The optoelectronic oscillator(OEO)is a typical time-delay system with rich nonlinear dynamical characteristics.Most of the previous research on OEOs has been focused on analyzing the properties of OEOs with a long tim...The optoelectronic oscillator(OEO)is a typical time-delay system with rich nonlinear dynamical characteristics.Most of the previous research on OEOs has been focused on analyzing the properties of OEOs with a long time delay,which makes it difficult to realize mode locking without additional phaselocking mechanisms.We have achieved,for the first time to our knowledge,a self-mode-locking OEO and generated stable microwave frequency combs by analyzing the characteristics of OEOs with an ultrashort time scale.In the experiment,the self-mode-locking OEOs with fundamental mode,second-order harmonic,and sixth-order harmonic were realized by adjusting the system parameters,all of which produced uniform square wave signals with tunable duty cycles,steep rising and falling edges,and periods of less than 20 ns.The self-fundamental-mode-locking OEOs with different time delays were also implemented and experimentally realized.Furthermore,the experiment revealed the self-hybrid mode-locking OEO,which is the coexistence and synchronization of the three measured self-locking modes in one OEO cavity,demonstrating the complex nonlinear dynamical behaviors of the OEO system and enabling the generation of periodic nonuniform hybrid square wave signals.The realization of the self-mode-locking OEO and the generation of flexible and stable square wave signals at ultrashort time scales enrich the study of OEO nonlinear dynamics in the realm of complex microwave waveform generation,offering promising applications in areas such as atomic clocks,radars,communications,and optoelectronic neural networks.展开更多
Parity‐time(PT)symmetry breaking offers mode selection capability for facilitating single‐mode oscillation in the optoelectronic oscillator(OEO)loop.However,most OEO implementations depend on discrete devices,which ...Parity‐time(PT)symmetry breaking offers mode selection capability for facilitating single‐mode oscillation in the optoelectronic oscillator(OEO)loop.However,most OEO implementations depend on discrete devices,which impedes proliferation due to size,weight,power consumption,and cost.In this work,we propose and experimentally demonstrate an on-chip tunable PT‐symmetric OEO.A tunable microwave photonic filter,a PT‐symmetric mode‐selective architecture,and two photodetectors are integrated on a silicon‐on‐insulator chip.By exploiting an on‐chip Mach–Zehnder interferometer to match the gain and loss of two mutually coupled optoelectronic loops,single‐mode oscillation can be obtained.In the experiment,the oscillation frequency of the on-chip tunable PT‐symmetric OEO can be tuned from 0 to 20 GHz.To emulate the integrated case,the OEO loop length is minimized,and no extra-long fiber is used in the experiment.When the oscillation frequency is 13.67 GHz,the single‐sideband phase noise at 10-kHz offset frequency is−80.96 dBc∕Hz and the side mode suppression ratio is 46 dB.The proposed on-chip tunable PT‐symmetric OEO significantly reduces the footprint of the system and enhances mode selection.展开更多
High-performance interrogation systems for optical fiber sensors are extensively required for environmental condition monitoring applications.In this article,we propose and demonstrate a Michelson interferometer(MI)in...High-performance interrogation systems for optical fiber sensors are extensively required for environmental condition monitoring applications.In this article,we propose and demonstrate a Michelson interferometer(MI)interrogation system based on an optoelectronic oscillator(OEO).The frequency of the OEO is related to the free spectral range(FSR)of the MI.Thus,when the FSR of the MI varies with a change in external physical factors,the frequency of the OEO shifts and can be used for interrogation.We demonstrate that the temperature sensitivity and interrogation resolution are 35.35 MHz/℃and 0.012℃,respectively.Such an OEO-based scheme enables wavelength-to-frequency mapping and promises a wide linear interrogation range,high resolution and high-speed interrogation.展开更多
A wideband tunable frequency-doubling optoelectronic oscillator （FD-OEO） is proposed and experimentally demonstrated based on a polarization modulator and an optical bandpass filter （OBPF）. The central frequency o...A wideband tunable frequency-doubling optoelectronic oscillator （FD-OEO） is proposed and experimentally demonstrated based on a polarization modulator and an optical bandpass filter （OBPF）. The central frequency of the correspondingly fundamental OEO could be adjusted by tuning the bandwidth and central frequency of the OBPF, which could also be regarded as a photonic-assisted tunable microwave filter. The frequency tuning range of the FD-OEO covers from 9.5 to 32.8？GHz, and the single sideband phase noise of the fundamental signal is lower than -100dBc/Hz at an offset of 10？kHz. Moreover, the frequency stability of the generated signal is investigated by measuring its Allan deviation. The Allan deviation of the generated fundamental signal at 10？GHz is 2.39×10^-9.展开更多
