Laser frequency microcombs provide a series of equidistant,coherent frequency markers across a broad spectrum,enabling advancements in laser spectroscopy,dense optical communications,precision distance metrology,and a...Laser frequency microcombs provide a series of equidistant,coherent frequency markers across a broad spectrum,enabling advancements in laser spectroscopy,dense optical communications,precision distance metrology,and astronomy.Here,we design and fabricate silicon nitride,dispersion-managed microresonators that effectively suppress avoided-mode crossings and achieve close-to-zero averaged dispersion.Both the stochastic noise and mode-locking dynamics of the resonator are numerically and experimentally investigated.First,we experimentally demonstrate thermally stabilized microcomb formation in the microresonator across different mode-locked states,showing negligible center frequency shifts and a broad frequency bandwidth.Next,we characterize the femtosecond timing jitter of the microcombs,supported by precise metrology of the timing phase and relative intensity noise.For the single-soliton state,we report a relative intensity noise of−153.2 dB∕Hz,close to the shot-noise limit,and a quantum-noise–limited timing jitter power spectral density of 0.4 as 2∕Hz at a 100 kHz offset frequency,measured using a self-heterodyne linear interferometer.In addition,we achieve an integrated timing jitter of 1.7 fs±0.07 fs,measured from 10 kHz to 1 MHz.Measuring and understanding these fundamental noise parameters in high clock rate frequency microcombs is critical for advancing soliton physics and enabling new applications in precision metrology.展开更多
An optical frequency comb comprises a cluster of equally spaced,phase-locked spectral lines.Replacing these classical components with correlated quantum light gives rise to cluster quantum frequency combs,providing ab...An optical frequency comb comprises a cluster of equally spaced,phase-locked spectral lines.Replacing these classical components with correlated quantum light gives rise to cluster quantum frequency combs,providing abundant quantum resources for measurement-based quantum computation,and multi-user quantum networks.We propose and generate cluster quantum microcombs within an on-chip optical microresonator driven by multi-frequency lasers.Through resonantly enhanced four-wave mixing processes,continuous-variable cluster states with 60 qumodes are deterministically created.The graph structures can be programmed into one-and two-dimensional lattices by adjusting the configurations of the pump lines,which are confirmed inseparable based on the measured covariance matrices.Our work demonstrates the largest-scale cluster states with unprecedented raw squeezing levels from a photonic chip,offering a compact and scalable platform for computational and communicational tasks with quantum advantages.展开更多
Soliton microcombs offer a compact means to generate equally spaced spectral lines via a delicate balance of Kerr nonlinearity and anomalous dispersion in nonlinear microresonators. However, the simultaneous excitatio...Soliton microcombs offer a compact means to generate equally spaced spectral lines via a delicate balance of Kerr nonlinearity and anomalous dispersion in nonlinear microresonators. However, the simultaneous excitation of multiple transverse mode families can disrupt soliton formation and degrade spectral uniformity. Here, we demonstrate universal spectral purification of microresonators with ultrahigh intrinsic Q factors exceeding 10^(8). An aluminum ring is deposited onto a silica microdisk to eliminate high-order transverse modes selectively by introducing additional losses. The resulting soliton microcombs exhibit an ideal sech^(2) spectral envelope and enable continuous tuning of the soliton repetition frequency over a 300 kHz range without compromising phase noise performance. Our approach can be universally applied to integrated photonic platforms to reduce transverse modes crowding in high-Q resonators, facilitating the generation of broadband classical and quantum light with ideal performance.展开更多
Acoustic perception is a fairly basic but extraordinary feature in nature,relying on multidimensional signal processing for detection,localization,and recognition.Replicating this capability in compact artificial syst...Acoustic perception is a fairly basic but extraordinary feature in nature,relying on multidimensional signal processing for detection,localization,and recognition.Replicating this capability in compact artificial systems,however,remains a formidable challenge due to limitations in scalability,sensitivity,and integration.Here,imitating the auditory system of insects,we introduce an opto-acoustic perception paradigm using fully-stabilized dual-soliton microcombs.By integrating digitally stabilized on-chip dual-microcombs,silicon optoelectronics and bionic fiber-microphone arrays on a single platform,we achieve parallelized interrogation of over 100 sensors.Leveraging the low-noise,multi-channel coherence of fully-stabilized soliton microcombs,this synergy enables ultra-sensitive detection of 29.3 nPa/Hz^(1/2),sub centimeter precise localization,real-time tracking and identification for versatile acoustic targets.Bridging silicon photonics,optical fiber sensing and intelligent signal processing in a chiplet microsystem,our scheme delivers outof-lab deployable capability on autonomous robotics.This work not only deepens the understanding of frequency comb science,but also establishes a concept of dual-comb-driven sensor networks as a scalable foundation for nextgeneration opto-acoustic intelligence.展开更多
Coherent frequency microcombs,generated in nonlinear high-Q microresonators and driven by a single continuouswave laser,have enabled several scientific breakthroughs in the past decade,thanks to their high intrinsic p...Coherent frequency microcombs,generated in nonlinear high-Q microresonators and driven by a single continuouswave laser,have enabled several scientific breakthroughs in the past decade,thanks to their high intrinsic phase coherence and individual comb line powers.Here,we report terabit-per-second-scale coherent data communications over a free-space atmospheric link,using a platicon frequency microcomb,employing wavelength-and polarizationdivision multiplexing for next-generation optical wireless networks.Spanning more than 55 optical carriers with 115 GHz channel spacing,we report the first free-space coherent communication link using a frequency microcomb,achieving up to 8.21 Tbit/s aggregate data transmission at a 20 Gbaud symbol rate per carrier over 160 m,even under log-normal turbulent conditions.Utilizing 16-state quadrature amplitude modulation,we demonstrate retrieved constellation maps across the broad microcomb spectrum,achieving bit-error rates below both hardand soft-decision thresholds for forward-error correction.Next,we examine a wavelength-division multiplexing free-space passive optical network as a baseline for free-space fronthaul,achieving an aggregate data rate of up to 5.21 Tbit/s and a field-tested spectral efficiency of 1.29 bit/s/Hz in the microcomb-based atmospheric link.We also quantify experimental power penalties of≈3.8 dB at the error-correction threshold,relative to the theoretical additive white Gaussian noise limit.Furthermore,we introduce the first-ever demonstration of master–slave free-space carrier phase retrieval with frequency microcombs,and the compensation for turbulence-induced intensity scintillation and pointing error fluctuations,to improve end-to-end symbol error rates.This work provides a foundational platform for broadband vertical heterogeneous connectivity,terrestrial backbone links,and groundsatellite communication.展开更多
