Based on a semiconductor laser （SL） with incoherent optical feedback, a novel all-optical scheme for generating tunable and broadband microwave frequency combs （MFCs） is proposed and investigated numerically. The ...Based on a semiconductor laser （SL） with incoherent optical feedback, a novel all-optical scheme for generating tunable and broadband microwave frequency combs （MFCs） is proposed and investigated numerically. The results show that, under suitable operation parameters, the SL with incoherent optical feedback can be driven to operate at a regular pulsing state, and the generated MFCs have bandwidths broader than 40 GHz within a 10 dB amplitude variation. For a fixed bias current, the line spacing （or repetition frequency） of the MFCs can be easily tuned by varying the feedback delay time and the feedback strength, and the tuning range of the line spacing increases with the increase in the bias current. The linewidth of the MFCs is sensitive to the variation of the feedback delay time and the feedback strength, and a linewidth of tens of KHz can be achieved through finely adjusting the feedback delay time and the feedback strength. In addition, mappings of amplitude variation, repetition frequency, and linewidth of MFCs in the parameter space of the feedback delay time and the feedback strength are presented.展开更多
Based on the nonlinear Schr?dinger equation(NLSE) with damping, detuning, and driving terms describing the evolution of signals in a Kerr microresonator, we apply periodic nonlinear Fourier transform(NFT) to the study...Based on the nonlinear Schr?dinger equation(NLSE) with damping, detuning, and driving terms describing the evolution of signals in a Kerr microresonator, we apply periodic nonlinear Fourier transform(NFT) to the study of signals during the generation of the Kerr optical frequency combs(OFCs). We find that the signals in different states, including the Turing pattern, the chaos, the single soliton state, and the multi-solitons state, can be distinguished according to different distributions of the eigenvalue spectrum. Specially, the eigenvalue spectrum of the single soliton pulse is composed of a pair of conjugate symmetric discrete eigenvalues and the quasi-continuous eigenvalue spectrum with eye-like structure.Moreover, we have successfully demonstrated that the number of discrete eigenvalue pairs in the eigenvalue spectrum corresponds to the number of solitons formed in a round-trip time inside the Kerr microresonator. This work shows that some characteristics of the time-domain signal can be well reflected in the nonlinear domain.展开更多
Frequency combs[1, 2] consisting of equally-spaced frequencylines can be fully described by two frequencies, i.e., carrieroffset (fCEO) and repetition rate (frep). Once the two frequenciesare stabilized, the frequency...Frequency combs[1, 2] consisting of equally-spaced frequencylines can be fully described by two frequencies, i.e., carrieroffset (fCEO) and repetition rate (frep). Once the two frequenciesare stabilized, the frequency comb is well defined. Frequencycombs can be used for various applications, i.e., metrology,spectroscopy, timing, communications, absolute distancemeasurements, and so on, due to their two importantcharacteristics, i.e., stabilized frequency lines and ultra-shortoptical pulses (if the mode-locking is obtained) as shown inFig. 1.展开更多
The optical injection locking of semiconductor lasers to dual-frequency lasers is studied by numerical simulations.The beat-note signals can be effectively transformed to optical frequency combs due to the effective f...The optical injection locking of semiconductor lasers to dual-frequency lasers is studied by numerical simulations.The beat-note signals can be effectively transformed to optical frequency combs due to the effective four wave-mixing in the active semiconductor gain medium. The low-noise Gaussian-like pulse can be obtained by locking the relaxation oscillation and compensating the gain asymmetry. The simulations suggest that pulse trains of width below 30 ps and repetition rate in GHz frequency can be generated simply by the optical injection locking of semiconductor lasers. Since the optical injection locking can broaden the spectrum and amplify the optical power simultaneously, it can be a good initial stage for generating optical frequency combs from dual-frequency lasers by multi-stage of spectral broadening in nonlinear waveguides.展开更多
Optical frequency comb with evenly spaced lines over a broad bandwidth has revolutionized the fields of optical metrology and spectroscopy.Here,we propose a fast interleaved dual-comb spectroscopy with sub-femtometer-...Optical frequency comb with evenly spaced lines over a broad bandwidth has revolutionized the fields of optical metrology and spectroscopy.Here,we propose a fast interleaved dual-comb spectroscopy with sub-femtometer-resolution and absolute frequency,in which two electro-optic frequency combs are swept.Electrically-modulated stabilized laser enables ultrahigh resolution of 0.16 fm(or 20 k Hz in optical frequency)and single-shot measurement in 90 ms.Total 20 million points are recorded spanning 3.2 nm(or 400 GHz)bandwidth,corresponding to a spectral sampling rate of 2.5×10^(8)points/s under Nyquist-limitation.Besides,considering the trade-off between the measurement time and spectral resolution,a fast single-shot measurement is also realized in 1.6 ms with 8 fm(or 1 MHz)resolution.We demonstrate the 25-averaged result with 30.6 d B spectral measurement signal-to-noise ratio(SNR)by reducing the filter bandwidth in demodulation.The results show great prospect for precise measurement with flexibly fast refresh time,high spectral resolution,and high SNR.展开更多
