We propose and analyze a novel Si-based electro-optic modulator with an improved metal-oxide-semiconductor （MOS） capacitor configuration integrated into silicon-on-insulator （SOl）. Three gate-oxide layers embedded...We propose and analyze a novel Si-based electro-optic modulator with an improved metal-oxide-semiconductor （MOS） capacitor configuration integrated into silicon-on-insulator （SOl）. Three gate-oxide layers embedded in the silicon waveguide constitute a triple MOS capacitor structure, which boosts the modulation efficiency compared with a single MOS capacitor. The simulation results demonstrate that the Vπ Lπ product is 2. 4V · cm. The rise time and fall time of the proposed device are calculated to be 80 and 40ps from the transient response curve, respectively,indicating a bandwidth of 8GHz. The phase shift efficiency and bandwidth can be enhanced by rib width scaling.展开更多
Numerically analyzed is the transmission performance of the optical millimeter （mm）-wave generated by frequency up-conversion via a phase modulator along the dispersive fiber. 60 GHz ram-wave subcarrier（SC） signal...Numerically analyzed is the transmission performance of the optical millimeter （mm）-wave generated by frequency up-conversion via a phase modulator along the dispersive fiber. 60 GHz ram-wave subcarrier（SC） signals can be obtained after fiber transmission, simultaneously, the phase-modulated signals can be converted to the intensity-modulated ones. The numerical results show that the optical ram-wave at fading loops has better performance, and the eye diagram still keeps open when optical mm-wave signal is transmitted over 98 km.展开更多
A tunable microwave photonic bandpass filter with high mainlobe-to-sidelobe ratio (MSR) based on a phase modulator and a dispersive device is proposed. The multi-tap characteristics of the filter are realized by slici...A tunable microwave photonic bandpass filter with high mainlobe-to-sidelobe ratio (MSR) based on a phase modulator and a dispersive device is proposed. The multi-tap characteristics of the filter are realized by slicing a broadband source using a Mach-Zehnder interferometer (MZI) which results in a high MSR of 25 dB. The tunability of the filter is realized by an optical variable delay line (OVDL) in one arm of the MZI, which changes the wavelength spacing of the sliced broadband source and results in a tunable free spectrum range (FSR) of the filter. The central frequency of the bandpass filter is tunable from 10.7 GHz to 27 GHz by changing the wavelength spacing from 0.145 nm to 0.054 nm.展开更多
Fourier-domain rapid scanning optical delay line (RSOD) was introduced for phase modulation and depth scanning in a time-domain optical coherence tomography (TD-OCT) system. Investigation of parameter optimization of ...Fourier-domain rapid scanning optical delay line (RSOD) was introduced for phase modulation and depth scanning in a time-domain optical coherence tomography (TD-OCT) system. Investigation of parameter optimization of RSOD was conducted. Experiments for RSOD characterization at different parameters of the groove pitch, focal length, galvomirror size, etc. were performed. By implementing the optimized RSOD in our established TD-OCT system with a broadband light source centered at 840 nm with 50 nm bandwidth, in vivo retina imaging of a rabbit was presented, demonstrating the feasibility of high-quality TD-OCT imaging using an RSOD-based phase modulator.展开更多
In laser systems requiring a flat-top distribution of beam intensity,beam smoothing is a critical technology for enhancing laser energy deposition onto the focal spot.The continuous phase modulator(CPM)is a key compon...In laser systems requiring a flat-top distribution of beam intensity,beam smoothing is a critical technology for enhancing laser energy deposition onto the focal spot.The continuous phase modulator(CPM)is a key component in beam smoothing,as it introduces high-frequency continuous phase modulation across the laser beam profile.However,the presence of the CPM makes it challenging to measure and correct the wavefront aberration of the input laser beam effectively,leading to unwanted beam intensity distribution and bringing difficulty to the design of the CPM.To address this issue,we propose a deep learning enabled robust wavefront sensing(DLWS)method to achieve effective wavefront measurement and active aberration correction,thereby facilitating active beam smoothing using the CPM.The experimental results show that the average wavefront reconstruction error of the DLWS method is 0.04μm in the root mean square,while the Shack–Hartmann wavefront sensor reconstruction error is 0.17μm.展开更多
