A new device of two parallel distributed feedback （DFB） lasers integrated monolithically with Y-branch waveguide coupler was fabricated by means of quantum well intermixing. Optical microwave signal was generated in...A new device of two parallel distributed feedback （DFB） lasers integrated monolithically with Y-branch waveguide coupler was fabricated by means of quantum well intermixing. Optical microwave signal was generated in the Y-branch waveguide coupler through frequency beating of the two laser modes coming from two DFB laser in parallel, which had a small difference in frequency. Continuous rapid tuning of optical microwave signal from 13 to 42 GHz were realized by adjusting independently the driving currents injected into the two DFB lasers.展开更多
Low-noise microwave generation is crucial for advanced applications such as 6G millimeter-wave communica-tions,satellite communications,and synthetic aperture radar systems.Traditional microwave sources encounter chal...Low-noise microwave generation is crucial for advanced applications such as 6G millimeter-wave communica-tions,satellite communications,and synthetic aperture radar systems.Traditional microwave sources encounter challenges in meeting stringent performance requirements while maintaining low size,weight,and power con-sumption(SWaP)at ever-increasing high frequencies.Photonic microwave generation is a promising solution to overcome these limitations,particularly when implemented with chip-scale integration using a simple yet efficient architecture.Here,we propose a chip-scale integrated photonic microwave generator(IPMG)scheme that features a low-noise hybrid InP/Si_(3)N_(4)comb laser based on the self-injection locking mechanism,in conjunction with the optic-electro-optic feedback to further enhance the RF generation performance.The proof-of-concept IPMG prototype has demonstrated superior performance,highlighting an ultra-narrow RF intrinsic linewidth of 0.8 Hz,low single-sideband phase noises of-92.1 dBc/Hz at 10 kHz offset and-128.3 dBc/Hz at 1 MHz offset,and excellent frequency stability with only 16 kHz fluctuations over 5 min.This work marks a substantial advancement in the development of fully integrated photonic microwave generators by unifying good performance,architectural simplicity,and low SWaP.展开更多
A low noise oscillator is a crucial component in determining system performance in modern communication,microwave spectroscopy,microwave-based sensing(including radar and remote sensing),and metrology systems.In recen...A low noise oscillator is a crucial component in determining system performance in modern communication,microwave spectroscopy,microwave-based sensing(including radar and remote sensing),and metrology systems.In recent years,ultra-low phase noise photonic microwave oscillators based on optical frequency division have become a paradigm shift for the generation of high performance microwave signals.In this work,we report on-chip low phase noise photonic microwave generation based on spiral resonator referenced lasers and an integrated electro-optical frequency comb.Dual lasers are co-locked to an ultra-high-Q silicon nitride spiral resonator and their relative phase noise is measured below the cavity thermal noise limit,resulting in record low onchip optical phase noise.A broadband integrated electro-optic frequency comb is utilized to divide down the relative phase noise of the spiral resonator referenced lasers to the microwave domain,resulting in recordlow phase noise for chip-based oscillators(-69 d Bc∕Hz at 10 Hz offset,and-144 d Bc∕Hz at 10 k Hz offset for a 10 GHz carrier scaled from 37.3 GHz output).The exceptional phase noise performance,planar chip design,high technology readiness level,and foundry-ready processing of the current work represent a major advance of integrated photonic microwave oscillators.展开更多
Ultra-low-noise microwave signals play a driving role in the development of modern scientific technologies such as radar,communication,and sensing.On-chip photonic integration provides an attractive approach for the i...Ultra-low-noise microwave signals play a driving role in the development of modern scientific technologies such as radar,communication,and sensing.On-chip photonic integration provides an attractive approach for the implementation of ultra-low-noise microwave signal sources with attractive added advantages of being compact and lightweight,which are vitally important for real-world applications.Coupled optoelectronic oscillators(COEOs)with a hybrid structure of an optical loop and an optoelectronic loop are high-performance microwave photonic signal sources,which feature a unique advantage over conventional single-loop OEOs since they can achieve ultra-low phase noise with a relatively short cavity length.Here we report a wideband tunable ultra-lownoise integrated COEO(ICOEO),which is realized by integrating its key optoelectronic components(electrooptic modulator,photodetector,optical filter,etc.)on silicon-on-insulator(SOI).A wideband frequency tuning range from 2 GHz to 30 GHz is obtained,covering the entire S,C,X,Ku,and K bands.The phase noise is as low as−132 dBc/Hz@10 kHz,which is 19 dB better than that of the single-loop OEO with a similar cavity length.We also improved the long-term stability of the ICOEO by injection locking,and the Allan deviation of the produced microwave signal reaches 10^(−12)@1 s.The high-performance ICOEO can find a wide range of applications including modern radar,electronic warfare,and communication systems.展开更多
