In this paper,a linear optimization method(LOM)for the design of terahertz circuits is presented,aimed at enhancing the simulation efficacy and reducing the time of the circuit design workflow.This method enables the ...In this paper,a linear optimization method(LOM)for the design of terahertz circuits is presented,aimed at enhancing the simulation efficacy and reducing the time of the circuit design workflow.This method enables the rapid determination of optimal embedding impedance for diodes across a specific bandwidth to achieve maximum efficiency through harmonic balance simulations.By optimizing the linear matching circuit with the optimal embedding impedance,the method effectively segregates the simulation of the linear segments from the nonlinear segments in the frequency multiplier circuit,substantially improving the speed of simulations.The design of on-chip linear matching circuits adopts a modular circuit design strategy,incorporating fixed load resistors to simplify the matching challenge.Utilizing this approach,a 340 GHz frequency doubler was developed and measured.The results demonstrate that,across a bandwidth of 330 GHz to 342 GHz,the efficiency of the doubler remains above 10%,with an input power ranging from 98 mW to 141mW and an output power exceeding 13 mW.Notably,at an input power of 141 mW,a peak output power of 21.8 mW was achieved at 334 GHz,corresponding to an efficiency of 15.8%.展开更多
A Y-band frequency doubler is analyzed and designed with GaAs planar Schottky diode, which is flip-chip solded into a 50 μm thick quartz substrate. Diode embedding impedance is found by full- wave analysis with lumpe...A Y-band frequency doubler is analyzed and designed with GaAs planar Schottky diode, which is flip-chip solded into a 50 μm thick quartz substrate. Diode embedding impedance is found by full- wave analysis with lumped port to model the nonlinear junction for impedance matching without the need of diode equivalent circuit model. All the matching circuit is designed ＂on-chip＂ and the mul- tiplier is self-biasing. To the doubler, a conversion efficiency of 6.1% and output power of 5.4mW are measured at 214GHz with input power of 88mW, and the typical measured efficiency is 4.5% in 200 - 225 GHz.展开更多
We report on the generation of self-oscillations from a continuously pumped singly resonant frequency doubler based on a periodically poled potassium titanyl phosphate crystal （PPKTP）. The sustained square-wave and ...We report on the generation of self-oscillations from a continuously pumped singly resonant frequency doubler based on a periodically poled potassium titanyl phosphate crystal （PPKTP）. The sustained square-wave and staircase curve of self-oscillations are obtained when the incident pump powers are below and above the threshold of subharmonic-pumped parametric oscillation （SPO）, respectively. The self-oscillations can be explained by the competition between the phase shifts induced by cascading nonlinearity and thermal effect, and the influence of fundamental nonlinear phase shift by the generation of SPO. The simulation results are in good agreement with the experiment data.展开更多
Conjugated polymers with well-balanced ambipolar charge transport is essential for organic circuits at low cost and large area with simplified fabrication techniques.Aiming at this point,herein,a novel asymmetric thio...Conjugated polymers with well-balanced ambipolar charge transport is essential for organic circuits at low cost and large area with simplified fabrication techniques.Aiming at this point,herein,a novel asymmetric thiophene/pyridine-flanked diketopyrrolopyrrole-based copolymer(PPyTDPP-2FBT)is designed and synthesized.Due to the effect of incorporating F atoms on molecular energy alignment and conjugation conformation,the PPyTDPP-2FBT copolymer exhibits typical V-shaped ambipolar field-effect transfer characteristics with well-balanced hole and electron mobilities of 0.64 and 0.46 cm^(2)V^(−1)s^(−1),respectively.Furthermore,organic digital and analog circuits such as inverters and frequency doublers are successfully constructed based on solution-processed films of the PPyTDPP-2FBT copolymers which show a typical circuit operating mode with a high gain of 133 due to the well-balanced electrical properties.In addition,PPyTDPP-2FBT-based devices also demonstrate good stability and batch repeatability,suggesting their great potential applications in organic integrated electronic circuits.展开更多
