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
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
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
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
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.
Chip-based optical microresonators with ultra-high Q-factors are becoming increasingly important to a variety of applications. However, the losses of on-chip microresonators with the highest Q-factor reported in the p...Chip-based optical microresonators with ultra-high Q-factors are becoming increasingly important to a variety of applications. However, the losses of on-chip microresonators with the highest Q-factor reported in the past are still far from their material absorption limits. Here, we demonstrate an on-chip silica microresonator that has approached the absorption limit of the state-of-the-art material on chip, realizing, to our knowledge, record intrinsic Q-factors exceeding 3 billion at both 1560 nm and 1064 nm. This fact is corroborated by photo-thermal spectroscopy measurements. Especially, compared with the standard optical fibers, its corresponding optical losses are only 38.4 times and 7.7 times higher at the wavelengths of 1560 nm and 1064 nm, respectively.To exhibit the performance of such fabricated microresonator, we achieve a record-low optical parametric oscillation threshold(31.9 μW) for millimeter-sized microresonators and generate a single-soliton microcomb with a record-low pump power of 220.2 μW for all soliton microcombs realized thus far.展开更多
Mid-infrared(MIR)Kerr microcombs are of significant interest for portable dual-comb spectroscopy and precision molecular sensing due to strong molecular vibrational absorption in the MIR band.However,achieving a compa...Mid-infrared(MIR)Kerr microcombs are of significant interest for portable dual-comb spectroscopy and precision molecular sensing due to strong molecular vibrational absorption in the MIR band.However,achieving a compact,octave-spanning MIR Kerr microcomb remains a challenge due to the lack of suitable MIR photonic materials for the core and cladding of integrated devices and appropriate MIR continuous-wave(CW)pump lasers.Here,we propose a novel slot concentric dual-ring(SCDR)microresonator based on an integrated chalcogenide glass chip,which offers excellent transmission performance and flexible dispersion engineering in the MIR band.This device achieves both phase-matching and group velocity matching in two separated anomalous dispersion regions,enabling phase-locked,two-color solitons in the MIR region with a commercial 2-μm CW laser as the pump source.Moreover,the spectral locking of the two-color soliton enhances pump wavelength selectivity,providing precise control over soliton dynamics.By leveraging the dispersion characteristics of the SCDR microresonator,we have demonstrated a multi-octave-spanning,two-color soliton microcomb,covering a spectral range from 1156.07 to 5054.95 nm(200 THz)at a-40 dB level,highlighting the versatility and broad applicability of our approach.And the proposed multi-octave MIR frequency comb is relevant for applications such as dual-comb spectroscopy and trace-gas sensing.展开更多
For the applications of the frequency comb in microresonators,it is essential to obtain a fully frequency-stabilized microcomb laser source.In this study,we present a system for generating a fully atom-referenced stab...For the applications of the frequency comb in microresonators,it is essential to obtain a fully frequency-stabilized microcomb laser source.In this study,we present a system for generating a fully atom-referenced stabilized soliton microcomb.The pump light around 1560.48 nm is locked to an ultra-low-expansion(ULE)cavity.This pump light is then frequency-doubled and referenced to the atomic transition of87Rb.The repetition rate of the soliton microcomb is injection-locked to an atomic-clockstabilized radio frequency(RF)source,leading to mHz stabilization at 1 s.As a result,all comb lines have been frequencystabilized based on the atomic reference and the ULE cavity,achieving a very high precision of approximately 18 Hz at 1 s,corresponding to the frequency stability of 9.5×10^(-14).Our approach provides a fully stabilized microcomb experiment scheme with no requirement of f-2f technique,which could be easily implemented and generalized to various photonic platforms,thus paving the way towards the ultraprecise optical sources for high precision spectroscopy.展开更多
High-quality photonic materials are critical for promoting integrated photonic devices with broad bandwidths,high efficiencies,and flexibilities for high-volume chip-scale fabrication.Recently,we designed a home-devel...High-quality photonic materials are critical for promoting integrated photonic devices with broad bandwidths,high efficiencies,and flexibilities for high-volume chip-scale fabrication.Recently,we designed a home-developed chalcogenide glass(ChG)-Ge_(25)Sb_(10)S_(65)(GeSbS)for optical information processing chips and systems,which featured an ultrabroad transmission window,a high Kerr nonlinearity and photoelastic coefficient,and compatibility with the photonic hybrid integration technology of silicon photonics.Chip-integrated GeSbS microresonators and microresonator arrays with high quality factors and lithographically controlled fine structures were fabricated using a modified nanofabrication process.Moreover,considering the high Kerr nonlinearity and photoelastic effect of ChGs,we realised a novel ChG hybrid integrated chip,inspired by recent advances in integrated soliton microcombs and acousto-optic(AO)modulators.展开更多