An approach for frequency division of an optical pulse train(OPT) based on an optoelectronic oscillator(OEO) is proposed and experimentally demonstrated. When the OPT is injected into the OEO, a microwave signal with ...An approach for frequency division of an optical pulse train(OPT) based on an optoelectronic oscillator(OEO) is proposed and experimentally demonstrated. When the OPT is injected into the OEO, a microwave signal with a frequency equaling fractional multiples of the repetition rate of the OPT is generated. This signal is then fed back to the OEO, maintaining its oscillation, while simultaneously serving as the control signal of a Mach–Zehnder modulator(MZM) in the OEO. The MZM acts as an optical switch, permitting specific pulses to pass through while blocking others. As a result, the repetition rate of the OPT is manipulated. A proof-of-concept experiment is carried out. Frequency division factors of 2 and 3 are successfully achieved. The phase noises of the OPT before and after the frequency division are investigated. Compared to previously reported systems, no external microwave source and sophisticated synchronization structure are needed.展开更多
An optoelectronic oscillator(OEO)is a microwave photonic system that produces microwave signals with ultralow phase noise using a high-quality-factor optical energy storage element.This type of oscillator is desired i...An optoelectronic oscillator(OEO)is a microwave photonic system that produces microwave signals with ultralow phase noise using a high-quality-factor optical energy storage element.This type of oscillator is desired in various practical applications,such as communication links,signal processing,radar,metrology,radio astronomy,and reference clock distribution.Recently,new mode control and selection methods based on Fourier domain mode-locking and parity-time symmetry have been proposed and experimentally demonstrated in OEOs,which overcomes the long-existing mode building time and mode selection problems in a traditional OEO.Due to these mode control and selection methods,continuously chirped microwave waveforms can be generated directly from the OEO cavity and single-mode operation can be achieved without the need of ultranarrowband filters,which are not possible in a traditional OEO.Integrated OEOs with a compact size and low power consumption have also been demonstrated,which are key steps toward a new generation of compact and versatile OEOs for demanding applications.We review recent progress in the field of OEOs,with particular attention to new mode control and selection methods,as well as chip-scale integration of OEOs.展开更多
A polarization-maintained coupled optoelectronic oscillator（COEO） with its performance significantly improved by a short-length unpumped erbium-doped fiber（EDF） is reported and experimentally investigated.A 10 GHz...A polarization-maintained coupled optoelectronic oscillator（COEO） with its performance significantly improved by a short-length unpumped erbium-doped fiber（EDF） is reported and experimentally investigated.A 10 GHz optical pulse train with a supermode suppression ratio of 61.8 d B and a 10 GHz radio frequency signal with a sidemode suppression ratio of 94 d B and a phase noise of-121.9 d Bc∕Hz at 10 k Hz offset are simultaneously generated. Thanks to saturable absorption of the 1 m unpumped EDF, which introduces relatively large cavity loss to the undesired modes and noise, the supermode suppression ratio and the phase noise are improved by 9.4 and 7.9 d B, respectively.展开更多
A tunable frequency-multiplying optoelectronic oscillator(OEO) based on a dual-parallel Mach-Zehnder modulator(DPMZM) is proposed and experimentally demonstrated. In the proposed system, the tunable fundamental microw...A tunable frequency-multiplying optoelectronic oscillator(OEO) based on a dual-parallel Mach-Zehnder modulator(DPMZM) is proposed and experimentally demonstrated. In the proposed system, the tunable fundamental microware signal is generated by a tunable optoelectronic oscillator incorporating a phase-shifted fiber Bragg grating(PS-FBG). By adjusting the DC bias of the DPMZM, the frequency-doubled microwave signal with a tunable frequency range from 11 GHz to 20 GHz and the frequency-quadrupled microwave signal with a tunable frequency range from 22.5 GHz to 26 GHz are generated. The phase noises of the fundamental, frequency-doubled and frequency-quadrupled signals at 10 k Hz offset frequency are-105.9 d Bc/Hz,-103.3 d Bc/Hz and-86.2 d Bc/Hz, respectively.展开更多
A novel fiber-optic magnetic field sensor with high interrogation speed and resolution by using an etched fiber Bragg grating(FBG)in conjunction with a dual-loop optoelectronic oscillator(OEO)is proposed and experimen...A novel fiber-optic magnetic field sensor with high interrogation speed and resolution by using an etched fiber Bragg grating(FBG)in conjunction with a dual-loop optoelectronic oscillator(OEO)is proposed and experimentally demonstrated.A commercial FBG is firstly dipped into mixed hydrofluoric acid solution to remove the cladding layer and then is embedded with the magnetic fluid(MF)as a sensing element.The central wavelength reflected from the FBG is related to the overall time delay of the dual-loop OEO,which determines the oscillating frequency of the OEO.Therefore,the magnetic field can be estimated by measuring the oscillating frequency shift of OEO.The experimental results show that the oscillating frequency linearly increases with the increment of the magnetic field,achieving the sensitivity of 16.3 Hz/Oe with a R-square of 0.991 in the range of 5 mT-10 mT.In addition,the maximum error is within±0.05 mT in the range of 7 mT-8 mT,which offers potentials in many fields where the high-precision magnetic field measurement is required.展开更多