A W-band frequency doubler MMIC is designed and fabricated using 1-μm InP DHBT technology. Ac tive halun is employed to transform the single-ended signal into differential output. Push-push configuration loaded with ...A W-band frequency doubler MMIC is designed and fabricated using 1-μm InP DHBT technology. Ac tive halun is employed to transform the single-ended signal into differential output. Push-push configuration loaded with harmonic resonant network is utilized to acquire the second harmonic frequency. A multi-stage differential structure improves the conversion gain and suppresses the fundamental frequency. The MMIC occupies an area of 0.55 x 0.5 mm2 with 18 DHBTs integrated. Measurements show that the output power is above 5.8 dBm with the suppression of fundamental frequency below -16 dBc and the conversion Rain above 4.7 dB over 75-80 GHz.展开更多
We present a semimonolithic frequency-doubler from 1080 to 540 nm with 80% doubling efficiency and up to 849-mW output power of green light. A frequency-stabilized laser diode (LD) pumped continuous wave (CW) Nd:YAP l...We present a semimonolithic frequency-doubler from 1080 to 540 nm with 80% doubling efficiency and up to 849-mW output power of green light. A frequency-stabilized laser diode (LD) pumped continuous wave (CW) Nd:YAP laser is used as the pump source of the doubler consisting of an α-cut KTP crystal and an input mirror. The frequency stabilities of the output second harmonic wave are better than ±246 kHz and ±2.3 MHz in 1 and 30 minutes, respectively, and the intensity fluctuation is less than ±0.65%.展开更多
A broadband frequency doubler using left-handed nonlinear transmission lines（LH NLTLs） based on MMIC technology is reported for the first time.The second harmonic generation on LH NLTLs was analyzed theoretically. A...A broadband frequency doubler using left-handed nonlinear transmission lines（LH NLTLs） based on MMIC technology is reported for the first time.The second harmonic generation on LH NLTLs was analyzed theoretically. A four-section LH NLTL which has a layout of 5.4×0.8 mm^2 was fabricated on GaAs semi-insulating substrate. With 20-dBm input power,the doubler obtained 6.33 dBm peak output power at 26.8 GHz with 24-43 GHz—6 dBm bandwidth.The experimental results were quite consistent with the simulated results.The compactness and the broad band characteristics of the circuit make it well suit for GaAs RF/MMIC application.展开更多
This paper presents an E-band frequency quadrupler in 40-nm CMOS technology.The circuit employs two push-push frequency doublers and two single-stage neutralized amplifiers.The pseudo-differential class-B biased casco...This paper presents an E-band frequency quadrupler in 40-nm CMOS technology.The circuit employs two push-push frequency doublers and two single-stage neutralized amplifiers.The pseudo-differential class-B biased cascode topo-logy is adopted for the frequency doubler,which improves the reverse isolation and the conversion gain.Neutralization tech-nique is applied to increase the stability and the power gain of the amplifiers simultaneously.The stacked transformers are used for single-ended-to-differential transformation as well as output bandpass filtering.The output bandpass filter enhances the 4th-harmonic output power,while rejecting the undesired harmonics,especially the 2nd harmonic.The core chip is 0.23 mm^(2)in size and consumes 34 mW.The measured 4th harmonic achieves a maximum output power of 1.7 dBm with a peak conversion gain of 3.4 dB at 76 GHz.The fundamental and 2nd-harmonic suppressions of over 45 and 20 dB are achieved for the spectrum from 74 to 82 GHz,respectively.展开更多
In this paper, a passively Q-switched and mode-locked c-cut Nd-doped vanadate crystal self-Raman laser at 1.17 μm is firstly demonstrated by using Cr4+:YAG. Two crystals of Nd3+:YVO4 and Nd3+:Gd VO4 are adopted to ge...In this paper, a passively Q-switched and mode-locked c-cut Nd-doped vanadate crystal self-Raman laser at 1.17 μm is firstly demonstrated by using Cr4+:YAG. Two crystals of Nd3+:YVO4 and Nd3+:Gd VO4 are adopted to generate laser, respectively. With the incident pump power of 13 W, the average output powers of 678 m W and 852 m W at 1.17 μm are obtained with the durations of Q-switched envelope of 1.8 ns and 2 ns, respectively. The mode-locked repetition rates are as high as 2.3 Hz and 2.2 GHz, respectively. As far as we know, the Q-switched envelope is the narrowest and the mode-locked repetition rate is the highest at present in this field. In addition, yellow laser output is also achieved by using the Li B3O5 frequency doubling crystal.展开更多