We demonstrate the ultra-stable frequency sources aiming to improve the short-time instability of primary frequency standards.These sources are realized by using photonic generation approach,and composed of ultra-stab...We demonstrate the ultra-stable frequency sources aiming to improve the short-time instability of primary frequency standards.These sources are realized by using photonic generation approach,and composed of ultra-stable lasers,optical-frequency-combs,optical signal detecting parts,and synthesizers.Preliminary evaluation shows that the sources produce fixed-frequency at 9.54(/9.63)GHz,10 MHz,and tunable-frequency around 9.192 GHz with relative frequency instability of 10^(-15) for short terms.展开更多
We demonstrate an all-fiber-based photonic microwave generation with 10^(-15) frequency instability.The system consists of an ultra-stable laser by optical fiber delay line,an all-fiber-based"figure-of-nine"...We demonstrate an all-fiber-based photonic microwave generation with 10^(-15) frequency instability.The system consists of an ultra-stable laser by optical fiber delay line,an all-fiber-based"figure-of-nine"optical frequency comb,a high signal-tonoise ratio photonic detection unit,and a microwave frequency synthesizer.The whole optical links are made from optical fiber and optical fiber components,which renders the whole system compactness,reliability,and robustness with respect to environmental influences.Frequency instabilities of 3.5×10^(-15) at 100 s for 6.834 GHz signal and 4.3×10^(-15) at 100 s for9.192 GHz signal were achieved.展开更多
Radio frequency/microwave-directed energy sources using wide bandgap SiC photoconductive semiconductors have attracted much attention due to their unique advantages of high-power output and multi-parameter adjustable ...Radio frequency/microwave-directed energy sources using wide bandgap SiC photoconductive semiconductors have attracted much attention due to their unique advantages of high-power output and multi-parameter adjustable ability.Over the past several years,benefitting from the sustainable innovations in laser technology and the significant progress in materials technology,megawatt-class output power electrical pulses with a flexible frequency in the P and L microwave wavebands have been achieved by photoconductive semiconductor devices.Here,we mainly summarize and review the recent progress of the high-power photonic microwave generation based on the SiC photoconductive semiconductor devices in the linear modulation mode,including the mechanism,system architecture,critical technology,and experimental demonstration of the proposed high-power photonic microwave sources.The outlooks and challenges for the future of multi-channel power synthesis development of higher power photonic microwave using wide bandgap photoconductors are also discussed.展开更多
Optical beating is the usual approach to generation of microwave signals.However,the highest frequency achievable for microwave signals is limited by the bandwidths of optoelectronic devices.To maximize the microwave ...Optical beating is the usual approach to generation of microwave signals.However,the highest frequency achievable for microwave signals is limited by the bandwidths of optoelectronic devices.To maximize the microwave frequency with a limited bandwidth of a photodetector(PD)and relieve the bandwidth bottleneck,we propose to generate microwave signals with the single sideband(SSB)format by beating a continuous wave(CW)light with an optical SSB signal.By simply adjusting the frequency diference between the CW light and the carrier of the optical SSB signal,the frequency of the generated microwave SSB signal is changed correspondingly.In the experiment,amplitude shift keying(ASK)microwave signals with the SSB format are successfully generated with diferent carrier frequencies and coding bit rates,and the recovered coding information agrees well with the original pseudo random binary sequence(PRBS)of 2^(7)−1 bits.The proposed approach can signifcantly relieve the bandwidth restriction set by optoelectronic devices in high-speed microwave communication systems.展开更多