In this work,via autocorrelation function(ACF)and permutation entropy(PE)methods,we numerically investigate the time-delay signature(TDS)characteristics of the chaotic signal output from an optoelectronic oscillator(O...In this work,via autocorrelation function(ACF)and permutation entropy(PE)methods,we numerically investigate the time-delay signature(TDS)characteristics of the chaotic signal output from an optoelectronic oscillator(OEO)after introducing an extra optical feedback loop.The results demonstrate that,for such a chaotic system,both the optoelectronic feedback with a delay time of T1 and the optical feedback with a delay time of T2 contribute to the TDS of generated chaos.The TDS of the chaotic signal should be evaluated within a large time window including T1 and T2 by the strongest peak in the ACF curve of the chaotic signal,and the strongest peak may locate at near T1 or T2.Through mapping the evolution of the TDS in the parameter space of the optical feedback strength and time,certain optimized parameter regions for achieving a chaotic signal with a relatively weak TDS can be determined.展开更多
Photonic generation of radio-frequency（RF） arbitrary microwave waveform with ultra-wide frequency tunable range based on a dispersion compensated optoelectronic oscillator（OEO） is proposed and experimentally demon...Photonic generation of radio-frequency（RF） arbitrary microwave waveform with ultra-wide frequency tunable range based on a dispersion compensated optoelectronic oscillator（OEO） is proposed and experimentally demonstrated. Dispersion compensation scheme and specially designed fiber Bragg grating（FBG）-based Fabry-Perot（F-P） filters are employed in the OEO loop to realize a frequency tunable range of 3.5-45.4 GHz. An optimization process provided by the combination of an erbium-doped fiber amplifier（EDFA）and FBG is employed to improve the signal-to-noise ratio（SNR） of final RF signals. The generation of linearfrequency and phase-coded microwave waveforms, with a tunable carrier frequency ranging from 4 to 45 GHz and tuned chirping bandwidths or code rates, is experimentally demonstrated.展开更多
The emerging new concepts and technologies based on microwave photonics have led to an ever-increasing interest in developing innovative radar systems with a net gain in functionality,bandwidth /resolution,size,mass,c...The emerging new concepts and technologies based on microwave photonics have led to an ever-increasing interest in developing innovative radar systems with a net gain in functionality,bandwidth /resolution,size,mass,complexity and cost when compared with the traditional implementations. This paper describes the techniques developed in the last few years in microwave photonics that might revolutionize the way to design multifunction radar systems,with an emphasis on the recent advances in optoelectronic oscillators( OEOs),arbitrary waveform generation,photonic mixing,phase coding,filtering,beamforming,analog-to-digital conversion,and stable radio-frequency signal transfer. Challenges in implementation of these components and subsystems for meeting the technique requirements of the multifunction radar applications are discussed.展开更多
A novel dual-loop technique was proposed for single-mode selection in an optoelectronic oscillator （OEO）. It consisted of a pump laser and a feedback circuit including an intensity modulator, a Fabry-Perot （FP） et...A novel dual-loop technique was proposed for single-mode selection in an optoelectronic oscillator （OEO）. It consisted of a pump laser and a feedback circuit including an intensity modulator, a Fabry-Perot （FP） etalon, two optical fiber delay lines, two photodetectors, and an amplifier. By inserting the Fabry-Perot etalon, the proposed dual-loop OEO realized a single mode oscillation ranging from 0 Hz to 20 GHz. The strong oscillation mode was present at 15 GHz, and the side modes suppression ratio （SMSR） exceeded 140dB. More over the length of the two fiber loops were just 5 meters and 36 meters.展开更多
Weak RF signal detection with high resolution and no blind zone based on directly modulated multi-mode optoelectronic oscillation has been proposed.The high-sensitivity optical modulators and optical filters are avoid...Weak RF signal detection with high resolution and no blind zone based on directly modulated multi-mode optoelectronic oscillation has been proposed.The high-sensitivity optical modulators and optical filters are avoided because multi-mode oscillation is obtained based on directly modulating the semiconductor laser at the relaxation oscillation frequency.For the directly modulated optoelectronic oscillator,the detection characteristics such as gain for the RF signal,resolution,noise floor,and sensitivity are firstly analyzed.The experimental results are consistent with the simulated results.For the RF signal of unknown frequency,it can be detected out and amplified by tuning the bias current and delay time of the loop.There is no blind zone within 1–4.5 GHz.The system provides a maximum gain of 17.88 dB for the low-power RF signal.The sensitivity of the system can reach as high as-95 dBm.The properties such as gain dynamic range and power stability are also investigated.The system has potential for weak RF signal detection,especially for the RF signal with unknown frequency.展开更多
