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
The authors demonstrate a Bull's eye cavity design that is composed of circular Bragg gratings and micropillar optical cavity in 4H silicon carbide(4H-SiC) for single photon emission. Numerical calculations are us...The authors demonstrate a Bull's eye cavity design that is composed of circular Bragg gratings and micropillar optical cavity in 4H silicon carbide(4H-SiC) for single photon emission. Numerical calculations are used to investigate and optimize the emission rate and directionality of emission. Thanks to the optical mode resonances and Bragg reflections,the radiative decay rates of a dipole embedded in the cavity center is enhanced by 12.8 times as compared to that from a bulk 4H-SiC. In particular, a convergent angular distribution of the emission in far field is simultaneously achieved, which remarkably boost the collection efficiency. The findings of this work provide an alternative architecture to manipulate light-matter interactions for achieving high-efficient SiC single photon sources towards applications in quantum information technologies.展开更多
This paper presents the design,fabrication,and characterization of a high-performance heterogeneous silicon on insulator(SOI)/thin film lithium niobate(TFLN)electro-optical modulator based on wafer-scale direct bondin...This paper presents the design,fabrication,and characterization of a high-performance heterogeneous silicon on insulator(SOI)/thin film lithium niobate(TFLN)electro-optical modulator based on wafer-scale direct bonding followed by ion-cut technology.The SOI wafer has been processed by an 8 inch standard fabrication line and cut into 6 inch for direct bonding with TFLN.The hybrid SOI/LN electro-optical modulator operated at the wavelength of 1.55μmis composed of couplers on the Si layer and aMach-Zehnder interferometer(MZI)structure on theLNlayer.The fabricated device exhibits a stable value of the product of half-wave voltage and length(V_(π)L)of around 2.9 V·cm.It shows a good low-frequency electro-optic response flatness and supports 96 Gbit/s data transmission for the NRZ format and 192 Gbit/s data transmission for the PAM-4 format.展开更多
Frequency microcombs with microwave and millimeter-wave repetition rates provide a compact solution for coherent communication and information processing.The implementation of these microcombs using a CMOS-compatible ...Frequency microcombs with microwave and millimeter-wave repetition rates provide a compact solution for coherent communication and information processing.The implementation of these microcombs using a CMOS-compatible platform further paves the way for large-scale photonic integration and modularity.Here,we demonstrate free-running soliton microcombs with K-band repetition rates with very low phase noise over a 4 GHz pump detuning range reaching−117(−123)dBc/Hz at 10 kHz offset for a 19.7(10)GHz carrier without active pump stabilization,exceeding commercial electronic microwave oscillators at frequency offsets above 40 kHz.The minimum laser noise to soliton microwave signal transduction factor observed is−73dB.This noise performance is achieved using a hybridized dual-mode for soliton generation to achieve passive thermal stabilization and minimal soliton spectrum shift from prior Raman scattering and dispersive wave formation.We further examine the locking of the repetition rate to an external ultrastable photonic oscillator to illustrate the feasibility of phase noise suppression below the thermorefractive noise limits of microresonator frequency combs.展开更多
Femtosecond mode-locked laser frequency combs have served as the cornerstone in precision spectroscopy,alloptical atomic clocks,and measurements of ultrafast dynamics.Recently frequency microcombs based on nonlinear m...Femtosecond mode-locked laser frequency combs have served as the cornerstone in precision spectroscopy,alloptical atomic clocks,and measurements of ultrafast dynamics.Recently frequency microcombs based on nonlinear microresonators have been examined,exhibiting remarkable precision approaching that of laser frequency combs,on a solid-state chip-scale platform and from a fundamentally different physical origin.Despite recent successes,to date,the real-time dynamical origins and high-power stabilities of such frequency microcombs have not been fully addressed.Here,we unravel the transitional dynamics of frequency microcombs from chaotic background routes to femtosecond mode-locking in real time,enabled by our ultrafast temporal magnifier metrology and improved stability of dispersion-managed dissipative solitons.Through our dispersion-managed oscillator,we further report a stability zone that is more than an order-of-magnitude larger than its prior static homogeneous counterparts,providing a novel platform for understanding ultrafast dissipative dynamics and offering a new path towards high-power frequency microcombs.展开更多
