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
An exhaustive study of the noncontinuous-state laser dynamics associated with the transient optical process is significant because it reveals the complex physical mechanisms and characteristics in nonlinear laser syst...An exhaustive study of the noncontinuous-state laser dynamics associated with the transient optical process is significant because it reveals the complex physical mechanisms and characteristics in nonlinear laser systems.In this study,in-depth theoretical interpretation and experimental verification of the noncontinuous-state dynamics in laser system are presented,based on developed pulse-modulated frequency-shifted laser feedback interferometry(LFI).By introducing external pulse modulation,we investigate the nonlinear time-of-flight dynamics and related photon behaviors evolution of the pulsed LFI system by observing the changes in effective interference time sequences for interference realization and attainable minimum feedback photon number of the signal under various modulated noncontinuous states.Implementation of the pulse-modulated LFI scheme should exceed the pulse overlapping time window limit of 1.93μs to effectively extract and preserve the extracavity feedback photon information.Experiments reveal that the minimum feedback photon number of signals successfully measured by the pulsed LFI sensor is 0.067 feedback photons per Doppler cycle,exhibiting high sensitivity for extremely weak signal detection.Further,simultaneous measurement for velocity and distance of the moving object is performed to validate the feasibility and applicability of the pulsed LFI.The system can successfully achieve large-range simultaneous measurements within the velocity range of 73.5-612.6 mm∕s,over a distance of 25.5 km.This work opens the way to unexplored frontiers of pulsed LFI to fill the research gap in noncontinuous laser dynamics in this field,showcasing diverse and wide-ranging applications in the realm of integrated sensing,remote monitoring,and positioning and navigation.展开更多
Quantization noise caused by analog-to-digital converter(ADC)gives rise to the reliability performance degradation of communication systems.In this paper,a quantized non-Hermitian symmetry(NHS)orthogonal frequency-div...Quantization noise caused by analog-to-digital converter(ADC)gives rise to the reliability performance degradation of communication systems.In this paper,a quantized non-Hermitian symmetry(NHS)orthogonal frequency-division multiplexing-based visible light communication(OFDM-VLC)system is presented.In order to analyze the effect of the resolution of ADC on NHS OFDM-VLC,a quantized mathematical model of NHS OFDM-VLC is established.Based on the proposed quantized model,a closed-form bit error rate(BER)expression is derived.The theoretical analysis and simulation results both confirm the effectiveness of the obtained BER formula in high-resolution ADC.In addition,channel coding is helpful in compensating for the BER performance loss due to the utilization of lower resolution ADC.展开更多
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National Natural Science Foundation of China(62275001,62105001)China Postdoctoral Science Foundation(GZC20242187)Zhejiang Province Postdoctoral Research Funding(ZJ2024097)。
文摘An exhaustive study of the noncontinuous-state laser dynamics associated with the transient optical process is significant because it reveals the complex physical mechanisms and characteristics in nonlinear laser systems.In this study,in-depth theoretical interpretation and experimental verification of the noncontinuous-state dynamics in laser system are presented,based on developed pulse-modulated frequency-shifted laser feedback interferometry(LFI).By introducing external pulse modulation,we investigate the nonlinear time-of-flight dynamics and related photon behaviors evolution of the pulsed LFI system by observing the changes in effective interference time sequences for interference realization and attainable minimum feedback photon number of the signal under various modulated noncontinuous states.Implementation of the pulse-modulated LFI scheme should exceed the pulse overlapping time window limit of 1.93μs to effectively extract and preserve the extracavity feedback photon information.Experiments reveal that the minimum feedback photon number of signals successfully measured by the pulsed LFI sensor is 0.067 feedback photons per Doppler cycle,exhibiting high sensitivity for extremely weak signal detection.Further,simultaneous measurement for velocity and distance of the moving object is performed to validate the feasibility and applicability of the pulsed LFI.The system can successfully achieve large-range simultaneous measurements within the velocity range of 73.5-612.6 mm∕s,over a distance of 25.5 km.This work opens the way to unexplored frontiers of pulsed LFI to fill the research gap in noncontinuous laser dynamics in this field,showcasing diverse and wide-ranging applications in the realm of integrated sensing,remote monitoring,and positioning and navigation.
基金supported by the National Natural Science Foundation of China(No.62201508)the Zhejiang Provincial Natural Science Foundation of China(Nos.LZ21F010001 and LQ23F010004)the State Key Laboratory of Millimeter Waves of Southeast University,China(No.K202212).
文摘Quantization noise caused by analog-to-digital converter(ADC)gives rise to the reliability performance degradation of communication systems.In this paper,a quantized non-Hermitian symmetry(NHS)orthogonal frequency-division multiplexing-based visible light communication(OFDM-VLC)system is presented.In order to analyze the effect of the resolution of ADC on NHS OFDM-VLC,a quantized mathematical model of NHS OFDM-VLC is established.Based on the proposed quantized model,a closed-form bit error rate(BER)expression is derived.The theoretical analysis and simulation results both confirm the effectiveness of the obtained BER formula in high-resolution ADC.In addition,channel coding is helpful in compensating for the BER performance loss due to the utilization of lower resolution ADC.