Continuous-wave green laser with a maximum power of 34 W has been obtained by intracavity frequency doubling with KTP in diode-side-pumped Nd：YAG. The Nd：YAG/KTP green laser has a simple three- mirror V-fold cavity ...Continuous-wave green laser with a maximum power of 34 W has been obtained by intracavity frequency doubling with KTP in diode-side-pumped Nd：YAG. The Nd：YAG/KTP green laser has a simple three- mirror V-fold cavity structure. The optical-to-optical conversion efficiency is 9.5%. The instability of the laser is measured when the output powers are near 16, 21, 30, and 34 W after the beam is filtered. At the maximum output power, the M^2 factor is measured to be 8.展开更多
A pulsed master oscillator power amplifier system is constructed using a double-cladding polarized Yb- doped fiber and an all-fiber Q-switched narrow-linewidth pulsed laser used as seed laser. This system has a high r...A pulsed master oscillator power amplifier system is constructed using a double-cladding polarized Yb- doped fiber and an all-fiber Q-switched narrow-linewidth pulsed laser used as seed laser. This system has a high repetition rate and provides a nanosecond pulsed laser with a narrow linewidth and linear polarization. Moreover, it generates amplified radiation with up to 14 W of average power, narrow linewidth （full-width at half-maximum is smaller than 0.12 am）, linear polarization at 1080-am wavelength, repetition rate of 51 kHz, and pulse duration of approximately 50 ns. Based on this pulsed amplified radiation, 3.5 W of green laser, with an optical-to-optical efficiency of 27.3%, is obtained via single-pass frequency doubling using a noncritical phase matching KTP crystal.展开更多
We report low pump power high-efficiency frequency doubling of a fundamental laser beam at 795 nm, corresponding to the rubidium D1 line, to generate UV light at 397.5 nm using a periodically poled KTi OPO4（PPKTP） c...We report low pump power high-efficiency frequency doubling of a fundamental laser beam at 795 nm, corresponding to the rubidium D1 line, to generate UV light at 397.5 nm using a periodically poled KTi OPO4（PPKTP） crystal in a ring cavity. We obtain maximum stable output power of 49 m W for mode-matching pump power of 110 m W, corresponding to 45% raw efficiency（56% net efficiency when considering the output coupling mirror’s 80% transmission）. This is the highest efficiency obtained at this wavelength in PPKTP with such low pump power. We obtain 80% beam coupling efficiency to single-mode fiber, demonstrating high beam quality.展开更多
An approach to reducing the harmonic distortion in frequency-doubled triangular-shaped pulse train generation is proposed. It requires a dual-parallel Mach Zehnder modulator followed by a section of dispersive fiber, ...An approach to reducing the harmonic distortion in frequency-doubled triangular-shaped pulse train generation is proposed. It requires a dual-parallel Mach Zehnder modulator followed by a section of dispersive fiber, as the key component. The basic principle is to make the expression of optical intensity approximately equal to the Fourier expansion of idea triangular-shaped waveform. A detailed expression of the final optical intensity is given by theory and then verified by simulation. It is found that the impact of the undesired harmonic distortion is greatlv reduced.展开更多
The temperature acceptance bandwidth of second-harmonic generation（SHG） can be dramatically improved by using two different kinds of nonlinear crystals with opposite signs of temperature derivation of phase mismatch...The temperature acceptance bandwidth of second-harmonic generation（SHG） can be dramatically improved by using two different kinds of nonlinear crystals with opposite signs of temperature derivation of phase mismatch. We study two SHG processes for the existing 1064 and 1550 nm high-average-power lasers. The numerical results show that the temperature acceptance bandwidth for SHG at 1064 nm can be three to five times larger than that of traditional single-crystal design, and it is also larger than that of using temperature-insensitive yttrium calcium oxyborate crystal. Importantly, the proposed design is applicable to various wavelengths, which suggests its potential in high-average-power SHG applications.展开更多