Optical frequency combs,a revolutionary light source characterized by discrete and equally spaced frequencies,are usually regarded as a cornerstone for advanced frequency metrology,precision spectroscopy,high-speed co...Optical frequency combs,a revolutionary light source characterized by discrete and equally spaced frequencies,are usually regarded as a cornerstone for advanced frequency metrology,precision spectroscopy,high-speed communication,distance ranging,molecule detection,and many others.Due to the rapid development of micro/nanofabrication technology,breakthroughs in the quality factor of microresonators enable ultrahigh energy buildup inside cavities,which gives birth to microcavity-based frequency combs.In particular,the full coherent spectrum of the soliton microcomb(SMC)provides a route to low-noise ultrashort pulses with a repetition rate over two orders of magnitude higher than that of traditional mode-locking approaches.This enables lower power consumption and cost for a wide range of applications.This review summarizes recent achievements in SMCs,including the basic theory and physical model,as well as experimental techniques for single-soliton generation and various extraordinary soliton states(soliton crystals,Stokes solitons,breathers,molecules,cavity solitons,and dark solitons),with a perspective on their potential applications and remaining challenges.展开更多
Dual-comb spectroscopy(DCS) is a powerful tool in molecular spectroscopy benefiting from the advantages of high resolution and short measurement time. The recently developed soliton microcomb(SMC) can potentially tran...Dual-comb spectroscopy(DCS) is a powerful tool in molecular spectroscopy benefiting from the advantages of high resolution and short measurement time. The recently developed soliton microcomb(SMC) can potentially transfer the dual-comb method to an on-chip platform. In this paper, we demonstrate DCS using two frequency scanning SMCs, termed scanning dual-microcomb spectroscopy(SDMCS). The two SMCs are generated by an auxiliary-assisted thermal balance scheme, and the pump laser frequency sweeps over one free spectral range of the microresonator(~49 GHz) using a feedback control system. The proposed SDMCS has a spectral resolution of 12.5 MHz, which is determined by the minimum sweeping step of the pump laser. Using this SDMCS system, we perform three types of gas molecule absorption spectroscopy recognition and gas concentration detection.This study paves the way for integrated DCS with a high signal-to-noise ratio, high spectral resolution, and fast acquisition rate.展开更多
The dissipative Kerr soliton microcomb provides a promising laser source for wavelength-division multiplexing(WDM)communication systems thanks to its compatibility with chip integration.However,the soliton microcomb c...The dissipative Kerr soliton microcomb provides a promising laser source for wavelength-division multiplexing(WDM)communication systems thanks to its compatibility with chip integration.However,the soliton microcomb commonly suffers from a low-power level due to the intrinsically limited energy conversion efficiency from the continuous-wave pump laser to ultra-short solitary pulses.Here,we exploit laser injection locking to amplify and equalize dissipative Kerr soliton comb lines,superior gain factor larger than 30 dB,and optical-signal-to-noise-ratio(OSNR)as high as 60 dB obtained experimentally,providing a potential pathway to constitute a high-power chip-integrated WDM laser source for optical communications.展开更多
Microcombs are revolutionizing optoelectronics by providing parallel, mutually coherent wavelengthchannels for time-frequency metrology and information processing. To implement this essential function inintegrated pho...Microcombs are revolutionizing optoelectronics by providing parallel, mutually coherent wavelengthchannels for time-frequency metrology and information processing. To implement this essential function inintegrated photonic systems, it is desirable to drive microcombs directly with an on-chip laser in a simpleand flexible way. However, two major difficulties have prevented this goal: (1) generating mode-lockedcomb states usually requires a significant amount of pump power and (2) the requirement to align laser andresonator frequency significantly complicates operation and limits the tunability of the comb lines. Here, weaddress these problems by using microresonators on an AlGaAs on-insulator platform to generate dark-pulsemicrocombs. This highly nonlinear platform dramatically relaxes fabrication requirements and leads to arecord-low pump power of <1 mW for coherent comb generation. Dark-pulse microcombs facilitated bythermally controlled avoided mode crossings are accessed by direct distributed feedback laser pumping.Without any feedback or control circuitries, the comb shows good coherence and stability. With around150 mW on-chip power, this approach also leads to an unprecedentedly wide tuning range of over one freespectral range (97.5 GHz). Our work provides a route to realize power-efficient, simple, and reconfigurablemicrocombs that can be seamlessly integrated with a wide range of photonic systems.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supported by the ERC Consolidator Grant TeraSHAPE(#773248)the H2020 project TeraSlice(#863322)+9 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-Stiftung,and by 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 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.