Kerr soliton microcombs have the potential to disrupt a variety of applications such as ultra-high-speed optical communications,ultra-fast distance measurements,massively parallel light detection and ranging(LiDAR)or ...Kerr soliton microcombs have the potential to disrupt a variety of applications such as ultra-high-speed optical communications,ultra-fast distance measurements,massively parallel light detection and ranging(LiDAR)or high-resolution optical spectroscopy.Similarly,ultra-broadband photonic-electronic signal processing could also benefit from chip-scale frequency comb sources that offer wideband optical emission along with ultra-low phase noise and timing jitter.However,while photonic analogue-to-digital converters(ADC)based on femtosecond lasers have been shown to overcome the jitter-related limitations of electronic oscillators,the potential of Kerr combs in photonic-electronic signal processing remains to be explored.In this work,we demonstrate a microcomb-based photonic-electronic ADC that combines a high-speed electro-optic modulator with a Kerr comb for spectrally sliced coherent detection of the generated optical waveform.The system offers a record-high acquisition bandwidth of 320 GHz,corresponding to an effective sampling rate of at least 640GSa/s.In a proof-of-concept experiment,we demonstrate the viability of the concept by acquiring a broadband analogue data signal comprising different channels with centre frequencies between 24 GHz and 264 GHz,offering bit error ratios(BER)below widely used forward-error-correction(FEC)thresholds.To the best of our knowledge,this is the first demonstration of a microcomb-based ADC,leading to the largest acquisition bandwidth demonstrated for any ADC so far.展开更多
The exceptional temporal and spatial photon confinement properties of whispering gallery mode (WGM) microcavities render them ideally suitable for nonlinear frequency conversion.Here,we present a reliable packaged mic...The exceptional temporal and spatial photon confinement properties of whispering gallery mode (WGM) microcavities render them ideally suitable for nonlinear frequency conversion.Here,we present a reliable packaged microcavity device with vibration isolation,air tightness,temperature adaptability,and quality factors greater than 2 billion that can serve as a compact and stable platform for soliton optical comb generation.Low-noise soliton combs can be initiated with a repetition rate of 24.98 GHz at wavelengths near 1550 nm with 4 mW threshold power.Our work provides innovative solutions for investigating and manufacturing miniature,economical,and robust microcomb devices.展开更多
The optical frequency comb based on microresonators(microcombs)is an integrated coherent light source and has the potential to promise a high-precision frequency standard;self-reference and a long-term stable microcom...The optical frequency comb based on microresonators(microcombs)is an integrated coherent light source and has the potential to promise a high-precision frequency standard;self-reference and a long-term stable microcomb are the keys to this realization.Here,we demonstrated a 0.7-octave spectrum Kerr comb via dispersion engineering in a thin-film lithium niobate microresonator,and the single-soliton state can be accessed passively with long-term stability over 3 h.With such a robust broadband coherent comb source using thin-film lithium niobate,a fully stabilized microcomb can be expected for massive practical applications.展开更多
The increasing demand for dispersion engineering in various photonic applications necessitates spectrometry with both kilohertz resolution and several terahertz bandwidth.A laser with sufficiently large frequency tuni...The increasing demand for dispersion engineering in various photonic applications necessitates spectrometry with both kilohertz resolution and several terahertz bandwidth.A laser with sufficiently large frequency tuning range is required in traditional methods,Yielding bulky and expensive systems that are difficult to integrated on a chip.Compact,high-resolution,and broadband spectrometers are crucial,yet onchip integration,particularly of the optical source,remains challenging.Here,we propose a 5.2-THz-bandwidth miniaturized spectrometer utilizing a laser only in GHz tuning range.The laser’s tuning range is leveraged by integrated Si_(3)N_(4)soliton microcombs to achieve a 650-times larger measurement bandwidth,extending the measurement range from 1525.3 to 1566.8 nm and surpassing the optical C-band.The soliton microcomb is meticulously frequency-stabilized,achieving frequency fluctuations below 100 Hz,ensuring high frequency precision for our spectrometer.By combining optical asymmetrical double sideband modulation with soliton microcombs,we significantly enhance the spectrometer’s performance,offering higher resolution,larger dynamic range,and greater bandwidth.This optical spectrum measurement approach enabled by GHz-tunable laser opens a way to significantly simplify system complexity.展开更多
Mode-locked microcombs with flat spectral profiles provide the high signal-to-noise ratio and are in high demand for wavelength division multiplexing(WDM)-based applications,particularly in future high-capacity commun...Mode-locked microcombs with flat spectral profiles provide the high signal-to-noise ratio and are in high demand for wavelength division multiplexing(WDM)-based applications,particularly in future high-capacity communication and parallel optical computing.Here,we present two solutions to generate local relatively flat spectral profiles.One microcavity with ultra-flat integrated dispersion is pumped to generate one relatively flat single soliton source spanning over 150 nm.Besides,one extraordinary soliton crystal with single vacancy demonstrates the local relatively flat microcomb lines when the inner soliton spacings are slightly irregular.Our work paves a new way for soliton-based applications owing to the relatively flat spectral characteristics.展开更多
