We have proposed and demonstrated a nearly-noncritical phase-matched (NCPM) optical parametric oscillation (OPO) in an MgO:LiNbO_(3) crystal with 5 mol% MgO by temperature tuning. By giving up perfect NCPM, the practi...We have proposed and demonstrated a nearly-noncritical phase-matched (NCPM) optical parametric oscillation (OPO) in an MgO:LiNbO_(3) crystal with 5 mol% MgO by temperature tuning. By giving up perfect NCPM, the practical tuning range for the OPO is increased by two times. For the crystal, the operated temperature decreases with the phase-matching angle at degeneracy. With a cutting angle of 82° instead of the noncritical case of 90°, the tuning range was increased. In order to obtain a sufficiently high output pulse energy for both signal and idler throughout the entire tuning range, five sets of mirrors were used for the resonator. The tuning range of the OPO was 800-1700 nm with temperatures tuning from 83°C to 224.2°C. The output energy was about 6.45 mJ with a conversion efficiency of nearly 13%. The bandwidth of the output was 1.0-L1 nm.展开更多
By using p-type polymer poly(2,5-Didodecyloxy-1,4-Phenylenylenevinylene)(PDDOPV)and n-type inorganic material ZnO:Zn,the electronluminescent(EL)emission from bilayer device based on polymer/inorganic hetero-junction w...By using p-type polymer poly(2,5-Didodecyloxy-1,4-Phenylenylenevinylene)(PDDOPV)and n-type inorganic material ZnO:Zn,the electronluminescent(EL)emission from bilayer device based on polymer/inorganic hetero-junction was successfully demonstrated.In comparison with single layer polymer device,with dc voltage of 10V,the brightness and luminous efficiency of bilayer device were enhanced 14 and 26 times,respectively.The EL spectrum of bilayer device is not identical to the characteristic emission spectrum of either PDDOPV or ZnO:Zn,and shifts continuously towards to short wavelength direction as the applied voltage increases.展开更多
We report on a high power output quasi-continuous-wave nanosecond optical parametric generator （OPG） of congruent periodically poled lithium niobate （PPLN） pumped by a 1 064 nm acousto-optically Q-switched Nd:YVO4...We report on a high power output quasi-continuous-wave nanosecond optical parametric generator （OPG） of congruent periodically poled lithium niobate （PPLN） pumped by a 1 064 nm acousto-optically Q-switched Nd:YVO4 laser （duration: 70 ns,repetition rate:45 kHz,spatial beam quality M2<1.3）.The OPG consists of a 38.7 mm long PPLN crystal with a domain period of 28.93 μm. With 5.43 W of average pump power the maximum average output power is 991 mW at 1 517.1 nm signal wave of the PPLN OPG.展开更多
Theoretical investigation of the phase-matching properties for the tunable coherent terahertz wave generation in the isotro- pic semiconductor nonlinear materials of CdTe and GaP is presented according to their optica...Theoretical investigation of the phase-matching properties for the tunable coherent terahertz wave generation in the isotro- pic semiconductor nonlinear materials of CdTe and GaP is presented according to their optical dispersion properties, based on a pulsed dual-wavelength KTP-OPO operating near degenerate point in the process of the difference frequency mixing. The cross-Reststrahlen band dispersion compensation phase-matching technique involved in this interaction is introduced concisely. The optimum lengths of DFG crystals are decided according to the minimum coherence lengths of the crystals in the given pump wavelength ranges. The results of analysis and calculation provide the useful and necessary theoretical basis and guidance for the future experiments.展开更多
An ultrabroad and sharp transition bandpass flexible terahertz(THz)filter is designed using a multiple-layered metamaterial.This bandpass filter has excellent filtering capability,with a 3 dB bandwidth of about 0.47 T...An ultrabroad and sharp transition bandpass flexible terahertz(THz)filter is designed using a multiple-layered metamaterial.This bandpass filter has excellent filtering capability,with a 3 dB bandwidth of about 0.47 THz and sharp band-edge transitions of 80 dB/THz and 96 dB/THz,respectively,and it can be realized by a coupling individual resonance mode.We find that the geometry parameters have an influence on the transmission profile,which are capable of giving us meaningful guidance in design of high profile bandpass THz filters.The numerical results show that the multiple-layered flexible metamaterial provides an effective way to achieve ultrabroad THz devices.展开更多
We experimentally demonstrate a high power nanosecond pulsed terahertz(THz)-wave parametric oscillator(TPO)by using a wide pump beam.A surface emitted cavity configuration is employed to reduce the THz absorption in M...We experimentally demonstrate a high power nanosecond pulsed terahertz(THz)-wave parametric oscillator(TPO)by using a wide pump beam.A surface emitted cavity configuration is employed to reduce the THz absorption in MgO:LiNbO_(3) crystal.The THz wave can be tuned from 1 THz to 3 THz.A maximum THz output energy of 438 nJ/pulse is achieved at 1.56 Hz using a 4.5-mm-diameter pump beam with a pulse energy of 226 mJ pump energy with the repetition of 10 Hz,corresponding to the energy conversion efficiency of 1.94×10^(-6).展开更多