Optical solitons—stable waves balancing delicately between nonlinearities and dispersive effects—have advanced the field of ultrafast optics and dynamics,with contributions spanning from supercontinuum generation to...Optical solitons—stable waves balancing delicately between nonlinearities and dispersive effects—have advanced the field of ultrafast optics and dynamics,with contributions spanning from supercontinuum generation to soliton fission,optical event horizons,Hawking radiation and optical rogue waves,among others.Here,we investigate picojoule soliton dynamics in silicon slow-light,photonic-bandgap waveguides under the influence of Drude-modeled,free-carrier-induced nonlinear effects.Using real-time and single-shot amplified dispersive Fourier transform spectroscopy simultaneously with high-fidelity cross-correlation frequency resolved optical gating at femtojoule sensitivity and femtosecond resolution,we examine the soliton stability limits,the soliton dynamics including free-carrier quartic slow-light scaling and acceleration,and the Drude electron–hole plasma-induced perturbations in the Cherenkov radiation and modulation instability.Our real-time single-shot and time-averaged cross-correlation measurements are matched with our detailed theoretical modeling,examining the reduced group velocity free-carrier kinetics on solitons at the picojoule scale.展开更多
We demonstrate a GeSi electro-absorption modulator with on-chip thermal tuning for the first time,to the best of our knowledge.Theoretical simulation proves that the device temperature can be tuned and the effective o...We demonstrate a GeSi electro-absorption modulator with on-chip thermal tuning for the first time,to the best of our knowledge.Theoretical simulation proves that the device temperature can be tuned and the effective operating wavelength range can be broadened.When the heater power is 4.63 mW,the temperature of the waveguide increases by about 27 K and the theoretical operating wavelength range is broadened by 23.7 nm.The experimental results show that the optical transmission line shifted to the longer wavelength by 4.8 nm by every 1 mW heater power.The effective static operating wavelength range of the device is increased from 34.4 nm to 60.1 nm,which means it is broadened by 25.7 nm.The band edge shift coefficient of 0.76 nm/K is obtained by temperature simulation and linear fitting of the measured data.The device has a 3 dB EO bandwidth of 89 GHz at 3 V reverse bias,and the eye diagram measurement shows a data rate of 80 Gbit/s for non-return-to-zero on–off keying modulation and 100 Gbit/s for 4 pulse amplitude modulation in the 1526.8 nm to 1613.2 nm wavelength range as the heater power increases from 0 mW to 10.1 mW.展开更多
Dissipative Kerr soliton generation in chip-scale nonlinear resonators has recently observed remarkable advances,spanning from massively parallel communications, to self-referenced oscillators, and to dual-comb spectr...Dissipative Kerr soliton generation in chip-scale nonlinear resonators has recently observed remarkable advances,spanning from massively parallel communications, to self-referenced oscillators, and to dual-comb spectroscopy.Often working in the anomalous dispersion regime, unique driving protocols and dispersion in these nonlinear resonators have been examined to achieve the soliton and soliton-like temporal pulse shapes and coherent frequency comb generation. The normal dispersion regime provides a complementary approach to bridge the nonlinear dynamical studies, including the possibility of square pulse formation with flattop plateaus, or platicons.Here we report observations of square pulse formation in chip-scale frequency combs through stimulated pumping at one free spectral range and in silicon nitride rings with +55 fs~2∕mm normal group velocity dispersion.Tuning of the platicon frequency comb via a varied sideband modulation frequency is examined in both spectral and temporal measurements. Determined by second-harmonic autocorrelation and cross correlation, we observe bright square platicon pulse of 17 ps pulse width on a 19 GHz flat frequency comb. With auxiliary-laser-assisted thermal stabilization, we surpass the thermal bistable dragging and extend the mode-locking access to narrower 2 ps platicon pulse states, supported by nonlinear dynamical modeling and boundary limit discussions.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Project supported by the National Natural Science Foundation of China (Grant Nos. 91850112, 61774081, 62004099, and 61921005)in part by Shenzhen Fundamental Research Program (Grant Nos. JCYJ20180307163240991 and JCYJ20180307154632609)+3 种基金in part by the State Key Research and Development Project of Jiangsu Province, China (Grant No. BE2018115)in part by the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20201253)in part by the State Key Research and Development Project of Guangdong Province, China (Grant No. 2020B010174002)in part by Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB43020500)。
文摘The authors demonstrate a Bull's eye cavity design that is composed of circular Bragg gratings and micropillar optical cavity in 4H silicon carbide(4H-SiC) for single photon emission. Numerical calculations are used to investigate and optimize the emission rate and directionality of emission. Thanks to the optical mode resonances and Bragg reflections,the radiative decay rates of a dipole embedded in the cavity center is enhanced by 12.8 times as compared to that from a bulk 4H-SiC. In particular, a convergent angular distribution of the emission in far field is simultaneously achieved, which remarkably boost the collection efficiency. The findings of this work provide an alternative architecture to manipulate light-matter interactions for achieving high-efficient SiC single photon sources towards applications in quantum information technologies.