We review recent work on broadband RF channelizers based on integrated optical frequency Kerr micro-combs combined with passive micro-ring resonator filters,with microcombs having channel spacings of 200 and 49 GHz.Th...We review recent work on broadband RF channelizers based on integrated optical frequency Kerr micro-combs combined with passive micro-ring resonator filters,with microcombs having channel spacings of 200 and 49 GHz.This approach to realizing RF channelizers offers reduced complexity,size,and potential cost for a wide range of applications to microwave signal detection.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
A novel dispersion-compensation scheme based on double-chirped Bragg mirrors is implemented in a mid-infrared quantum cascade laser.As a result,stable and broadband frequency combs are generated,which are indispensabl...A novel dispersion-compensation scheme based on double-chirped Bragg mirrors is implemented in a mid-infrared quantum cascade laser.As a result,stable and broadband frequency combs are generated,which are indispensable for high-precision applications in spectroscopy and metrology.展开更多
Superconducting optomechanical circuits enable frequency mixing of optical and mechanical modes,facilitating the generation of microwave frequency combs.However,such optomechanical combs suffer from frequency fluctuat...Superconducting optomechanical circuits enable frequency mixing of optical and mechanical modes,facilitating the generation of microwave frequency combs.However,such optomechanical combs suffer from frequency fluctuations,requiring their stabilization for applications in precision sensing and signal processing.Here,we investigate the sideband injection locking of microwave frequency combs in a niobium-based superconducting optomechanical circuit.By strongly driving the device with a blue-detuned pump to induce parametric instability and introducing an additional tone near individual comb peaks,we study how the locking range varies with the power,the frequency position,and the sweep direction of the injection tone.The locking responses show interesting features such as injection hysteresis,which cannot be explained by existing models.Numerical simulations of the classical optomechanical equations implementing a cubic mechanical nonlinearity show that the nonlinearity contributes to broadening the locking range.We also characterize the Allan deviations and phase noise of the injection-locked combs for different injection frequencies,demonstrating enhanced stability performance.Our results lay the foundation for the utilization of optomechanical combs for applications in nanomechanical sensing and cryogenic microwave pulse generation.展开更多
Dispersion engineering is critical for the creation of integrated broadband laser frequency combs.In the long wavelength infrared range(LWIR,8-13µm),frequency combs based on quantum cascade lasers are attractive ...Dispersion engineering is critical for the creation of integrated broadband laser frequency combs.In the long wavelength infrared range(LWIR,8-13µm),frequency combs based on quantum cascade lasers are attractive since they are monolithic,fundamental oscillators with high power levels and efficiencies.One effective approach for expanding quantum cascade laser gain bandwidth is by stacking multiple gain media with different center lasing frequencies,as this leads to flatter broadband gain spectra.However,as the gain bandwidth is increased,dispersion becomes the main limiting factor for comb bandwidth.Therefore,achieving broadband combs requires schemes that can flexibly engineer the dispersion over broad bandwidths.Here,we demonstrate the ultimate nanophotonic dispersion compensation scheme:an air-dielectric slab double-chirped mirror,which we fully integrate with the quantum cascade laser gain section.This scheme relies on the highest possible index contrast and therefore provides the maximum correction per unit length over a very broad bandwidth.With this approach,we report the successful demonstration of a broadband room-temperature LWIR laser frequency comb on a gain medium that normally does not form combs without deliberate dispersion compensations.Our air-dielectric mirrors are versatile and can be extended to other integrated laser frequency combs in different material platforms and frequency bands.展开更多
Self-injection-locked Kerr frequency combs have attracted attention as a promising platform for integrated comb sources.Precise phase matching remains an issue for reliable soliton generation.Conventional approaches u...Self-injection-locked Kerr frequency combs have attracted attention as a promising platform for integrated comb sources.Precise phase matching remains an issue for reliable soliton generation.Conventional approaches usually rely on manual manipulation of the coupling between different components,imposing challenges for photonic integration.In this work,we analyze the principle of the phase dependence of soliton generation and propose an architecture incorporating an on-chip phase shifter and a feedback control system.By characterizing the parameter space that tracks the soliton evolution dynamics,this system autonomously generates soliton states within several seconds.This architecture demonstrates potential for enabling self-starting of integrated Kerr combs in applications.展开更多