W-band quartz based high output power fix-tuned doublers are analyzed and designed with planar Schot- tky diodes. Full-wave analysis is carried out to find diode embedding impedances with a lumped port to model the no...W-band quartz based high output power fix-tuned doublers are analyzed and designed with planar Schot- tky diodes. Full-wave analysis is carried out to find diode embedding impedances with a lumped port to model the nonlinear junction. Passive networks of the circuit, such as the low pass filter, the E-plane waveguide to strip transitions, input and output matching networks, and passive diode parts are analyzed by using electromagnetic simulators, and the different parts are then combined and optimized together. The exported S-parameters of the doubler circuit are used for multiply efficiency analysis. The highest measured output power is 29.5 mW at 80 GHz and higher than 15 mW in 76-94 GHz. The highest measured efficiency is 11.5% at 92.5 GHz, and the typical value is 6.0% in 70-100 GHz.展开更多
This paper presents the design and performance of a broadband millimeter-wave frequency doubler MMIC using active 0.15 μm GaAs PHEMT and operating at output frequencies from 20 to 44 GHz. This chip is composed of a s...This paper presents the design and performance of a broadband millimeter-wave frequency doubler MMIC using active 0.15 μm GaAs PHEMT and operating at output frequencies from 20 to 44 GHz. This chip is composed of a single ended-into differential-out active Balun, balanced FETs in push-push configuration, and a distributed amplifier. The MMIC doubler exhibits more than 4 dB conversion gain with 12 dBm of output power, and the fundamental frequency suppression is typically -20 dBc up to 44 GHz. The MMIC works at VDD = 3.5 V, Vss = -3.5 V, Id = 200 mA and the chip size is 1.5× 1.8 mm^2.展开更多
A compact, all-solid-state, narrow-linewidth, pulsed 455-nm blue laser based on Ti：sapphire crystal is developed. Pumped by a 10-Hz, frequency-doubled all-solid-state Nd：YAG laser and injection-seeded by an external...A compact, all-solid-state, narrow-linewidth, pulsed 455-nm blue laser based on Ti：sapphire crystal is developed. Pumped by a 10-Hz, frequency-doubled all-solid-state Nd：YAG laser and injection-seeded by an external cavity laser diode, the narrow-linewidth 910-nm laser with pulse width of 20 ns is obtained from a Ti：sapphire laser. 3.43-mJ blue laser can be obtained from the laser system by frequency-doubling with BBO crystal. This research is very useful to determine the roadmap of developing the practical, high power blue laser. This kind of laser will have potential application for underwater communication.展开更多
An efficient, stable diode-end-pumped simultaneous continuous-wave （CW） dual-wavelength laser operating at 1.319 and 1.338 ttm in a Nd：YAG crystal has been demonstrated. A total output power of 6.3 W is achieved at...An efficient, stable diode-end-pumped simultaneous continuous-wave （CW） dual-wavelength laser operating at 1.319 and 1.338 ttm in a Nd：YAG crystal has been demonstrated. A total output power of 6.3 W is achieved at an absorbed pump power of 15 W, with a slope efficiency of 43.5%. The instability of output power is less than 1%. With a type II critical phase-matched KTP crystal inserted into the cavity as frequency doubler, a maximum output power of 200 mW in red region is acquired. In addition, a sixwavelength laser operation at 1.319 μm, 1.338 μm, 1.356 μm, 659.5 nm, 669 nm, and 678 nm is observed.展开更多
We report on our high-contrast laser based on high-contrast, high-energy seed injection, low-gain optical para- metric chirped pulse amplification （OPCPA）, and Nd：glass amplifiers, which can be used as the high-con...We report on our high-contrast laser based on high-contrast, high-energy seed injection, low-gain optical para- metric chirped pulse amplification （OPCPA）, and Nd：glass amplifiers, which can be used as the high-contrast front end of a high-power Nd：glass chirped pulse amplification （CPA） laser system. The energy of the stretched 1053 nm high-contrast seed pulse increases to 60 DJ by optimizing the frequency doubling crystal in the pulse cleaning device. After passing through a two-stage low-gain OPCPA, a 2-pass 2-rod Nd：glass amplifier, and a compressor the amplified pulse of 131 mJ/282 fs is achieved. The third-order correlation scanning measurement shows that the pulse contrast in the tens of ps range is about 10^-7-10^-8. With the high-contrast seed passing through the stretcher and compressor only, the contrast measurement indicates that the stretching-compressing process leads mainly to the contrast degradation of the amplified pulse.展开更多
