Efficient coupling from the silicon waveguide to the GeSi layer is the key to success in the GeSi electro-absorption （EA） modulator based on evanescent coupling. A lateral taper in the upper GeSi layer has room for ...Efficient coupling from the silicon waveguide to the GeSi layer is the key to success in the GeSi electro-absorption （EA） modulator based on evanescent coupling. A lateral taper in the upper GeSi layer has room for increasing the modulating efficiency and alleviating the sensitivity of the extinction ratio （ER） and insertion loss （IL） to the length of the active region. The light behavior and the effect of the taper are explored in detail using the beam propagation method （BPM）. After optimization, the light can nearly be totally confined in the GeSi layer without any oscillation. The modulator with the designed taper can achieve low IL and high ER.展开更多
We report optimal phase modulation based on enhanced electro–optic effects in a Mach–Zehnder（MZ） modulator constructed by AlGaAs/GaAs coupled double quantum well（CDQW） waveguides with optical gain. The net chang...We report optimal phase modulation based on enhanced electro–optic effects in a Mach–Zehnder（MZ） modulator constructed by AlGaAs/GaAs coupled double quantum well（CDQW） waveguides with optical gain. The net change of refractive indexes between two arms of the CDQW MZ modulator is derived by both the electronic polarization method and the normal-surface method. The numerical results show that very large refractive index change over 10^（-1） can be obtained, making the phase modulation in the CDQW MZ modulator very highly efficient. It is desirable and important that a very small voltage-length product for π phase shift, V_π× L_0= 0.0226 V · mm, is obtained by optimizing bias electric field and CDQW structural parameters, which is about seven times smaller than that in single quantum-well MZ modulators.These properties open an avenue for CDQW nanostructures in device applications such as electro–optical switches and phase modulators.展开更多
Cavity electro-optic(EO)modulation plays a pivotal role in optical pulse and frequency comb synthesis,supporting a wide range of applications including communication,computing,ranging,and quantum information.The ever-...Cavity electro-optic(EO)modulation plays a pivotal role in optical pulse and frequency comb synthesis,supporting a wide range of applications including communication,computing,ranging,and quantum information.The ever-growing demand for these applications has driven efforts in enhancing modulation coupling strength and bandwidth towards advanced pulse-comb synthesis.However,the effects of strong-coupling and high-bandwidth cavity EO modulation remain underexplored,due to the lack of a general,unified model that captures this extreme condition.In this work,we present a universal framework for pulse-comb synthesis under cavity EO modulation,where coupling strength and modulation bandwidth far exceed the cavity’s free spectral range(FSR).We show that,under such intense and ultrafast driving conditions,EO-driven frequency combs and pulses exhibit rich higher-order nonlinear dynamics,including temporal pulse compression and comb generation with arbitrary pump detuning.Leveraging this framework,we reveal a direct link between the higher-order dynamics of EO pulse-comb generation and the band structure of synthetic dimension.Furthermore,we demonstrate arbitrary comb shaping via machine-learning-based inverse microwave drive design,achieving a tenfold enhancement in cavity EO comb flatness by exploring the synergistic effects of high-bandwidth driving and detuning-induced frequency boundaries.Our findings push cavity EO modulation into a new frontier,unlocking significant potential for universal and machine-learning-programmable EO frequency combs,topological photonics,as well as photonic quantum computing in the strong-coupling and high-bandwidth regimes.展开更多
Integrated photonics has emerged as a promising alternative for data communication and computing,ferroelectric BaTiO_(3)^(-)(BTO)stands out for its exceptional electro-optic response among candidate materials.However,...Integrated photonics has emerged as a promising alternative for data communication and computing,ferroelectric BaTiO_(3)^(-)(BTO)stands out for its exceptional electro-optic response among candidate materials.However,direct epitaxial growth of BTO entails a fundamental trade-off:substrates with low refractive index are required for strong optical confinement,yet those with large lattice mismatch degrade film crystalline quality and electro-optic performance.We report a buffer-free,strain-engineered approach to integrate high-performance BTO thin films directly on LaAlO3-Sr2TaAlO6(LSAT)oxide-insulator substrates.By exploiting a self-buffer layer formed during the initial growth stage,we achieve periodic in-plane strain modulation that stabilizes a polymorphic phase boundary with orthorhombic polar nanoregions,yielding a Pockels coefficient exceeding 358 pm V^(-1)and a Curie temperature raised to 200℃.Leveraging this material platform,we demonstrate the first realization of a Mach-Zehnder modulator using epitaxial BTO on LSAT.The device exhibits a half-wave voltage-length product of 0.7 V cm at 1550 nm,which closely matches finite-element simulations,and supports a 6-dB electro-optic bandwidth of 28 GHz.Our results validate BTO on LSAT as a viable photonic platform for scalable,low-voltage and high-speed modulators.展开更多