Frequency combs show various applications in molecular fingerprinting,imaging,communications,and so on.In the terahertz frequency range,semiconductor-based quantum cascade lasers(QCLs)are ideal platforms for realizing...Frequency combs show various applications in molecular fingerprinting,imaging,communications,and so on.In the terahertz frequency range,semiconductor-based quantum cascade lasers(QCLs)are ideal platforms for realizing the frequency comb operation.Although self-started frequency comb operation can be obtained in free-running terahertz QCLs due to the four-wave mixing locking effects,resonant/off-resonant microwave injection,phase locking,and femtosecond laser based locking techniques have been widely used to broaden and stabilize terahertz QCL combs.These active locking methods indeed show significant effects on the frequency stabilization of terahertz QCL combs,but they simultaneously have drawbacks,such as introducing large phase noise and requiring complex optical coupling and/or electrical circuits.Here,we demonstrate Farey tree locking of terahertz QCL frequency combs under microwave injection.The frequency competition between the Farey fraction frequency and the cavity round-trip frequency results in the frequency locking of terahertz QCL combs,and the Farey fraction frequencies can be accurately anticipated based on the downward trend of the Farey tree hierarchy.Furthermore,dual-comb experimental results show that the phase noise of the dual-comb spectral lines is significantly reduced by employing the Farey tree locking method.These results pave the way to deploying compact and low phase noise terahertz frequency comb sources.展开更多
Optical frequency combs are indispensable links between the optical and microwave domains.Chip-scale integration promises compact,scalable,and power-efficient frequency comb sources,enabled by the resonantly-enhanced ...Optical frequency combs are indispensable links between the optical and microwave domains.Chip-scale integration promises compact,scalable,and power-efficient frequency comb sources,enabled by the resonantly-enhanced Kerr effect or the electro-optic effect.While combs utilizing the former can reach octave-spanning bandwidths,and combs based on the latter can feature microwave-rate spacings,achieving both features at the same time has been challenging.Here,we simultaneously leverage the strong Kerr and electro-optic effects on thin-film lithium niobate,where dissipative Kerr soliton generation is followed by electro-optic phase modulation,to realize an integrated frequency comb reference with 2,589 lines spaced by 29.308 GHz and spanning 75.9THz(588 nm).Further,we demonstrate electronic stabilization and control of the comb spacing,naturally facilitated by this approach.The broadband,microwave-rate frequency comb in our work overcomes the spacing-span tradeoff that exists in nonlinear integrated frequency comb sources,paving the way towards chip-scale solutions for next-generation laser spectroscopy,microwave and millimeter wave synthesis,as well as optical communications.展开更多
This paper presents a novel technique for low-power generation of frequency combs(FC)over a wide frequency range.It leverages modal interactions between electrical and mechanical resonators in electrostatic NEMS opera...This paper presents a novel technique for low-power generation of frequency combs(FC)over a wide frequency range.It leverages modal interactions between electrical and mechanical resonators in electrostatic NEMS operating in air to provide a simple architecture for FC generators.A biased voltage signal drives the electrical resonator at resonance which is set to match an integer submultiple of twice the mechanical resonator’s resonance.Experimental results demonstrate that the NEMS displacement exhibit more than 150 equidistant peaks in the case of a 2:1 modal interaction and more than 60 equidistant peaks in the case of a 1:1 modal interaction.In both cases,the Free Spectral Range(FSR)was equal to the mechanical resonance frequency.Comparison between the FCs generated by the 2:1 and 1:1 modal interactions demonstrate the superiority of the former in terms of bandwidth and stability.The superior phase coherence of the FC generated via the 2:1 modal interaction was demonstrated via time-domain analysis.Our technique has the flexibility to generate multiple frequency combs and to fine-tune their FSR depending on the number of mechanical modes accessible to and the order of the activated modal interaction.It can be integrated into portable devices and is well aligned with modern miniaturization technology.展开更多
The results of an optoelectronic system—frequency-shifted feedback(FSF)laser experimental examination are presented.The considered FSF laser is seeded only with optical amplifer spontaneous emission(ASE)and operates ...The results of an optoelectronic system—frequency-shifted feedback(FSF)laser experimental examination are presented.The considered FSF laser is seeded only with optical amplifer spontaneous emission(ASE)and operates in the mode-locked regime,whereby the output radiation is sequence of short pulses with a repetition rate determined by the delay time in its optical feedback circuit.In the frequency domain,the spectrum of such a pulse sequence is an optical frequency comb(OFC).These OFCs we call initial.We consider the possibility of tunable acousto-optic(AO)dual and quad-comb frequency spacing downconversion in the FSF laser seeded with ASE and operating in the mode-locked regime.The examined system applies a single frequency shifting loop with single AO tunable flter as the frequency shifter that is fed with several radio frequency signals simultaneously.The initial OFCs with frequency spacing of about 6.5 MHz may be obtained in the wide spectral range and their width,envelope shape and position in the optical spectrum may be tuned.The dual-combs are obtained with a pair of initial OFCs aroused by two various ultrasound waves in the acousto-optic tunable flter(AOTF).The dual-combs frequency spacing is determined by the frequency diference of the signals applied to the AOTF piezoelectric transducer and can be tuned simply.The quad-combs are obtained with three initial OFCs,forming a pair of dual-combs,appearing when three ultrasound frequencies feed the AOTF transducer.The quad-combs frequency spacing is defned by the diference between the frequency spacing of dual-combs.Quad-combs with more than 5000 spectral lines and tunable frequency spacing are observed.The successive frequency downconversion gives the possibility to reduce the OFC frequency spacing form several MHz for initial OFC to tens of kHz for quad-combs.展开更多
