Optical frequency combs play a crucial role in optical communications,time-frequency metrology,precise ranging,and sensing.Among various generation schemes,resonant electro-optic combs are particularly attractive for ...Optical frequency combs play a crucial role in optical communications,time-frequency metrology,precise ranging,and sensing.Among various generation schemes,resonant electro-optic combs are particularly attractive for their excellent stability,flexibility,and broad bandwidths.In this approach,an optical pump undergoes multiple electro-optic modulation processes in a high-Q optical resonator,resulting in cascaded spectral sidebands.However,most resonant electro-optic combs to date make use of lumped-capacitor electrodes with relatively inefficient utilization of the input electrical power.This design also reflects most electrical power back to the driving circuits and necessitates costly radio-frequency(RF)isolators in between,presenting substantial challenges in practical applications.To address these issues,we present an RF circuit friendly electro-optic frequency comb generator incorporated with on-chip coplanar microwave resonator electrodes,based on a thin-film lithium niobate platform.Our design achieves more than three times electrical power reduction with minimal reflection at the designed comb repetition rate of~25 GHz.We experimentally demonstrate broadband electro-optic frequency comb generation with a comb span of>85 nm at a moderate electrical driving power of740 m W(28.7 d Bm).Our power-efficient and isolator-free electro-optic comb source could offer a compact,low-cost,and simple-to-design solution for applications in spectroscopy,high-precise metrology,and optical communications.展开更多
Integrated lithium niobate(LN)photonics is a promising platform for future chip-scale microwave photonics systems owing to its unique electro-optic properties,low optical loss,and excellent scalability.A key enabler f...Integrated lithium niobate(LN)photonics is a promising platform for future chip-scale microwave photonics systems owing to its unique electro-optic properties,low optical loss,and excellent scalability.A key enabler for such systems is a highly linear electro-optic modulator that could faithfully convert analog electrical signals into optical signals.In this work,we demonstrate a monolithic integrated LN modulator with an ultra-high spurious-free dynamic range(SFDR)of 120.04 dB·Hz^(4/5)at 1 GHz,using a ring-assisted Mach–Zehnder interferometer configuration.The excellent synergy between the intrinsically linear electro-optic response of LN and an optimized linearization strategy allows us to fully suppress the cubic terms of third-order intermodulation distortions(IMD3)without active feedback controls,leading to∼20 dB improvement over previous results in the thin-film LN platform.Our ultra-high-linearity LN modulators could become a core building block for future large-scale functional microwave photonic integrated circuits by further integration with other high-performance components like low-loss delay lines,tunable filters,and phase shifters available on the LN platform.展开更多
Optical vector analysis(OVA)is an enabling technology for comprehensively characterizing both amplitude and phase responses of optical devices or systems.Conventional OVA technologies are mostly based on discrete opto...Optical vector analysis(OVA)is an enabling technology for comprehensively characterizing both amplitude and phase responses of optical devices or systems.Conventional OVA technologies are mostly based on discrete optoelectronic components,leading to unsatisfactory system sizes,complexity,and stability.They also encounter challenges in revealing the on-chip characteristics of integrated photonic devices,which are often overwhelmed by the substantial coupling loss and extra spectral response at chip facets.In this work,we demonstrate a miniaturized OVA system based on broadband single-sideband(SSB)modulators on a thin-film lithium niobate(LN)platform.The OVA could provide a direct probe of both amplitude and phase responses of photonic devices with kilohertz-level resolution and tens of terahertz of measurement bandwidth.We perform in situ characterizations of single and coupled microring resonators fabricated on the same chip as the OVA,unfolding their intrinsic loss and coupling states unambiguously.Furthermore,we achieve the direct measurement of collective phase dynamics and density of states of the Bloch modes in a synthetic frequency crystal by in situ OVA of a dynamically modulated microring resonator.Our OVA system provides a compact,high-precision,and broadband solution for characterizing future integrated photonic devices and circuits,with potential applications ranging from optical communications,biosensing,and neuromorphic computing,to quantum information processing.展开更多
High-Q lithium niobate(LN) optical micro-resonators are an excellent platform for future applications in optical communications, nonlinear optics, and quantum optics. To date, high-Q factors are typically achieved in ...High-Q lithium niobate(LN) optical micro-resonators are an excellent platform for future applications in optical communications, nonlinear optics, and quantum optics. To date, high-Q factors are typically achieved in LN using either dielectric masks or femtosecond laser ablation, while the more standard and commonly available lift-off metallic masks are often believed to lead to rough sidewalls and lowered Q factors. Here, we show that LN microring resonators with strong light confinement and intrinsic Q factors over 1 million can be fabricated using optimized lift-off metallic masks and dry etching processes, corresponding to a waveguide propagation loss of ~0.3 d B=cm. The entire process is fully compatible with wafer-scale production and could be transferred to other photonic materials.展开更多
基金Research Grants Council,University Grants Committee(CityU 11212721,CityU 11204022,N_City U113/20)Croucher Foundation(9509005)City University of Hong Kong(9610682)。
文摘Optical frequency combs play a crucial role in optical communications,time-frequency metrology,precise ranging,and sensing.Among various generation schemes,resonant electro-optic combs are particularly attractive for their excellent stability,flexibility,and broad bandwidths.In this approach,an optical pump undergoes multiple electro-optic modulation processes in a high-Q optical resonator,resulting in cascaded spectral sidebands.However,most resonant electro-optic combs to date make use of lumped-capacitor electrodes with relatively inefficient utilization of the input electrical power.This design also reflects most electrical power back to the driving circuits and necessitates costly radio-frequency(RF)isolators in between,presenting substantial challenges in practical applications.To address these issues,we present an RF circuit friendly electro-optic frequency comb generator incorporated with on-chip coplanar microwave resonator electrodes,based on a thin-film lithium niobate platform.Our design achieves more than three times electrical power reduction with minimal reflection at the designed comb repetition rate of~25 GHz.We experimentally demonstrate broadband electro-optic frequency comb generation with a comb span of>85 nm at a moderate electrical driving power of740 m W(28.7 d Bm).Our power-efficient and isolator-free electro-optic comb source could offer a compact,low-cost,and simple-to-design solution for applications in spectroscopy,high-precise metrology,and optical communications.
