Conventional approaches for obtaining the second and third harmonics typically employ several nonlinear crystals to generate them,which is restricted in application due to the complexity of the optical path and the bu...Conventional approaches for obtaining the second and third harmonics typically employ several nonlinear crystals to generate them,which is restricted in application due to the complexity of the optical path and the bulkiness of the device.In this work,we present a comprehensive theoretical and numerical investigation of the simultaneous generation and competition between the second harmonic waves(SHW)and the third harmonic waves(THW)in a single nonlinear crystal.Through analyzing both small-signal and large-signal regimes,we reveal the complex coupling mechanisms between SHW and THW generation processes.Using periodically poled lithium niobate as an example,we demonstrate that the relative conversion efficiencies between SHW and THW can be freely adjusted by controlling the input fundamental wave power.This work provides new insights for designing efficient frequency converters capable of generating both SHW and THW outputs with controllable intensity ratios.展开更多
Due to its broken out-of-plane symmetry,z-cut periodically poled lithium niobate(PPLN)has exhibited ultrahigh second-order optical nonlinearity.Precise quantification of the domain structure of z-cut PPLN plays a crit...Due to its broken out-of-plane symmetry,z-cut periodically poled lithium niobate(PPLN)has exhibited ultrahigh second-order optical nonlinearity.Precise quantification of the domain structure of z-cut PPLN plays a critical role during poling fabrication.To enhance the imaging detection efficiency of the domain structure in z-cut PPLN,we have developed a second-harmonic generation microscope system specifically designed to produce a longitudinal electric field in foci for the imaging domain inversion.We demonstrated that imaging using a longitudinal electric field can achieve a contrast ratio enhancement by a factor of 1.77,showing high imaging efficiency and making the proposed method suitable for in situ monitoring of the z-cut PPLN poling process.展开更多
A Mach-Zehnder(MZ) electro-optic(EO) modulator are real iz ed,with three optical layers as polymer materials.The functional layer is the co rona poled crosslinkable polyurethane.The ridge waveguide is fabricated by us...A Mach-Zehnder(MZ) electro-optic(EO) modulator are real iz ed,with three optical layers as polymer materials.The functional layer is the co rona poled crosslinkable polyurethane.The ridge waveguide is fabricated by using the spin-coating,poling,photolithography and oxygen reactive ion etching(RIE) techniques.The mode and the modulation properties of these devices are demonstra ted in a micron control system,while the light source works at the wavelength of 1 31 or 1 55 micron.展开更多
This paper reports a continuous-wave （CW） mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. C...This paper reports a continuous-wave （CW） mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN＇s grating period of 28.5 μm and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 μm has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%.展开更多
In this paper we report on a continuous-wave （CW） intracavity singly resonant optical parametric oscillator （ICSRO） based on periodically poled LiNbO3 （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Consi...In this paper we report on a continuous-wave （CW） intracavity singly resonant optical parametric oscillator （ICSRO） based on periodically poled LiNbO3 （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects and diffraction loss, an optical ballast lens and a near-concentric cavity are adopted for better operation. Through varying the grating period and the temperature, the tunable signal output from 1406 nm to 1513 nm is obtained. At a PPLN grating period of 29 pm and a temperature of 413 K, a maximum signal output power of 820 mW at 1500 nm is achieved when the 808 nm pump power is 10.9 W, leading to an optical-to-optical conversion efficiency of 7.51%.展开更多
Tunable coherent emission is generated in a single-pass, cascaded wavelength conversion process from mode-locked laser-pumped monolithic periodically poled lithium niobate（PPLN）. Three ranges of wavelength, includin...Tunable coherent emission is generated in a single-pass, cascaded wavelength conversion process from mode-locked laser-pumped monolithic periodically poled lithium niobate（PPLN）. Three ranges of wavelength, including visible output from 628 nm to 639 nm, near-infrared output from 797 nm to 816 nm, and mid-infrared output from 3167 nm to 3459 nm,were obtained from the monolithic PPLN, which consists of a 10-mm section for 532-nm-pumped optical parametric generation（OPG） and a 7-mm section for 1064-nm-pumped sum frequency generation（SFG）. A pump-to-signal conversion efficiency of 23.4% for OPG at 50°C and a quantum efficiency of 26.2% for SFG at 200°C were obtained.展开更多