Single-crystalline Ga-doped SnO2 nanowires and SnO2：Ga2O3 heterogeneous microcombs were synthesized by a simple one-step thermal evaporation and condensation method. They were characterized by means of X-ray powder d...Single-crystalline Ga-doped SnO2 nanowires and SnO2：Ga2O3 heterogeneous microcombs were synthesized by a simple one-step thermal evaporation and condensation method. They were characterized by means of X-ray powder diffraction （XRD）, field-emission scanning electron microscopy （FE-SEM）, energy-dispersive X-ray spectroscopy （EDS）, transmission electron microscopy （TEM） and selected-area electron diffraction （SAED）. FE-SEM images showed that the products consisted of nanowires and mierocombs that represent a novel morphology. XRD, SAED and EDS indicated that they were single-crystalline tetragonal SnO2. The influence of experimental conditions on the morphologies of the products is discussed. The morphology of the product showed a ribbon-like stem and nanoribbon array aligned evenly along one or both side of the nanoribbon. It was found that many Ga2O3 nanoparticles deposited on the surface of the microcombs. The major core nanoribbon grew mainly along the [110] direction and the self-organized branching nanoribbons grew epitaxially along [110] or [110] orientation from the （110） plane of the stem. A growth process was proposed for interpreting the growth of these remarkable SnO2：Ga2O3 heterogeneous microcombs. Due to the heavy doping of Ga, the emission peak in photoluminescence spectra has red-shifted as well as broadened significantly.展开更多
Dual-comb ranging allows rapid and precise distance measurement and can be universally implemented on different comb platforms,e.g.,fiber combs and microcombs.To date,dual-fiber-comb ranging has become a mature and po...Dual-comb ranging allows rapid and precise distance measurement and can be universally implemented on different comb platforms,e.g.,fiber combs and microcombs.To date,dual-fiber-comb ranging has become a mature and powerful tool for metrology and industry,but the measurement speed is often at a kilohertz level due to the lower repetition rates.Recently,dual-microcomb ranging has given rise to a new opportunity for distance measurement,in consequence of its small footprint and high repetition rates,but full-comb stabilization is challenging.Here,we report a dual-hybrid-comb distance meter capable of ultrarapid and submicrometer precision distance measurement,which can not only leverage the advantage of easy locking inherited from the fiber comb but also sustain ultrarapid measurement speed due to the microcomb.The experimental results show that the measurement precision can reach 3.572μm at 4.136μs and 432 nm at 827.2μs averaging time.Benefiting from the large difference between the repetition rates of the hybrid combs,the measurement speed can be enhanced by 196 folds,in contrast to the dual-fiber-comb system with about a 250 MHz repetition rate.Our work can offer a solution for the fields of rapid dimensional measurement and spectroscopy.展开更多
Microresonator-based Kerr frequency combs(“Kerr microcombs”)constitute chip-scale frequency combs of broad spectral bandwidth and repetition rate ranging from gigahertz to terahertz.A critical application that explo...Microresonator-based Kerr frequency combs(“Kerr microcombs”)constitute chip-scale frequency combs of broad spectral bandwidth and repetition rate ranging from gigahertz to terahertz.A critical application that exploits the coherence and high repetition rate of microcombs is microwave and millimeter-wave generation.Latest endeavor applying two-point optical frequency division(OFD)to photonic-chip-based microcombs has created microwaves with remarkably low phase noise.Nevertheless,existing approaches to achieve exceptionally coherent microcombs still require extensive active locking,additional lasers,and external RF or microwave sources,as well as sophisticated initiation.Here we demonstrate a simple and entirely passive(no active locking)architecture,which incorporates an optoelectronic oscillator(OEO)and symphonizes a coherent microcomb and a low-noise microwave spontaneously.Our OEO microcomb leverages state-of-the-art integrated chip devices,including a high-power DFB laser,a broadband silicon Mach–Zehnder modulator,an ultralow-loss silicon nitride microresonator,and a high-speed photodetector.Each can be manufactured in large volume with low cost and high yield using established CMOS and Ⅲ-Ⅴ foundries.Our system synergizes a microcomb of 10.7 GHz repetition rate and an X-band microwave with phase noise of−97/−126/−130 dBc/Hz at 1/10/100 kHz Fourier frequency offset,yet does not demand active locking,additional lasers,and external RF or microwave sources.With potential to be fully integrated,our OEO microcomb can become an invaluable technology and building block for microwave photonics,radio-over-fiber,and optical communication.展开更多
The demand for high-throughput,low-latency data aggregation at network edges is growing rapidly.However,existing integrated wavelength-division multiplexing(WDM)parallel light sources often suffer from limited coheren...The demand for high-throughput,low-latency data aggregation at network edges is growing rapidly.However,existing integrated wavelength-division multiplexing(WDM)parallel light sources often suffer from limited coherence,low optical carrier-to-noise ratio(OCNR),insufficient output power,or large footprint,hindering the deployment of efficient and lightweight optical interconnects at network edges.展开更多
Kerr frequency combs, or microcombs, are revolutionizing fields such as precision metrology, optical clocks, and astronomical spectrometer calibration. However, conventional dissipative Kerr soliton(DKS) microcombs of...Kerr frequency combs, or microcombs, are revolutionizing fields such as precision metrology, optical clocks, and astronomical spectrometer calibration. However, conventional dissipative Kerr soliton(DKS) microcombs often suffer from limited conversion efficiency and low output power, and achieving deterministic single-soliton generation remains a challenge due to limited thermal accessibility arising from the intricate interplay of Kerr and thermal effects. In this work, we present an optimized microresonator design combined with a robust pumping scheme to enhance the thermal accessibility of single-soliton states for deterministic generation. By operating a silicon nitride microresonator with tailored dispersion in the over-coupled regime, we demonstrate a thermally accessible pathway to single solitons with high conversion efficiency(approaching 30%), and high output power(up to 50 m W). Through a pump forward-tuning process with power ramping, followed by backward tuning, we achieve deterministic single-soliton generation across 80 consecutive trials via automated laser tuning, eliminating the need for complex thermal compensation or rapid tuning schemes. Our work provides a straightforward and robust solution for generating high-power solitons, advancing the practicality and accessibility of microcombs for real-world applications.展开更多