基金National Key Research and Development Program of China (2023YFB3906401, 2021YFA1400803)National Natural Science Foundation of China (12341403,12293054, 92463304, 12341402)+2 种基金Fundamental Research Funds for the Central Universities (021314380260)Zhangjiang LaboratoryNatural Science Foundation of Jiangsu Province (BK20221440)。
文摘Chip-based optical microresonators with ultra-high Q-factors are becoming increasingly important to a variety of applications. However, the losses of on-chip microresonators with the highest Q-factor reported in the past are still far from their material absorption limits. Here, we demonstrate an on-chip silica microresonator that has approached the absorption limit of the state-of-the-art material on chip, realizing, to our knowledge, record intrinsic Q-factors exceeding 3 billion at both 1560 nm and 1064 nm. This fact is corroborated by photo-thermal spectroscopy measurements. Especially, compared with the standard optical fibers, its corresponding optical losses are only 38.4 times and 7.7 times higher at the wavelengths of 1560 nm and 1064 nm, respectively.To exhibit the performance of such fabricated microresonator, we achieve a record-low optical parametric oscillation threshold(31.9 μW) for millimeter-sized microresonators and generate a single-soliton microcomb with a record-low pump power of 220.2 μW for all soliton microcombs realized thus far.
基金National Natural Science Foundation of China(NSFC)(Grant Nos.62375292 and 61975242)Natural Science Foundation of Guangdong Province for Distinguished Young Scholars(No.2023B1515020028)Fund of Sun Yat-sen University(No.12240012).
文摘Mid-infrared(MIR)Kerr microcombs are of significant interest for portable dual-comb spectroscopy and precision molecular sensing due to strong molecular vibrational absorption in the MIR band.However,achieving a compact,octave-spanning MIR Kerr microcomb remains a challenge due to the lack of suitable MIR photonic materials for the core and cladding of integrated devices and appropriate MIR continuous-wave(CW)pump lasers.Here,we propose a novel slot concentric dual-ring(SCDR)microresonator based on an integrated chalcogenide glass chip,which offers excellent transmission performance and flexible dispersion engineering in the MIR band.This device achieves both phase-matching and group velocity matching in two separated anomalous dispersion regions,enabling phase-locked,two-color solitons in the MIR region with a commercial 2-μm CW laser as the pump source.Moreover,the spectral locking of the two-color soliton enhances pump wavelength selectivity,providing precise control over soliton dynamics.By leveraging the dispersion characteristics of the SCDR microresonator,we have demonstrated a multi-octave-spanning,two-color soliton microcomb,covering a spectral range from 1156.07 to 5054.95 nm(200 THz)at a-40 dB level,highlighting the versatility and broad applicability of our approach.And the proposed multi-octave MIR frequency comb is relevant for applications such as dual-comb spectroscopy and trace-gas sensing.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFB2205801)the National Natural Science Foundation of China(Grant Nos.12293052,12293050,11934012,12104442,12304435,and 92050109)+3 种基金the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-069)the Fundamental Research Funds for the Central Universitiesthe China Postdoctoral Science Foundation(Grant No.2023M733414)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB24030600)。
文摘For the applications of the frequency comb in microresonators,it is essential to obtain a fully frequency-stabilized microcomb laser source.In this study,we present a system for generating a fully atom-referenced stabilized soliton microcomb.The pump light around 1560.48 nm is locked to an ultra-low-expansion(ULE)cavity.This pump light is then frequency-doubled and referenced to the atomic transition of87Rb.The repetition rate of the soliton microcomb is injection-locked to an atomic-clockstabilized radio frequency(RF)source,leading to mHz stabilization at 1 s.As a result,all comb lines have been frequencystabilized based on the atomic reference and the ULE cavity,achieving a very high precision of approximately 18 Hz at 1 s,corresponding to the frequency stability of 9.5×10^(-14).Our approach provides a fully stabilized microcomb experiment scheme with no requirement of f-2f technique,which could be easily implemented and generalized to various photonic platforms,thus paving the way towards the ultraprecise optical sources for high precision spectroscopy.
基金supported by the National Key R&D Program of China under Grant(2019YFA0706301)the Key Project in Broadband Communication and New Network of the Ministry of Science and Technology(MOST)(2018YFB1801003)+1 种基金the National Science Foundation of China(NSFC)(U2001601,61975242,61525502,62175095,62375292)the Natural Science Foundation of Guangdong Province for Distinguished Young Scholars(2023B1515020028).