We report a widely tunable,narrow linewidth,pulsed Ti:sapphire laser pumped by an all-solid-state Q-switched intra-cavity frequency-doubled Nd:YAG laser.By using four dense flint glass prisms as intra-cavity dispersiv...We report a widely tunable,narrow linewidth,pulsed Ti:sapphire laser pumped by an all-solid-state Q-switched intra-cavity frequency-doubled Nd:YAG laser.By using four dense flint glass prisms as intra-cavity dispersive elements,the output wavelength can be continuously tuned over 675–970 nm and the spectral linewidth is shortened to 0.5 nm.The maximum output power of 6.65 W at 780 nm is obtained under 23.4 W pump power with repetition rate of 5.5 kHz;corresponding to an conversion efficiency of 28.4%.Due to the gain-switching characteristics of the Ti:sapphire laser,the output pulse duration is as short as 17.6 ns.展开更多
We propose a simple birefringent terahertz （THz） waveguide which is a polymer elliptical tube with a cross section of elliptical ring structure. It can be achieved by stretching a normal circular-tube in one directi...We propose a simple birefringent terahertz （THz） waveguide which is a polymer elliptical tube with a cross section of elliptical ring structure. It can be achieved by stretching a normal circular-tube in one direction. Simulations based on the full-vector finite element method （FEM） show that this kind of waveguides exhibits high birefringenee on a level of 10- 2 over a wide THz frequency range. Moreover, as a majority of modal power is trapped in the air core inside the polymer elliptical tube, the THz waveguide guiding loss caused by material absorption can be reduced effectively.展开更多
The parametric gain of a terahertz wave parametric oscillator （TPO） is analyzed. Meanwhile the expression of TPO threshold pump intensity is derived and theoretically analyzed with different factors. The effective i...The parametric gain of a terahertz wave parametric oscillator （TPO） is analyzed. Meanwhile the expression of TPO threshold pump intensity is derived and theoretically analyzed with different factors. The effective interaction length between the pump wave and Stokes wave is calculated, and particular attention is paid to the coupling efficiency of the pump wave and Stokes wave. Such an analysis is useful for the experiments of TPO.展开更多
In the simulation of Intensity Modulation-Direct Detection WDM Systems,when the dispersion and nonlinear effects play equally important roles,the intensity fluctuation caused by cross-phase modulation may be overestim...In the simulation of Intensity Modulation-Direct Detection WDM Systems,when the dispersion and nonlinear effects play equally important roles,the intensity fluctuation caused by cross-phase modulation may be overestimated as a result of the improper step size.Therefore,the step size in numerical simulation should be selected to suppress false XPM intensity modulation (keep it much less than signal power).According to this criterion,the step size is variable along the fiber.For a WDM system,the step size depends on the channel separation.Different type of transmission fiber has different step size.In the split-step Fourier method,this criterion can reduce simulation time,and when the step size is bigger than 100 meters,the simulation accuracy can also be improved.展开更多
The dielectric properties of near-stoichiometric LiNbO3：Fe and LiNbO3：Ce single crystals have been investigated using terahertz time domain spectroscopy in a frequency range of 0.71.6 THz at room temperature. When c...The dielectric properties of near-stoichiometric LiNbO3：Fe and LiNbO3：Ce single crystals have been investigated using terahertz time domain spectroscopy in a frequency range of 0.71.6 THz at room temperature. When coupled with an applied external optical field, obvious photorefractive effects were observed, resulting in a modulation of the complex dielectric constant for the crystals. The variation in refractive index, ｜△n｜, had a linear relationship with the applied light intensity, accompanied by a step-like decrease at high intensity. The findings were attributed to the internal space charge field of the photorefraction and the light-induced domain reversal in the crystals.展开更多
We report a method for improving temporal response of FBG-based temperature sensors.It has been demonstrated that by filling thermal conductive pastes between a sensing FBG and its package,the temporal response of the...We report a method for improving temporal response of FBG-based temperature sensors.It has been demonstrated that by filling thermal conductive pastes between a sensing FBG and its package,the temporal response of the FBG-based temperature sensor can be significantly improved while isolating the strain and vibration.展开更多
