes.Achieving frequency conversion between two light beams with a small frequency interval is a central challenge.In this work,we design a pair of coupled silicon microrings wherein coupled-induced modesplitting exists to achieve a small frequency shift by the process of four-wave mixing Bragg scattering.As an example,the signal can be up or down converted to the idler which is 15.5 GHz spaced when two pumps align with another pair of split resonances.The results unveil the potential of coupled microring resonators for small interval frequency conversion in a high-fidelity,all-optical,and signal processing quantum frequency interface.展开更多
Microring resonators(MRRs)are extensively utilized in photonic chips for generating quantum light sources and enabling high-efficiency nonlinear frequency conversion.However,conventional microrings are typically optim...Microring resonators(MRRs)are extensively utilized in photonic chips for generating quantum light sources and enabling high-efficiency nonlinear frequency conversion.However,conventional microrings are typically optimized for a single specific function,limiting their versatility in multifunctional applications.In this work,we propose a reconfigurable microring resonator architecture designed to accommodate diverse application requirements.By integrating a cascaded Mach–Zehnder interferometer(MZI)as the microring coupler,the design enables independent control of the quality factors for pump,signal and idler photons through two tunable phase shifters.This capability allows for dynamic tuning and optimization of critical performance parameters,including photon-pair generation rate(PGR),spectral purity and single photon heralding efficiency(HE).The proposed structure is implemented on a silicon photonic chip,and experimental results exhibit a wide range of tunability for these parameters,with excellent agreement with theoretical predictions.This flexible and multi-functional design offers a promising pathway for high-performance,highly integrated on-chip quantum information processing systems.展开更多
Microring resonators,as essential components of photonic integrated circuits,offer compact size,wavelength selectivity,and strong resonance effects,making them invaluable in optical computing,on-chip interconnects,and...Microring resonators,as essential components of photonic integrated circuits,offer compact size,wavelength selectivity,and strong resonance effects,making them invaluable in optical computing,on-chip interconnects,and quantum photonics.The proposal of the pulley-type microring enhances the coupling strength,but also brings about issues such as mode mismatch and the excitation of higher-order modes.Here,a lithium niobate microring resonator coupled with a pulley bus waveguide based on modified Euler curves is proposed.This Euler-modified pulley bus minimizes mode mismatch at bending junctions,effectively suppressing higher-order mode excitation.The design achieves a high Q factor(exceeding 105)and strong coupling efficiency(83%)within a compact structure of 70μm radius.Due to its simple structure and ease of fabrication,the Euler-modified pulley-type microring holds practical value for applications requiring high-quality microring resonators.展开更多
We propose a novel high-performance digital optical sensor based on the Mach-Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the se...We propose a novel high-performance digital optical sensor based on the Mach-Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the sensitivity of the sensor can be orders of magnitude higher than that of aconventional sensor, and high quality factor is not critical in it. Moreover, by optimizing the length of the feedback waveguide to be equal to the perimeter of the ring, the measurement range of the proposed sensor is twice as much as that of the conventional sensor in the weak coupling case.展开更多
In this paper, a slot microring resonator with a piece of spiral feedback waveguide for CH_4 sensing application is proposed. This sensor is based on silicon-on-insulator(SOI) substrate and with the operation waveleng...In this paper, a slot microring resonator with a piece of spiral feedback waveguide for CH_4 sensing application is proposed. This sensor is based on silicon-on-insulator(SOI) substrate and with the operation wavelength in mid-infrared region. To reach high sensitivity and good selectivity, slot cross section and spiral feedback waveguide are carefully tailored. The sensor shows ppb-scale trace gas sensing potential and is easy to be packaged in integrated photonics circuits. Calculation results show that the sensitivity reaches 1.4×10^(-2) dB/ppm and the detection limit achieves 700 ppb in the case of L_(spiral)=100 L_r.展开更多