Deployment of terahertz communication and spectroscopy systems relies on the availability of low-noise and fast detectors,with plug-and-play capabilities.However,most current technologies are stand-alone,discrete comp...Deployment of terahertz communication and spectroscopy systems relies on the availability of low-noise and fast detectors,with plug-and-play capabilities.However,most current technologies are stand-alone,discrete components.They are often slow or susceptible to temperature drifts and require tight beam focusing to maximize the signal-tonoise of the detector.Here,we demonstrate an integrated photonic architecture in thin-film lithium niobate that addresses these challenges by exploiting the electro-optic modulation induced by a terahertz signal onto an optical beam at telecom frequencies.Leveraging on the low optical losses provided by this platform,we integrate a double array of up to 18 terahertz antennas within a Mach-Zehnder interferometer,considerably extending the device collection area and boosting the interaction efficiency between the terahertz signal and the optical beam.We show that the double array coherently builds up the probe modulation through a mechanism of quasi-phase-matching,driven by a periodic terahertz near-field pattern,circumventing physical inversion of the crystallographic domains.This provides means to fully custom-tailor the frequency response of the device,limit it to a desired frequency band and effectively suppress out-of-band signals.The large detection area ensures correct operation with diverse terahertz beam settings.Furthermore,we show that the antennas act as pixels that allow reconstruction of the terahertz beam profile impinging on the detector area.Our on-chip design in thin-film lithium niobate overcomes the detrimental effects of two-photon absorption and fixed phase-matching conditions,which have plagued previously explored electro-optic detection systems,especially in the telecom band,paving the way for more advanced on-chip terahertz systems.展开更多
Chip-based soliton frequency microcombs combine compact size,broad bandwidth,and high coherence,presenting a promising solution for integrated optical telecommunications,precision sensing,and spectroscopy.Recent progr...Chip-based soliton frequency microcombs combine compact size,broad bandwidth,and high coherence,presenting a promising solution for integrated optical telecommunications,precision sensing,and spectroscopy.Recent progress in ferroelectric thin films,particularly thin-film lithium niobate(LiNbO_(3))and thin-film lithium tantalate(LiTaO_(3)),has significantly advanced electro-optic(EO)modulation and soliton microcombs generation,leveraging their strong third-order nonlinearity and high Pockels coefficients.However,achieving soliton frequency combs in X-cut ferroelectric materials remains challenging due to the competing effects of thermo-optic and photorefractive phenomena.These issues hinder the simultaneous realization of soliton generation and high-speed EO modulation.Here,following the thermal-regulated carrier behavior and auxiliary-laser-assisted approach,we propose a convenient mechanism to suppress both photorefractive and thermal dragging effects at once,and implement a facile method for soliton formation and its longterm stabilization in integrated X-cut LiTaO_(3) microresonators for the first time,to the best of our knowledge.The resulting mode-locked states exhibit robust stability against perturbations,enabling new pathways for fully integrated photonic circuits that combine Kerr nonlinearity with high-speed EO functionality.展开更多
文摘Efficient coupling from the silicon waveguide to the GeSi layer is the key to success in the GeSi electro-absorption （EA） modulator based on evanescent coupling. A lateral taper in the upper GeSi layer has room for increasing the modulating efficiency and alleviating the sensitivity of the extinction ratio （ER） and insertion loss （IL） to the length of the active region. The light behavior and the effect of the taper are explored in detail using the beam propagation method （BPM）. After optimization, the light can nearly be totally confined in the GeSi layer without any oscillation. The modulator with the designed taper can achieve low IL and high ER.