We propose a novel automatic phase-matching method for generating optical frequency combs using cascaded electrooptic modulators.By analyzing the power changes of different spectral lines,our method enables real-time ...We propose a novel automatic phase-matching method for generating optical frequency combs using cascaded electrooptic modulators.By analyzing the power changes of different spectral lines,our method enables real-time monitoring and dynamic adjustment to achieve precise phase matching.Experiments have confirmed the fast phase matching and the adjustable spacing of a flat electro-optic frequency comb and its long-term stability.This method provides flexible and efficient light source solutions for optical communications,spectral analysis,and optical measurements.展开更多
Chip-scale integration of optical frequency combs,particularly soliton microcombs,enables miniaturized instrumentation for timekeeping,ranging,and spectroscopy.Although soliton microcombs have been demonstrated on var...Chip-scale integration of optical frequency combs,particularly soliton microcombs,enables miniaturized instrumentation for timekeeping,ranging,and spectroscopy.Although soliton microcombs have been demonstrated on various material platforms,realizing complete comb functionality on photonic chips requires the co-integration of highspeed modulators and efficient frequency doublers,features that are available in a monolithic form on X-cut thin-film lithium niobate(TFLN).However,the pronounced Raman nonlinearity associated with extraordinary light in this platform has so far precluded soliton microcomb generation.Here,we report the generation of transverse-electric-polarized soliton microcombs with a 25 GHz repetition rate in high-Q microresonators on X-cut TFLN chips.By precisely orienting the racetrack microresonator relative to the optical axis,we mitigate Raman nonlinearity and enable soliton formation under continuous-wave laser pumping.Moreover,the soliton microcomb spectra are extended to 350 nm with pulsed laser pumping.This work expands the capabilities of TFLN photonics and paves the way for the monolithic integration of fast-tunable,self-referenced microcombs.展开更多
Optical frequency combs(OFCs)with precise line spacing play a crucial role in modern optical communication systems.We propose and fabricate a dumbbell-shaped-taper(DST)quantum-well laser diode that generates a frequen...Optical frequency combs(OFCs)with precise line spacing play a crucial role in modern optical communication systems.We propose and fabricate a dumbbell-shaped-taper(DST)quantum-well laser diode that generates a frequency-modulated(FM)optical frequency comb.Effective control of the optical field distribution can be achieved by adjusting the ridge width.In the ridge design,the wide section delivers high optical gain and a broadband spectral output,while the narrow section simultaneously serves as a high-order lateral-mode filter and provides strong optical nonlinearity.Compared with a conventional Fabry-Pérot structure,the device achieves an output power of 48 mW at a drive current of 420 m A and expands the 3 dB spectral bandwidth to 0.90 THz,along with a notable reduction in radio frequency linewidth.Relying on a quantum-well active region,this design avoids complex epitaxial engineering and furnishes a low-cost,high-power,and broadband OFC source.展开更多
The dissipative Kerr soliton(DKS)frequency comb exhibits broad and narrow-linewidth frequency modes,which make it suitable for quantum communication.However,a scalable quantum network based on multiple independent com...The dissipative Kerr soliton(DKS)frequency comb exhibits broad and narrow-linewidth frequency modes,which make it suitable for quantum communication.However,a scalable quantum network based on multiple independent combs is still a challenge due to fabrication-induced frequency mismatches.This limitation becomes critical in measurement-deviceindependent quantum key distribution,which requires high visibility of Hong–Ou–Mandel interference between multiple frequency channels.Here,we experimentally demonstrate two independent DKS combs with 10 spectrally aligned lines without any frequency locking system.The visibility for individual comb-line pairs reaches up to 46.72%±0.63%via precision frequency translation,establishing a foundation for deploying DKS combs in multi-user quantum networks.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.61178011,11204248,61475127,and 61275116)the Natural Science Foundation of Chongqing City,China(Grant Nos.2012jj B40011 and 2012jj A40012)the Open Fund of the State Key Lab of Millimeter Waves of China(Grant No.K201418)