文摘High-quality photonic materials are critical for promoting integrated photonic devices with broad bandwidths,high efficiencies,and flexibilities for high-volume chip-scale fabrication.Recently,we designed a home-developed chalcogenide glass(ChG)-Ge_(25)Sb_(10)S_(65)(GeSbS)for optical information processing chips and systems,which featured an ultrabroad transmission window,a high Kerr nonlinearity and photoelastic coefficient,and compatibility with the photonic hybrid integration technology of silicon photonics.Chip-integrated GeSbS microresonators and microresonator arrays with high quality factors and lithographically controlled fine structures were fabricated using a modified nanofabrication process.Moreover,considering the high Kerr nonlinearity and photoelastic effect of ChGs,we realised a novel ChG hybrid integrated chip,inspired by recent advances in integrated soliton microcombs and acousto-optic(AO)modulators.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.61635013 and 61675231)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB24030600)the Youth Innovation Promotion Association of CAS(Grant No.2016353)。
文摘Optical frequency combs,a revolutionary light source characterized by discrete and equally spaced frequencies,are usually regarded as a cornerstone for advanced frequency metrology,precision spectroscopy,high-speed communication,distance ranging,molecule detection,and many others.Due to the rapid development of micro/nanofabrication technology,breakthroughs in the quality factor of microresonators enable ultrahigh energy buildup inside cavities,which gives birth to microcavity-based frequency combs.In particular,the full coherent spectrum of the soliton microcomb(SMC)provides a route to low-noise ultrashort pulses with a repetition rate over two orders of magnitude higher than that of traditional mode-locking approaches.This enables lower power consumption and cost for a wide range of applications.This review summarizes recent achievements in SMCs,including the basic theory and physical model,as well as experimental techniques for single-soliton generation and various extraordinary soliton states(soliton crystals,Stokes solitons,breathers,molecules,cavity solitons,and dark solitons),with a perspective on their potential applications and remaining challenges.
基金supported by the National Key R&D Program of China(Grant No. 2021YFB2800600)National Natural Science Foundation of China (Grant No. 62075238)。
文摘Dual-comb spectroscopy(DCS) is a powerful tool in molecular spectroscopy benefiting from the advantages of high resolution and short measurement time. The recently developed soliton microcomb(SMC) can potentially transfer the dual-comb method to an on-chip platform. In this paper, we demonstrate DCS using two frequency scanning SMCs, termed scanning dual-microcomb spectroscopy(SDMCS). The two SMCs are generated by an auxiliary-assisted thermal balance scheme, and the pump laser frequency sweeps over one free spectral range of the microresonator(~49 GHz) using a feedback control system. The proposed SDMCS has a spectral resolution of 12.5 MHz, which is determined by the minimum sweeping step of the pump laser. Using this SDMCS system, we perform three types of gas molecule absorption spectroscopy recognition and gas concentration detection.This study paves the way for integrated DCS with a high signal-to-noise ratio, high spectral resolution, and fast acquisition rate.
基金supported by the National Key R&D Program of China(Nos.2019YFB-2203103 and 2018YFA0307400)the National Natural Science Foundation of China(NSFC)(Nos.62001086 and 61705033)。
文摘The dissipative Kerr soliton microcomb provides a promising laser source for wavelength-division multiplexing(WDM)communication systems thanks to its compatibility with chip integration.However,the soliton microcomb commonly suffers from a low-power level due to the intrinsically limited energy conversion efficiency from the continuous-wave pump laser to ultra-short solitary pulses.Here,we exploit laser injection locking to amplify and equalize dissipative Kerr soliton comb lines,superior gain factor larger than 30 dB,and optical-signal-to-noise-ratio(OSNR)as high as 60 dB obtained experimentally,providing a potential pathway to constitute a high-power chip-integrated WDM laser source for optical communications.
文摘Microcombs are revolutionizing optoelectronics by providing parallel, mutually coherent wavelengthchannels for time-frequency metrology and information processing. To implement this essential function inintegrated photonic systems, it is desirable to drive microcombs directly with an on-chip laser in a simpleand flexible way. However, two major difficulties have prevented this goal: (1) generating mode-lockedcomb states usually requires a significant amount of pump power and (2) the requirement to align laser andresonator frequency significantly complicates operation and limits the tunability of the comb lines. Here, weaddress these problems by using microresonators on an AlGaAs on-insulator platform to generate dark-pulsemicrocombs. This highly nonlinear platform dramatically relaxes fabrication requirements and leads to arecord-low pump power of <1 mW for coherent comb generation. Dark-pulse microcombs facilitated bythermally controlled avoided mode crossings are accessed by direct distributed feedback laser pumping.Without any feedback or control circuitries, the comb shows good coherence and stability. With around150 mW on-chip power, this approach also leads to an unprecedentedly wide tuning range of over one freespectral range (97.5 GHz). Our work provides a route to realize power-efficient, simple, and reconfigurablemicrocombs that can be seamlessly integrated with a wide range of photonic systems.