基金Project supported by the National Natural Science Foundation of China(Grant No.11474106)the Natural Science Foundation of Guangdong Province,China(Grant No.2016A030313439)the Science and Technology Program of Guangzhou City,China(Grant No.201707010403)
文摘We report optimal phase modulation based on enhanced electro–optic effects in a Mach–Zehnder（MZ） modulator constructed by AlGaAs/GaAs coupled double quantum well（CDQW） waveguides with optical gain. The net change of refractive indexes between two arms of the CDQW MZ modulator is derived by both the electronic polarization method and the normal-surface method. The numerical results show that very large refractive index change over 10^（-1） can be obtained, making the phase modulation in the CDQW MZ modulator very highly efficient. It is desirable and important that a very small voltage-length product for π phase shift, V_π× L_0= 0.0226 V · mm, is obtained by optimizing bias electric field and CDQW structural parameters, which is about seven times smaller than that in single quantum-well MZ modulators.These properties open an avenue for CDQW nanostructures in device applications such as electro–optical switches and phase modulators.
基金National Research Foundation funded by the Korea government(NRF-2022M3K4A1094782).
文摘Cavity electro-optic(EO)modulation plays a pivotal role in optical pulse and frequency comb synthesis,supporting a wide range of applications including communication,computing,ranging,and quantum information.The ever-growing demand for these applications has driven efforts in enhancing modulation coupling strength and bandwidth towards advanced pulse-comb synthesis.However,the effects of strong-coupling and high-bandwidth cavity EO modulation remain underexplored,due to the lack of a general,unified model that captures this extreme condition.In this work,we present a universal framework for pulse-comb synthesis under cavity EO modulation,where coupling strength and modulation bandwidth far exceed the cavity’s free spectral range(FSR).We show that,under such intense and ultrafast driving conditions,EO-driven frequency combs and pulses exhibit rich higher-order nonlinear dynamics,including temporal pulse compression and comb generation with arbitrary pump detuning.Leveraging this framework,we reveal a direct link between the higher-order dynamics of EO pulse-comb generation and the band structure of synthetic dimension.Furthermore,we demonstrate arbitrary comb shaping via machine-learning-based inverse microwave drive design,achieving a tenfold enhancement in cavity EO comb flatness by exploring the synergistic effects of high-bandwidth driving and detuning-induced frequency boundaries.Our findings push cavity EO modulation into a new frontier,unlocking significant potential for universal and machine-learning-programmable EO frequency combs,topological photonics,as well as photonic quantum computing in the strong-coupling and high-bandwidth regimes.
基金supported by Ministry of Education of China Scientific Research Innovation Capability Support Project for Young Faculty under Grant No.ZYGXQNJSKYCXNLZCXM-M17the Basic Science Center Project of National Natural Science Foundation of China(NSFC)under Grant No.52388201,NSFC grants No.U24A2009 and 12474087+2 种基金Beijing Municipal Natural Science Foundation under Grant No.JQ24011 and Z240008by China Postdoctoral Science Foundation under Grant No.2023M741873.supported by Synergetic Extreme Condition User Facility(SECUF,https://cstr.cn/31123.02.SECUF).
文摘Integrated photonics has emerged as a promising alternative for data communication and computing,ferroelectric BaTiO_(3)^(-)(BTO)stands out for its exceptional electro-optic response among candidate materials.However,direct epitaxial growth of BTO entails a fundamental trade-off:substrates with low refractive index are required for strong optical confinement,yet those with large lattice mismatch degrade film crystalline quality and electro-optic performance.We report a buffer-free,strain-engineered approach to integrate high-performance BTO thin films directly on LaAlO3-Sr2TaAlO6(LSAT)oxide-insulator substrates.By exploiting a self-buffer layer formed during the initial growth stage,we achieve periodic in-plane strain modulation that stabilizes a polymorphic phase boundary with orthorhombic polar nanoregions,yielding a Pockels coefficient exceeding 358 pm V^(-1)and a Curie temperature raised to 200℃.Leveraging this material platform,we demonstrate the first realization of a Mach-Zehnder modulator using epitaxial BTO on LSAT.The device exhibits a half-wave voltage-length product of 0.7 V cm at 1550 nm,which closely matches finite-element simulations,and supports a 6-dB electro-optic bandwidth of 28 GHz.Our results validate BTO on LSAT as a viable photonic platform for scalable,low-voltage and high-speed modulators.