A modulator is an essential building block in the integrated photonics,connecting the electrical with optical signals.The microring modulator gains much attention because of the small footprint,low drive voltage and h...A modulator is an essential building block in the integrated photonics,connecting the electrical with optical signals.The microring modulator gains much attention because of the small footprint,low drive voltage and high extinction ratio.An ultra-low V_(pp)and high-modulation-depth indium phosphide-based racetrack microring modulator is demonstrated in this paper.The proposed device mainly comprises one racetrack microring,incorporating a semiconductor amplifier,and coupling with a bus waveguide through a multimode interference coupler.Traveling wave electrodes are employed to supply bidirectional bias ports,terminating with a 50-Ω impedance.The on/off extinction ratio of the microring reaches 43.3 dB due to the delicately tuning of the gain.An 11 mV V_(pp),a maximum 42.5 dB modulation depth and a 6.6 GHz bandwidth are realized,respectively.This proposed microring modulator could enrich the functionalities and designability of the fundamental integrated devices.展开更多
This paper investigated the design and the characterization of a photonic delay line based on passive cascaded silicon-on-insulator （SOI） microrings. We considered the compromise of group delay, bandwidth and insert...This paper investigated the design and the characterization of a photonic delay line based on passive cascaded silicon-on-insulator （SOI） microrings. We considered the compromise of group delay, bandwidth and insertion loss. A 3-stage double channel side-coupled integrated spaced sequence of resonator （SCISSOR） device was optimized by shifting the resonance of each microring and fabricated with electron beam lithography and dry etching. The group delay was measured to be 17 ps for non-return-to-zero signals at different bit rates and the bandwidth of 78 GHz was achieved. The experiment result agreed well with our simulation.展开更多
To improve the output characteristics of all-fiber Mach-Zehnder interferometer(MZI)-interleaver,a dual microring-assisted MZI interleaver is designed.According to its structure,the output expression of the device is d...To improve the output characteristics of all-fiber Mach-Zehnder interferometer(MZI)-interleaver,a dual microring-assisted MZI interleaver is designed.According to its structure,the output expression of the device is derived from the signal flow diagram.After simulation analysis,the optimal structural parameters during the transmission process are obtained.In addition,the coupling coefficient and transmission loss of the coupler are analyzed.The results show that the improved interleaver output line wave is closer to the square wave,and its 25 dB cutoff band bandwidth and 0.5 dB passband bandwidth are significantly improved,with the values of 41.2 GHz and 18.9 GHz,respectively.The device has a certain resistantability to deviation,and the transmission loss has less influence on the extinction characteristics of the filter.展开更多
A high-performance microring resonator in a silicon-on-insulator rib waveguide is realized by using the electron beam lithography followed by inductively coupled plasma etching. The design and the experimental realiza...A high-performance microring resonator in a silicon-on-insulator rib waveguide is realized by using the electron beam lithography followed by inductively coupled plasma etching. The design and the experimental realization of this device are presented in detail. In addition to improving relevant processes to minimize propagation loss, the coupling efficiency between the ring and the bus is carefully chosen to approach a critical coupling for high performance operating. We have measured a quality factor of 21,200 and an extinction ratio of 12.SdB at a resonant wavelength of 1549.32nm. Meanwhile, a low propagation loss of 0.89dB/mm in a curved waveguide with a bending radius of 40μm is demonstrated as well.展开更多
On the silicon-on-insulator platform, an ultra compact temperature-insensitive modulator based on a cascaded microring assistant Mach-Zehnder interferometer is proposed and demonstrated with numerical simulation. Acco...On the silicon-on-insulator platform, an ultra compact temperature-insensitive modulator based on a cascaded microring assistant Mach-Zehnder interferometer is proposed and demonstrated with numerical simulation. According to the calculated results, the tolerated variation of ambient temperature can be as high as 134 ℃ while the footprint of such a silicon modulator is only 340 μm2.展开更多