Chip-based soliton frequency microcombs combine compact size,broad bandwidth,and high coherence,presenting a promising solution for integrated optical telecommunications,precision sensing,and spectroscopy.Recent progr...Chip-based soliton frequency microcombs combine compact size,broad bandwidth,and high coherence,presenting a promising solution for integrated optical telecommunications,precision sensing,and spectroscopy.Recent progress in ferroelectric thin films,particularly thin-film lithium niobate(LiNbO_(3))and thin-film lithium tantalate(LiTaO_(3)),has significantly advanced electro-optic(EO)modulation and soliton microcombs generation,leveraging their strong third-order nonlinearity and high Pockels coefficients.However,achieving soliton frequency combs in X-cut ferroelectric materials remains challenging due to the competing effects of thermo-optic and photorefractive phenomena.These issues hinder the simultaneous realization of soliton generation and high-speed EO modulation.Here,following the thermal-regulated carrier behavior and auxiliary-laser-assisted approach,we propose a convenient mechanism to suppress both photorefractive and thermal dragging effects at once,and implement a facile method for soliton formation and its longterm stabilization in integrated X-cut LiTaO_(3) microresonators for the first time,to the best of our knowledge.The resulting mode-locked states exhibit robust stability against perturbations,enabling new pathways for fully integrated photonic circuits that combine Kerr nonlinearity with high-speed EO functionality.展开更多
With the widespread application of quantum communication technology,there is an urgent need to enhance unconditionally secure key rates and capacity.Measurement-device-independent quantum key distribution(MDI-QKD),pro...With the widespread application of quantum communication technology,there is an urgent need to enhance unconditionally secure key rates and capacity.Measurement-device-independent quantum key distribution(MDI-QKD),proven to be immune to detection-side channel attacks,is a secure and reliable quantum communication scheme.The core of this scheme is Hong–Ou–Mandle(HOM)interference,a quantum optical phenomenon with no classical analog,where identical photons meeting on a symmetric beam splitter(BS)undergo interference and bunching.Any differences in the degrees of freedom(frequency,arrival time,spectrum,polarization,and the average number of photons per pulse)between the photons will deteriorate the interference visibility.Here,we demonstrate 16-channel weak coherent pulses(WCPs)of HOM interference with all channels’interference visibility over 46%based on two independent frequency-post-aligned soliton microcombs(SMCs).In our experiment,full locking and frequency alignment of the comb teeth between the two SMCs were achieved through pump frequency stabilization,SMC repetition rate locking,and fine tuning of the repetition rate.This demonstrates the feasibility of using independently generated SMCs as multi-wavelength sources for quantum communication.Meanwhile,SMC can achieve hundreds of frequency-stable comb teeth by locking only two parameters,which further reduces the complexity of frequency locking and the need for finding sufficient suitable frequency references compared to independent laser arrays.展开更多
In this paper,an all-optical tuning scheme of a multi-walled carbon nanotube(MWCNT)-coated microcavity is introduced,achieving high-speed precise resonance control across the free spectral range(FSR).A modulation lase...In this paper,an all-optical tuning scheme of a multi-walled carbon nanotube(MWCNT)-coated microcavity is introduced,achieving high-speed precise resonance control across the free spectral range(FSR).A modulation laser input through the microcavity tail fiber adjusts the resonance peak position,achieving a tuning efficiency of 107.3 pm/mW below 15 mW,with a maximum range exceeding one FSR and a response time of~20 ms.Combined with a fixed-wavelength pump,this scheme can precisely control the microcomb states.The scheme offers high tuning efficiency,simple fabrication,and low cost,making it suitable for applications in microcomb control and optical filters.展开更多
A microcomb-based coherent free-space optical link achieves a record-high bandwidth of 8.21 Tbps.Novel beam stabilisation and carrier phase retrieval schemes are employed for turbulence suppression and error correction.
In recent years,microcomb technology has emerged as a transformative tool in photonics,providing a compact and energyefficient on-chip source for optical frequency combs that have wide-ranging applications in high-pre...In recent years,microcomb technology has emerged as a transformative tool in photonics,providing a compact and energyefficient on-chip source for optical frequency combs that have wide-ranging applications in high-precision metrology,frequency synthesis,and optical communications[1–3].Generated in high-Q microresonators,microcombs have gained attention due to their ability to generate broadband optical combs in a small footprint,offering much compactness over traditional laser-based frequency combs.Most notably,microcombs can provide large-scale parallel frequency with compressible noise,making them a cornerstone technology for next-generation integrated photonic information systems[3–5].展开更多
基金support from the Lawrence Livermore National Laboratory(Grant No.B622827)the National Science Foundation(Grant Nos.1824568,1810506,1741707,and 1829071)the Office of Naval Research(Grant No.N00014-16-1-2094).
文摘Laser frequency microcombs provide a series of equidistant,coherent frequency markers across a broad spectrum,enabling advancements in laser spectroscopy,dense optical communications,precision distance metrology,and astronomy.Here,we design and fabricate silicon nitride,dispersion-managed microresonators that effectively suppress avoided-mode crossings and achieve close-to-zero averaged dispersion.Both the stochastic noise and mode-locking dynamics of the resonator are numerically and experimentally investigated.First,we experimentally demonstrate thermally stabilized microcomb formation in the microresonator across different mode-locked states,showing negligible center frequency shifts and a broad frequency bandwidth.Next,we characterize the femtosecond timing jitter of the microcombs,supported by precise metrology of the timing phase and relative intensity noise.For the single-soliton state,we report a relative intensity noise of−153.2 dB∕Hz,close to the shot-noise limit,and a quantum-noise–limited timing jitter power spectral density of 0.4 as 2∕Hz at a 100 kHz offset frequency,measured using a self-heterodyne linear interferometer.In addition,we achieve an integrated timing jitter of 1.7 fs±0.07 fs,measured from 10 kHz to 1 MHz.Measuring and understanding these fundamental noise parameters in high clock rate frequency microcombs is critical for advancing soliton physics and enabling new applications in precision metrology.