文摘Based on a semiconductor laser （SL） with incoherent optical feedback, a novel all-optical scheme for generating tunable and broadband microwave frequency combs （MFCs） is proposed and investigated numerically. The results show that, under suitable operation parameters, the SL with incoherent optical feedback can be driven to operate at a regular pulsing state, and the generated MFCs have bandwidths broader than 40 GHz within a 10 dB amplitude variation. For a fixed bias current, the line spacing （or repetition frequency） of the MFCs can be easily tuned by varying the feedback delay time and the feedback strength, and the tuning range of the line spacing increases with the increase in the bias current. The linewidth of the MFCs is sensitive to the variation of the feedback delay time and the feedback strength, and a linewidth of tens of KHz can be achieved through finely adjusting the feedback delay time and the feedback strength. In addition, mappings of amplitude variation, repetition frequency, and linewidth of MFCs in the parameter space of the feedback delay time and the feedback strength are presented.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61475099 and 61922040)Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices,China(Grant No.KF201701)the Key R&D Program of Guangdong Province,China(Grant No.2018B030325002)。
文摘Based on the nonlinear Schr?dinger equation(NLSE) with damping, detuning, and driving terms describing the evolution of signals in a Kerr microresonator, we apply periodic nonlinear Fourier transform(NFT) to the study of signals during the generation of the Kerr optical frequency combs(OFCs). We find that the signals in different states, including the Turing pattern, the chaos, the single soliton state, and the multi-solitons state, can be distinguished according to different distributions of the eigenvalue spectrum. Specially, the eigenvalue spectrum of the single soliton pulse is composed of a pair of conjugate symmetric discrete eigenvalues and the quasi-continuous eigenvalue spectrum with eye-like structure.Moreover, we have successfully demonstrated that the number of discrete eigenvalue pairs in the eigenvalue spectrum corresponds to the number of solitons formed in a round-trip time inside the Kerr microresonator. This work shows that some characteristics of the time-domain signal can be well reflected in the nonlinear domain.
基金supported by the "Hundred-Talent" Program of Chinese Academy of Sciencesthe National Natural Science Foundation of China(61875220,61575214,61404150,61405233,and 61704181)+1 种基金the National Key R&D Program of China(2017YFF0106302 and 2017YFA0701005)Shanghai Municipal Commission of Science and Technology(17YF1430000)
文摘Frequency combs[1, 2] consisting of equally-spaced frequencylines can be fully described by two frequencies, i.e., carrieroffset (fCEO) and repetition rate (frep). Once the two frequenciesare stabilized, the frequency comb is well defined. Frequencycombs can be used for various applications, i.e., metrology,spectroscopy, timing, communications, absolute distancemeasurements, and so on, due to their two importantcharacteristics, i.e., stabilized frequency lines and ultra-shortoptical pulses (if the mode-locking is obtained) as shown inFig. 1.
基金Project supported by the National Natural Science Foundation of China(Grant No.62005215)。
文摘The optical injection locking of semiconductor lasers to dual-frequency lasers is studied by numerical simulations.The beat-note signals can be effectively transformed to optical frequency combs due to the effective four wave-mixing in the active semiconductor gain medium. The low-noise Gaussian-like pulse can be obtained by locking the relaxation oscillation and compensating the gain asymmetry. The simulations suggest that pulse trains of width below 30 ps and repetition rate in GHz frequency can be generated simply by the optical injection locking of semiconductor lasers. Since the optical injection locking can broaden the spectrum and amplify the optical power simultaneously, it can be a good initial stage for generating optical frequency combs from dual-frequency lasers by multi-stage of spectral broadening in nonlinear waveguides.
基金funding from National Natural Science Foundation of China(NSFC)under Grant Nos.61775132,61735015,61620106015supported by the Major Key Project of Peng Cheng Laboratory(PCL)。
文摘Optical frequency comb with evenly spaced lines over a broad bandwidth has revolutionized the fields of optical metrology and spectroscopy.Here,we propose a fast interleaved dual-comb spectroscopy with sub-femtometer-resolution and absolute frequency,in which two electro-optic frequency combs are swept.Electrically-modulated stabilized laser enables ultrahigh resolution of 0.16 fm(or 20 k Hz in optical frequency)and single-shot measurement in 90 ms.Total 20 million points are recorded spanning 3.2 nm(or 400 GHz)bandwidth,corresponding to a spectral sampling rate of 2.5×10^(8)points/s under Nyquist-limitation.Besides,considering the trade-off between the measurement time and spectral resolution,a fast single-shot measurement is also realized in 1.6 ms with 8 fm(or 1 MHz)resolution.We demonstrate the 25-averaged result with 30.6 d B spectral measurement signal-to-noise ratio(SNR)by reducing the filter bandwidth in demodulation.The results show great prospect for precise measurement with flexibly fast refresh time,high spectral resolution,and high SNR.
文摘We review recent work on broadband RF channelizers based on integrated optical frequency Kerr micro-combs combined with passive micro-ring resonator filters,with microcombs having channel spacings of 200 and 49 GHz.This approach to realizing RF channelizers offers reduced complexity,size,and potential cost for a wide range of applications to microwave signal detection.