A widely tunable quasi-phase-matched optical parametric generator pumped by a 1 064 nm acousto-optically Q-switched diode-end-pumped Nd:YAG laser based on a MgO-doped periodically poled LiNbO3 crystal with a multigrat...A widely tunable quasi-phase-matched optical parametric generator pumped by a 1 064 nm acousto-optically Q-switched diode-end-pumped Nd:YAG laser based on a MgO-doped periodically poled LiNbO3 crystal with a multigrating structure （29.2-30.4 μm） is reported.A broad continuous signal spectrum 1 513-1 731 nm is obtained by changing the crystal grating periods from 29.2 μm to 30.4 μm and by tuning simultaneously the crystal temperature from 60℃ to 150℃.When the average pump power is 1.82 W with about 120 ns pulse duration operating at a repetition rate of 10 KHz,the maximum total output power of the PPMgLN OPG is about 323.58 mW consisting of 210 mW of 1.639 μm signal radiation and 113.58 mW of 3.02 μm idler radiation.展开更多
We investigate 750 nm and 532 nm dual-wavelength laser for applications in the internet of things.A kind of optical maser is developed,in which the semiconductor module outputs the 808 nm pump light and then it goes i...We investigate 750 nm and 532 nm dual-wavelength laser for applications in the internet of things.A kind of optical maser is developed,in which the semiconductor module outputs the 808 nm pump light and then it goes into a double-clad Nd^(3+):YAG monocrystal optical fiber through the intermediate coupler and forms a 1064 nm laser.The laser outputs come from both left and right terminals.In the right branch,the laser goes into the right cycle polarization LinNbO3(PPLN)crystal through the right coupler,produces the optical parametric oscillation and forms the signal lightλ_(1)(1500 nm),the idle frequency lightλ_(2)(3660.55 nm),and the second-harmonic of the signal lightλ3(750 nm).These three kinds of light and the pump lightλ4 together form the frequency matching and the quasi-phase matching,then the four-wave mixing occurs to create the high-gain light at wavelength 750 nm.Meanwhile,in the left branch,the laser goes into the left PPLN crystal through the left coupler,engenders frequency doubling and forms the light at wavelength 532 nm.That is to say,the optical maser provides 750 nm and 532 nm dual-wavelength laser outputting from two terminals,which is workable.展开更多
An asymmetric quantum well (AQW) is designed to emit a terahertz (THz) wave by using difference frequency generation (DFG) with the structure of GaAs/Al_(0.2)Ga_(0.8)As/Al_(0.5) Ga_(0.5)As under a doubly resonant cond...An asymmetric quantum well (AQW) is designed to emit a terahertz (THz) wave by using difference frequency generation (DFG) with the structure of GaAs/Al_(0.2)Ga_(0.8)As/Al_(0.5) Ga_(0.5)As under a doubly resonant condition.It is found that the second-order nonlinear susceptibility χ^((2)) varies with the two pump wavelengths,and it can reach the peak value of 1.61 μm/V when the wavelengths are given as λ_(p1) =9.756 μm and λ_(p2) =10.96 μm,respectively.The numerical results show that the refractive index of one pump wave in the AQW is concerned with not only its own wavelength but also the other wavelength.Phase-matching inside the AQW can be obtained through the tuning of the two pump wavelengths.展开更多
The three-dimensional thermal properties of 18-core photonic crystal fiber lasers operated under natural convection are investigated.The temperature sensing technique based on a fiber Bragg grating sensor array is pro...The three-dimensional thermal properties of 18-core photonic crystal fiber lasers operated under natural convection are investigated.The temperature sensing technique based on a fiber Bragg grating sensor array is proposed to measure the longitudinal temperature distribution of a 1.6-m-long ytterbium-doped 18-core photonic crystal fiber.The results show that the temperature decreases from the pump end to the launch end exponentially.Moreover,the radial temperature distribution of the fiber end is investigated by using the full-vector finite-element method.The numerical results match well with the experimental data and the coating temperature reaches 422.7K,approaching the critical value of polymer cladding,when the pumping power is 40 W.Therefore the fiber end cooling is necessary to achieve power scaling.Compared with natural convection methods,the copper cooling scheme is found to be an effective method to reduce the fiber temperature.展开更多
Tunable high-power THz-wave radiation is achieved via a compact eudipleural THz-wave parametric oscillator.The maximum THz-wave output is 1.164 V at 1.755 THz when the pump energy is 90 mJ.In the experiments we find t...Tunable high-power THz-wave radiation is achieved via a compact eudipleural THz-wave parametric oscillator.The maximum THz-wave output is 1.164 V at 1.755 THz when the pump energy is 90 mJ.In the experiments we find that the maximum output of THz-wave moves to the high frequency band as the pump energy increases and this phenomenon is reasonably explained.The polarization characteristics of the THz-wave are analyzed.展开更多
基金Supported partially by the National Key Laboratory of Laser Technology,Huazhong University of Science&Technologyby the Open Laboratory of Optoelectronic Information Engineering,Tianjin University,Ministry of Education,China.