We propose a novel resonator containing an elliptical microring based on a silicon-on-insulator platform. Simu- lations using the three-dimensional finite-difference time-domain method show that the novel elliptical m...We propose a novel resonator containing an elliptical microring based on a silicon-on-insulator platform. Simu- lations using the three-dimensional finite-difference time-domain method show that the novel elliptical microring can efficiently enhance the mode coupling between straight bus waveguides and resonator waveguides or between adjacent resonators while preserving relatively high intrinsic quality factors with large free spectral range. The proposed resonator would be an alternative choice for future high-density integrated photonic circuits.展开更多
Silicon nitride(Si3N4)waveguides with high confinement and low loss have been widely used in integrated nonlinear photonics.Indeed,state-of-the-art ultralow-loss Si3N4 waveguides are all fabricated using complex fabri...Silicon nitride(Si3N4)waveguides with high confinement and low loss have been widely used in integrated nonlinear photonics.Indeed,state-of-the-art ultralow-loss Si3N4 waveguides are all fabricated using complex fabrication processes,and all of those reported that high Q microring resonators(MRRs)are fabricated in laboratories.We propose and demonstrate an ultralow-loss Si3N4 racetrack MRR by shaping the mode using a uniform multimode structure to reduce its overlap with the waveguide.The MRR is fabricated by the standard multi project wafer(MPW)foundry process.It consists of two multimode straight waveguides(MSWs)connected by two multimode waveguide bends(MWBs).In particular,the MWBs are based on modified Euler bends,and an MSW directional coupler is used to avoid higher-order mode excitation.In this way,although a multimode waveguide is used in the MRR,only the fundamental mode is excited and transmitted with ultralow loss.Meanwhile,thanks to the 180 deg Euler bend,a compact chip footprint of 2.226 mm perimeter with an effective radius as small as 195μm and a waveguide width of 3μm is achieved.Results show that based on the widely used MPW process,a propagation loss of only 3.3 dB∕m and a mean intrinsic Q of around 10.8 million are achieved for the first time.展开更多
We designed a reconfigurable dual-interferometer coupled silicon nitride microring resonator.By tuning the integrated heater on interferometer's arms,the"critical coupling"bandwidth of resonant mode is c...We designed a reconfigurable dual-interferometer coupled silicon nitride microring resonator.By tuning the integrated heater on interferometer's arms,the"critical coupling"bandwidth of resonant mode is continuously adjustable whose quality factor varies from 7.9×10^(4) to 1.9×10^(5) with the extinction ratio keeping higher than 25 dB.Also a variety of coupling spanning from"under-coupling"to"over-coupling"were achieved,showing the ability to tune the quality factor from 6.0×10^(3) to 2.3×10^(5).Our design can provide an adjustable filtering method on silicon nitride photonic chip and contribute to optimize the nonlinear process for quantum photonics and all-optical signal processing.展开更多
An N×N optical switch based on cascaded microring resonators on chip is proposed.As an example,the 4×4 optical switch is further investigated.It is successfully demonstrated that its insertion loss is relati...An N×N optical switch based on cascaded microring resonators on chip is proposed.As an example,the 4×4 optical switch is further investigated.It is successfully demonstrated that its insertion loss is relatively low as 2.2 d B,the crosstalk is negligible,and the extinction ratio(ER)is as large as 130 d B.Thermal tuning is employed to make the microrings be in resonance or not,which leads to a response time of several hundred microseconds.Alternatively,doping the desired waveguide regions with p-type or n-type dopants is able to achieve a better response time of several nanoseconds.The proposed design is easily integrated to a large scale with less microring resonators,which ensures the compact size and the low power consumption.展开更多
We experimentally engineer a high-spectral-purity single-photon source using a single-interferometer-coupled silicon microring. By the reconfiguration of the interferometer, different coupling conditions can be obtain...We experimentally engineer a high-spectral-purity single-photon source using a single-interferometer-coupled silicon microring. By the reconfiguration of the interferometer, different coupling conditions can be obtained, corresponding to different quality factors for the pump and signal/idler. The ratio between the quality factor of the pump and signal/idler ranges from 0.29 to 2.57. By constructing the signal–idler joint spectral intensity, we intuitively demonstrate the spectral correlation of the signal and idler. As the ratio between the quality factor of the pump and signal/idler increases, the spectral correlation of the signal and idler decreases, i.e., the spectral purity of the signal/idler photons increases. Furthermore,time-integrated second-order correlation of the signal photons is measured, giving a value up to 94.95 ± 3.46%. Such high-spectral-purity photons will improve the visibility of quantum interference and facilitate the development of on-chip quantum information processing.展开更多