In this Letter, a gray-tracking-resistant--potassium titanyl phosphate （GTR-KTP） crystal is used for intracav- ity frequency doubling red laser generation for the first time. Under the 808 nm LD pump power of 180 W,...In this Letter, a gray-tracking-resistant--potassium titanyl phosphate （GTR-KTP） crystal is used for intracav- ity frequency doubling red laser generation for the first time. Under the 808 nm LD pump power of 180 W, as high as 12.5 W of red laser output is obtained with the optimum repetition rate of 7 kHz. Within the red laser power variation range between the maximum to 70%, a temperature tolerance is measured to be 35℃. The results prove that GTR-KTP should be a potential nonlinear crystal for red laser generation.展开更多
基金Supported by the Beijing Municipal Science&Technology Commission(Z211100004421012),the Key Reaserch and Development Pro⁃gram of China(2022YFF0605902)。
文摘In this paper,a linear optimization method(LOM)for the design of terahertz circuits is presented,aimed at enhancing the simulation efficacy and reducing the time of the circuit design workflow.This method enables the rapid determination of optimal embedding impedance for diodes across a specific bandwidth to achieve maximum efficiency through harmonic balance simulations.By optimizing the linear matching circuit with the optimal embedding impedance,the method effectively segregates the simulation of the linear segments from the nonlinear segments in the frequency multiplier circuit,substantially improving the speed of simulations.The design of on-chip linear matching circuits adopts a modular circuit design strategy,incorporating fixed load resistors to simplify the matching challenge.Utilizing this approach,a 340 GHz frequency doubler was developed and measured.The results demonstrate that,across a bandwidth of 330 GHz to 342 GHz,the efficiency of the doubler remains above 10%,with an input power ranging from 98 mW to 141mW and an output power exceeding 13 mW.Notably,at an input power of 141 mW,a peak output power of 21.8 mW was achieved at 334 GHz,corresponding to an efficiency of 15.8%.
基金Supported by the 12th Five-year Defense Pre-research Fund of China(No.51308030509)
文摘A Y-band frequency doubler is analyzed and designed with GaAs planar Schottky diode, which is flip-chip solded into a 50 μm thick quartz substrate. Diode embedding impedance is found by full- wave analysis with lumped port to model the nonlinear junction for impedance matching without the need of diode equivalent circuit model. All the matching circuit is designed ＂on-chip＂ and the mul- tiplier is self-biasing. To the doubler, a conversion efficiency of 6.1% and output power of 5.4mW are measured at 214GHz with input power of 88mW, and the typical measured efficiency is 4.5% in 200 - 225 GHz.
基金supported by the National Basic Research Program of China (Grant No. 2010CB923101)the National Natural Science Foundation of China (Grant Nos. 61227015 and 61121064)
文摘We report on the generation of self-oscillations from a continuously pumped singly resonant frequency doubler based on a periodically poled potassium titanyl phosphate crystal （PPKTP）. The sustained square-wave and staircase curve of self-oscillations are obtained when the incident pump powers are below and above the threshold of subharmonic-pumped parametric oscillation （SPO）, respectively. The self-oscillations can be explained by the competition between the phase shifts induced by cascading nonlinearity and thermal effect, and the influence of fundamental nonlinear phase shift by the generation of SPO. The simulation results are in good agreement with the experiment data.
基金This work is financially supported by the Ministry of Science and Technology of China(2018YFA0703200,2017YFA0204503)the National Natural Science Foundation of China(91833306,61890943,51725304,22021002)Beijing National Laboratory for Molecular Sciences(BNLMS-CXXM-202012),the Youth Innovation Promotion Association of the Chinese Academy of Sciences,and the National Program for Support of Top-notch Young Professionals.