Quasi phase matching (QPM) periodical poled LiNbO 3(PPLN) is designed and successfully fabricated to enable second harmonic generation(SHG).The samples were Z cut 0.5 mm thick and grating period is Λ=6.8 μm for the ...Quasi phase matching (QPM) periodical poled LiNbO 3(PPLN) is designed and successfully fabricated to enable second harmonic generation(SHG).The samples were Z cut 0.5 mm thick and grating period is Λ=6.8 μm for the first order QPM of continual wave λ=1.064 μm which is emitted by Nd∶YAG laser at room temperature 27 ℃. The output single pass SHG power was tested by an authorized optical system. The normalized max conversion efficiency is calculated to be 0.25 0 0(W·cm) -1 .The fabrication and parameters calculated method are introduced, and testing scheme is described in this paper. Even some ideas to improve conversion efficiency are offered.展开更多
The experiment on quasi-phase-matched second harmonic generation (SHG) in a channel waveguide was reported. The waveguide was made by annealed proton exchange in the periodically poled lithium niobate (PPLN) with the ...The experiment on quasi-phase-matched second harmonic generation (SHG) in a channel waveguide was reported. The waveguide was made by annealed proton exchange in the periodically poled lithium niobate (PPLN) with the period of PPLN of 14.9 μm, which was designed for cascading wavelength conversion in dense wavelength division multiplexer optical communications. The measurement results of SHG conversion efficiency as a function of fundamental wavelength at room temperature fit well to sinc^2 shape. The peak of SHG conversion efficiency was 75%·W~ -1 ·cm~ -2 as well as reported. The relationship between the center fundamental wavelength and temperature shows that SHG can be effectively tuned by the temperature in PPLN waveguide.展开更多
The Ti-doped waveguide-type periodically poled LiNbO_(3)(PPLN)were fabricated and the dependence of domain wall velocity on an external field applied for domain inversion was investigated.The whole polarization revers...The Ti-doped waveguide-type periodically poled LiNbO_(3)(PPLN)were fabricated and the dependence of domain wall velocity on an external field applied for domain inversion was investigated.The whole polarization reversal process was computer-controlled to regulate domain wall expansion at a feedback time shorter than 5μs.The coercive voltage and several values of excess voltage were applied on 500μm-thick wafers serially connected to a 1-MOhm external resistor which had an effect of the poling current reduction,i.e.the deceleration of domain wall expansion.The domain wall velocity is sensitive to the poling voltage,precisely speaking,to the excess voltage.The domain wall velocities were 28.70,16.02 and 5.75μm·s^(-1)under poling field of 23.5,22.0 and 21.0 kV·mm^(-1),respectively.Moreover,average duty cycle of PPLN is about 49.93%.展开更多
Films were prepared from mixtures of copolymers of 4-nitro-4'-[N-methylacryloyloxyethyl, N'-ethyl] amino azobenzene with glycidyl methacrylate (chromophore content: 6 mol%) and copolymers containing anhydride ...Films were prepared from mixtures of copolymers of 4-nitro-4'-[N-methylacryloyloxyethyl, N'-ethyl] amino azobenzene with glycidyl methacrylate (chromophore content: 6 mol%) and copolymers containing anhydride units, which was obtained by the reaction of 4-nitro-4'-[N-hydroxyethyl, N'-ethyl] amino azobenzene with polymethacryloyl chloride (chromophore content: 25 mol %). During thermal poling process the anhydride reacts with the epoxy group and the resulting crosslinked network structure will stabilize the second harmonic generation in the poled film. The second harmonic generation of the poled film shows a maximum with the variation of composition this is presumed to be due to the effects of the increasing of concentration, orientation order as well as orientation stability of chromophore groups during crosslinking.展开更多