This paper uses an innovative improved artificial bee colony(IABC)algorithm to aid in the fabrication of a highly responsive phasemodulation surface plasmon resonance(SPR)biosensor.In this biosensor’s sensing structu...This paper uses an innovative improved artificial bee colony(IABC)algorithm to aid in the fabrication of a highly responsive phasemodulation surface plasmon resonance(SPR)biosensor.In this biosensor’s sensing structure,a double-layer Ag-Au metal film is combined with a blue phosphorene/transition metal dichalcogenide(BlueP/TMDC)hybrid structure and graphene.In the optimization function of the IABC method,the reflectivity at resonance angle is incorporated as a constraint to achieve high phase sensitivity.The performance of the Ag-Au-BlueP/TMDC-graphene heterostructure as optimized by the IABC method is compared with that of a similar structure optimized using the traditional ABC algorithm.The results indicate that optimization using the IABC method gives significantly more phase sensitivity,together with lower reflectivity,than can be achieved with the traditional ABC method.The highest phase sensitivity of 3.662×10^(6) °/RIU is achieved with a bilayer of BlueP/WS2 and three layers of graphene.Moreover,analysis of the electric field distribution demonstrates that the optimal arrangement can be utilized for enhanced detection of small biomolecules.Thus,given the exceptional sensitivity achieved,the proposed method based on the IABC algorithm has great promise for use in the design of high-performance SPR biosensors with a variety of multilayer structures.展开更多
Polarization-independent liquid-crystal(LC)phase modulators can significantly improve the efficiency and reduce the complexity of optical systems.However,achieving good polarization independence for LC phase modulator...Polarization-independent liquid-crystal(LC)phase modulators can significantly improve the efficiency and reduce the complexity of optical systems.However,achieving good polarization independence for LC phase modulators with a simple structure is difficult.A light-controlled azimuth angle(LCAA)process based on the optical rotatory effect of cholesteric liquid crystals(CLC)was developed for fabricating single-layer,multi-microdomain,orthogonally twisted(MMOT)structures.The developed LC phase modulator with a single-layer MMOT structure may have a low polarization dependence with a large phase depth.This device shows good potential for applications in optical communications,wearable devices,and displays.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
A special-velocity-matched electro-optic （EO） phase modulator employing a microwave resonant design in lithium niobate is presented. Both the microwave property and phase-modulation performances of the 3.25-GHz modu...A special-velocity-matched electro-optic （EO） phase modulator employing a microwave resonant design in lithium niobate is presented. Both the microwave property and phase-modulation performances of the 3.25-GHz modulator agree well with the numerical simulations. Using this modulator in a single-pass configuration with 1-kW microwave drive power, the spectral bandwidth of a 1053-nm, 3-ns pulse-length laser is broadened to 0.13 nm. With a clear aperture of 5×5 （mm）, the modulator is suited for two- dimensional smoothing by spectral dispersion in high Dower laser systems.展开更多
The theoretical construction of the fundamental × NOR gate using two injection semiconductor laser diodes due to mutual coupling is presented. Two laser diodes that are commonly driven by a monochromatic light be...The theoretical construction of the fundamental × NOR gate using two injection semiconductor laser diodes due to mutual coupling is presented. Two laser diodes that are commonly driven by a monochromatic light beam result in chaos; however, chaotic synchronization between the two lasers may be achieved by coupling them. The all-optical logic gate is finally implemented by synchronizing or un-synchronizing appropriately the two chaotic states under a phase modulator （PM） control. Numerical results validate the feasibility of the method.展开更多
A phase modulator is employed in the scheme of soliton pulse compression with dispersion shifted fiber （DSF）. Stimulated Brillouin scattering （SBS） effect, as a negative influence here, can be dramatically suppres...A phase modulator is employed in the scheme of soliton pulse compression with dispersion shifted fiber （DSF）. Stimulated Brillouin scattering （SBS） effect, as a negative influence here, can be dramatically suppressed after optical phase modulation. The experimental result shows that the launched power required for high-order soliton pulse compression has been significantly increased by 11 dB under the condition of 100-MHz phase modulation. Accordingly, the experiment of picosecond pulse compression generated from electro-absorption sampling window （EASW） has also been implemented.展开更多
The generation of coherent optical subcarriers based on a concatenated dual-drive Mach-Zehnder intensity modulator （IM） and two phase modulators （PMs） is proposed and experimentally demonstrated. The modulation in...The generation of coherent optical subcarriers based on a concatenated dual-drive Mach-Zehnder intensity modulator （IM） and two phase modulators （PMs） is proposed and experimentally demonstrated. The modulation index and DC bias of PM＋IM modulation are theoretically investigated. Theoretical analysis and numerical study are also carried out to examine the proposed scheme. We use 25-GHz RF synchronous sinusoidal signals to drive cascaded two-stage PMs and IM, through which we generate 28 subcaxriers with peak power fluctuations less than 4 dB. The measured tone-to-noise ratio of the subcarrier is higher than 40 dB. The experimental results show that for 100-Gb/s polarization multiplexing QPSK signal, the receiver sensitivity of the back-to-back signal is -28.6 dBm, and the power penalty is lower than 1 dB after 100-km transmission at the BER of 1 × 10-9.展开更多