Photonic microwave harmonic down-converters (PMHDCs) based on self-oscillation optical frequency combs (OFCs) are interesting because of their broad bandwidth compared with plain optoelectronic oscillators. In this pa...Photonic microwave harmonic down-converters (PMHDCs) based on self-oscillation optical frequency combs (OFCs) are interesting because of their broad bandwidth compared with plain optoelectronic oscillators. In this paper, a high-efficiency and flexible PMHDC is proposed and demonstrated. The properties of the OFC, such as the carrier-to-noise ratio (CNR),bandwidth and free spectral range (FSR), and the influence of optical injection, are investigated. The broadband OFC provides a frequency tunable and high-quality local oscillation (LO), which guarantees flexible down-conversion for the radio frequency (RF) signal. The sideband selective amplification (SSA) effect not only improves the conversion efficiency but also promotes single-sideband modulation. The conversion range can reach 100 GHz. The 12–40 GHz RF signal can be downconverted to intermediate frequency (IF) signals with a high conversion efficiency of 14.9 dB. The fixed 40-GHz RF signal is flexibly down-converted to an IF signal with the frequency from 55.4 to 2129.4 MHz. The phase noise of an IF signal at a frequency offset of 10 kHz is the same as that of the input RF signal. The PMHDC shows great performance and will find applications in radio-over-fiber (RoF) networks, electronic warfare receivers, avionics, and wireless communication systems.展开更多
Microwave photonics （MWP） is an interdisci- plinary field that combines two different areas of microwave engineering and photonics. It has several key features by transferring signals between the optical domain and ...Microwave photonics （MWP） is an interdisci- plinary field that combines two different areas of microwave engineering and photonics. It has several key features by transferring signals between the optical domain and microwave domain, which leads to the advantages of broad operation bandwidth for generation, processing and distribution of microwave signals and high resolution for optical spectrum measurement. In this paper, we comprehensively review past and current status of MWP in China by introducing the representative works from most of the active MWP research groups. Future prospective is also discussed fi＇om the national strategy to key enabling technology that we have developed.展开更多
This paper presents an introduction to the researches in microwave photonics based packages and its application, a 973 project （No. 2012CB315600）, which focuses on addressing new requirements for millimeter wave （...This paper presents an introduction to the researches in microwave photonics based packages and its application, a 973 project （No. 2012CB315600）, which focuses on addressing new requirements for millimeter wave （MMW） system to work with higher frequency, wider bandwidth, larger dynamic range and longer distance of signal distribution. Its key scientific problems, main research contents and objectives are briefed, and some latest achievements by the project team, including generation of linear frequency modulation wave （LFMW）, tunable optoelectronic oscillator （OEO） with lower phase noise, reconfigurable filter with higher Q value, time delay line with wider frequency range, down conversion with gain, and local oscillator （LO） transmission with stable phase, are introduced briefly.展开更多
This paper reviews recent progresses on optical arbitrary waveform generation （AWG） techniques, which could be used to break the speed and bandwidth bottle- necks of electronics technologies for waveform generation....This paper reviews recent progresses on optical arbitrary waveform generation （AWG） techniques, which could be used to break the speed and bandwidth bottle- necks of electronics technologies for waveform generation. The main enabling techniques for optically generating optical and microwave waveforms are introduced and reviewed in this paper, such as wavelength-to-time mapping techniques, space-to-time mapping techniques, temporal pulse shaping （TPS） system, optoelectronics oscillator （OEO）, programmable optical filters, optical differentiator and integrator and versatile electro-optic modulation implementations. The main advantages and challenges of these optical AWG techniques are also discussed.展开更多
The output characteristics of neodymium-doped gadolinium vanadate(Nd:GdVO4) crystals laser with dual c-axis orthogonal gains end-pumped by two fiber-coupled diode lasers are investigated. With two 1 W semiconductor di...The output characteristics of neodymium-doped gadolinium vanadate(Nd:GdVO4) crystals laser with dual c-axis orthogonal gains end-pumped by two fiber-coupled diode lasers are investigated. With two 1 W semiconductor diode lasers pumping, the output power of TEM00 laser is 920 m W, and the optical conversion efficiency is close to 46%. By changing the relative orientations of both Nd:Gd VO4 crystals, the polarization characteristics of laser are varied. In particular, by keeping the c-axes of two Nd:Gd VO4 crystals orthogonal to each other and adjusting two diode pump lasers to operate at the same power level, the completely unpolarized light is obtained.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.62301495)the Project of the National Key Laboratory of Microwave Photonics(Nanjing University of Aeronautics and Astronautics),Ministry of Education(Grant No.NJ20220007).