Microresonator-based Kerr frequency combs(“Kerr microcombs”)constitute chip-scale frequency combs of broad spectral bandwidth and repetition rate ranging from gigahertz to terahertz.A critical application that explo...Microresonator-based Kerr frequency combs(“Kerr microcombs”)constitute chip-scale frequency combs of broad spectral bandwidth and repetition rate ranging from gigahertz to terahertz.A critical application that exploits the coherence and high repetition rate of microcombs is microwave and millimeter-wave generation.Latest endeavor applying two-point optical frequency division(OFD)to photonic-chip-based microcombs has created microwaves with remarkably low phase noise.Nevertheless,existing approaches to achieve exceptionally coherent microcombs still require extensive active locking,additional lasers,and external RF or microwave sources,as well as sophisticated initiation.Here we demonstrate a simple and entirely passive(no active locking)architecture,which incorporates an optoelectronic oscillator(OEO)and symphonizes a coherent microcomb and a low-noise microwave spontaneously.Our OEO microcomb leverages state-of-the-art integrated chip devices,including a high-power DFB laser,a broadband silicon Mach–Zehnder modulator,an ultralow-loss silicon nitride microresonator,and a high-speed photodetector.Each can be manufactured in large volume with low cost and high yield using established CMOS and Ⅲ-Ⅴ foundries.Our system synergizes a microcomb of 10.7 GHz repetition rate and an X-band microwave with phase noise of−97/−126/−130 dBc/Hz at 1/10/100 kHz Fourier frequency offset,yet does not demand active locking,additional lasers,and external RF or microwave sources.With potential to be fully integrated,our OEO microcomb can become an invaluable technology and building block for microwave photonics,radio-over-fiber,and optical communication.展开更多
An approach to generate high-speed and wideband frequency shift keying(FSK)signals based on carrier phase-shifted double sideband(CPS-DSB)modulation is proposed and experimentally validated.The core part of the scheme...An approach to generate high-speed and wideband frequency shift keying(FSK)signals based on carrier phase-shifted double sideband(CPS-DSB)modulation is proposed and experimentally validated.The core part of the scheme is a pair of cascaded polarization-sensitive LiNbO_(3) Mach–Zehnder modulators and phase modulators,whose polarization directions of the principal axes are mutually orthogonal to each other.A proof-of-concept experiment is carried out,where a 0.5 Gb/s FSK signal with the carrier frequencies of 4 and 8 GHz and a 1 Gb/s FSK signal with the carrier frequencies of 8 and 16 GHz are generated successfully.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 90401025）. Acknowledgments The authors are grateful to the Multiple-function 0ptoelectronic Integration group, Institute of Semiconductors, CAS for sponsoring this project. We extend our thanks to Professor Wang Zi-Yu of Peking University for microwave signal testing.
文摘A new device of two parallel distributed feedback （DFB） lasers integrated monolithically with Y-branch waveguide coupler was fabricated by means of quantum well intermixing. Optical microwave signal was generated in the Y-branch waveguide coupler through frequency beating of the two laser modes coming from two DFB laser in parallel, which had a small difference in frequency. Continuous rapid tuning of optical microwave signal from 13 to 42 GHz were realized by adjusting independently the driving currents injected into the two DFB lasers.
基金National Natural Science Foundation of China(U22A6004)Pengcheng Laboratory-China Mobile Scientific and Technological Innovation Fund(2024ZY2A0020).
文摘Low-noise microwave generation is crucial for advanced applications such as 6G millimeter-wave communica-tions,satellite communications,and synthetic aperture radar systems.Traditional microwave sources encounter challenges in meeting stringent performance requirements while maintaining low size,weight,and power con-sumption(SWaP)at ever-increasing high frequencies.Photonic microwave generation is a promising solution to overcome these limitations,particularly when implemented with chip-scale integration using a simple yet efficient architecture.Here,we propose a chip-scale integrated photonic microwave generator(IPMG)scheme that features a low-noise hybrid InP/Si_(3)N_(4)comb laser based on the self-injection locking mechanism,in conjunction with the optic-electro-optic feedback to further enhance the RF generation performance.The proof-of-concept IPMG prototype has demonstrated superior performance,highlighting an ultra-narrow RF intrinsic linewidth of 0.8 Hz,low single-sideband phase noises of-92.1 dBc/Hz at 10 kHz offset and-128.3 dBc/Hz at 1 MHz offset,and excellent frequency stability with only 16 kHz fluctuations over 5 min.This work marks a substantial advancement in the development of fully integrated photonic microwave generators by unifying good performance,architectural simplicity,and low SWaP.