文摘We have proposed and demonstrated a nearly-noncritical phase-matched (NCPM) optical parametric oscillation (OPO) in an MgO:LiNbO_(3) crystal with 5 mol% MgO by temperature tuning. By giving up perfect NCPM, the practical tuning range for the OPO is increased by two times. For the crystal, the operated temperature decreases with the phase-matching angle at degeneracy. With a cutting angle of 82° instead of the noncritical case of 90°, the tuning range was increased. In order to obtain a sufficiently high output pulse energy for both signal and idler throughout the entire tuning range, five sets of mirrors were used for the resonator. The tuning range of the OPO was 800-1700 nm with temperatures tuning from 83°C to 224.2°C. The output energy was about 6.45 mJ with a conversion efficiency of nearly 13%. The bandwidth of the output was 1.0-L1 nm.
基金Supported by the National Natural Science Foundation of China under Grant No.69606002the Key Project Foundation of High Education Bureau of Tianjin。
文摘By using p-type polymer poly(2,5-Didodecyloxy-1,4-Phenylenylenevinylene)(PDDOPV)and n-type inorganic material ZnO:Zn,the electronluminescent(EL)emission from bilayer device based on polymer/inorganic hetero-junction was successfully demonstrated.In comparison with single layer polymer device,with dc voltage of 10V,the brightness and luminous efficiency of bilayer device were enhanced 14 and 26 times,respectively.The EL spectrum of bilayer device is not identical to the characteristic emission spectrum of either PDDOPV or ZnO:Zn,and shifts continuously towards to short wavelength direction as the applied voltage increases.
文摘We report on a high power output quasi-continuous-wave nanosecond optical parametric generator （OPG） of congruent periodically poled lithium niobate （PPLN） pumped by a 1 064 nm acousto-optically Q-switched Nd:YVO4 laser （duration: 70 ns,repetition rate:45 kHz,spatial beam quality M2<1.3）.The OPG consists of a 38.7 mm long PPLN crystal with a domain period of 28.93 μm. With 5.43 W of average pump power the maximum average output power is 991 mW at 1 517.1 nm signal wave of the PPLN OPG.
基金This work is supported by the National Natural Science Founda-tion of China (Grant No. 10474071)the Specialized ResearchFund for the Doctoral Program of Higher Education of China(Grant No. 20040056010).
文摘Theoretical investigation of the phase-matching properties for the tunable coherent terahertz wave generation in the isotro- pic semiconductor nonlinear materials of CdTe and GaP is presented according to their optical dispersion properties, based on a pulsed dual-wavelength KTP-OPO operating near degenerate point in the process of the difference frequency mixing. The cross-Reststrahlen band dispersion compensation phase-matching technique involved in this interaction is introduced concisely. The optimum lengths of DFG crystals are decided according to the minimum coherence lengths of the crystals in the given pump wavelength ranges. The results of analysis and calculation provide the useful and necessary theoretical basis and guidance for the future experiments.
基金Supported by the National Basic Research Program of China under Grant No 2007CB310403the High Education Science Technology Project of Shandong Province(No J11LG74)the Science and Technology Project of Zaozhuang(No 201127).