基金China State Key Laboratory of Materials for Integrated Circuits(NKLJC-Z2023-A04)National Natural Science Foundation of China(62204250,61935003)National Key Research and Development Program of China(2021YFB2800303).
文摘This paper presents the design,fabrication,and characterization of a high-performance heterogeneous silicon on insulator(SOI)/thin film lithium niobate(TFLN)electro-optical modulator based on wafer-scale direct bonding followed by ion-cut technology.The SOI wafer has been processed by an 8 inch standard fabrication line and cut into 6 inch for direct bonding with TFLN.The hybrid SOI/LN electro-optical modulator operated at the wavelength of 1.55μmis composed of couplers on the Si layer and aMach-Zehnder interferometer(MZI)structure on theLNlayer.The fabricated device exhibits a stable value of the product of half-wave voltage and length(V_(π)L)of around 2.9 V·cm.It shows a good low-frequency electro-optic response flatness and supports 96 Gbit/s data transmission for the NRZ format and 192 Gbit/s data transmission for the PAM-4 format.
基金Defense Advanced Research Projects Agency(HR001122C0017).
文摘Frequency microcombs with microwave and millimeter-wave repetition rates provide a compact solution for coherent communication and information processing.The implementation of these microcombs using a CMOS-compatible platform further paves the way for large-scale photonic integration and modularity.Here,we demonstrate free-running soliton microcombs with K-band repetition rates with very low phase noise over a 4 GHz pump detuning range reaching−117(−123)dBc/Hz at 10 kHz offset for a 19.7(10)GHz carrier without active pump stabilization,exceeding commercial electronic microwave oscillators at frequency offsets above 40 kHz.The minimum laser noise to soliton microwave signal transduction factor observed is−73dB.This noise performance is achieved using a hybridized dual-mode for soliton generation to achieve passive thermal stabilization and minimal soliton spectrum shift from prior Raman scattering and dispersive wave formation.We further examine the locking of the repetition rate to an external ultrastable photonic oscillator to illustrate the feasibility of phase noise suppression below the thermorefractive noise limits of microresonator frequency combs.
基金supported by the Air Force Office of Scientific Research under award number FA9550-15-1-0081the Office of Naval Research under award number N00014-16-1-2094the National Science Foundation under award numbers 17-41707,18-10506,and 18-24568.
文摘Femtosecond mode-locked laser frequency combs have served as the cornerstone in precision spectroscopy,alloptical atomic clocks,and measurements of ultrafast dynamics.Recently frequency microcombs based on nonlinear microresonators have been examined,exhibiting remarkable precision approaching that of laser frequency combs,on a solid-state chip-scale platform and from a fundamentally different physical origin.Despite recent successes,to date,the real-time dynamical origins and high-power stabilities of such frequency microcombs have not been fully addressed.Here,we unravel the transitional dynamics of frequency microcombs from chaotic background routes to femtosecond mode-locking in real time,enabled by our ultrafast temporal magnifier metrology and improved stability of dispersion-managed dissipative solitons.Through our dispersion-managed oscillator,we further report a stability zone that is more than an order-of-magnitude larger than its prior static homogeneous counterparts,providing a novel platform for understanding ultrafast dissipative dynamics and offering a new path towards high-power frequency microcombs.