基金supported by the National Key R&D Plan of China(Grant No.2021ZD0301500)Beijing Natural Science Foundation(Z210004,Z240007)+2 种基金National Natural Science Foundation of China(92150108,62222515,12125402,12174438)the High-performance Computing Platform of Peking Universitysupported by the Micro/nano Fabrication Laboratory of Synergetic Extreme Condition User Facility(SECUF).
文摘An optical frequency comb comprises a cluster of equally spaced,phase-locked spectral lines.Replacing these classical components with correlated quantum light gives rise to cluster quantum frequency combs,providing abundant quantum resources for measurement-based quantum computation,and multi-user quantum networks.We propose and generate cluster quantum microcombs within an on-chip optical microresonator driven by multi-frequency lasers.Through resonantly enhanced four-wave mixing processes,continuous-variable cluster states with 60 qumodes are deterministically created.The graph structures can be programmed into one-and two-dimensional lattices by adjusting the configurations of the pump lines,which are confirmed inseparable based on the measured covariance matrices.Our work demonstrates the largest-scale cluster states with unprecedented raw squeezing levels from a photonic chip,offering a compact and scalable platform for computational and communicational tasks with quantum advantages.
基金National Natural Science Foundation of China(62222515, 12174438)Innovation Program for Quantum Science and Technology (2023ZD0301100)+2 种基金National Key Research and Development Program of China(2021YFA1400700)Basic Frontier Science Research Program of Chinese Academy of Sciences (ZDBS-LYJSC003)CAS Project for Young Scientists in Basic Research (YSBR-100)
文摘Soliton microcombs offer a compact means to generate equally spaced spectral lines via a delicate balance of Kerr nonlinearity and anomalous dispersion in nonlinear microresonators. However, the simultaneous excitation of multiple transverse mode families can disrupt soliton formation and degrade spectral uniformity. Here, we demonstrate universal spectral purification of microresonators with ultrahigh intrinsic Q factors exceeding 10^(8). An aluminum ring is deposited onto a silica microdisk to eliminate high-order transverse modes selectively by introducing additional losses. The resulting soliton microcombs exhibit an ideal sech^(2) spectral envelope and enable continuous tuning of the soliton repetition frequency over a 300 kHz range without compromising phase noise performance. Our approach can be universally applied to integrated photonic platforms to reduce transverse modes crowding in high-Q resonators, facilitating the generation of broadband classical and quantum light with ideal performance.
基金National Natural Science Foundation of China,U24A20311,BAICHENG YAO,62305050,Teng TanNational Key Research and Development Program of China,2023YFB2806200,BAICHENG YAO,2023YFB2805600,Teng TanNational Postdoctoral Innovation Talent Support Program of China,BX20220056,Teng Tan。
文摘Acoustic perception is a fairly basic but extraordinary feature in nature,relying on multidimensional signal processing for detection,localization,and recognition.Replicating this capability in compact artificial systems,however,remains a formidable challenge due to limitations in scalability,sensitivity,and integration.Here,imitating the auditory system of insects,we introduce an opto-acoustic perception paradigm using fully-stabilized dual-soliton microcombs.By integrating digitally stabilized on-chip dual-microcombs,silicon optoelectronics and bionic fiber-microphone arrays on a single platform,we achieve parallelized interrogation of over 100 sensors.Leveraging the low-noise,multi-channel coherence of fully-stabilized soliton microcombs,this synergy enables ultra-sensitive detection of 29.3 nPa/Hz^(1/2),sub centimeter precise localization,real-time tracking and identification for versatile acoustic targets.Bridging silicon photonics,optical fiber sensing and intelligent signal processing in a chiplet microsystem,our scheme delivers outof-lab deployable capability on autonomous robotics.This work not only deepens the understanding of frequency comb science,but also establishes a concept of dual-comb-driven sensor networks as a scalable foundation for nextgeneration opto-acoustic intelligence.
基金financial support from the Office of Naval Research(N00014-16-1-2094)the National Science Foundation(1824568,1810506,1741707,and 1919355).
文摘Coherent frequency microcombs,generated in nonlinear high-Q microresonators and driven by a single continuouswave laser,have enabled several scientific breakthroughs in the past decade,thanks to their high intrinsic phase coherence and individual comb line powers.Here,we report terabit-per-second-scale coherent data communications over a free-space atmospheric link,using a platicon frequency microcomb,employing wavelength-and polarizationdivision multiplexing for next-generation optical wireless networks.Spanning more than 55 optical carriers with 115 GHz channel spacing,we report the first free-space coherent communication link using a frequency microcomb,achieving up to 8.21 Tbit/s aggregate data transmission at a 20 Gbaud symbol rate per carrier over 160 m,even under log-normal turbulent conditions.Utilizing 16-state quadrature amplitude modulation,we demonstrate retrieved constellation maps across the broad microcomb spectrum,achieving bit-error rates below both hardand soft-decision thresholds for forward-error correction.Next,we examine a wavelength-division multiplexing free-space passive optical network as a baseline for free-space fronthaul,achieving an aggregate data rate of up to 5.21 Tbit/s and a field-tested spectral efficiency of 1.29 bit/s/Hz in the microcomb-based atmospheric link.We also quantify experimental power penalties of≈3.8 dB at the error-correction threshold,relative to the theoretical additive white Gaussian noise limit.Furthermore,we introduce the first-ever demonstration of master–slave free-space carrier phase retrieval with frequency microcombs,and the compensation for turbulence-induced intensity scintillation and pointing error fluctuations,to improve end-to-end symbol error rates.This work provides a foundational platform for broadband vertical heterogeneous connectivity,terrestrial backbone links,and groundsatellite communication.