文摘An ultrabroad and sharp transition bandpass flexible terahertz(THz)filter is designed using a multiple-layered metamaterial.This bandpass filter has excellent filtering capability,with a 3 dB bandwidth of about 0.47 THz and sharp band-edge transitions of 80 dB/THz and 96 dB/THz,respectively,and it can be realized by a coupling individual resonance mode.We find that the geometry parameters have an influence on the transmission profile,which are capable of giving us meaningful guidance in design of high profile bandpass THz filters.The numerical results show that the multiple-layered flexible metamaterial provides an effective way to achieve ultrabroad THz devices.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61107086,61172010 and 61101058,Science and Technology Committee of TianJin(No 11JCYBJC01100)the National High Technology Research and Development Program of China(No 2011AA010205)the Open-Fund of the Key Laboratory of Opto-electronic Information Technology(Ministry of Education)at Tianjin University。
文摘We experimentally demonstrate a high power nanosecond pulsed terahertz(THz)-wave parametric oscillator(TPO)by using a wide pump beam.A surface emitted cavity configuration is employed to reduce the THz absorption in MgO:LiNbO_(3) crystal.The THz wave can be tuned from 1 THz to 3 THz.A maximum THz output energy of 438 nJ/pulse is achieved at 1.56 Hz using a 4.5-mm-diameter pump beam with a pulse energy of 226 mJ pump energy with the repetition of 10 Hz,corresponding to the energy conversion efficiency of 1.94×10^(-6).
基金by the National Natural Science Foundation of China under Grant Nos 60978021 and 10804055the National Basic Research Program of China under Grant No 2007CB310403the Program for New Century Excellent Talents in University(NCET).
文摘We report a widely tunable,narrow linewidth,pulsed Ti:sapphire laser pumped by an all-solid-state Q-switched intra-cavity frequency-doubled Nd:YAG laser.By using four dense flint glass prisms as intra-cavity dispersive elements,the output wavelength can be continuously tuned over 675–970 nm and the spectral linewidth is shortened to 0.5 nm.The maximum output power of 6.65 W at 780 nm is obtained under 23.4 W pump power with repetition rate of 5.5 kHz;corresponding to an conversion efficiency of 28.4%.Due to the gain-switching characteristics of the Ti:sapphire laser,the output pulse duration is as short as 17.6 ns.
文摘We propose a simple birefringent terahertz （THz） waveguide which is a polymer elliptical tube with a cross section of elliptical ring structure. It can be achieved by stretching a normal circular-tube in one direction. Simulations based on the full-vector finite element method （FEM） show that this kind of waveguides exhibits high birefringenee on a level of 10- 2 over a wide THz frequency range. Moreover, as a majority of modal power is trapped in the air core inside the polymer elliptical tube, the THz waveguide guiding loss caused by material absorption can be reduced effectively.
文摘The parametric gain of a terahertz wave parametric oscillator （TPO） is analyzed. Meanwhile the expression of TPO threshold pump intensity is derived and theoretically analyzed with different factors. The effective interaction length between the pump wave and Stokes wave is calculated, and particular attention is paid to the coupling efficiency of the pump wave and Stokes wave. Such an analysis is useful for the experiments of TPO.
文摘In the simulation of Intensity Modulation-Direct Detection WDM Systems,when the dispersion and nonlinear effects play equally important roles,the intensity fluctuation caused by cross-phase modulation may be overestimated as a result of the improper step size.Therefore,the step size in numerical simulation should be selected to suppress false XPM intensity modulation (keep it much less than signal power).According to this criterion,the step size is variable along the fiber.For a WDM system,the step size depends on the channel separation.Different type of transmission fiber has different step size.In the split-step Fourier method,this criterion can reduce simulation time,and when the step size is bigger than 100 meters,the simulation accuracy can also be improved.
基金Project supported by the National Natural Science Foundation of China(Grant No.10974063)the Research Foundation of Wuhan National Laboratory,China(Grant No.P080008)the National Basic Research Program of China(Grant No.2007CB310403)
文摘The dielectric properties of near-stoichiometric LiNbO3：Fe and LiNbO3：Ce single crystals have been investigated using terahertz time domain spectroscopy in a frequency range of 0.71.6 THz at room temperature. When coupled with an applied external optical field, obvious photorefractive effects were observed, resulting in a modulation of the complex dielectric constant for the crystals. The variation in refractive index, ｜△n｜, had a linear relationship with the applied light intensity, accompanied by a step-like decrease at high intensity. The findings were attributed to the internal space charge field of the photorefraction and the light-induced domain reversal in the crystals.