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.
文摘A novel dispersion-compensation scheme based on double-chirped Bragg mirrors is implemented in a mid-infrared quantum cascade laser.As a result,stable and broadband frequency combs are generated,which are indispensable for high-precision applications in spectroscopy and metrology.
基金supported by the National Research Foundation of Korea(NRF)grant(RS-2022-NR072112)the National Research Council of Science&Technology(NST)grant(No.CAP21034-000)+1 种基金Institute for Information&Communications Technology Planning&Evaluation(IITP)grant(No.RS-2025-02219093)the Korea Research Institute of Standards and Science(GP2025-0010-03)funded by the Korea government(MSIT).
文摘Superconducting optomechanical circuits enable frequency mixing of optical and mechanical modes,facilitating the generation of microwave frequency combs.However,such optomechanical combs suffer from frequency fluctuations,requiring their stabilization for applications in precision sensing and signal processing.Here,we investigate the sideband injection locking of microwave frequency combs in a niobium-based superconducting optomechanical circuit.By strongly driving the device with a blue-detuned pump to induce parametric instability and introducing an additional tone near individual comb peaks,we study how the locking range varies with the power,the frequency position,and the sweep direction of the injection tone.The locking responses show interesting features such as injection hysteresis,which cannot be explained by existing models.Numerical simulations of the classical optomechanical equations implementing a cubic mechanical nonlinearity show that the nonlinearity contributes to broadening the locking range.We also characterize the Allan deviations and phase noise of the injection-locked combs for different injection frequencies,demonstrating enhanced stability performance.Our results lay the foundation for the utilization of optomechanical combs for applications in nanomechanical sensing and cryogenic microwave pulse generation.
基金supported in part by the Spectral Combs from UV to THz(SCOUT)and SIGMA+programs from the Defense Advanced Research Project Agency(DARPA)support from the Gordon and Betty Moore Foundation through Grant GBMF11446 to the University of Texas at Austin.
文摘Dispersion engineering is critical for the creation of integrated broadband laser frequency combs.In the long wavelength infrared range(LWIR,8-13µm),frequency combs based on quantum cascade lasers are attractive since they are monolithic,fundamental oscillators with high power levels and efficiencies.One effective approach for expanding quantum cascade laser gain bandwidth is by stacking multiple gain media with different center lasing frequencies,as this leads to flatter broadband gain spectra.However,as the gain bandwidth is increased,dispersion becomes the main limiting factor for comb bandwidth.Therefore,achieving broadband combs requires schemes that can flexibly engineer the dispersion over broad bandwidths.Here,we demonstrate the ultimate nanophotonic dispersion compensation scheme:an air-dielectric slab double-chirped mirror,which we fully integrate with the quantum cascade laser gain section.This scheme relies on the highest possible index contrast and therefore provides the maximum correction per unit length over a very broad bandwidth.With this approach,we report the successful demonstration of a broadband room-temperature LWIR laser frequency comb on a gain medium that normally does not form combs without deliberate dispersion compensations.Our air-dielectric mirrors are versatile and can be extended to other integrated laser frequency combs in different material platforms and frequency bands.
基金supported by the National Key Research and Development Program of China (No.2023YFB4604400)the Tsinghua University Beijing Electronics Holding Co.,Ltd.Joint Research Center for Chip Display Fusion and System Integration Technology。
文摘Self-injection-locked Kerr frequency combs have attracted attention as a promising platform for integrated comb sources.Precise phase matching remains an issue for reliable soliton generation.Conventional approaches usually rely on manual manipulation of the coupling between different components,imposing challenges for photonic integration.In this work,we analyze the principle of the phase dependence of soliton generation and propose an architecture incorporating an on-chip phase shifter and a feedback control system.By characterizing the parameter space that tracks the soliton evolution dynamics,this system autonomously generates soliton states within several seconds.This architecture demonstrates potential for enabling self-starting of integrated Kerr combs in applications.
基金supported by the Innovation Program for Quantum Science and Technology(2023ZD0301000)the National Science Fund for Distinguished Young Scholars(62325509)+2 种基金the National Natural Science Foundation of China(62235019,61875220,61927813,61991430,62035005,62105351,and 62305364)the“From 0 to 1”Innovation Program of the Chinese Academy of Sciences(ZDBS-LY-JSC009)the CAS Project for Young Scientists in Basic Research(YSBR-069).