High-dimensional entanglement provides valuable resources for quantum technologies,including quantum communication,quantum optical coherence tomography,and quantum computing.Obtaining a high brightness and dimensional...High-dimensional entanglement provides valuable resources for quantum technologies,including quantum communication,quantum optical coherence tomography,and quantum computing.Obtaining a high brightness and dimensional entanglement source has significant value.Here we utilize a tunable asymmetric Mach–Zehnder interferometer coupled silicon microring resonator with 100 GHz free spectral range to achieve this goal.With the strategy of the tunable coupler,the dynamical and extensive tuning range of quality factors of the microring can be obtained,and then the biphoton pair generation rate can be optimized.By selecting and characterizing 28 pairs from a more than 30-pair modes biphoton frequency comb,we obtain a Schmidt number of at least 23.4 and on-chip pair generation rate of 19.9 MHz/m W;under a low on-chip pump power,which corresponds to 547 dimensions Hilbert space in frequency freedom.These results will prompt the wide applications of quantum frequency comb and boost the further large density and scalable on-chip quantum information processing.展开更多
The microring resonator(MRR)plays an important role in signal processing because high-quality bandpass filtering can be obtained at its drop port.To promote the signal-to-noise ratio,a high rejection ratio is signific...The microring resonator(MRR)plays an important role in signal processing because high-quality bandpass filtering can be obtained at its drop port.To promote the signal-to-noise ratio,a high rejection ratio is significantly demanded.However,it is still challenging to promote the rejection ratio of the MRR-based bandpass filter.To solve this problem,we propose to use an all-pass filter to enhance the rejection ratio of the MRR-based bandpass filter.Experimental results show that the improved rejection ratio is as high as 47.7 dB,which is improved by 23.6 dB compared with that of the MRR.Meanwhile,the bandwidth of the MRR-based bandpass filter is reduced from 2.61 to 1.14 GHz due to the constructive interference in the passband.In addition,the center frequency of this ultrahigh rejection MRR can be continuously tuned from 6.26 to 46.25 GHz.The quality factor(Q)of the MRR is improved from 7.4×10^(4) to 1.7×10^(5).During the adjustment,the rejection ratio of the bandpass filter exceeds 40 dB.The proposed approach can be used to achieve optical bandpass filters with high performance.展开更多
In terms of the coupled mode theory, microring resonance and electro-optic modulation princeple, a reasonable project is proposed for designing an electro-optic switch with the series-coupled multiple microring resona...In terms of the coupled mode theory, microring resonance and electro-optic modulation princeple, a reasonable project is proposed for designing an electro-optic switch with the series-coupled multiple microring resonators. The simulation and optimization are performed at the resonant wavelength of 1550 nm. The results are as follows: the core size of the microring is 1.6 μm×1.6 μm, the confined layer between the core and the electrode is 1.6 μm, the thickness of the electrode is 0.15 μm, the radius of the m...展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFF0712800)。
文摘Frequency conversion is pivotal in nonlinear optics and quantum optics for manipulating and translating light signals across different wavelength regimes.Achieving frequency conversion between two light beams with a small frequency interval is a central challenge.In this work,we design a pair of coupled silicon microrings wherein coupled-induced modesplitting exists to achieve a small frequency shift by the process of four-wave mixing Bragg scattering.As an example,the signal can be up or down converted to the idler which is 15.5 GHz spaced when two pumps align with another pair of split resonances.The results unveil the potential of coupled microring resonators for small interval frequency conversion in a high-fidelity,all-optical,and signal processing quantum frequency interface.