基金supported by the ERC Consolidator Grant TeraSHAPE(#773248)the H2020 project TeraSlice(#863322)+10 种基金by the EIC Transition projects MAGNIFY(#101113302),HDLN(#101113260),and CombTools(#101136978)by the H2020 Marie Skłodowska-Curie Innovative Training Network“MICROCOMB”(#812818)by the Deutsche Forschungsgemeinschaft(DFG)project PACE(#403188360)within the Priority Programme“Electronic-Photonic Integrated Systems for Ultrafast Signal Processing”(SPP 2111)by the DFG Collaborative Research Centre(CRC)WavePhenomena(SFB 1173,Project-ID 258734477)by the BMBF project Open6GHub(#16KISK010)by the Alfried Krupp von Bohlen und Halbach-Stiftungby the Max-Planck School of Photonics(MPSP)by the European Regional Development Fund(ERDF,grant EFRE/FEIH_776267)the Deutsche Forschungsgemeinschaft(DFGgrants DFG/INST 121384/166-1 and DFG/INST 121384/167-1The Si3N4 samples were fabricated in the Centre of MicroNano Technology(CMi)at EPFL.
文摘Kerr soliton microcombs have the potential to disrupt a variety of applications such as ultra-high-speed optical communications,ultra-fast distance measurements,massively parallel light detection and ranging(LiDAR)or high-resolution optical spectroscopy.Similarly,ultra-broadband photonic-electronic signal processing could also benefit from chip-scale frequency comb sources that offer wideband optical emission along with ultra-low phase noise and timing jitter.However,while photonic analogue-to-digital converters(ADC)based on femtosecond lasers have been shown to overcome the jitter-related limitations of electronic oscillators,the potential of Kerr combs in photonic-electronic signal processing remains to be explored.In this work,we demonstrate a microcomb-based photonic-electronic ADC that combines a high-speed electro-optic modulator with a Kerr comb for spectrally sliced coherent detection of the generated optical waveform.The system offers a record-high acquisition bandwidth of 320 GHz,corresponding to an effective sampling rate of at least 640GSa/s.In a proof-of-concept experiment,we demonstrate the viability of the concept by acquiring a broadband analogue data signal comprising different channels with centre frequencies between 24 GHz and 264 GHz,offering bit error ratios(BER)below widely used forward-error-correction(FEC)thresholds.To the best of our knowledge,this is the first demonstration of a microcomb-based ADC,leading to the largest acquisition bandwidth demonstrated for any ADC so far.
基金supported by the National Natural Science Foundation of China (No. 62305006)the Natural Science FoundationofJiangsuProvince(Nos.BK20230287 and BK20230286)the Nantong Social Livelihood Science and Technology Planning Project (Nos. MS12022003 and MS2023071)。
文摘The exceptional temporal and spatial photon confinement properties of whispering gallery mode (WGM) microcavities render them ideally suitable for nonlinear frequency conversion.Here,we present a reliable packaged microcavity device with vibration isolation,air tightness,temperature adaptability,and quality factors greater than 2 billion that can serve as a compact and stable platform for soliton optical comb generation.Low-noise soliton combs can be initiated with a repetition rate of 24.98 GHz at wavelengths near 1550 nm with 4 mW threshold power.Our work provides innovative solutions for investigating and manufacturing miniature,economical,and robust microcomb devices.
基金This work was supported by the National Key R&D Program of China(Nos.2022YFA1205100,2023YFB2805700,and 2019YFA0705000)the National Natural Science Foundation of China(Nos.62293523 and 12304421)+4 种基金the Leading-edge Technology Program of Jiangsu Natural Science Foundation(No.BK20192001)the Zhangjiang Laboratory(No.ZJSP21A001)the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030009)the Jiangsu Natural Science Foundation(No.BK20230770)the Jiangsu Funding Program for Excellent Postdoctoral Talent.
文摘The optical frequency comb based on microresonators(microcombs)is an integrated coherent light source and has the potential to promise a high-precision frequency standard;self-reference and a long-term stable microcomb are the keys to this realization.Here,we demonstrated a 0.7-octave spectrum Kerr comb via dispersion engineering in a thin-film lithium niobate microresonator,and the single-soliton state can be accessed passively with long-term stability over 3 h.With such a robust broadband coherent comb source using thin-film lithium niobate,a fully stabilized microcomb can be expected for massive practical applications.
基金supported in part by the National Key Research and Development Program of China(2022YFB2802700)the National Natural Science Foundation of China(62205145,62271249)+1 种基金the Natural Science Foundation of Jiangsu Province(BK20220887)Leading-Edge Technology Program of Jiangsu Natural Science Foundation(BK20232001).
文摘The increasing demand for dispersion engineering in various photonic applications necessitates spectrometry with both kilohertz resolution and several terahertz bandwidth.A laser with sufficiently large frequency tuning range is required in traditional methods,Yielding bulky and expensive systems that are difficult to integrated on a chip.Compact,high-resolution,and broadband spectrometers are crucial,yet onchip integration,particularly of the optical source,remains challenging.Here,we propose a 5.2-THz-bandwidth miniaturized spectrometer utilizing a laser only in GHz tuning range.The laser’s tuning range is leveraged by integrated Si_(3)N_(4)soliton microcombs to achieve a 650-times larger measurement bandwidth,extending the measurement range from 1525.3 to 1566.8 nm and surpassing the optical C-band.The soliton microcomb is meticulously frequency-stabilized,achieving frequency fluctuations below 100 Hz,ensuring high frequency precision for our spectrometer.By combining optical asymmetrical double sideband modulation with soliton microcombs,we significantly enhance the spectrometer’s performance,offering higher resolution,larger dynamic range,and greater bandwidth.This optical spectrum measurement approach enabled by GHz-tunable laser opens a way to significantly simplify system complexity.