文摘Frequency combs show various applications in molecular fingerprinting,imaging,communications,and so on.In the terahertz frequency range,semiconductor-based quantum cascade lasers(QCLs)are ideal platforms for realizing the frequency comb operation.Although self-started frequency comb operation can be obtained in free-running terahertz QCLs due to the four-wave mixing locking effects,resonant/off-resonant microwave injection,phase locking,and femtosecond laser based locking techniques have been widely used to broaden and stabilize terahertz QCL combs.These active locking methods indeed show significant effects on the frequency stabilization of terahertz QCL combs,but they simultaneously have drawbacks,such as introducing large phase noise and requiring complex optical coupling and/or electrical circuits.Here,we demonstrate Farey tree locking of terahertz QCL frequency combs under microwave injection.The frequency competition between the Farey fraction frequency and the cavity round-trip frequency results in the frequency locking of terahertz QCL combs,and the Farey fraction frequencies can be accurately anticipated based on the downward trend of the Farey tree hierarchy.Furthermore,dual-comb experimental results show that the phase noise of the dual-comb spectral lines is significantly reduced by employing the Farey tree locking method.These results pave the way to deploying compact and low phase noise terahertz frequency comb sources.
基金support by the Defense Advanced Research Projects Agency(D23AP00251-00)Y.S.,Y.H.,and M.L.acknowledge support by the Defense Advanced Research Projects Agency(HR001120C0137)+4 种基金Office of Naval Research(N00014-22-C-1041)National Science Foundation(OMA-2137723,OMA-2138068)Korea Advanced Institute of Science and Technology(NRF-2022M3K4A1094782)support by the AWS Generation Q Fund at the Harvard Quantum Initiativesupported by the National Science Foundation under NSF award no.ECCS-2025158.
文摘Optical frequency combs are indispensable links between the optical and microwave domains.Chip-scale integration promises compact,scalable,and power-efficient frequency comb sources,enabled by the resonantly-enhanced Kerr effect or the electro-optic effect.While combs utilizing the former can reach octave-spanning bandwidths,and combs based on the latter can feature microwave-rate spacings,achieving both features at the same time has been challenging.Here,we simultaneously leverage the strong Kerr and electro-optic effects on thin-film lithium niobate,where dissipative Kerr soliton generation is followed by electro-optic phase modulation,to realize an integrated frequency comb reference with 2,589 lines spaced by 29.308 GHz and spanning 75.9THz(588 nm).Further,we demonstrate electronic stabilization and control of the comb spacing,naturally facilitated by this approach.The broadband,microwave-rate frequency comb in our work overcomes the spacing-span tradeoff that exists in nonlinear integrated frequency comb sources,paving the way towards chip-scale solutions for next-generation laser spectroscopy,microwave and millimeter wave synthesis,as well as optical communications.
基金K.M.acknowledges funding from the Canada Foundation for Innovation John R.Evans Leaders Fund(Project 35552)Ontario Research Fund—Research Infrastructure(Project 35552),the Waterloo Institute for Nanotechnology(WIN-NRC seed grant),and a Mitacs Globalink Research Award.
文摘This paper presents a novel technique for low-power generation of frequency combs(FC)over a wide frequency range.It leverages modal interactions between electrical and mechanical resonators in electrostatic NEMS operating in air to provide a simple architecture for FC generators.A biased voltage signal drives the electrical resonator at resonance which is set to match an integer submultiple of twice the mechanical resonator’s resonance.Experimental results demonstrate that the NEMS displacement exhibit more than 150 equidistant peaks in the case of a 2:1 modal interaction and more than 60 equidistant peaks in the case of a 1:1 modal interaction.In both cases,the Free Spectral Range(FSR)was equal to the mechanical resonance frequency.Comparison between the FCs generated by the 2:1 and 1:1 modal interactions demonstrate the superiority of the former in terms of bandwidth and stability.The superior phase coherence of the FC generated via the 2:1 modal interaction was demonstrated via time-domain analysis.Our technique has the flexibility to generate multiple frequency combs and to fine-tune their FSR depending on the number of mechanical modes accessible to and the order of the activated modal interaction.It can be integrated into portable devices and is well aligned with modern miniaturization technology.
基金Russian Science Foundation.Sections 1,2,and 3.3 were supported by Grant 23-12-00057,Sects.3.1 and 3.2 were supported by Grant 20-12-00344.
文摘The results of an optoelectronic system—frequency-shifted feedback(FSF)laser experimental examination are presented.The considered FSF laser is seeded only with optical amplifer spontaneous emission(ASE)and operates in the mode-locked regime,whereby the output radiation is sequence of short pulses with a repetition rate determined by the delay time in its optical feedback circuit.In the frequency domain,the spectrum of such a pulse sequence is an optical frequency comb(OFC).These OFCs we call initial.We consider the possibility of tunable acousto-optic(AO)dual and quad-comb frequency spacing downconversion in the FSF laser seeded with ASE and operating in the mode-locked regime.The examined system applies a single frequency shifting loop with single AO tunable flter as the frequency shifter that is fed with several radio frequency signals simultaneously.The initial OFCs with frequency spacing of about 6.5 MHz may be obtained in the wide spectral range and their width,envelope shape and position in the optical spectrum may be tuned.The dual-combs are obtained with a pair of initial OFCs aroused by two various ultrasound waves in the acousto-optic tunable flter(AOTF).The dual-combs frequency spacing is determined by the frequency diference of the signals applied to the AOTF piezoelectric transducer and can be tuned simply.The quad-combs are obtained with three initial OFCs,forming a pair of dual-combs,appearing when three ultrasound frequencies feed the AOTF transducer.The quad-combs frequency spacing is defned by the diference between the frequency spacing of dual-combs.Quad-combs with more than 5000 spectral lines and tunable frequency spacing are observed.The successive frequency downconversion gives the possibility to reduce the OFC frequency spacing form several MHz for initial OFC to tens of kHz for quad-combs.