With the pulsed laser deposition （PLD） method, amorphous 80GeS2-15Ga2S3-5CdS chalcogenide film was deposited on glassy substrate. Obvious second harmonic generation （SHG） was observed in the ultraviolet （UV）-pol...With the pulsed laser deposition （PLD） method, amorphous 80GeS2-15Ga2S3-5CdS chalcogenide film was deposited on glassy substrate. Obvious second harmonic generation （SHG） was observed in the ultraviolet （UV）-polarized film and the SHG intensity increased with the increase in single pulse energy and irradiation time. Through Raman spectra and transmission spectra, the mechanism of SHG was studied. The experimental results demonstrated that effective electron traps and hole traps were generated in the UV- polarized film. The energy of electrons and holes was using up due to the collision with other particles and crystal fields during their movement and finally they were captured by the traps and fixed, which made the electric charge distribution nonuniform in the film and destroyed the spatial isotropy. In the meantime, the center of positive and negative charges separated and a built-in electric field was formed which generated the optical second-order nonlinearity of the film.展开更多
The temperature dependency of a 5-mo1% MgO-doped periodically poled lithium niobate waveguide was investi- gated in this paper. We started with the temperature-dependent refractive index equation for the waveguide. Se...The temperature dependency of a 5-mo1% MgO-doped periodically poled lithium niobate waveguide was investi- gated in this paper. We started with the temperature-dependent refractive index equation for the waveguide. Secondly, the temperature dependency of the second harmonic generation effect was experimentally researched under different temperatures and pump powers. The quasi-phase matched wavelengths, efficiency bandwidths and peak efficiencies of the waveguide were measured. The experimental results agreed with theoretical simulations, which are indispensable in the following all-optical sampling studies based on the cascaded second harmonic generation/difference-frequency generation process in the current device.展开更多
In this paper a high-repetition-rate mid-infrared （mid-IR） optical parametric oscillator based on periodically poled MgO-doped LiNbO3 （PPMgLN） at room temperature was demonstrated. The maximum average mid-IR outpu...In this paper a high-repetition-rate mid-infrared （mid-IR） optical parametric oscillator based on periodically poled MgO-doped LiNbO3 （PPMgLN） at room temperature was demonstrated. The maximum average mid-IR output power at 3.63μm was 1.02 W with the repetition rate of 60kHz and corresponding efficiency from the pump to the idler was 26.7%. The temperature tuning and the period tuning characteristics were also discussed.展开更多
This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched dlode-endpumped Nd：YVO4 laser with periodically poled MgO：LiNbO3（PPMgLN）. With the Q-switch set at a repetition rat...This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched dlode-endpumped Nd：YVO4 laser with periodically poled MgO：LiNbO3（PPMgLN）. With the Q-switch set at a repetition rate of 25kHz and the PPMgLN crystal operated at room temperature （25℃）, the intracavity optical parametric generator threshold was reached as a diode pump power of 0.9 W. A maximum signal output power of 0.34 W with a pulse width of 25 ns and a beam quality factor of 1.4 was obtained at an incident diode power of 3.4 W, leading to a conversion efficiency of 10% with a slope efficiency of 14.4%. By varying the crystal temperature from 25 to 200℃, the output signal wavelengths were tuned in range of 1506-1565 nm. Over a 30-minutes interval, the instability of the signal power was measured to be less than 1%. In addition, the threshold pump intensity for the intracavity optical parametric generator is theoretically investigated, and the obtained result is in good agreement with the experimental results.展开更多
The investigation of electrochromic effect of corona-poled nonlinear optical polymer films is an effective method for the estimation of poling level and the selection of poling conditions. The poling electric field E_...The investigation of electrochromic effect of corona-poled nonlinear optical polymer films is an effective method for the estimation of poling level and the selection of poling conditions. The poling electric field E_p and orientational order parameter Φ, which are the important parameters to predict d_(33) of poled films, can be calculated by a simple operation from the number of red shift of charge transfer absorption band. The calculated results are in good agreement with the experimental data.展开更多