基金funding support from Dream X International Innovation Teamthe support from the startup grant from Nanyang Technological University (022527-00001)。
文摘Mode-locked microcombs with flat spectral profiles provide the high signal-to-noise ratio and are in high demand for wavelength division multiplexing(WDM)-based applications,particularly in future high-capacity communication and parallel optical computing.Here,we present two solutions to generate local relatively flat spectral profiles.One microcavity with ultra-flat integrated dispersion is pumped to generate one relatively flat single soliton source spanning over 150 nm.Besides,one extraordinary soliton crystal with single vacancy demonstrates the local relatively flat microcomb lines when the inner soliton spacings are slightly irregular.Our work paves a new way for soliton-based applications owing to the relatively flat spectral characteristics.
基金This work was supported by the National Natural Science Foundation of China （No.20671027）, and the Natural Science Foundation of Anhui province, China （No.050440904）.
文摘Single-crystalline Ga-doped SnO2 nanowires and SnO2：Ga2O3 heterogeneous microcombs were synthesized by a simple one-step thermal evaporation and condensation method. They were characterized by means of X-ray powder diffraction （XRD）, field-emission scanning electron microscopy （FE-SEM）, energy-dispersive X-ray spectroscopy （EDS）, transmission electron microscopy （TEM） and selected-area electron diffraction （SAED）. FE-SEM images showed that the products consisted of nanowires and mierocombs that represent a novel morphology. XRD, SAED and EDS indicated that they were single-crystalline tetragonal SnO2. The influence of experimental conditions on the morphologies of the products is discussed. The morphology of the product showed a ribbon-like stem and nanoribbon array aligned evenly along one or both side of the nanoribbon. It was found that many Ga2O3 nanoparticles deposited on the surface of the microcombs. The major core nanoribbon grew mainly along the [110] direction and the self-organized branching nanoribbons grew epitaxially along [110] or [110] orientation from the （110） plane of the stem. A growth process was proposed for interpreting the growth of these remarkable SnO2：Ga2O3 heterogeneous microcombs. Due to the heavy doping of Ga, the emission peak in photoluminescence spectra has red-shifted as well as broadened significantly.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFB2800603)the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-069)+1 种基金the National Natural Science Foundation of China(Grant Nos.62075238 and 12275093)the Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0301500 and 2021ZD0300701).
文摘Dual-comb ranging allows rapid and precise distance measurement and can be universally implemented on different comb platforms,e.g.,fiber combs and microcombs.To date,dual-fiber-comb ranging has become a mature and powerful tool for metrology and industry,but the measurement speed is often at a kilohertz level due to the lower repetition rates.Recently,dual-microcomb ranging has given rise to a new opportunity for distance measurement,in consequence of its small footprint and high repetition rates,but full-comb stabilization is challenging.Here,we report a dual-hybrid-comb distance meter capable of ultrarapid and submicrometer precision distance measurement,which can not only leverage the advantage of easy locking inherited from the fiber comb but also sustain ultrarapid measurement speed due to the microcomb.The experimental results show that the measurement precision can reach 3.572μm at 4.136μs and 432 nm at 827.2μs averaging time.Benefiting from the large difference between the repetition rates of the hybrid combs,the measurement speed can be enhanced by 196 folds,in contrast to the dual-fiber-comb system with about a 250 MHz repetition rate.Our work can offer a solution for the fields of rapid dimensional measurement and spectroscopy.
基金support from the National Key R&D Program of China(Grant No.2024YFA1409300)National Natural Science Foundation of China(Grant No.12261131503,12404436,12404417,62405202,61975121,62205145)+3 种基金Innovation Program for Quantum Science and Technology(2023ZD0301500)Shenzhen Science and Technology Program(Grant No.RCJC20231211090042078)Shenzhen-Hong Kong Cooperation Zone for Technology and Innovation(HZQB-KCZYB2020050)Guangdong-Hong Kong Technology Cooperation Funding Scheme(Grant No.2024A0505040008).
文摘Microresonator-based Kerr frequency combs(“Kerr microcombs”)constitute chip-scale frequency combs of broad spectral bandwidth and repetition rate ranging from gigahertz to terahertz.A critical application that exploits the coherence and high repetition rate of microcombs is microwave and millimeter-wave generation.Latest endeavor applying two-point optical frequency division(OFD)to photonic-chip-based microcombs has created microwaves with remarkably low phase noise.Nevertheless,existing approaches to achieve exceptionally coherent microcombs still require extensive active locking,additional lasers,and external RF or microwave sources,as well as sophisticated initiation.Here we demonstrate a simple and entirely passive(no active locking)architecture,which incorporates an optoelectronic oscillator(OEO)and symphonizes a coherent microcomb and a low-noise microwave spontaneously.Our OEO microcomb leverages state-of-the-art integrated chip devices,including a high-power DFB laser,a broadband silicon Mach–Zehnder modulator,an ultralow-loss silicon nitride microresonator,and a high-speed photodetector.Each can be manufactured in large volume with low cost and high yield using established CMOS and Ⅲ-Ⅴ foundries.Our system synergizes a microcomb of 10.7 GHz repetition rate and an X-band microwave with phase noise of−97/−126/−130 dBc/Hz at 1/10/100 kHz Fourier frequency offset,yet does not demand active locking,additional lasers,and external RF or microwave sources.With potential to be fully integrated,our OEO microcomb can become an invaluable technology and building block for microwave photonics,radio-over-fiber,and optical communication.
文摘The demand for high-throughput,low-latency data aggregation at network edges is growing rapidly.However,existing integrated wavelength-division multiplexing(WDM)parallel light sources often suffer from limited coherence,low optical carrier-to-noise ratio(OCNR),insufficient output power,or large footprint,hindering the deployment of efficient and lightweight optical interconnects at network edges.
基金European Research Council(853522)HORIZON EUROPE European Innovation Council(101047289)+4 种基金Danmarks Grundforskningsfond(DNRF123)Villum Fonden(VIL50469)Innovationsfonden(2079-00040B)Danmarks Frie Forskningsfond(3164-00307A)Staatssekretariat für Bildung,Forschung und Innovation(CSOC).