We discuss the implementation and performance of an adaptive optics(AO)system that uses two cascaded deformable phase plates(DPPs),which are transparent optofluidic phase modulators,mimicking the common woofer/tweeter...We discuss the implementation and performance of an adaptive optics(AO)system that uses two cascaded deformable phase plates(DPPs),which are transparent optofluidic phase modulators,mimicking the common woofer/tweeter-type astronomical AO systems.One of the DPPs has 25 electrodes forming a keystone pattern best suited for the correction of low-order and radially symmetric modes;the second device has 37 hexagonally packed electrodes better suited for high-order correction.We also present simulation results and experimental validation for a new open-loop control strategy enabling simultaneous control of both DPPs,which ensures optimum correction for both large-amplitude low-order,and complex combinations of low-and high-order aberrations.The resulting system can reproduce Zernike modes up to the sixth radial order with stroke and fidelity up to twice better than what is attainable with either of the DPPs individually.The performance of the new AO configuration is also verified in a custom-developed fluorescence microscope with sensorless aberration correction.展开更多
An adaptive modulation system for a liquid crystal（LC） phase modulator is demonstrated. The phase retardation may be modulated by resetting the driving voltage automatically by matching the measured and ideal transm...An adaptive modulation system for a liquid crystal（LC） phase modulator is demonstrated. The phase retardation may be modulated by resetting the driving voltage automatically by matching the measured and ideal transmittance of an LC cell sandwiched by crossed polarizers. By using this system, an LC phase modulator can get a low error function of 0.25% in a short modulation time, which is less than the 10% obtained using a conventional modulation method.展开更多
An optical microfiber phase modulator （OMPM） directly driven with low-power light is presented. Phase modulation response of OMPM is theoretically analyzed. A 10-mm optical microfiber （OM）, tapered from convention...An optical microfiber phase modulator （OMPM） directly driven with low-power light is presented. Phase modulation response of OMPM is theoretically analyzed. A 10-mm optical microfiber （OM）, tapered from conventional single-mode fiber, is inserted in one arm of a Michelson fiber interferometer. To drive the OMPM, 980-nm wavelength light with sinusoidal intensity modulation is injected into the interferometer. The OMPM response properties are measured and π-phase modulation amplitude can be obtained with only 7.5-mW average power light at 1-kHz modulation frequency. The OMPMs shown in this study have advantages of simple structure, potential compact size, and low-power-driven light.展开更多
The phase modulation characteristics of liquid crystal SLM （spatial light modulator） and the system for calibrating are proposed. Michelson interferometer is employed for measuring the modulation properties of devic...The phase modulation characteristics of liquid crystal SLM （spatial light modulator） and the system for calibrating are proposed. Michelson interferometer is employed for measuring the modulation properties of device. A system interface for operating SLM is designed with VC＋＋ compiler. The initial distortion phase is determined by measuring the reflective interference, and modulation of device is compensated by using our system. By using the LUT （lookup table） data provided by manufacture the wavelength disperse calibration is also achieved successfully.展开更多
Organic-inorganic hybrid perovskite solar cells achieve remarkable efficiencies(>26%)yet face stability challenges.Quasi-2D alternating-cation-interlayer perovskites offer enhanced stability through hydrophobic spa...Organic-inorganic hybrid perovskite solar cells achieve remarkable efficiencies(>26%)yet face stability challenges.Quasi-2D alternating-cation-interlayer perovskites offer enhanced stability through hydrophobic spacer cations but suffer from vertical phase segregation and buried interface defects.Herein,we introduce dicyanodiamide(DCD)to simultaneously address these dual limitations in GA(MA)_(n)Pb_(n)I_(3n+1)perovskites.The guanidine group in DCD passivates undercoordinated Pb^(2+)and MA^(+)vacancies at the perovskite/TiO_(2)interface,while cyano groups eliminate oxygen vacancies in TiO_(2)via Ti^(4+)-CN coordination,reducing interfacial trap density by 73%with respect to the control sample.In addition,DCD regulates crystallization kinetics,suppressing low-n-phase aggregation and promoting vertical alignment of high-n phases,which benefit for carrier transport.This dual-functional modification enhances charge transport and stabilizes energy-level alignment.The optimized devices achieve a record power conversion efficiency of 21.54%(vs.19.05%control)and retain 94%initial efficiency after 1200 h,outperforming unmodified counterparts(84%retention).Combining defect passivation with phase homogenization,this work establishes a molecular bridge strategy to decouple stability-efficiency trade-offs in low-dimensional perovskites,providing a universal framework for interface engineering in high-performance optoelectronics.展开更多