Thermally poled germanium-doped channel waveguides are presented. Multilayer waveguides containing a silicon oxynitride layer were used as charge trapper in this investigation on the effect of the internal field insid...Thermally poled germanium-doped channel waveguides are presented. Multilayer waveguides containing a silicon oxynitride layer were used as charge trapper in this investigation on the effect of the internal field inside the waveguide. Compared to waveguides without the trapping layer, experimental results showed that the induced linear electro-optic (EO) coefficient increases about 20% after poling, suggesting strongly that the internal field is relatively enhanced, and showed it is a promising means for improving nonlinearity by poling in waveguides.展开更多
Bulk Acoustic Wave(BAW)filters find applications in radio frequency(RF)communication systems for Wi-Fi,3G,4G,and 5G networks.In the beyond-5G(potential 6G)era,high-frequency bands(>8 GHz)are expected to require res...Bulk Acoustic Wave(BAW)filters find applications in radio frequency(RF)communication systems for Wi-Fi,3G,4G,and 5G networks.In the beyond-5G(potential 6G)era,high-frequency bands(>8 GHz)are expected to require resonators with high-quality factor(Q)and electromechanical coupling(k_(t)^(2))to form filters with low insertion loss and high selectivity.However,both the Q and k_(t)^(2)of resonator devices formed in traditional uniform polarization piezoelectric films of aluminum nitride(AlN)and aluminum scandium nitride(AlScN)decrease when scaled beyond 8 GHz.In this work,we utilized 4-layer AlScN periodically poled piezoelectric films(P3F)to construct high-frequency(~17–18 GHz)resonators and filters.The resonator performance is studied over a range of device geometries,with the best resonator achieving a k_(t)^(2)of 11.8%and a Qp of 236.6 at the parallel resonance frequency(f_(p))of 17.9 GHz.These resulting figures-of-merit are(FoM_(1)=k_(t)^(2)Qp and FoM_(2)=f_(p)FoM_(1)×10^(-9))27.9 and 500,respectively.These and the k_(t)^(2)are significantly higher than previously reported AlN/AlScN-based resonators operating at similar frequencies.Fabricated 3-element and 6-element filters formed from these resonators demonstrated low insertion losses(IL)of 1.86 and 3.25 dB,and−3 dB bandwidths(BW)of 680 MHz(fractional BW of 3.9%)and 590 MHz(fractional BW of 3.3%)at a~17.4 GHz center frequency.The 3-element and 6-element filters achieved excellent linearity with in-band input third-order intercept point(IIP3)values of+36 and+40 dBm,respectively,which are significantly higher than previously reported acoustic filters operating at similar frequencies.展开更多
Submicron-thick thin-film lithium niobate(TFLN)has emerged as a promising platform for nonlinear integrated photonics.In this work,we demonstrate the efficient simultaneous generation of broadband 2nd–8th harmonics i...Submicron-thick thin-film lithium niobate(TFLN)has emerged as a promising platform for nonlinear integrated photonics.In this work,we demonstrate the efficient simultaneous generation of broadband 2nd–8th harmonics in chirped periodically poled(CPP)TFLN.This is achieved through the synergistic effects of cascadedχ^((2))nonlinear up-conversion andχ^((3))self-phase modulation,driven by near-infrared femtosecond pulses with a central wavelength of 2100 nm and a pulse energy of 1.2μJ.Remarkably,the 7th and 8th harmonics extend into the deep ultraviolet(DUV)region,reaching wavelengths as short as 250 nm.The 3rd–8th harmonic spectra seamlessly connect,forming a broadband supercontinuum spanning from the DUV to the visible range(250–800 nm,-25 d B),with an on-chip conversion efficiency of 19%(0.23μJ).This achievement is attributed to the CPP-TFLN providing multiple broadband reciprocal lattice vector bands,enabling quasi-phase matching for a series ofχ^((2))nonlinear processes,including second harmonic generation(SHG),cascaded SHG,and third harmonic generation.Furthermore,we demonstrated the significant role of cascadedχ^((2))phase-mismatched nonlinear processes in high-harmonic generation(HHG).Our work unveils the intricate and diverse nonlinear optical interactions in TFLN,offering a clear path toward efficient on-chip HHG and compact coherent white-light sources extending into the DUV.展开更多
基金supported by the Science and Technology Project of Guangdong Province,China(Grant No.2020B010190001)the National Natural Science Foundation of China(Grant No.12434016)+1 种基金the National Key Research and Development Program of China(Grant No.2023YFA1406900)the Fund of the National Postdoctoral Researcher Program(Grant No.GZB20240785).