文摘Conjugated polymers with well-balanced ambipolar charge transport is essential for organic circuits at low cost and large area with simplified fabrication techniques.Aiming at this point,herein,a novel asymmetric thiophene/pyridine-flanked diketopyrrolopyrrole-based copolymer(PPyTDPP-2FBT)is designed and synthesized.Due to the effect of incorporating F atoms on molecular energy alignment and conjugation conformation,the PPyTDPP-2FBT copolymer exhibits typical V-shaped ambipolar field-effect transfer characteristics with well-balanced hole and electron mobilities of 0.64 and 0.46 cm^(2)V^(−1)s^(−1),respectively.Furthermore,organic digital and analog circuits such as inverters and frequency doublers are successfully constructed based on solution-processed films of the PPyTDPP-2FBT copolymers which show a typical circuit operating mode with a high gain of 133 due to the well-balanced electrical properties.In addition,PPyTDPP-2FBT-based devices also demonstrate good stability and batch repeatability,suggesting their great potential applications in organic integrated electronic circuits.
基金supported by the National Basic Research Program of China(No.2010CB327502)
文摘A W-band frequency doubler MMIC is designed and fabricated using 1-μm InP DHBT technology. Ac tive halun is employed to transform the single-ended signal into differential output. Push-push configuration loaded with harmonic resonant network is utilized to acquire the second harmonic frequency. A multi-stage differential structure improves the conversion gain and suppresses the fundamental frequency. The MMIC occupies an area of 0.55 x 0.5 mm2 with 18 DHBTs integrated. Measurements show that the output power is above 5.8 dBm with the suppression of fundamental frequency below -16 dBc and the conversion Rain above 4.7 dB over 75-80 GHz.
基金This research was supported by the Major State Ba- sic Research Project of China (No. 2001CB3099304) the National Natural Science Foundation of China (No. 60238010, 60178012, 60378014) Shanxi Provincial Science Foundation (No. 20041038).
文摘We present a semimonolithic frequency-doubler from 1080 to 540 nm with 80% doubling efficiency and up to 849-mW output power of green light. A frequency-stabilized laser diode (LD) pumped continuous wave (CW) Nd:YAP laser is used as the pump source of the doubler consisting of an α-cut KTP crystal and an input mirror. The frequency stabilities of the output second harmonic wave are better than ±246 kHz and ±2.3 MHz in 1 and 30 minutes, respectively, and the intensity fluctuation is less than ±0.65%.
基金Project supported by the National Natural Science Foundation of China(No.60806024)the International Collaboration Program of the Ministry of Science and Technology(No.2009DFA12130)
文摘A broadband frequency doubler using left-handed nonlinear transmission lines（LH NLTLs） based on MMIC technology is reported for the first time.The second harmonic generation on LH NLTLs was analyzed theoretically. A four-section LH NLTL which has a layout of 5.4×0.8 mm^2 was fabricated on GaAs semi-insulating substrate. With 20-dBm input power,the doubler obtained 6.33 dBm peak output power at 26.8 GHz with 24-43 GHz—6 dBm bandwidth.The experimental results were quite consistent with the simulated results.The compactness and the broad band characteristics of the circuit make it well suit for GaAs RF/MMIC application.
基金the National Key Research,Development Program of China under Grant 2018YFB1802100the Major Key Project of PCL(PCL2021A01-2).
文摘This paper presents an E-band frequency quadrupler in 40-nm CMOS technology.The circuit employs two push-push frequency doublers and two single-stage neutralized amplifiers.The pseudo-differential class-B biased cascode topo-logy is adopted for the frequency doubler,which improves the reverse isolation and the conversion gain.Neutralization tech-nique is applied to increase the stability and the power gain of the amplifiers simultaneously.The stacked transformers are used for single-ended-to-differential transformation as well as output bandpass filtering.The output bandpass filter enhances the 4th-harmonic output power,while rejecting the undesired harmonics,especially the 2nd harmonic.The core chip is 0.23 mm^(2)in size and consumes 34 mW.The measured 4th harmonic achieves a maximum output power of 1.7 dBm with a peak conversion gain of 3.4 dB at 76 GHz.The fundamental and 2nd-harmonic suppressions of over 45 and 20 dB are achieved for the spectrum from 74 to 82 GHz,respectively.