Fe-based catalysts are widely used for CO_(2)hydrogenation to light olefins(C_(2–4)=);however,precise regulation of active phases and the balance between intermediate reactions remain significant challenges.Herein,we...Fe-based catalysts are widely used for CO_(2)hydrogenation to light olefins(C_(2–4)=);however,precise regulation of active phases and the balance between intermediate reactions remain significant challenges.Herein,we find that the addition of moderate amounts of Ti forms a strong interaction with Fe compositions,modulating the Fe_(3)O_(4)and Fe_(5)C_(2)contents.Enhanced interaction leads to an increased Fe_(5)C_(2)/Fe_(3)O_(4)ratio,which in turn enhances the adsorption of reactants and intermediates,promoting CO hydrogenation to unsaturated alkyl groups and facilitating C–C coupling.Furthermore,the strong Fe-Ti interaction induces the preferential growth of Fe_(5)C_(2)into prismatic structures that expose the(020),(–112),and(311)facets,forming compact active interfacial sites with Fe_(3)O_(4)nanoparticles.These facet and interfacial effects significantly promote the synergistic coupling of the reverse water gas shift and Fischer-Tropsch reactions.The optimized 3K/FeTi catalyst with the highest Fe_(5)C_(2)/Fe_(3)O_(4)ratio of 3.6 achieves a 52.2%CO_(2)conversion rate,with 44.5%selectivity for C2–4=and 9.5%for CO,and the highest space-time yield of 412.0 mg gcat^(–1)h^(–1)for C_(2–4)=.展开更多
In this paper, we propose a siliconbased highspeed plasmonic modulator. The modulator has a double-layer structure with a 16 The long metaldielectricmetal plasmonic waveguide at the upper layer and two silicon singlem...In this paper, we propose a siliconbased highspeed plasmonic modulator. The modulator has a double-layer structure with a 16 The long metaldielectricmetal plasmonic waveguide at the upper layer and two silicon singlemode waveguides at the bottom layer. The upperlayer plasmonic waveguide acts as a phase shifter and has a dielectric slot that is 30 nm wide. Two taper structures that have gradually varied widths are introduced at the bottom layer to convert the photonic mode into plasmonicslot mode with improved coupling efficiency. For a modulator with two 1 mlong mode couplers, simulation shows that there is an insertion loss of less than 11 dB and a halfwave voltage of 3.65 V. The modulation bandwidth of the proposed modulator can be more than 100 GHz without the carrier effect being a limiting factor in silicon. The fabrication process is also discussed, and the proposed design is shown to be feasible with a hybrid of CMOS and polymer technology.展开更多
A novel scheme for generating optical chaos is proposed and experimentally demonstrated,which supports to simultaneously produce two low-correlation chaotic signals with wideband spectrum and suppressed time-delay-sig...A novel scheme for generating optical chaos is proposed and experimentally demonstrated,which supports to simultaneously produce two low-correlation chaotic signals with wideband spectrum and suppressed time-delay-signature(TDS).In the proposed scheme,we use the output of an external-cavity semiconductor laser(ECSL)as the driving signal of a phase modulator to modulate the output of a CW laser.Then the phase-modulated continuous-wave(CW)light is split into two parts,one is injected back into the ECSL that outputs one chaotic signal,while the other part is passed through a dispersion module for generating another chaotic signal simultaneously.The experimental results prove that the proposed scheme has three merits.Firstly,it can improve the bandwidth of ECSL-based chaos by several times,and simultaneously generate another wideband flat-spectrum chaotic signal.Secondly,the undesired TDS characteristics of the simultaneously-generated chaotic signals can be efficiently suppressed to an indistinguishable level within a wide parameter range,as such the complexities of the chaotic signals are considerably high.Thirdly,the correlation coefficient between these two simultaneously-generated chaotic signals is smaller than 0.1.The proposed scheme provides an attractive solution for parallel multiple chaos generation,and shows great potential for multiple channel chaos communications and multiple random bit generations.展开更多
文摘We propose and analyze a novel Si-based electro-optic modulator with an improved metal-oxide-semiconductor （MOS） capacitor configuration integrated into silicon-on-insulator （SOl）. Three gate-oxide layers embedded in the silicon waveguide constitute a triple MOS capacitor structure, which boosts the modulation efficiency compared with a single MOS capacitor. The simulation results demonstrate that the Vπ Lπ product is 2. 4V · cm. The rise time and fall time of the proposed device are calculated to be 80 and 40ps from the transient response curve, respectively,indicating a bandwidth of 8GHz. The phase shift efficiency and bandwidth can be enhanced by rib width scaling.