基金Defense Advanced Research Projects Agency(HR001122C0019)。
文摘A low noise oscillator is a crucial component in determining system performance in modern communication,microwave spectroscopy,microwave-based sensing(including radar and remote sensing),and metrology systems.In recent years,ultra-low phase noise photonic microwave oscillators based on optical frequency division have become a paradigm shift for the generation of high performance microwave signals.In this work,we report on-chip low phase noise photonic microwave generation based on spiral resonator referenced lasers and an integrated electro-optical frequency comb.Dual lasers are co-locked to an ultra-high-Q silicon nitride spiral resonator and their relative phase noise is measured below the cavity thermal noise limit,resulting in record low onchip optical phase noise.A broadband integrated electro-optic frequency comb is utilized to divide down the relative phase noise of the spiral resonator referenced lasers to the microwave domain,resulting in recordlow phase noise for chip-based oscillators(-69 d Bc∕Hz at 10 Hz offset,and-144 d Bc∕Hz at 10 k Hz offset for a 10 GHz carrier scaled from 37.3 GHz output).The exceptional phase noise performance,planar chip design,high technology readiness level,and foundry-ready processing of the current work represent a major advance of integrated photonic microwave oscillators.
基金Natural Science Foundation of Beijing Municipality(Z210005)National Natural Science Foundation of China(62205329,61925505,62235015)Young Elite Scientists Sponsorship Program by CAST(YESS20230216)。
文摘Ultra-low-noise microwave signals play a driving role in the development of modern scientific technologies such as radar,communication,and sensing.On-chip photonic integration provides an attractive approach for the implementation of ultra-low-noise microwave signal sources with attractive added advantages of being compact and lightweight,which are vitally important for real-world applications.Coupled optoelectronic oscillators(COEOs)with a hybrid structure of an optical loop and an optoelectronic loop are high-performance microwave photonic signal sources,which feature a unique advantage over conventional single-loop OEOs since they can achieve ultra-low phase noise with a relatively short cavity length.Here we report a wideband tunable ultra-lownoise integrated COEO(ICOEO),which is realized by integrating its key optoelectronic components(electrooptic modulator,photodetector,optical filter,etc.)on silicon-on-insulator(SOI).A wideband frequency tuning range from 2 GHz to 30 GHz is obtained,covering the entire S,C,X,Ku,and K bands.The phase noise is as low as−132 dBc/Hz@10 kHz,which is 19 dB better than that of the single-loop OEO with a similar cavity length.We also improved the long-term stability of the ICOEO by injection locking,and the Allan deviation of the produced microwave signal reaches 10^(−12)@1 s.The high-performance ICOEO can find a wide range of applications including modern radar,electronic warfare,and communication systems.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91536217,61127901,and 11775253)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2015334)The authors would like to thank special funds for scientific equipment development(YZ201518)from Chinese academy of sciences for the use of the developed equipment
文摘We demonstrate the ultra-stable frequency sources aiming to improve the short-time instability of primary frequency standards.These sources are realized by using photonic generation approach,and composed of ultra-stable lasers,optical-frequency-combs,optical signal detecting parts,and synthesizers.Preliminary evaluation shows that the sources produce fixed-frequency at 9.54(/9.63)GHz,10 MHz,and tunable-frequency around 9.192 GHz with relative frequency instability of 10^(-15) for short terms.
基金This work was supported by the National Natural Science Foundation of China(Nos.11034008,11274324,11604353,and 61805262)。
文摘We demonstrate an all-fiber-based photonic microwave generation with 10^(-15) frequency instability.The system consists of an ultra-stable laser by optical fiber delay line,an all-fiber-based"figure-of-nine"optical frequency comb,a high signal-tonoise ratio photonic detection unit,and a microwave frequency synthesizer.The whole optical links are made from optical fiber and optical fiber components,which renders the whole system compactness,reliability,and robustness with respect to environmental influences.Frequency instabilities of 3.5×10^(-15) at 100 s for 6.834 GHz signal and 4.3×10^(-15) at 100 s for9.192 GHz signal were achieved.
基金supported in part by the National Natural Science Foundation of China(Nos.62071477 and 62101577)the Natural Science Foundation of Hunan Province(No.2021JJ40660)。
文摘Radio frequency/microwave-directed energy sources using wide bandgap SiC photoconductive semiconductors have attracted much attention due to their unique advantages of high-power output and multi-parameter adjustable ability.Over the past several years,benefitting from the sustainable innovations in laser technology and the significant progress in materials technology,megawatt-class output power electrical pulses with a flexible frequency in the P and L microwave wavebands have been achieved by photoconductive semiconductor devices.Here,we mainly summarize and review the recent progress of the high-power photonic microwave generation based on the SiC photoconductive semiconductor devices in the linear modulation mode,including the mechanism,system architecture,critical technology,and experimental demonstration of the proposed high-power photonic microwave sources.The outlooks and challenges for the future of multi-channel power synthesis development of higher power photonic microwave using wide bandgap photoconductors are also discussed.