文摘We report a method for improving temporal response of FBG-based temperature sensors.It has been demonstrated that by filling thermal conductive pastes between a sensing FBG and its package,the temporal response of the FBG-based temperature sensor can be significantly improved while isolating the strain and vibration.
文摘A widely tunable quasi-phase-matched optical parametric generator pumped by a 1 064 nm acousto-optically Q-switched diode-end-pumped Nd:YAG laser based on a MgO-doped periodically poled LiNbO3 crystal with a multigrating structure （29.2-30.4 μm） is reported.A broad continuous signal spectrum 1 513-1 731 nm is obtained by changing the crystal grating periods from 29.2 μm to 30.4 μm and by tuning simultaneously the crystal temperature from 60℃ to 150℃.When the average pump power is 1.82 W with about 120 ns pulse duration operating at a repetition rate of 10 KHz,the maximum total output power of the PPMgLN OPG is about 323.58 mW consisting of 210 mW of 1.639 μm signal radiation and 113.58 mW of 3.02 μm idler radiation.
文摘We investigate 750 nm and 532 nm dual-wavelength laser for applications in the internet of things.A kind of optical maser is developed,in which the semiconductor module outputs the 808 nm pump light and then it goes into a double-clad Nd^(3+):YAG monocrystal optical fiber through the intermediate coupler and forms a 1064 nm laser.The laser outputs come from both left and right terminals.In the right branch,the laser goes into the right cycle polarization LinNbO3(PPLN)crystal through the right coupler,produces the optical parametric oscillation and forms the signal lightλ_(1)(1500 nm),the idle frequency lightλ_(2)(3660.55 nm),and the second-harmonic of the signal lightλ3(750 nm).These three kinds of light and the pump lightλ4 together form the frequency matching and the quasi-phase matching,then the four-wave mixing occurs to create the high-gain light at wavelength 750 nm.Meanwhile,in the left branch,the laser goes into the left PPLN crystal through the left coupler,engenders frequency doubling and forms the light at wavelength 532 nm.That is to say,the optical maser provides 750 nm and 532 nm dual-wavelength laser outputting from two terminals,which is workable.
基金Supported by National Natural Science Foundation of China under Grant Nos 60801017,61172010,61101058,and 61107086the Science and Technology Committee of Tianjin under Grant No 11JCYBJC01100.
文摘An asymmetric quantum well (AQW) is designed to emit a terahertz (THz) wave by using difference frequency generation (DFG) with the structure of GaAs/Al_(0.2)Ga_(0.8)As/Al_(0.5) Ga_(0.5)As under a doubly resonant condition.It is found that the second-order nonlinear susceptibility χ^((2)) varies with the two pump wavelengths,and it can reach the peak value of 1.61 μm/V when the wavelengths are given as λ_(p1) =9.756 μm and λ_(p2) =10.96 μm,respectively.The numerical results show that the refractive index of one pump wave in the AQW is concerned with not only its own wavelength but also the other wavelength.Phase-matching inside the AQW can be obtained through the tuning of the two pump wavelengths.
基金Supported by the National Basic Research Program of China under Grant No 2010CB327801the Key Program of National Natural Science Foundation of China under Grant No 60637010THE Natural Science Research Project in University of Hebei Province under Grant No Z2010163.
文摘The three-dimensional thermal properties of 18-core photonic crystal fiber lasers operated under natural convection are investigated.The temperature sensing technique based on a fiber Bragg grating sensor array is proposed to measure the longitudinal temperature distribution of a 1.6-m-long ytterbium-doped 18-core photonic crystal fiber.The results show that the temperature decreases from the pump end to the launch end exponentially.Moreover,the radial temperature distribution of the fiber end is investigated by using the full-vector finite-element method.The numerical results match well with the experimental data and the coating temperature reaches 422.7K,approaching the critical value of polymer cladding,when the pumping power is 40 W.Therefore the fiber end cooling is necessary to achieve power scaling.Compared with natural convection methods,the copper cooling scheme is found to be an effective method to reduce the fiber temperature.
基金by the National Basic Research Program of China under Grant No 2007CB310403the National Natural Science Foundation of China under Grant No 60801017.
文摘Tunable high-power THz-wave radiation is achieved via a compact eudipleural THz-wave parametric oscillator.The maximum THz-wave output is 1.164 V at 1.755 THz when the pump energy is 90 mJ.In the experiments we find that the maximum output of THz-wave moves to the high frequency band as the pump energy increases and this phenomenon is reasonably explained.The polarization characteristics of the THz-wave are analyzed.