基金Dr Start-up Fund of Wuyi University,National Natural Science Foundation of China(60677004)
文摘Numerically analyzed is the transmission performance of the optical millimeter （mm）-wave generated by frequency up-conversion via a phase modulator along the dispersive fiber. 60 GHz ram-wave subcarrier（SC） signals can be obtained after fiber transmission, simultaneously, the phase-modulated signals can be converted to the intensity-modulated ones. The numerical results show that the optical ram-wave at fading loops has better performance, and the eye diagram still keeps open when optical mm-wave signal is transmitted over 98 km.
基金supported by the National Natural Science Foundation of China (No.60808004)the New Century Excellent Talents in University (No.NCET-07-0611)the Tianjin Natural Science Foundation (No.08JCYBJC14500)
文摘A tunable microwave photonic bandpass filter with high mainlobe-to-sidelobe ratio (MSR) based on a phase modulator and a dispersive device is proposed. The multi-tap characteristics of the filter are realized by slicing a broadband source using a Mach-Zehnder interferometer (MZI) which results in a high MSR of 25 dB. The tunability of the filter is realized by an optical variable delay line (OVDL) in one arm of the MZI, which changes the wavelength spacing of the sliced broadband source and results in a tunable free spectrum range (FSR) of the filter. The central frequency of the bandpass filter is tunable from 10.7 GHz to 27 GHz by changing the wavelength spacing from 0.145 nm to 0.054 nm.
基金supported by the National Natural Science Foundation of China (Nos. 60878057, 60478040 and 30770685)the Hi-Tech Re-search and Development Program (863) of China (Nos. 2006AA02Z4E0 and 2008AA02Z422)+1 种基金the Program for New Century Excellent Talents in University of China (No. NCET-04-0528)the Natural Science Foundation of Zhejiang Province, China (No. Z603003)
文摘Fourier-domain rapid scanning optical delay line (RSOD) was introduced for phase modulation and depth scanning in a time-domain optical coherence tomography (TD-OCT) system. Investigation of parameter optimization of RSOD was conducted. Experiments for RSOD characterization at different parameters of the groove pitch, focal length, galvomirror size, etc. were performed. By implementing the optimized RSOD in our established TD-OCT system with a broadband light source centered at 840 nm with 50 nm bandwidth, in vivo retina imaging of a rabbit was presented, demonstrating the feasibility of high-quality TD-OCT imaging using an RSOD-based phase modulator.
基金supported by the National Natural Science Foundation of China(Grant No.61775112).
文摘In laser systems requiring a flat-top distribution of beam intensity,beam smoothing is a critical technology for enhancing laser energy deposition onto the focal spot.The continuous phase modulator(CPM)is a key component in beam smoothing,as it introduces high-frequency continuous phase modulation across the laser beam profile.However,the presence of the CPM makes it challenging to measure and correct the wavefront aberration of the input laser beam effectively,leading to unwanted beam intensity distribution and bringing difficulty to the design of the CPM.To address this issue,we propose a deep learning enabled robust wavefront sensing(DLWS)method to achieve effective wavefront measurement and active aberration correction,thereby facilitating active beam smoothing using the CPM.The experimental results show that the average wavefront reconstruction error of the DLWS method is 0.04μm in the root mean square,while the Shack–Hartmann wavefront sensor reconstruction error is 0.17μm.
基金funded by the National Natural Science Foundation of China(Grant No.52375547)the Natural Science Foundation of Chongqing,China(Grant Nos.CSTB2022NSCQ-BHX0736 and CSTB2022NSCQ-MSX1523)the Chongqing Scientific Institution Incentive Performance Guiding Special Projects(Grant No.CSTB2024JXJL-YFX0034).