基金support is from the Office of Naval Research with grant N00014-14-1-0041UESTC Young Faculty Award ZYGX2015KYQD051+2 种基金the 111 project(B14039)funding from NSFC Grant 61070040funding from AFOSR Young Investigator Award with grant FA9550-15-1-0081.
文摘Optical solitons—stable waves balancing delicately between nonlinearities and dispersive effects—have advanced the field of ultrafast optics and dynamics,with contributions spanning from supercontinuum generation to soliton fission,optical event horizons,Hawking radiation and optical rogue waves,among others.Here,we investigate picojoule soliton dynamics in silicon slow-light,photonic-bandgap waveguides under the influence of Drude-modeled,free-carrier-induced nonlinear effects.Using real-time and single-shot amplified dispersive Fourier transform spectroscopy simultaneously with high-fidelity cross-correlation frequency resolved optical gating at femtojoule sensitivity and femtosecond resolution,we examine the soliton stability limits,the soliton dynamics including free-carrier quartic slow-light scaling and acceleration,and the Drude electron–hole plasma-induced perturbations in the Cherenkov radiation and modulation instability.Our real-time single-shot and time-averaged cross-correlation measurements are matched with our detailed theoretical modeling,examining the reduced group velocity free-carrier kinetics on solitons at the picojoule scale.
基金National Key Research and Development Program of China(2021YFB0301000)Strategic Pioneer Research Projects of Defense Science and Technology(XDB43020500)Shanghai Sailing Program(20YF1456900)。
文摘We demonstrate a GeSi electro-absorption modulator with on-chip thermal tuning for the first time,to the best of our knowledge.Theoretical simulation proves that the device temperature can be tuned and the effective operating wavelength range can be broadened.When the heater power is 4.63 mW,the temperature of the waveguide increases by about 27 K and the theoretical operating wavelength range is broadened by 23.7 nm.The experimental results show that the optical transmission line shifted to the longer wavelength by 4.8 nm by every 1 mW heater power.The effective static operating wavelength range of the device is increased from 34.4 nm to 60.1 nm,which means it is broadened by 25.7 nm.The band edge shift coefficient of 0.76 nm/K is obtained by temperature simulation and linear fitting of the measured data.The device has a 3 dB EO bandwidth of 89 GHz at 3 V reverse bias,and the eye diagram measurement shows a data rate of 80 Gbit/s for non-return-to-zero on–off keying modulation and 100 Gbit/s for 4 pulse amplitude modulation in the 1526.8 nm to 1613.2 nm wavelength range as the heater power increases from 0 mW to 10.1 mW.
基金National Science Foundation(1741707,1810506,1824568)Office of Naval Research(N00014-16-1-2094)Air Force Office of Scientific Research(FA9550-15-1-0081)。
文摘Dissipative Kerr soliton generation in chip-scale nonlinear resonators has recently observed remarkable advances,spanning from massively parallel communications, to self-referenced oscillators, and to dual-comb spectroscopy.Often working in the anomalous dispersion regime, unique driving protocols and dispersion in these nonlinear resonators have been examined to achieve the soliton and soliton-like temporal pulse shapes and coherent frequency comb generation. The normal dispersion regime provides a complementary approach to bridge the nonlinear dynamical studies, including the possibility of square pulse formation with flattop plateaus, or platicons.Here we report observations of square pulse formation in chip-scale frequency combs through stimulated pumping at one free spectral range and in silicon nitride rings with +55 fs~2∕mm normal group velocity dispersion.Tuning of the platicon frequency comb via a varied sideband modulation frequency is examined in both spectral and temporal measurements. Determined by second-harmonic autocorrelation and cross correlation, we observe bright square platicon pulse of 17 ps pulse width on a 19 GHz flat frequency comb. With auxiliary-laser-assisted thermal stabilization, we surpass the thermal bistable dragging and extend the mode-locking access to narrower 2 ps platicon pulse states, supported by nonlinear dynamical modeling and boundary limit discussions.