基金Project supported by the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301500)the National Natural Science Foundation of China(Grant No.62105366)。
文摘Microring resonators(MRRs)are extensively utilized in photonic chips for generating quantum light sources and enabling high-efficiency nonlinear frequency conversion.However,conventional microrings are typically optimized for a single specific function,limiting their versatility in multifunctional applications.In this work,we propose a reconfigurable microring resonator architecture designed to accommodate diverse application requirements.By integrating a cascaded Mach–Zehnder interferometer(MZI)as the microring coupler,the design enables independent control of the quality factors for pump,signal and idler photons through two tunable phase shifters.This capability allows for dynamic tuning and optimization of critical performance parameters,including photon-pair generation rate(PGR),spectral purity and single photon heralding efficiency(HE).The proposed structure is implemented on a silicon photonic chip,and experimental results exhibit a wide range of tunability for these parameters,with excellent agreement with theoretical predictions.This flexible and multi-functional design offers a promising pathway for high-performance,highly integrated on-chip quantum information processing systems.
基金supported by the National Key Research and Development Program of China(Grant No.2024YFB2808300)the National Natural Science Foundation of China(Grant Nos.62293523,62288101,62305156,92463304,92463308,12304421,and 12341403)+2 种基金Zhangjiang Laboratory(Grant No.ZJSP21A001)Program of Jiangsu Natural Science Foundation(Grant Nos.BK20230770 and BK20232033)Guangdong Major Project of Basic and Applied Basic Re-search(Grant No.2020B0301030009).
文摘Microring resonators,as essential components of photonic integrated circuits,offer compact size,wavelength selectivity,and strong resonance effects,making them invaluable in optical computing,on-chip interconnects,and quantum photonics.The proposal of the pulley-type microring enhances the coupling strength,but also brings about issues such as mode mismatch and the excitation of higher-order modes.Here,a lithium niobate microring resonator coupled with a pulley bus waveguide based on modified Euler curves is proposed.This Euler-modified pulley bus minimizes mode mismatch at bending junctions,effectively suppressing higher-order mode excitation.The design achieves a high Q factor(exceeding 105)and strong coupling efficiency(83%)within a compact structure of 70μm radius.Due to its simple structure and ease of fabrication,the Euler-modified pulley-type microring holds practical value for applications requiring high-quality microring resonators.
基金National Natural Science Foundation of China(No.81102703)Science and Technology Planning Project of Guangdong Province(No.2013A032500005)+1 种基金Administration of Traditional Chinese Medicine of Guangdong Province(No.20123001)Natural Science Foundation for Fostering of Guangdong Pharmaceutical University(No.GYFYLH201303)~~
基金Project supported by the National Basic Research Program of China(Grant No.2010CB327601)
文摘We propose a novel high-performance digital optical sensor based on the Mach-Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the sensitivity of the sensor can be orders of magnitude higher than that of aconventional sensor, and high quality factor is not critical in it. Moreover, by optimizing the length of the feedback waveguide to be equal to the perimeter of the ring, the measurement range of the proposed sensor is twice as much as that of the conventional sensor in the weak coupling case.
基金supported by the National Natural Science Foundation of China(Nos.61601253,61704094 and 61771267)the Natural Science Foundation of Ningbo(No.2017A610102)the K.C.Wong Magna Fund of Ningbo University
文摘In this paper, a slot microring resonator with a piece of spiral feedback waveguide for CH_4 sensing application is proposed. This sensor is based on silicon-on-insulator(SOI) substrate and with the operation wavelength in mid-infrared region. To reach high sensitivity and good selectivity, slot cross section and spiral feedback waveguide are carefully tailored. The sensor shows ppb-scale trace gas sensing potential and is easy to be packaged in integrated photonics circuits. Calculation results show that the sensitivity reaches 1.4×10^(-2) dB/ppm and the detection limit achieves 700 ppb in the case of L_(spiral)=100 L_r.