文摘This paper uses an innovative improved artificial bee colony(IABC)algorithm to aid in the fabrication of a highly responsive phasemodulation surface plasmon resonance(SPR)biosensor.In this biosensor’s sensing structure,a double-layer Ag-Au metal film is combined with a blue phosphorene/transition metal dichalcogenide(BlueP/TMDC)hybrid structure and graphene.In the optimization function of the IABC method,the reflectivity at resonance angle is incorporated as a constraint to achieve high phase sensitivity.The performance of the Ag-Au-BlueP/TMDC-graphene heterostructure as optimized by the IABC method is compared with that of a similar structure optimized using the traditional ABC algorithm.The results indicate that optimization using the IABC method gives significantly more phase sensitivity,together with lower reflectivity,than can be achieved with the traditional ABC method.The highest phase sensitivity of 3.662×10^(6) °/RIU is achieved with a bilayer of BlueP/WS2 and three layers of graphene.Moreover,analysis of the electric field distribution demonstrates that the optimal arrangement can be utilized for enhanced detection of small biomolecules.Thus,given the exceptional sensitivity achieved,the proposed method based on the IABC algorithm has great promise for use in the design of high-performance SPR biosensors with a variety of multilayer structures.
基金supported by the National Natural Science Foundation of China under Grant No.62175148。
文摘Polarization-independent liquid-crystal(LC)phase modulators can significantly improve the efficiency and reduce the complexity of optical systems.However,achieving good polarization independence for LC phase modulators with a simple structure is difficult.A light-controlled azimuth angle(LCAA)process based on the optical rotatory effect of cholesteric liquid crystals(CLC)was developed for fabricating single-layer,multi-microdomain,orthogonally twisted(MMOT)structures.The developed LC phase modulator with a single-layer MMOT structure may have a low polarization dependence with a large phase depth.This device shows good potential for applications in optical communications,wearable devices,and displays.
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.
文摘A special-velocity-matched electro-optic （EO） phase modulator employing a microwave resonant design in lithium niobate is presented. Both the microwave property and phase-modulation performances of the 3.25-GHz modulator agree well with the numerical simulations. Using this modulator in a single-pass configuration with 1-kW microwave drive power, the spectral bandwidth of a 1053-nm, 3-ns pulse-length laser is broadened to 0.13 nm. With a clear aperture of 5×5 （mm）, the modulator is suited for two- dimensional smoothing by spectral dispersion in high Dower laser systems.
文摘The theoretical construction of the fundamental × NOR gate using two injection semiconductor laser diodes due to mutual coupling is presented. Two laser diodes that are commonly driven by a monochromatic light beam result in chaos; however, chaotic synchronization between the two lasers may be achieved by coupling them. The all-optical logic gate is finally implemented by synchronizing or un-synchronizing appropriately the two chaotic states under a phase modulator （PM） control. Numerical results validate the feasibility of the method.
基金supported by the Natural Science Foundation of Beijing (No. 4062027)the National "863" Project of China (No. 2007AA01Z258)
文摘A phase modulator is employed in the scheme of soliton pulse compression with dispersion shifted fiber （DSF）. Stimulated Brillouin scattering （SBS） effect, as a negative influence here, can be dramatically suppressed after optical phase modulation. The experimental result shows that the launched power required for high-order soliton pulse compression has been significantly increased by 11 dB under the condition of 100-MHz phase modulation. Accordingly, the experiment of picosecond pulse compression generated from electro-absorption sampling window （EASW） has also been implemented.
基金supported by the National "973" Program of China(No.2010CB328300)the National Natural Science Foundation of China(Nos. 61107064,61177071,and 600837004)+3 种基金the Doctoral Fund of Ministry of Educationthe Open Fund of the State Key Lab of ASIC & System(No.11MS009)the Pujiang Fundthe Shuguang Fund
文摘The generation of coherent optical subcarriers based on a concatenated dual-drive Mach-Zehnder intensity modulator （IM） and two phase modulators （PMs） is proposed and experimentally demonstrated. The modulation index and DC bias of PM＋IM modulation are theoretically investigated. Theoretical analysis and numerical study are also carried out to examine the proposed scheme. We use 25-GHz RF synchronous sinusoidal signals to drive cascaded two-stage PMs and IM, through which we generate 28 subcaxriers with peak power fluctuations less than 4 dB. The measured tone-to-noise ratio of the subcarrier is higher than 40 dB. The experimental results show that for 100-Gb/s polarization multiplexing QPSK signal, the receiver sensitivity of the back-to-back signal is -28.6 dBm, and the power penalty is lower than 1 dB after 100-km transmission at the BER of 1 × 10-9.