基金supported by the National Natural Science Foundation of China(No.61108021)the Beijing Natural Science Foundation(No.4102048)the Fundamental Research Funds for the Central Universities(No.2013JBM091)
文摘In this paper, a passively Q-switched and mode-locked c-cut Nd-doped vanadate crystal self-Raman laser at 1.17 μm is firstly demonstrated by using Cr4+:YAG. Two crystals of Nd3+:YVO4 and Nd3+:Gd VO4 are adopted to generate laser, respectively. With the incident pump power of 13 W, the average output powers of 678 m W and 852 m W at 1.17 μm are obtained with the durations of Q-switched envelope of 1.8 ns and 2 ns, respectively. The mode-locked repetition rates are as high as 2.3 Hz and 2.2 GHz, respectively. As far as we know, the Q-switched envelope is the narrowest and the mode-locked repetition rate is the highest at present in this field. In addition, yellow laser output is also achieved by using the Li B3O5 frequency doubling crystal.
基金supported by the National Natural Science Foundation of China(No.60671036)the Research Project of "SUST Spring Bud"(No.2008AZZ094).
文摘Continuous-wave green laser with a maximum power of 34 W has been obtained by intracavity frequency doubling with KTP in diode-side-pumped Nd：YAG. The Nd：YAG/KTP green laser has a simple three- mirror V-fold cavity structure. The optical-to-optical conversion efficiency is 9.5%. The instability of the laser is measured when the output powers are near 16, 21, 30, and 34 W after the beam is filtered. At the maximum output power, the M^2 factor is measured to be 8.
基金supported by the Natural Science Foundation of Shanghai (No.10ZR1433600)the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20103705110001)
文摘A pulsed master oscillator power amplifier system is constructed using a double-cladding polarized Yb- doped fiber and an all-fiber Q-switched narrow-linewidth pulsed laser used as seed laser. This system has a high repetition rate and provides a nanosecond pulsed laser with a narrow linewidth and linear polarization. Moreover, it generates amplified radiation with up to 14 W of average power, narrow linewidth （full-width at half-maximum is smaller than 0.12 am）, linear polarization at 1080-am wavelength, repetition rate of 51 kHz, and pulse duration of approximately 50 ns. Based on this pulsed amplified radiation, 3.5 W of green laser, with an optical-to-optical efficiency of 27.3%, is obtained via single-pass frequency doubling using a noncritical phase matching KTP crystal.
基金supported by the National Fundamental Research Program of China(No.2011CBA00200)the National Natural Science Foundation of China(Nos.11174271,61275115,and 10874171)the Innovation Fund of the Chinese Academy of Sciences
文摘We report low pump power high-efficiency frequency doubling of a fundamental laser beam at 795 nm, corresponding to the rubidium D1 line, to generate UV light at 397.5 nm using a periodically poled KTi OPO4（PPKTP） crystal in a ring cavity. We obtain maximum stable output power of 49 m W for mode-matching pump power of 110 m W, corresponding to 45% raw efficiency（56% net efficiency when considering the output coupling mirror’s 80% transmission）. This is the highest efficiency obtained at this wavelength in PPKTP with such low pump power. We obtain 80% beam coupling efficiency to single-mode fiber, demonstrating high beam quality.
基金supported by the National Natural Science Foundation of China(No.61405007)the Fundamental Research Funds for the Central Universities(No.2014JBM013)the Research Foundation for Talented Scholars of Beijing Jiaotong University(No.2013RC021)
文摘An approach to reducing the harmonic distortion in frequency-doubled triangular-shaped pulse train generation is proposed. It requires a dual-parallel Mach Zehnder modulator followed by a section of dispersive fiber, as the key component. The basic principle is to make the expression of optical intensity approximately equal to the Fourier expansion of idea triangular-shaped waveform. A detailed expression of the final optical intensity is given by theory and then verified by simulation. It is found that the impact of the undesired harmonic distortion is greatlv reduced.
基金partially supported by the National Natural Science Foundation of China(No.61308005)the China Postdoctoral Science Foundation Funded Project(No.2013M542106)+2 种基金the Hunan Postdoctoral Scientific Program(No.2013RS4047)the Scientific Research Fund of Hunan Provincial Education Department(No.14C0099)the Science and Technology Program of Changsha(No.K1309012-11)
文摘The temperature acceptance bandwidth of second-harmonic generation（SHG） can be dramatically improved by using two different kinds of nonlinear crystals with opposite signs of temperature derivation of phase mismatch. We study two SHG processes for the existing 1064 and 1550 nm high-average-power lasers. The numerical results show that the temperature acceptance bandwidth for SHG at 1064 nm can be three to five times larger than that of traditional single-crystal design, and it is also larger than that of using temperature-insensitive yttrium calcium oxyborate crystal. Importantly, the proposed design is applicable to various wavelengths, which suggests its potential in high-average-power SHG applications.