基金supported by the National Natural Science Foundation of China(61535012,61925505)the National Key R&D Program of China(2018YFB2201900)。
文摘A modulator is an essential building block in the integrated photonics,connecting the electrical with optical signals.The microring modulator gains much attention because of the small footprint,low drive voltage and high extinction ratio.An ultra-low V_(pp)and high-modulation-depth indium phosphide-based racetrack microring modulator is demonstrated in this paper.The proposed device mainly comprises one racetrack microring,incorporating a semiconductor amplifier,and coupling with a bus waveguide through a multimode interference coupler.Traveling wave electrodes are employed to supply bidirectional bias ports,terminating with a 50-Ω impedance.The on/off extinction ratio of the microring reaches 43.3 dB due to the delicately tuning of the gain.An 11 mV V_(pp),a maximum 42.5 dB modulation depth and a 6.6 GHz bandwidth are realized,respectively.This proposed microring modulator could enrich the functionalities and designability of the fundamental integrated devices.
基金Project supported by the National Basic Research Program of China (Grant Nos.2006CB302803 and 2011CB301701)the National Natural Science Foundation of China (Grant No.60877036)+1 种基金State Key Laboratory of Advanced Optical Communication Systems and Networks of China (Grant No.2008SH02)the Knowledge Innovation Program of Institute of Semiconductors,Chinese Academy of Sciences (Grant No.ISCAS2008T10)
文摘This paper investigated the design and the characterization of a photonic delay line based on passive cascaded silicon-on-insulator （SOI） microrings. We considered the compromise of group delay, bandwidth and insertion loss. A 3-stage double channel side-coupled integrated spaced sequence of resonator （SCISSOR） device was optimized by shifting the resonance of each microring and fabricated with electron beam lithography and dry etching. The group delay was measured to be 17 ps for non-return-to-zero signals at different bit rates and the bandwidth of 78 GHz was achieved. The experiment result agreed well with our simulation.
基金National Natural Science Foundation of China(No.61461024)Foundation of a Hundred Youth Talent Training Program of Lanzhou Jiaotong University(No.1520220232)。
文摘To improve the output characteristics of all-fiber Mach-Zehnder interferometer(MZI)-interleaver,a dual microring-assisted MZI interleaver is designed.According to its structure,the output expression of the device is derived from the signal flow diagram.After simulation analysis,the optimal structural parameters during the transmission process are obtained.In addition,the coupling coefficient and transmission loss of the coupler are analyzed.The results show that the improved interleaver output line wave is closer to the square wave,and its 25 dB cutoff band bandwidth and 0.5 dB passband bandwidth are significantly improved,with the values of 41.2 GHz and 18.9 GHz,respectively.The device has a certain resistantability to deviation,and the transmission loss has less influence on the extinction characteristics of the filter.
基金supported by the State Key Development Program for Basic Research of China (Grant Nos 2006CB302803 and2007CB613405)the National High Technology Research and Development Program of China (Grant No 2006AA03Z424)the National Natural Science Foundation of China (Grant No 60577044)
文摘A high-performance microring resonator in a silicon-on-insulator rib waveguide is realized by using the electron beam lithography followed by inductively coupled plasma etching. The design and the experimental realization of this device are presented in detail. In addition to improving relevant processes to minimize propagation loss, the coupling efficiency between the ring and the bus is carefully chosen to approach a critical coupling for high performance operating. We have measured a quality factor of 21,200 and an extinction ratio of 12.SdB at a resonant wavelength of 1549.32nm. Meanwhile, a low propagation loss of 0.89dB/mm in a curved waveguide with a bending radius of 40μm is demonstrated as well.
基金Project supported by the National Basic Research Program of China(Grant Nos.2011CBA00608,2011CBA00303,2011CB301803, and 2010CB327405)the National Natural Science Foundation of China(Grant Nos.61036011 and 61036010)the Project of Science and Technology from the Communication Information Security Control Laboratory
文摘On the silicon-on-insulator platform, an ultra compact temperature-insensitive modulator based on a cascaded microring assistant Mach-Zehnder interferometer is proposed and demonstrated with numerical simulation. According to the calculated results, the tolerated variation of ambient temperature can be as high as 134 ℃ while the footprint of such a silicon modulator is only 340 μm2.