文摘Conventional approaches for obtaining the second and third harmonics typically employ several nonlinear crystals to generate them,which is restricted in application due to the complexity of the optical path and the bulkiness of the device.In this work,we present a comprehensive theoretical and numerical investigation of the simultaneous generation and competition between the second harmonic waves(SHW)and the third harmonic waves(THW)in a single nonlinear crystal.Through analyzing both small-signal and large-signal regimes,we reveal the complex coupling mechanisms between SHW and THW generation processes.Using periodically poled lithium niobate as an example,we demonstrate that the relative conversion efficiencies between SHW and THW can be freely adjusted by controlling the input fundamental wave power.This work provides new insights for designing efficient frequency converters capable of generating both SHW and THW outputs with controllable intensity ratios.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFC3401100 and 2022YFF0712500)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030009)+2 种基金the National Natural Science Foundation of China(Grant Nos.12204017,12004012,12004013,12041602,91750203,91850111,and 92150301)the China Postdoctoral Science Foundation(Grant No.2020M680220 and 2020M680230)the Clinical Medicine Plus X-Young Scholars Project,Peking University,Fundamental Research Funds for the Central Universities.
文摘Due to its broken out-of-plane symmetry,z-cut periodically poled lithium niobate(PPLN)has exhibited ultrahigh second-order optical nonlinearity.Precise quantification of the domain structure of z-cut PPLN plays a critical role during poling fabrication.To enhance the imaging detection efficiency of the domain structure in z-cut PPLN,we have developed a second-harmonic generation microscope system specifically designed to produce a longitudinal electric field in foci for the imaging domain inversion.We demonstrated that imaging using a longitudinal electric field can achieve a contrast ratio enhancement by a factor of 1.77,showing high imaging efficiency and making the proposed method suitable for in situ monitoring of the z-cut PPLN poling process.
文摘A Mach-Zehnder(MZ) electro-optic(EO) modulator are real iz ed,with three optical layers as polymer materials.The functional layer is the co rona poled crosslinkable polyurethane.The ridge waveguide is fabricated by using the spin-coating,poling,photolithography and oxygen reactive ion etching(RIE) techniques.The mode and the modulation properties of these devices are demonstra ted in a micron control system,while the light source works at the wavelength of 1 31 or 1 55 micron.
基金Project supported in part by the National Natural Science Foundation of China (Grant Nos 10474071, 60637010, 60671036 and60278001)Tianjin Applied Fundamental Research Project, China (07JCZDJC05900)
文摘This paper reports a continuous-wave （CW） mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN＇s grating period of 28.5 μm and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 μm has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%.