基金National Natural Science Foundation of China(61922092)Research Grants Council,University Grants Committee(CityU 11204820,CityU 21208219,N_CityU113/20)+1 种基金Croucher Foundation(9509005)City University of Hong Kong(9610402,9610455).
文摘Integrated lithium niobate(LN)photonics is a promising platform for future chip-scale microwave photonics systems owing to its unique electro-optic properties,low optical loss,and excellent scalability.A key enabler for such systems is a highly linear electro-optic modulator that could faithfully convert analog electrical signals into optical signals.In this work,we demonstrate a monolithic integrated LN modulator with an ultra-high spurious-free dynamic range(SFDR)of 120.04 dB·Hz^(4/5)at 1 GHz,using a ring-assisted Mach–Zehnder interferometer configuration.The excellent synergy between the intrinsically linear electro-optic response of LN and an optimized linearization strategy allows us to fully suppress the cubic terms of third-order intermodulation distortions(IMD3)without active feedback controls,leading to∼20 dB improvement over previous results in the thin-film LN platform.Our ultra-high-linearity LN modulators could become a core building block for future large-scale functional microwave photonic integrated circuits by further integration with other high-performance components like low-loss delay lines,tunable filters,and phase shifters available on the LN platform.
基金supported by the Research Grants Council,University Grants Committee(CityU 11212721,CityU 11204022,N_CityU113/20,C1002-22Y)Croucher Foundation(9509005).
文摘Optical vector analysis(OVA)is an enabling technology for comprehensively characterizing both amplitude and phase responses of optical devices or systems.Conventional OVA technologies are mostly based on discrete optoelectronic components,leading to unsatisfactory system sizes,complexity,and stability.They also encounter challenges in revealing the on-chip characteristics of integrated photonic devices,which are often overwhelmed by the substantial coupling loss and extra spectral response at chip facets.In this work,we demonstrate a miniaturized OVA system based on broadband single-sideband(SSB)modulators on a thin-film lithium niobate(LN)platform.The OVA could provide a direct probe of both amplitude and phase responses of photonic devices with kilohertz-level resolution and tens of terahertz of measurement bandwidth.We perform in situ characterizations of single and coupled microring resonators fabricated on the same chip as the OVA,unfolding their intrinsic loss and coupling states unambiguously.Furthermore,we achieve the direct measurement of collective phase dynamics and density of states of the Bloch modes in a synthetic frequency crystal by in situ OVA of a dynamically modulated microring resonator.Our OVA system provides a compact,high-precision,and broadband solution for characterizing future integrated photonic devices and circuits,with potential applications ranging from optical communications,biosensing,and neuromorphic computing,to quantum information processing.
基金supported by the National Natural Science Foundation of China(No.61922092)Research Grants Council,University Grants Committee(No.City U 21208219)City University of Hong Kong(Nos.9667182,9610402,and 9610455)。
文摘High-Q lithium niobate(LN) optical micro-resonators are an excellent platform for future applications in optical communications, nonlinear optics, and quantum optics. To date, high-Q factors are typically achieved in LN using either dielectric masks or femtosecond laser ablation, while the more standard and commonly available lift-off metallic masks are often believed to lead to rough sidewalls and lowered Q factors. Here, we show that LN microring resonators with strong light confinement and intrinsic Q factors over 1 million can be fabricated using optimized lift-off metallic masks and dry etching processes, corresponding to a waveguide propagation loss of ~0.3 d B=cm. The entire process is fully compatible with wafer-scale production and could be transferred to other photonic materials.