基金Project supported by the National Basic Research Program of China (Grant Nos. 2011CB301701, 2012CB933502, and2012CB933504)the National Natural Science Foundation of China (Grant Nos. 60877036 and 61107048)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KGCX2-EW-102)
文摘We propose a novel resonator containing an elliptical microring based on a silicon-on-insulator platform. Simu- lations using the three-dimensional finite-difference time-domain method show that the novel elliptical microring can efficiently enhance the mode coupling between straight bus waveguides and resonator waveguides or between adjacent resonators while preserving relatively high intrinsic quality factors with large free spectral range. The proposed resonator would be an alternative choice for future high-density integrated photonic circuits.
基金supported by the National Natural Science Foundation of China(Grant No.61975249)the National Key Research and Development Program of China(Grant No.2018YFA0704403)the Program for HUST Academic Frontier Youth Team(Grant No.2018QYTD08).
文摘Silicon nitride(Si3N4)waveguides with high confinement and low loss have been widely used in integrated nonlinear photonics.Indeed,state-of-the-art ultralow-loss Si3N4 waveguides are all fabricated using complex fabrication processes,and all of those reported that high Q microring resonators(MRRs)are fabricated in laboratories.We propose and demonstrate an ultralow-loss Si3N4 racetrack MRR by shaping the mode using a uniform multimode structure to reduce its overlap with the waveguide.The MRR is fabricated by the standard multi project wafer(MPW)foundry process.It consists of two multimode straight waveguides(MSWs)connected by two multimode waveguide bends(MWBs).In particular,the MWBs are based on modified Euler bends,and an MSW directional coupler is used to avoid higher-order mode excitation.In this way,although a multimode waveguide is used in the MRR,only the fundamental mode is excited and transmitted with ultralow loss.Meanwhile,thanks to the 180 deg Euler bend,a compact chip footprint of 2.226 mm perimeter with an effective radius as small as 195μm and a waveguide width of 3μm is achieved.Results show that based on the widely used MPW process,a propagation loss of only 3.3 dB∕m and a mean intrinsic Q of around 10.8 million are achieved for the first time.
基金the National Key Research and Development Program of China(Grant Nos.2019YFA0308700and 2017YFA0303700)the National Natural Science Foundation of China(Grant Nos.11627810 and 11690031)the Open Funds from the State Key Laboratory of High Performance Computing of China(HPCL,National University of Defense Technology).
文摘We designed a reconfigurable dual-interferometer coupled silicon nitride microring resonator.By tuning the integrated heater on interferometer's arms,the"critical coupling"bandwidth of resonant mode is continuously adjustable whose quality factor varies from 7.9×10^(4) to 1.9×10^(5) with the extinction ratio keeping higher than 25 dB.Also a variety of coupling spanning from"under-coupling"to"over-coupling"were achieved,showing the ability to tune the quality factor from 6.0×10^(3) to 2.3×10^(5).Our design can provide an adjustable filtering method on silicon nitride photonic chip and contribute to optimize the nonlinear process for quantum photonics and all-optical signal processing.
基金supported by the National Natural Science and Foundation of China(No.11474048)
文摘An N×N optical switch based on cascaded microring resonators on chip is proposed.As an example,the 4×4 optical switch is further investigated.It is successfully demonstrated that its insertion loss is relatively low as 2.2 d B,the crosstalk is negligible,and the extinction ratio(ER)is as large as 130 d B.Thermal tuning is employed to make the microrings be in resonance or not,which leads to a response time of several hundred microseconds.Alternatively,doping the desired waveguide regions with p-type or n-type dopants is able to achieve a better response time of several nanoseconds.The proposed design is easily integrated to a large scale with less microring resonators,which ensures the compact size and the low power consumption.