基金funding from the European Union’s Horizon Europe research and innovation programme under project MIRAQLS with grant agreement No 101070700 and from the Swiss National Science Foundation(SPARK,grant number 221119)the Swiss National Science Foundation-National Science Foundation(SNSFNSF)Lead Agency program under award number 219409+1 种基金funding from the National Science Foundation-Swiss National Science Foundation(NSF-SNSF)ECCS-2407727 and DARPA LUMOS program HR001120C0137 Defense Advanced Research Projects Agency(HR0011-20-C-0137)performed in part at the Center for Nanoscale Systems(CNS),a member of the National Nanotechnology Coordinated Infrastructure Network(NNCI),which is supported by the National Science Foundation under NSF Award no.1541959.
文摘Deployment of terahertz communication and spectroscopy systems relies on the availability of low-noise and fast detectors,with plug-and-play capabilities.However,most current technologies are stand-alone,discrete components.They are often slow or susceptible to temperature drifts and require tight beam focusing to maximize the signal-tonoise of the detector.Here,we demonstrate an integrated photonic architecture in thin-film lithium niobate that addresses these challenges by exploiting the electro-optic modulation induced by a terahertz signal onto an optical beam at telecom frequencies.Leveraging on the low optical losses provided by this platform,we integrate a double array of up to 18 terahertz antennas within a Mach-Zehnder interferometer,considerably extending the device collection area and boosting the interaction efficiency between the terahertz signal and the optical beam.We show that the double array coherently builds up the probe modulation through a mechanism of quasi-phase-matching,driven by a periodic terahertz near-field pattern,circumventing physical inversion of the crystallographic domains.This provides means to fully custom-tailor the frequency response of the device,limit it to a desired frequency band and effectively suppress out-of-band signals.The large detection area ensures correct operation with diverse terahertz beam settings.Furthermore,we show that the antennas act as pixels that allow reconstruction of the terahertz beam profile impinging on the detector area.Our on-chip design in thin-film lithium niobate overcomes the detrimental effects of two-photon absorption and fixed phase-matching conditions,which have plagued previously explored electro-optic detection systems,especially in the telecom band,paving the way for more advanced on-chip terahertz systems.
基金National Key Research and Development Program of China(2022YFA1404601)National Natural Science Foundation of China(62293520,62293521,12074400,62205363,12104442,12404446,12293052)+4 种基金Shanghai Science and Technology Innovation Action Plan Program(20JC1416200,22JC1403300)CAS Project for Young Scientists in Basic Research(YSBR-69)Natural Science Foundation of Anhui Province(2408085QA010)China Postdoctoral Science Foundation(2024M753078)Postdoctoral Fellowship Program of CPSF(GZC20232560)。
文摘Chip-based soliton frequency microcombs combine compact size,broad bandwidth,and high coherence,presenting a promising solution for integrated optical telecommunications,precision sensing,and spectroscopy.Recent progress in ferroelectric thin films,particularly thin-film lithium niobate(LiNbO_(3))and thin-film lithium tantalate(LiTaO_(3)),has significantly advanced electro-optic(EO)modulation and soliton microcombs generation,leveraging their strong third-order nonlinearity and high Pockels coefficients.However,achieving soliton frequency combs in X-cut ferroelectric materials remains challenging due to the competing effects of thermo-optic and photorefractive phenomena.These issues hinder the simultaneous realization of soliton generation and high-speed EO modulation.Here,following the thermal-regulated carrier behavior and auxiliary-laser-assisted approach,we propose a convenient mechanism to suppress both photorefractive and thermal dragging effects at once,and implement a facile method for soliton formation and its longterm stabilization in integrated X-cut LiTaO_(3) microresonators for the first time,to the best of our knowledge.The resulting mode-locked states exhibit robust stability against perturbations,enabling new pathways for fully integrated photonic circuits that combine Kerr nonlinearity with high-speed EO functionality.