文摘The optoelectronic oscillator(OEO)is a typical time-delay system with rich nonlinear dynamical characteristics.Most of the previous research on OEOs has been focused on analyzing the properties of OEOs with a long time delay,which makes it difficult to realize mode locking without additional phaselocking mechanisms.We have achieved,for the first time to our knowledge,a self-mode-locking OEO and generated stable microwave frequency combs by analyzing the characteristics of OEOs with an ultrashort time scale.In the experiment,the self-mode-locking OEOs with fundamental mode,second-order harmonic,and sixth-order harmonic were realized by adjusting the system parameters,all of which produced uniform square wave signals with tunable duty cycles,steep rising and falling edges,and periods of less than 20 ns.The self-fundamental-mode-locking OEOs with different time delays were also implemented and experimentally realized.Furthermore,the experiment revealed the self-hybrid mode-locking OEO,which is the coexistence and synchronization of the three measured self-locking modes in one OEO cavity,demonstrating the complex nonlinear dynamical behaviors of the OEO system and enabling the generation of periodic nonuniform hybrid square wave signals.The realization of the self-mode-locking OEO and the generation of flexible and stable square wave signals at ultrashort time scales enrich the study of OEO nonlinear dynamics in the realm of complex microwave waveform generation,offering promising applications in areas such as atomic clocks,radars,communications,and optoelectronic neural networks.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFA0704403)the National Natural Science Foundation of China(Grant No.61975249)the Program for HUST Academic Frontier Youth Team(Grant No.2018QYTD08).
文摘Parity‐time(PT)symmetry breaking offers mode selection capability for facilitating single‐mode oscillation in the optoelectronic oscillator(OEO)loop.However,most OEO implementations depend on discrete devices,which impedes proliferation due to size,weight,power consumption,and cost.In this work,we propose and experimentally demonstrate an on-chip tunable PT‐symmetric OEO.A tunable microwave photonic filter,a PT‐symmetric mode‐selective architecture,and two photodetectors are integrated on a silicon‐on‐insulator chip.By exploiting an on‐chip Mach–Zehnder interferometer to match the gain and loss of two mutually coupled optoelectronic loops,single‐mode oscillation can be obtained.In the experiment,the oscillation frequency of the on-chip tunable PT‐symmetric OEO can be tuned from 0 to 20 GHz.To emulate the integrated case,the OEO loop length is minimized,and no extra-long fiber is used in the experiment.When the oscillation frequency is 13.67 GHz,the single‐sideband phase noise at 10-kHz offset frequency is−80.96 dBc∕Hz and the side mode suppression ratio is 46 dB.The proposed on-chip tunable PT‐symmetric OEO significantly reduces the footprint of the system and enhances mode selection.
文摘High-performance interrogation systems for optical fiber sensors are extensively required for environmental condition monitoring applications.In this article,we propose and demonstrate a Michelson interferometer(MI)interrogation system based on an optoelectronic oscillator(OEO).The frequency of the OEO is related to the free spectral range(FSR)of the MI.Thus,when the FSR of the MI varies with a change in external physical factors,the frequency of the OEO shifts and can be used for interrogation.We demonstrate that the temperature sensitivity and interrogation resolution are 35.35 MHz/℃and 0.012℃,respectively.Such an OEO-based scheme enables wavelength-to-frequency mapping and promises a wide linear interrogation range,high resolution and high-speed interrogation.
基金Supported by the National Natural Science Foundation of China under Grant No 61675196the National Basic Research Program of China under Grant No 2014CB340102+1 种基金the National High-Tech Research and Development Program of China under Grant No 2015AA016903the Open Research of Beijing University of Posts and Telecommunications under Grant No IOOC2013A002
文摘A wideband tunable frequency-doubling optoelectronic oscillator （FD-OEO） is proposed and experimentally demonstrated based on a polarization modulator and an optical bandpass filter （OBPF）. The central frequency of the correspondingly fundamental OEO could be adjusted by tuning the bandwidth and central frequency of the OBPF, which could also be regarded as a photonic-assisted tunable microwave filter. The frequency tuning range of the FD-OEO covers from 9.5 to 32.8？GHz, and the single sideband phase noise of the fundamental signal is lower than -100dBc/Hz at an offset of 10？kHz. Moreover, the frequency stability of the generated signal is investigated by measuring its Allan deviation. The Allan deviation of the generated fundamental signal at 10？GHz is 2.39×10^-9.