文摘We discuss the implementation and performance of an adaptive optics(AO)system that uses two cascaded deformable phase plates(DPPs),which are transparent optofluidic phase modulators,mimicking the common woofer/tweeter-type astronomical AO systems.One of the DPPs has 25 electrodes forming a keystone pattern best suited for the correction of low-order and radially symmetric modes;the second device has 37 hexagonally packed electrodes better suited for high-order correction.We also present simulation results and experimental validation for a new open-loop control strategy enabling simultaneous control of both DPPs,which ensures optimum correction for both large-amplitude low-order,and complex combinations of low-and high-order aberrations.The resulting system can reproduce Zernike modes up to the sixth radial order with stroke and fidelity up to twice better than what is attainable with either of the DPPs individually.The performance of the new AO configuration is also verified in a custom-developed fluorescence microscope with sensorless aberration correction.
基金supported by the National Basic Research Program of China(No.2013CB328804)the National High Technology Research and Development Program of China(No.SS2015AA017001)the National Natural Science Foundation of China(No.61275026)
文摘An adaptive modulation system for a liquid crystal（LC） phase modulator is demonstrated. The phase retardation may be modulated by resetting the driving voltage automatically by matching the measured and ideal transmittance of an LC cell sandwiched by crossed polarizers. By using this system, an LC phase modulator can get a low error function of 0.25% in a short modulation time, which is less than the 10% obtained using a conventional modulation method.
文摘An optical microfiber phase modulator （OMPM） directly driven with low-power light is presented. Phase modulation response of OMPM is theoretically analyzed. A 10-mm optical microfiber （OM）, tapered from conventional single-mode fiber, is inserted in one arm of a Michelson fiber interferometer. To drive the OMPM, 980-nm wavelength light with sinusoidal intensity modulation is injected into the interferometer. The OMPM response properties are measured and π-phase modulation amplitude can be obtained with only 7.5-mW average power light at 1-kHz modulation frequency. The OMPMs shown in this study have advantages of simple structure, potential compact size, and low-power-driven light.
文摘The phase modulation characteristics of liquid crystal SLM （spatial light modulator） and the system for calibrating are proposed. Michelson interferometer is employed for measuring the modulation properties of device. A system interface for operating SLM is designed with VC＋＋ compiler. The initial distortion phase is determined by measuring the reflective interference, and modulation of device is compensated by using our system. By using the LUT （lookup table） data provided by manufacture the wavelength disperse calibration is also achieved successfully.
基金support from the National Key R&D Program of China(Grant No.2023YFE0111500)the National Natural Science Foundation of China(Grant No.52321006,T2394480,T2394484,22109143,22479131)+8 种基金Beijing National Laboratory for Molecular Sciences(BNLMS-CXXM-202005)the China Postdoctoral Innovative Talent Support Program(Grant No.BX2021271)the China Postdoctoral Science Foundation(2022M712851)the Opening Project of State Key Laboratory of Advanced Technology for Float Glass(Grant No.2022KF04)Graduate Education Reform Project of Henan Province(Grant No.2023SJGLX136Y)Key R&D Special Program of Henan Province(Grant No.241111242000)Program for Science and Technology Innovation Talents in Universities of Henan Province(Grant No.25HASTIT005)Training Plan for Young Backbone Teachers of Zhengzhou University(Grant No.2023ZDGGJS017)the Joint Research Project of Puyang Shengtong Juyuan New Materials Co.,Ltd.(Grant No.20230128A).
文摘Organic-inorganic hybrid perovskite solar cells achieve remarkable efficiencies(>26%)yet face stability challenges.Quasi-2D alternating-cation-interlayer perovskites offer enhanced stability through hydrophobic spacer cations but suffer from vertical phase segregation and buried interface defects.Herein,we introduce dicyanodiamide(DCD)to simultaneously address these dual limitations in GA(MA)_(n)Pb_(n)I_(3n+1)perovskites.The guanidine group in DCD passivates undercoordinated Pb^(2+)and MA^(+)vacancies at the perovskite/TiO_(2)interface,while cyano groups eliminate oxygen vacancies in TiO_(2)via Ti^(4+)-CN coordination,reducing interfacial trap density by 73%with respect to the control sample.In addition,DCD regulates crystallization kinetics,suppressing low-n-phase aggregation and promoting vertical alignment of high-n phases,which benefit for carrier transport.This dual-functional modification enhances charge transport and stabilizes energy-level alignment.The optimized devices achieve a record power conversion efficiency of 21.54%(vs.19.05%control)and retain 94%initial efficiency after 1200 h,outperforming unmodified counterparts(84%retention).Combining defect passivation with phase homogenization,this work establishes a molecular bridge strategy to decouple stability-efficiency trade-offs in low-dimensional perovskites,providing a universal framework for interface engineering in high-performance optoelectronics.