基金Project supported by the National Basic Research Program of China (Grant Nos. 2019YFA0308700 and 2017YFA0303700)the Open Funds from the State Key Laboratory of High Performance Computing of China (HPCL, National University of Defense Technology)。
文摘We experimentally engineer a high-spectral-purity single-photon source using a single-interferometer-coupled silicon microring. By the reconfiguration of the interferometer, different coupling conditions can be obtained, corresponding to different quality factors for the pump and signal/idler. The ratio between the quality factor of the pump and signal/idler ranges from 0.29 to 2.57. By constructing the signal–idler joint spectral intensity, we intuitively demonstrate the spectral correlation of the signal and idler. As the ratio between the quality factor of the pump and signal/idler increases, the spectral correlation of the signal and idler decreases, i.e., the spectral purity of the signal/idler photons increases. Furthermore,time-integrated second-order correlation of the signal photons is measured, giving a value up to 94.95 ± 3.46%. Such high-spectral-purity photons will improve the visibility of quantum interference and facilitate the development of on-chip quantum information processing.
基金supported by the National Basic Research Program of China(Grant Nos.2019YFA0308700 and 2017YFA0303700)the National Natural Science Foundation of China(Grant Nos.61632021 and 11690031)the Open Funds from the State Key Laboratory of High Performance Computing of China(HPCL,National University of Defense Technology)。
文摘High-dimensional entanglement provides valuable resources for quantum technologies,including quantum communication,quantum optical coherence tomography,and quantum computing.Obtaining a high brightness and dimensional entanglement source has significant value.Here we utilize a tunable asymmetric Mach–Zehnder interferometer coupled silicon microring resonator with 100 GHz free spectral range to achieve this goal.With the strategy of the tunable coupler,the dynamical and extensive tuning range of quality factors of the microring can be obtained,and then the biphoton pair generation rate can be optimized.By selecting and characterizing 28 pairs from a more than 30-pair modes biphoton frequency comb,we obtain a Schmidt number of at least 23.4 and on-chip pair generation rate of 19.9 MHz/m W;under a low on-chip pump power,which corresponds to 547 dimensions Hilbert space in frequency freedom.These results will prompt the wide applications of quantum frequency comb and boost the further large density and scalable on-chip quantum information processing.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFA0704403)the National Natural Science Foundation of China(Grant No.61975249)+2 种基金the Program for HUST Academic Frontier Youth Team(Grant No.2018QYTD08)the Project of Key Laboratory of Radar Imaging and Microwave Photonics(Nanjing University of Aeronautics and Astronautics),Ministry of Education(Grant No.NJ20230001)the Independent Innovation Foundation of HUST(Grant No.5003187117).
文摘The microring resonator(MRR)plays an important role in signal processing because high-quality bandpass filtering can be obtained at its drop port.To promote the signal-to-noise ratio,a high rejection ratio is significantly demanded.However,it is still challenging to promote the rejection ratio of the MRR-based bandpass filter.To solve this problem,we propose to use an all-pass filter to enhance the rejection ratio of the MRR-based bandpass filter.Experimental results show that the improved rejection ratio is as high as 47.7 dB,which is improved by 23.6 dB compared with that of the MRR.Meanwhile,the bandwidth of the MRR-based bandpass filter is reduced from 2.61 to 1.14 GHz due to the constructive interference in the passband.In addition,the center frequency of this ultrahigh rejection MRR can be continuously tuned from 6.26 to 46.25 GHz.The quality factor(Q)of the MRR is improved from 7.4×10^(4) to 1.7×10^(5).During the adjustment,the rejection ratio of the bandpass filter exceeds 40 dB.The proposed approach can be used to achieve optical bandpass filters with high performance.
基金supported by the National Natural ScienceFoundation of China (60706011)the National "973" Project ofChina(2006CB302803)+1 种基金the Fund of Chinese Ministry of Educa-tion (20070183087)the Fund of Science and Technology ofJilin Province of China(20080125).
文摘In terms of the coupled mode theory, microring resonance and electro-optic modulation princeple, a reasonable project is proposed for designing an electro-optic switch with the series-coupled multiple microring resonators. The simulation and optimization are performed at the resonant wavelength of 1550 nm. The results are as follows: the core size of the microring is 1.6 μm×1.6 μm, the confined layer between the core and the electrode is 1.6 μm, the thickness of the electrode is 0.15 μm, the radius of the m...