基金supported by the National Key Research and Development Program of China(No.2021YFB2800800)。
文摘We propose a novel automatic phase-matching method for generating optical frequency combs using cascaded electrooptic modulators.By analyzing the power changes of different spectral lines,our method enables real-time monitoring and dynamic adjustment to achieve precise phase matching.Experiments have confirmed the fast phase matching and the adjustable spacing of a flat electro-optic frequency comb and its long-term stability.This method provides flexible and efficient light source solutions for optical communications,spectral analysis,and optical measurements.
基金supported by Beijing Natural Science Foundation(Z210004)National Key R&D Plan of China(Grant No.2021ZD0301500)+2 种基金National Natural Science Foundation of China(92150108,12293050,12304412)the highperformance computing Platform of Peking Universitythe Advanced Photonic Integrated Center(APIC)of State Key Laboratory of Advanced Optical Communication System and Networks.
文摘Chip-scale integration of optical frequency combs,particularly soliton microcombs,enables miniaturized instrumentation for timekeeping,ranging,and spectroscopy.Although soliton microcombs have been demonstrated on various material platforms,realizing complete comb functionality on photonic chips requires the co-integration of highspeed modulators and efficient frequency doublers,features that are available in a monolithic form on X-cut thin-film lithium niobate(TFLN).However,the pronounced Raman nonlinearity associated with extraordinary light in this platform has so far precluded soliton microcomb generation.Here,we report the generation of transverse-electric-polarized soliton microcombs with a 25 GHz repetition rate in high-Q microresonators on X-cut TFLN chips.By precisely orienting the racetrack microresonator relative to the optical axis,we mitigate Raman nonlinearity and enable soliton formation under continuous-wave laser pumping.Moreover,the soliton microcomb spectra are extended to 350 nm with pulsed laser pumping.This work expands the capabilities of TFLN photonics and paves the way for the monolithic integration of fast-tunable,self-referenced microcombs.
基金supported by the National Key Research and Development Program of China(No.2022YFB2803104)the Taishan Scholars Program。
文摘Optical frequency combs(OFCs)with precise line spacing play a crucial role in modern optical communication systems.We propose and fabricate a dumbbell-shaped-taper(DST)quantum-well laser diode that generates a frequency-modulated(FM)optical frequency comb.Effective control of the optical field distribution can be achieved by adjusting the ridge width.In the ridge design,the wide section delivers high optical gain and a broadband spectral output,while the narrow section simultaneously serves as a high-order lateral-mode filter and provides strong optical nonlinearity.Compared with a conventional Fabry-Pérot structure,the device achieves an output power of 48 mW at a drive current of 420 m A and expands the 3 dB spectral bandwidth to 0.90 THz,along with a notable reduction in radio frequency linewidth.Relying on a quantum-well active region,this design avoids complex epitaxial engineering and furnishes a low-cost,high-power,and broadband OFC source.
基金supported by the National Key Research and Development Program of China(No.2022YFE0137000)the Natural Science Foundation of Jiangsu Province(Nos.BK20240006 and BK20233001)+2 种基金the Leading-Edge Technology Program of Jiangsu Natural Science Foundation(No.BK20192001)the Fundamental Research Funds for the Central Universities,and the Innovation Program for Quantum Science and Technology(Nos.2021ZD0300700 and 2021ZD0301500)the Fundamental Research Funds for the Central Universities(No.2024300324)。
文摘The dissipative Kerr soliton(DKS)frequency comb exhibits broad and narrow-linewidth frequency modes,which make it suitable for quantum communication.However,a scalable quantum network based on multiple independent combs is still a challenge due to fabrication-induced frequency mismatches.This limitation becomes critical in measurement-deviceindependent quantum key distribution,which requires high visibility of Hong–Ou–Mandel interference between multiple frequency channels.Here,we experimentally demonstrate two independent DKS combs with 10 spectrally aligned lines without any frequency locking system.The visibility for individual comb-line pairs reaches up to 46.72%±0.63%via precision frequency translation,establishing a foundation for deploying DKS combs in multi-user quantum networks.