文摘Kerr frequency combs, or microcombs, are revolutionizing fields such as precision metrology, optical clocks, and astronomical spectrometer calibration. However, conventional dissipative Kerr soliton(DKS) microcombs often suffer from limited conversion efficiency and low output power, and achieving deterministic single-soliton generation remains a challenge due to limited thermal accessibility arising from the intricate interplay of Kerr and thermal effects. In this work, we present an optimized microresonator design combined with a robust pumping scheme to enhance the thermal accessibility of single-soliton states for deterministic generation. By operating a silicon nitride microresonator with tailored dispersion in the over-coupled regime, we demonstrate a thermally accessible pathway to single solitons with high conversion efficiency(approaching 30%), and high output power(up to 50 m W). Through a pump forward-tuning process with power ramping, followed by backward tuning, we achieve deterministic single-soliton generation across 80 consecutive trials via automated laser tuning, eliminating the need for complex thermal compensation or rapid tuning schemes. Our work provides a straightforward and robust solution for generating high-power solitons, advancing the practicality and accessibility of microcombs for real-world applications.
基金National Key Research and Development Program of China(2022YFA1404601)National Natural Science Foundation of China(62293520,62293521,12074400,62205363,12104442,12404446,12293052)+4 种基金Shanghai Science and Technology Innovation Action Plan Program(20JC1416200,22JC1403300)CAS Project for Young Scientists in Basic Research(YSBR-69)Natural Science Foundation of Anhui Province(2408085QA010)China Postdoctoral Science Foundation(2024M753078)Postdoctoral Fellowship Program of CPSF(GZC20232560)。
文摘Chip-based soliton frequency microcombs combine compact size,broad bandwidth,and high coherence,presenting a promising solution for integrated optical telecommunications,precision sensing,and spectroscopy.Recent progress in ferroelectric thin films,particularly thin-film lithium niobate(LiNbO_(3))and thin-film lithium tantalate(LiTaO_(3)),has significantly advanced electro-optic(EO)modulation and soliton microcombs generation,leveraging their strong third-order nonlinearity and high Pockels coefficients.However,achieving soliton frequency combs in X-cut ferroelectric materials remains challenging due to the competing effects of thermo-optic and photorefractive phenomena.These issues hinder the simultaneous realization of soliton generation and high-speed EO modulation.Here,following the thermal-regulated carrier behavior and auxiliary-laser-assisted approach,we propose a convenient mechanism to suppress both photorefractive and thermal dragging effects at once,and implement a facile method for soliton formation and its longterm stabilization in integrated X-cut LiTaO_(3) microresonators for the first time,to the best of our knowledge.The resulting mode-locked states exhibit robust stability against perturbations,enabling new pathways for fully integrated photonic circuits that combine Kerr nonlinearity with high-speed EO functionality.
基金Innovation Program for Quantum Science and Technology(2021ZD0300701,2021ZD0301500)CAS Project for Young Scientists in Basic Research(YSBR-069)+1 种基金National Natural Science Foundation of China(62075238,62205036)National Key Research and Development Program of China(2021YFB2800603)。
文摘With the widespread application of quantum communication technology,there is an urgent need to enhance unconditionally secure key rates and capacity.Measurement-device-independent quantum key distribution(MDI-QKD),proven to be immune to detection-side channel attacks,is a secure and reliable quantum communication scheme.The core of this scheme is Hong–Ou–Mandle(HOM)interference,a quantum optical phenomenon with no classical analog,where identical photons meeting on a symmetric beam splitter(BS)undergo interference and bunching.Any differences in the degrees of freedom(frequency,arrival time,spectrum,polarization,and the average number of photons per pulse)between the photons will deteriorate the interference visibility.Here,we demonstrate 16-channel weak coherent pulses(WCPs)of HOM interference with all channels’interference visibility over 46%based on two independent frequency-post-aligned soliton microcombs(SMCs).In our experiment,full locking and frequency alignment of the comb teeth between the two SMCs were achieved through pump frequency stabilization,SMC repetition rate locking,and fine tuning of the repetition rate.This demonstrates the feasibility of using independently generated SMCs as multi-wavelength sources for quantum communication.Meanwhile,SMC can achieve hundreds of frequency-stable comb teeth by locking only two parameters,which further reduces the complexity of frequency locking and the need for finding sufficient suitable frequency references compared to independent laser arrays.
基金supported by the National Natural Science Foundation of China(No.62175116)the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(No.NY223154)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX23_0970)。
文摘In this paper,an all-optical tuning scheme of a multi-walled carbon nanotube(MWCNT)-coated microcavity is introduced,achieving high-speed precise resonance control across the free spectral range(FSR).A modulation laser input through the microcavity tail fiber adjusts the resonance peak position,achieving a tuning efficiency of 107.3 pm/mW below 15 mW,with a maximum range exceeding one FSR and a response time of~20 ms.Combined with a fixed-wavelength pump,this scheme can precisely control the microcomb states.The scheme offers high tuning efficiency,simple fabrication,and low cost,making it suitable for applications in microcomb control and optical filters.
文摘A microcomb-based coherent free-space optical link achieves a record-high bandwidth of 8.21 Tbps.Novel beam stabilisation and carrier phase retrieval schemes are employed for turbulence suppression and error correction.
文摘In recent years,microcomb technology has emerged as a transformative tool in photonics,providing a compact and energyefficient on-chip source for optical frequency combs that have wide-ranging applications in high-precision metrology,frequency synthesis,and optical communications[1–3].Generated in high-Q microresonators,microcombs have gained attention due to their ability to generate broadband optical combs in a small footprint,offering much compactness over traditional laser-based frequency combs.Most notably,microcombs can provide large-scale parallel frequency with compressible noise,making them a cornerstone technology for next-generation integrated photonic information systems[3–5].