基金the National Natural Science Foundation of China(Grant No.61975249)the National Key Research and Development Program of China(Nos.2018YFB2201700 and 2018YFA0704403)the Program for HUST Academic Frontier Youth Team(No.2018QYTD08).
文摘Optical beating is the usual approach to generation of microwave signals.However,the highest frequency achievable for microwave signals is limited by the bandwidths of optoelectronic devices.To maximize the microwave frequency with a limited bandwidth of a photodetector(PD)and relieve the bandwidth bottleneck,we propose to generate microwave signals with the single sideband(SSB)format by beating a continuous wave(CW)light with an optical SSB signal.By simply adjusting the frequency diference between the CW light and the carrier of the optical SSB signal,the frequency of the generated microwave SSB signal is changed correspondingly.In the experiment,amplitude shift keying(ASK)microwave signals with the SSB format are successfully generated with diferent carrier frequencies and coding bit rates,and the recovered coding information agrees well with the original pseudo random binary sequence(PRBS)of 2^(7)−1 bits.The proposed approach can signifcantly relieve the bandwidth restriction set by optoelectronic devices in high-speed microwave communication systems.
基金support from the National Key R&D Program of China(Grant No.2024YFA1409300)National Natural Science Foundation of China(Grant No.12261131503,12404436,12404417,62405202,61975121,62205145)+3 种基金Innovation Program for Quantum Science and Technology(2023ZD0301500)Shenzhen Science and Technology Program(Grant No.RCJC20231211090042078)Shenzhen-Hong Kong Cooperation Zone for Technology and Innovation(HZQB-KCZYB2020050)Guangdong-Hong Kong Technology Cooperation Funding Scheme(Grant No.2024A0505040008).
文摘Microresonator-based Kerr frequency combs(“Kerr microcombs”)constitute chip-scale frequency combs of broad spectral bandwidth and repetition rate ranging from gigahertz to terahertz.A critical application that exploits the coherence and high repetition rate of microcombs is microwave and millimeter-wave generation.Latest endeavor applying two-point optical frequency division(OFD)to photonic-chip-based microcombs has created microwaves with remarkably low phase noise.Nevertheless,existing approaches to achieve exceptionally coherent microcombs still require extensive active locking,additional lasers,and external RF or microwave sources,as well as sophisticated initiation.Here we demonstrate a simple and entirely passive(no active locking)architecture,which incorporates an optoelectronic oscillator(OEO)and symphonizes a coherent microcomb and a low-noise microwave spontaneously.Our OEO microcomb leverages state-of-the-art integrated chip devices,including a high-power DFB laser,a broadband silicon Mach–Zehnder modulator,an ultralow-loss silicon nitride microresonator,and a high-speed photodetector.Each can be manufactured in large volume with low cost and high yield using established CMOS and Ⅲ-Ⅴ foundries.Our system synergizes a microcomb of 10.7 GHz repetition rate and an X-band microwave with phase noise of−97/−126/−130 dBc/Hz at 1/10/100 kHz Fourier frequency offset,yet does not demand active locking,additional lasers,and external RF or microwave sources.With potential to be fully integrated,our OEO microcomb can become an invaluable technology and building block for microwave photonics,radio-over-fiber,and optical communication.
基金supported by the National Natural Science Foundation of China(Nos.U2006217,61775015,61801017,and 61827818)。
文摘An approach to generate high-speed and wideband frequency shift keying(FSK)signals based on carrier phase-shifted double sideband(CPS-DSB)modulation is proposed and experimentally validated.The core part of the scheme is a pair of cascaded polarization-sensitive LiNbO_(3) Mach–Zehnder modulators and phase modulators,whose polarization directions of the principal axes are mutually orthogonal to each other.A proof-of-concept experiment is carried out,where a 0.5 Gb/s FSK signal with the carrier frequencies of 4 and 8 GHz and a 1 Gb/s FSK signal with the carrier frequencies of 8 and 16 GHz are generated successfully.