基金Project supported partly by the National Natural Science Foundation of China (Grant Nos 60637010 and 60671036)the National Basic Research Program of China (Grant No 2007CB310403)the Tianjin Applied Fundamental Research Project, China(Grant No 07JCZDJC05900)
文摘In this paper we report on a continuous-wave （CW） intracavity singly resonant optical parametric oscillator （ICSRO） based on periodically poled LiNbO3 （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects and diffraction loss, an optical ballast lens and a near-concentric cavity are adopted for better operation. Through varying the grating period and the temperature, the tunable signal output from 1406 nm to 1513 nm is obtained. At a PPLN grating period of 29 pm and a temperature of 413 K, a maximum signal output power of 820 mW at 1500 nm is achieved when the 808 nm pump power is 10.9 W, leading to an optical-to-optical conversion efficiency of 7.51%.
基金Project supported by the National Basic Research Program of China(Grant No.2013CB632704)
文摘Tunable coherent emission is generated in a single-pass, cascaded wavelength conversion process from mode-locked laser-pumped monolithic periodically poled lithium niobate（PPLN）. Three ranges of wavelength, including visible output from 628 nm to 639 nm, near-infrared output from 797 nm to 816 nm, and mid-infrared output from 3167 nm to 3459 nm,were obtained from the monolithic PPLN, which consists of a 10-mm section for 532-nm-pumped optical parametric generation（OPG） and a 7-mm section for 1064-nm-pumped sum frequency generation（SFG）. A pump-to-signal conversion efficiency of 23.4% for OPG at 50°C and a quantum efficiency of 26.2% for SFG at 200°C were obtained.
文摘Quasi phase matching (QPM) periodical poled LiNbO 3(PPLN) is designed and successfully fabricated to enable second harmonic generation(SHG).The samples were Z cut 0.5 mm thick and grating period is Λ=6.8 μm for the first order QPM of continual wave λ=1.064 μm which is emitted by Nd∶YAG laser at room temperature 27 ℃. The output single pass SHG power was tested by an authorized optical system. The normalized max conversion efficiency is calculated to be 0.25 0 0(W·cm) -1 .The fabrication and parameters calculated method are introduced, and testing scheme is described in this paper. Even some ideas to improve conversion efficiency are offered.
基金The National Natural Science Foundation ofChina (No 60477016)Shanghai MunicipalEducation Commission"Shu Guang"Project
文摘The experiment on quasi-phase-matched second harmonic generation (SHG) in a channel waveguide was reported. The waveguide was made by annealed proton exchange in the periodically poled lithium niobate (PPLN) with the period of PPLN of 14.9 μm, which was designed for cascading wavelength conversion in dense wavelength division multiplexer optical communications. The measurement results of SHG conversion efficiency as a function of fundamental wavelength at room temperature fit well to sinc^2 shape. The peak of SHG conversion efficiency was 75%·W~ -1 ·cm~ -2 as well as reported. The relationship between the center fundamental wavelength and temperature shows that SHG can be effectively tuned by the temperature in PPLN waveguide.
文摘The Ti-doped waveguide-type periodically poled LiNbO_(3)(PPLN)were fabricated and the dependence of domain wall velocity on an external field applied for domain inversion was investigated.The whole polarization reversal process was computer-controlled to regulate domain wall expansion at a feedback time shorter than 5μs.The coercive voltage and several values of excess voltage were applied on 500μm-thick wafers serially connected to a 1-MOhm external resistor which had an effect of the poling current reduction,i.e.the deceleration of domain wall expansion.The domain wall velocity is sensitive to the poling voltage,precisely speaking,to the excess voltage.The domain wall velocities were 28.70,16.02 and 5.75μm·s^(-1)under poling field of 23.5,22.0 and 21.0 kV·mm^(-1),respectively.Moreover,average duty cycle of PPLN is about 49.93%.