基金supported by the National Natural Science Foundation of China (Nos. 61901215 and 62271249)the Fundamental Research Funds for the Central Universities。
文摘An approach for frequency division of an optical pulse train(OPT) based on an optoelectronic oscillator(OEO) is proposed and experimentally demonstrated. When the OPT is injected into the OEO, a microwave signal with a frequency equaling fractional multiples of the repetition rate of the OPT is generated. This signal is then fed back to the OEO, maintaining its oscillation, while simultaneously serving as the control signal of a Mach–Zehnder modulator(MZM) in the OEO. The MZM acts as an optical switch, permitting specific pulses to pass through while blocking others. As a result, the repetition rate of the OPT is manipulated. A proof-of-concept experiment is carried out. Frequency division factors of 2 and 3 are successfully achieved. The phase noises of the OPT before and after the frequency division are investigated. Compared to previously reported systems, no external microwave source and sophisticated synchronization structure are needed.
基金supported by the National Key Research and Development Program of China(2018YFB2201902,2018YFB2201901,2018YFB2201903)the National Natural Science Foundation of China(61925505,61535012,61705217)
文摘An optoelectronic oscillator(OEO)is a microwave photonic system that produces microwave signals with ultralow phase noise using a high-quality-factor optical energy storage element.This type of oscillator is desired in various practical applications,such as communication links,signal processing,radar,metrology,radio astronomy,and reference clock distribution.Recently,new mode control and selection methods based on Fourier domain mode-locking and parity-time symmetry have been proposed and experimentally demonstrated in OEOs,which overcomes the long-existing mode building time and mode selection problems in a traditional OEO.Due to these mode control and selection methods,continuously chirped microwave waveforms can be generated directly from the OEO cavity and single-mode operation can be achieved without the need of ultranarrowband filters,which are not possible in a traditional OEO.Integrated OEOs with a compact size and low power consumption have also been demonstrated,which are key steps toward a new generation of compact and versatile OEOs for demanding applications.We review recent progress in the field of OEOs,with particular attention to new mode control and selection methods,as well as chip-scale integration of OEOs.
基金supported by the National Natural Science Foundation of China(No.61422108)the Natural Science Foundation of Jiangsu Province(No.BK20160082)+1 种基金the Jiangsu Provincial Program for High-level Talents in Six Areas(No.DZXX-030)the Fundamental Research Funds for Central Universities(Nos.NE2017002 and NS2016037)
文摘A polarization-maintained coupled optoelectronic oscillator（COEO） with its performance significantly improved by a short-length unpumped erbium-doped fiber（EDF） is reported and experimentally investigated.A 10 GHz optical pulse train with a supermode suppression ratio of 61.8 d B and a 10 GHz radio frequency signal with a sidemode suppression ratio of 94 d B and a phase noise of-121.9 d Bc∕Hz at 10 k Hz offset are simultaneously generated. Thanks to saturable absorption of the 1 m unpumped EDF, which introduces relatively large cavity loss to the undesired modes and noise, the supermode suppression ratio and the phase noise are improved by 9.4 and 7.9 d B, respectively.
基金supported by the National Key R&D Program of China (No.2018YFB1801003)the National Natural Science Foundation of China (Nos.61525501 and 61827817)+1 种基金the Beijing Natural Science Foundation (No.4192022)the Project of Shandong Province Higher Educational Science and Technology Program (No.J17KA089)。
文摘A tunable frequency-multiplying optoelectronic oscillator(OEO) based on a dual-parallel Mach-Zehnder modulator(DPMZM) is proposed and experimentally demonstrated. In the proposed system, the tunable fundamental microware signal is generated by a tunable optoelectronic oscillator incorporating a phase-shifted fiber Bragg grating(PS-FBG). By adjusting the DC bias of the DPMZM, the frequency-doubled microwave signal with a tunable frequency range from 11 GHz to 20 GHz and the frequency-quadrupled microwave signal with a tunable frequency range from 22.5 GHz to 26 GHz are generated. The phase noises of the fundamental, frequency-doubled and frequency-quadrupled signals at 10 k Hz offset frequency are-105.9 d Bc/Hz,-103.3 d Bc/Hz and-86.2 d Bc/Hz, respectively.
基金This work was supported by the National Natural Science Foundation of China(Grant No.62075022)the Chongqing Technology Innovation and Development Project(Grant No.cstc2020jscxmsxmX0216)+1 种基金the Special Project of Science and Technology Innovation and Entrepreneurship Fund of Tiandi Technology Co.,Ltd.(Grant No.2020-TDZD007)the Science and Technology Plan Project Support of Jiulongpo District(Grant No.2020-02-004-Z).