文摘Fe-based catalysts are widely used for CO_(2)hydrogenation to light olefins(C_(2–4)=);however,precise regulation of active phases and the balance between intermediate reactions remain significant challenges.Herein,we find that the addition of moderate amounts of Ti forms a strong interaction with Fe compositions,modulating the Fe_(3)O_(4)and Fe_(5)C_(2)contents.Enhanced interaction leads to an increased Fe_(5)C_(2)/Fe_(3)O_(4)ratio,which in turn enhances the adsorption of reactants and intermediates,promoting CO hydrogenation to unsaturated alkyl groups and facilitating C–C coupling.Furthermore,the strong Fe-Ti interaction induces the preferential growth of Fe_(5)C_(2)into prismatic structures that expose the(020),(–112),and(311)facets,forming compact active interfacial sites with Fe_(3)O_(4)nanoparticles.These facet and interfacial effects significantly promote the synergistic coupling of the reverse water gas shift and Fischer-Tropsch reactions.The optimized 3K/FeTi catalyst with the highest Fe_(5)C_(2)/Fe_(3)O_(4)ratio of 3.6 achieves a 52.2%CO_(2)conversion rate,with 44.5%selectivity for C2–4=and 9.5%for CO,and the highest space-time yield of 412.0 mg gcat^(–1)h^(–1)for C_(2–4)=.
基金supported in part by National Natural Science Foundation of China (61077052/61125504)Science and Technology Commission of Shanghai Municipality (11530700400)
文摘In this paper, we propose a siliconbased highspeed plasmonic modulator. The modulator has a double-layer structure with a 16 The long metaldielectricmetal plasmonic waveguide at the upper layer and two silicon singlemode waveguides at the bottom layer. The upperlayer plasmonic waveguide acts as a phase shifter and has a dielectric slot that is 30 nm wide. Two taper structures that have gradually varied widths are introduced at the bottom layer to convert the photonic mode into plasmonicslot mode with improved coupling efficiency. For a modulator with two 1 mlong mode couplers, simulation shows that there is an insertion loss of less than 11 dB and a halfwave voltage of 3.65 V. The modulation bandwidth of the proposed modulator can be more than 100 GHz without the carrier effect being a limiting factor in silicon. The fabrication process is also discussed, and the proposed design is shown to be feasible with a hybrid of CMOS and polymer technology.
基金This work was supported by the National Natural Science Foundation of China(Grant no.62171087,61671119)the Sichuan Science and Technology Program(Grant no.2021JDJQ0023)the Fundamental Research Funds for the Central Universities(Grant no.ZYGX2019J003).
文摘A novel scheme for generating optical chaos is proposed and experimentally demonstrated,which supports to simultaneously produce two low-correlation chaotic signals with wideband spectrum and suppressed time-delay-signature(TDS).In the proposed scheme,we use the output of an external-cavity semiconductor laser(ECSL)as the driving signal of a phase modulator to modulate the output of a CW laser.Then the phase-modulated continuous-wave(CW)light is split into two parts,one is injected back into the ECSL that outputs one chaotic signal,while the other part is passed through a dispersion module for generating another chaotic signal simultaneously.The experimental results prove that the proposed scheme has three merits.Firstly,it can improve the bandwidth of ECSL-based chaos by several times,and simultaneously generate another wideband flat-spectrum chaotic signal.Secondly,the undesired TDS characteristics of the simultaneously-generated chaotic signals can be efficiently suppressed to an indistinguishable level within a wide parameter range,as such the complexities of the chaotic signals are considerably high.Thirdly,the correlation coefficient between these two simultaneously-generated chaotic signals is smaller than 0.1.The proposed scheme provides an attractive solution for parallel multiple chaos generation,and shows great potential for multiple channel chaos communications and multiple random bit generations.