文摘Films were prepared from mixtures of copolymers of 4-nitro-4'-[N-methylacryloyloxyethyl, N'-ethyl] amino azobenzene with glycidyl methacrylate (chromophore content: 6 mol%) and copolymers containing anhydride units, which was obtained by the reaction of 4-nitro-4'-[N-hydroxyethyl, N'-ethyl] amino azobenzene with polymethacryloyl chloride (chromophore content: 25 mol %). During thermal poling process the anhydride reacts with the epoxy group and the resulting crosslinked network structure will stabilize the second harmonic generation in the poled film. The second harmonic generation of the poled film shows a maximum with the variation of composition this is presumed to be due to the effects of the increasing of concentration, orientation order as well as orientation stability of chromophore groups during crosslinking.
基金Funded by the National Natural Science Foundaition of China(Nos.51172169 and 61177084),NCET\(NCET-11-0687)the Fundamental Research Funds for the Central Universities(Wuhan University of Technology)
文摘With the pulsed laser deposition （PLD） method, amorphous 80GeS2-15Ga2S3-5CdS chalcogenide film was deposited on glassy substrate. Obvious second harmonic generation （SHG） was observed in the ultraviolet （UV）-polarized film and the SHG intensity increased with the increase in single pulse energy and irradiation time. Through Raman spectra and transmission spectra, the mechanism of SHG was studied. The experimental results demonstrated that effective electron traps and hole traps were generated in the UV- polarized film. The energy of electrons and holes was using up due to the collision with other particles and crystal fields during their movement and finally they were captured by the traps and fixed, which made the electric charge distribution nonuniform in the film and destroyed the spatial isotropy. In the meantime, the center of positive and negative charges separated and a built-in electric field was formed which generated the optical second-order nonlinearity of the film.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60777024 and 60978007)
文摘The temperature dependency of a 5-mo1% MgO-doped periodically poled lithium niobate waveguide was investi- gated in this paper. We started with the temperature-dependent refractive index equation for the waveguide. Secondly, the temperature dependency of the second harmonic generation effect was experimentally researched under different temperatures and pump powers. The quasi-phase matched wavelengths, efficiency bandwidths and peak efficiencies of the waveguide were measured. The experimental results agreed with theoretical simulations, which are indispensable in the following all-optical sampling studies based on the cascaded second harmonic generation/difference-frequency generation process in the current device.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60637010 and 10471071)the Ministry of Education of China+1 种基金the National Research Foundation for the Doctoral Program of Ministry of Education of China (Grant No20040056010)Tianjin Application Bases and Advanced Technology Plan (Grant No 07JCYBJC06200)
文摘In this paper a high-repetition-rate mid-infrared （mid-IR） optical parametric oscillator based on periodically poled MgO-doped LiNbO3 （PPMgLN） at room temperature was demonstrated. The maximum average mid-IR output power at 3.63μm was 1.02 W with the repetition rate of 60kHz and corresponding efficiency from the pump to the idler was 26.7%. The temperature tuning and the period tuning characteristics were also discussed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10474071 and 60671036)
文摘This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched dlode-endpumped Nd：YVO4 laser with periodically poled MgO：LiNbO3（PPMgLN）. With the Q-switch set at a repetition rate of 25kHz and the PPMgLN crystal operated at room temperature （25℃）, the intracavity optical parametric generator threshold was reached as a diode pump power of 0.9 W. A maximum signal output power of 0.34 W with a pulse width of 25 ns and a beam quality factor of 1.4 was obtained at an incident diode power of 3.4 W, leading to a conversion efficiency of 10% with a slope efficiency of 14.4%. By varying the crystal temperature from 25 to 200℃, the output signal wavelengths were tuned in range of 1506-1565 nm. Over a 30-minutes interval, the instability of the signal power was measured to be less than 1%. In addition, the threshold pump intensity for the intracavity optical parametric generator is theoretically investigated, and the obtained result is in good agreement with the experimental results.
文摘The investigation of electrochromic effect of corona-poled nonlinear optical polymer films is an effective method for the estimation of poling level and the selection of poling conditions. The poling electric field E_p and orientational order parameter Φ, which are the important parameters to predict d_(33) of poled films, can be calculated by a simple operation from the number of red shift of charge transfer absorption band. The calculated results are in good agreement with the experimental data.