文摘A novel fiber-optic magnetic field sensor with high interrogation speed and resolution by using an etched fiber Bragg grating(FBG)in conjunction with a dual-loop optoelectronic oscillator(OEO)is proposed and experimentally demonstrated.A commercial FBG is firstly dipped into mixed hydrofluoric acid solution to remove the cladding layer and then is embedded with the magnetic fluid(MF)as a sensing element.The central wavelength reflected from the FBG is related to the overall time delay of the dual-loop OEO,which determines the oscillating frequency of the OEO.Therefore,the magnetic field can be estimated by measuring the oscillating frequency shift of OEO.The experimental results show that the oscillating frequency linearly increases with the increment of the magnetic field,achieving the sensitivity of 16.3 Hz/Oe with a R-square of 0.991 in the range of 5 mT-10 mT.In addition,the maximum error is within±0.05 mT in the range of 7 mT-8 mT,which offers potentials in many fields where the high-precision magnetic field measurement is required.
基金the National Natural Science Foundation of China(Grant Nos.61575163,61775184,11704316,and 61875167).
文摘In this work,via autocorrelation function(ACF)and permutation entropy(PE)methods,we numerically investigate the time-delay signature(TDS)characteristics of the chaotic signal output from an optoelectronic oscillator(OEO)after introducing an extra optical feedback loop.The results demonstrate that,for such a chaotic system,both the optoelectronic feedback with a delay time of T1 and the optical feedback with a delay time of T2 contribute to the TDS of generated chaos.The TDS of the chaotic signal should be evaluated within a large time window including T1 and T2 by the strongest peak in the ACF curve of the chaotic signal,and the strongest peak may locate at near T1 or T2.Through mapping the evolution of the TDS in the parameter space of the optical feedback strength and time,certain optimized parameter regions for achieving a chaotic signal with a relatively weak TDS can be determined.
文摘Photonic generation of radio-frequency（RF） arbitrary microwave waveform with ultra-wide frequency tunable range based on a dispersion compensated optoelectronic oscillator（OEO） is proposed and experimentally demonstrated. Dispersion compensation scheme and specially designed fiber Bragg grating（FBG）-based Fabry-Perot（F-P） filters are employed in the OEO loop to realize a frequency tunable range of 3.5-45.4 GHz. An optimization process provided by the combination of an erbium-doped fiber amplifier（EDFA）and FBG is employed to improve the signal-to-noise ratio（SNR） of final RF signals. The generation of linearfrequency and phase-coded microwave waveforms, with a tunable carrier frequency ranging from 4 to 45 GHz and tuned chirping bandwidths or code rates, is experimentally demonstrated.
基金Supported in part by the National Basic Research Program of China(2012CB315705)the Natural Science Foundation of Jiangsu Province(BK2012031,BK2012381)+1 种基金the National Natural Science Foundation of China(61201048,61107063)the Fundamental Research Funds for the Central Universities
文摘The emerging new concepts and technologies based on microwave photonics have led to an ever-increasing interest in developing innovative radar systems with a net gain in functionality,bandwidth /resolution,size,mass,complexity and cost when compared with the traditional implementations. This paper describes the techniques developed in the last few years in microwave photonics that might revolutionize the way to design multifunction radar systems,with an emphasis on the recent advances in optoelectronic oscillators( OEOs),arbitrary waveform generation,photonic mixing,phase coding,filtering,beamforming,analog-to-digital conversion,and stable radio-frequency signal transfer. Challenges in implementation of these components and subsystems for meeting the technique requirements of the multifunction radar applications are discussed.
文摘A novel dual-loop technique was proposed for single-mode selection in an optoelectronic oscillator （OEO）. It consisted of a pump laser and a feedback circuit including an intensity modulator, a Fabry-Perot （FP） etalon, two optical fiber delay lines, two photodetectors, and an amplifier. By inserting the Fabry-Perot etalon, the proposed dual-loop OEO realized a single mode oscillation ranging from 0 Hz to 20 GHz. The strong oscillation mode was present at 15 GHz, and the side modes suppression ratio （SMSR） exceeded 140dB. More over the length of the two fiber loops were just 5 meters and 36 meters.
基金supported in part by the National Natural Science Foundation of China(Nos.62071487 and 61974165)National Key R&D Program of China(No.2020YFB2205804)Chinese National Key Basic Research Special Fund(No.2017YFA0206401)。
文摘Weak RF signal detection with high resolution and no blind zone based on directly modulated multi-mode optoelectronic oscillation has been proposed.The high-sensitivity optical modulators and optical filters are avoided because multi-mode oscillation is obtained based on directly modulating the semiconductor laser at the relaxation oscillation frequency.For the directly modulated optoelectronic oscillator,the detection characteristics such as gain for the RF signal,resolution,noise floor,and sensitivity are firstly analyzed.The experimental results are consistent with the simulated results.For the RF signal of unknown frequency,it can be detected out and amplified by tuning the bias current and delay time of the loop.There is no blind zone within 1–4.5 GHz.The system provides a maximum gain of 17.88 dB for the low-power RF signal.The sensitivity of the system can reach as high as-95 dBm.The properties such as gain dynamic range and power stability are also investigated.The system has potential for weak RF signal detection,especially for the RF signal with unknown frequency.