文摘Thermally poled germanium-doped channel waveguides are presented. Multilayer waveguides containing a silicon oxynitride layer were used as charge trapper in this investigation on the effect of the internal field inside the waveguide. Compared to waveguides without the trapping layer, experimental results showed that the induced linear electro-optic (EO) coefficient increases about 20% after poling, suggesting strongly that the internal field is relatively enhanced, and showed it is a promising means for improving nonlinearity by poling in waveguides.
文摘Bulk Acoustic Wave(BAW)filters find applications in radio frequency(RF)communication systems for Wi-Fi,3G,4G,and 5G networks.In the beyond-5G(potential 6G)era,high-frequency bands(>8 GHz)are expected to require resonators with high-quality factor(Q)and electromechanical coupling(k_(t)^(2))to form filters with low insertion loss and high selectivity.However,both the Q and k_(t)^(2)of resonator devices formed in traditional uniform polarization piezoelectric films of aluminum nitride(AlN)and aluminum scandium nitride(AlScN)decrease when scaled beyond 8 GHz.In this work,we utilized 4-layer AlScN periodically poled piezoelectric films(P3F)to construct high-frequency(~17–18 GHz)resonators and filters.The resonator performance is studied over a range of device geometries,with the best resonator achieving a k_(t)^(2)of 11.8%and a Qp of 236.6 at the parallel resonance frequency(f_(p))of 17.9 GHz.These resulting figures-of-merit are(FoM_(1)=k_(t)^(2)Qp and FoM_(2)=f_(p)FoM_(1)×10^(-9))27.9 and 500,respectively.These and the k_(t)^(2)are significantly higher than previously reported AlN/AlScN-based resonators operating at similar frequencies.Fabricated 3-element and 6-element filters formed from these resonators demonstrated low insertion losses(IL)of 1.86 and 3.25 dB,and−3 dB bandwidths(BW)of 680 MHz(fractional BW of 3.9%)and 590 MHz(fractional BW of 3.3%)at a~17.4 GHz center frequency.The 3-element and 6-element filters achieved excellent linearity with in-band input third-order intercept point(IIP3)values of+36 and+40 dBm,respectively,which are significantly higher than previously reported acoustic filters operating at similar frequencies.
基金National Natural Science Foundation of China(12434016,11974119)Science and Technology Project of Guangdong(2020B010190001)National Funded Postdoctoral Researcher Program(GZB20240785)。
文摘Submicron-thick thin-film lithium niobate(TFLN)has emerged as a promising platform for nonlinear integrated photonics.In this work,we demonstrate the efficient simultaneous generation of broadband 2nd–8th harmonics in chirped periodically poled(CPP)TFLN.This is achieved through the synergistic effects of cascadedχ^((2))nonlinear up-conversion andχ^((3))self-phase modulation,driven by near-infrared femtosecond pulses with a central wavelength of 2100 nm and a pulse energy of 1.2μJ.Remarkably,the 7th and 8th harmonics extend into the deep ultraviolet(DUV)region,reaching wavelengths as short as 250 nm.The 3rd–8th harmonic spectra seamlessly connect,forming a broadband supercontinuum spanning from the DUV to the visible range(250–800 nm,-25 d B),with an on-chip conversion efficiency of 19%(0.23μJ).This achievement is attributed to the CPP-TFLN providing multiple broadband reciprocal lattice vector bands,enabling quasi-phase matching for a series ofχ^((2))nonlinear processes,including second harmonic generation(SHG),cascaded SHG,and third harmonic generation.Furthermore,we demonstrated the significant role of cascadedχ^((2))phase-mismatched nonlinear processes in high-harmonic generation(HHG).Our work unveils the intricate and diverse nonlinear optical interactions in TFLN,offering a clear path toward efficient on-chip HHG and compact coherent white-light sources extending into the DUV.