基金supported in part by the National Natural Science Foundation of China (Nos.62071487,62201615,62301569,and 62371470)。
文摘Photonic microwave harmonic down-converters (PMHDCs) based on self-oscillation optical frequency combs (OFCs) are interesting because of their broad bandwidth compared with plain optoelectronic oscillators. In this paper, a high-efficiency and flexible PMHDC is proposed and demonstrated. The properties of the OFC, such as the carrier-to-noise ratio (CNR),bandwidth and free spectral range (FSR), and the influence of optical injection, are investigated. The broadband OFC provides a frequency tunable and high-quality local oscillation (LO), which guarantees flexible down-conversion for the radio frequency (RF) signal. The sideband selective amplification (SSA) effect not only improves the conversion efficiency but also promotes single-sideband modulation. The conversion range can reach 100 GHz. The 12–40 GHz RF signal can be downconverted to intermediate frequency (IF) signals with a high conversion efficiency of 14.9 dB. The fixed 40-GHz RF signal is flexibly down-converted to an IF signal with the frequency from 55.4 to 2129.4 MHz. The phase noise of an IF signal at a frequency offset of 10 kHz is the same as that of the input RF signal. The PMHDC shows great performance and will find applications in radio-over-fiber (RoF) networks, electronic warfare receivers, avionics, and wireless communication systems.
基金We would like to thank all the colleagues who have been involved into these reported works in China and collaborated internationally. We would like to thank the supporting of the National High-Tech Research ＆ Development Program of China （Nos. 2011AA010303, 2013AA014201 and 2011AA010305） and the National Natural Science Foundation of China （Grant Nos, 61177080, 61377002, 61321063 and 61090391）. Ming Li was supported in part by the ＂Thousand Young Talent＂ program.
文摘Microwave photonics （MWP） is an interdisci- plinary field that combines two different areas of microwave engineering and photonics. It has several key features by transferring signals between the optical domain and microwave domain, which leads to the advantages of broad operation bandwidth for generation, processing and distribution of microwave signals and high resolution for optical spectrum measurement. In this paper, we comprehensively review past and current status of MWP in China by introducing the representative works from most of the active MWP research groups. Future prospective is also discussed fi＇om the national strategy to key enabling technology that we have developed.
文摘This paper presents an introduction to the researches in microwave photonics based packages and its application, a 973 project （No. 2012CB315600）, which focuses on addressing new requirements for millimeter wave （MMW） system to work with higher frequency, wider bandwidth, larger dynamic range and longer distance of signal distribution. Its key scientific problems, main research contents and objectives are briefed, and some latest achievements by the project team, including generation of linear frequency modulation wave （LFMW）, tunable optoelectronic oscillator （OEO） with lower phase noise, reconfigurable filter with higher Q value, time delay line with wider frequency range, down conversion with gain, and local oscillator （LO） transmission with stable phase, are introduced briefly.
基金Acknowledgements We would like to thank our colleagues for their contributions in these works, such as Reza Ashrafi, Chao Wang, Tae-Jung Ahn, Ze Li, Wei Li, Ningbo Huang, Ye Deng, Yi Hu, Roberto Morandotti, Yichen Han, Shilong Pan, Maria Rosario and Wangzhe Li. This work was supported by the National Natural Science Foundation of China （Grant Nos. 61377002, 61321063, and 61090391）. This work was also supported by the Natural Sciences and Engineering Research Council of Canada （NSERC）. Ming Li was supported in part by the ＂Thousand Young Talent＂ program.
文摘This paper reviews recent progresses on optical arbitrary waveform generation （AWG） techniques, which could be used to break the speed and bandwidth bottle- necks of electronics technologies for waveform generation. The main enabling techniques for optically generating optical and microwave waveforms are introduced and reviewed in this paper, such as wavelength-to-time mapping techniques, space-to-time mapping techniques, temporal pulse shaping （TPS） system, optoelectronics oscillator （OEO）, programmable optical filters, optical differentiator and integrator and versatile electro-optic modulation implementations. The main advantages and challenges of these optical AWG techniques are also discussed.
基金supported by the National Natural Science Foundation of China(No.11104234)
文摘The output characteristics of neodymium-doped gadolinium vanadate(Nd:GdVO4) crystals laser with dual c-axis orthogonal gains end-pumped by two fiber-coupled diode lasers are investigated. With two 1 W semiconductor diode lasers pumping, the output power of TEM00 laser is 920 m W, and the optical conversion efficiency is close to 46%. By changing the relative orientations of both Nd:Gd VO4 crystals, the polarization characteristics of laser are varied. In particular, by keeping the c-axes of two Nd:Gd VO4 crystals orthogonal to each other and adjusting two diode pump lasers to operate at the same power level, the completely unpolarized light is obtained.