文摘W-band quartz based high output power fix-tuned doublers are analyzed and designed with planar Schot- tky diodes. Full-wave analysis is carried out to find diode embedding impedances with a lumped port to model the nonlinear junction. Passive networks of the circuit, such as the low pass filter, the E-plane waveguide to strip transitions, input and output matching networks, and passive diode parts are analyzed by using electromagnetic simulators, and the different parts are then combined and optimized together. The exported S-parameters of the doubler circuit are used for multiply efficiency analysis. The highest measured output power is 29.5 mW at 80 GHz and higher than 15 mW in 76-94 GHz. The highest measured efficiency is 11.5% at 92.5 GHz, and the typical value is 6.0% in 70-100 GHz.
文摘This paper presents the design and performance of a broadband millimeter-wave frequency doubler MMIC using active 0.15 μm GaAs PHEMT and operating at output frequencies from 20 to 44 GHz. This chip is composed of a single ended-into differential-out active Balun, balanced FETs in push-push configuration, and a distributed amplifier. The MMIC doubler exhibits more than 4 dB conversion gain with 12 dBm of output power, and the fundamental frequency suppression is typically -20 dBc up to 44 GHz. The MMIC works at VDD = 3.5 V, Vss = -3.5 V, Id = 200 mA and the chip size is 1.5× 1.8 mm^2.
文摘A compact, all-solid-state, narrow-linewidth, pulsed 455-nm blue laser based on Ti：sapphire crystal is developed. Pumped by a 10-Hz, frequency-doubled all-solid-state Nd：YAG laser and injection-seeded by an external cavity laser diode, the narrow-linewidth 910-nm laser with pulse width of 20 ns is obtained from a Ti：sapphire laser. 3.43-mJ blue laser can be obtained from the laser system by frequency-doubling with BBO crystal. This research is very useful to determine the roadmap of developing the practical, high power blue laser. This kind of laser will have potential application for underwater communication.
基金This work was supportedby the National Natural Science Foundation of China(No. 10474071).
文摘An efficient, stable diode-end-pumped simultaneous continuous-wave （CW） dual-wavelength laser operating at 1.319 and 1.338 ttm in a Nd：YAG crystal has been demonstrated. A total output power of 6.3 W is achieved at an absorbed pump power of 15 W, with a slope efficiency of 43.5%. The instability of output power is less than 1%. With a type II critical phase-matched KTP crystal inserted into the cavity as frequency doubler, a maximum output power of 200 mW in red region is acquired. In addition, a sixwavelength laser operation at 1.319 μm, 1.338 μm, 1.356 μm, 659.5 nm, 669 nm, and 678 nm is observed.
文摘We report on our high-contrast laser based on high-contrast, high-energy seed injection, low-gain optical para- metric chirped pulse amplification （OPCPA）, and Nd：glass amplifiers, which can be used as the high-contrast front end of a high-power Nd：glass chirped pulse amplification （CPA） laser system. The energy of the stretched 1053 nm high-contrast seed pulse increases to 60 DJ by optimizing the frequency doubling crystal in the pulse cleaning device. After passing through a two-stage low-gain OPCPA, a 2-pass 2-rod Nd：glass amplifier, and a compressor the amplified pulse of 131 mJ/282 fs is achieved. The third-order correlation scanning measurement shows that the pulse contrast in the tens of ps range is about 10^-7-10^-8. With the high-contrast seed passing through the stretcher and compressor only, the contrast measurement indicates that the stretching-compressing process leads mainly to the contrast degradation of the amplified pulse.
基金supported by the National Natural Science Foundation of China(Grant Nos.61308042 and 61275142)the China Postdoctoral Science Foundation(Grant Nos.2013M531594 and 2014T70633)
文摘In this Letter, a gray-tracking-resistant--potassium titanyl phosphate （GTR-KTP） crystal is used for intracav- ity frequency doubling red laser generation for the first time. Under the 808 nm LD pump power of 180 W, as high as 12.5 W of red laser output is obtained with the optimum repetition rate of 7 kHz. Within the red laser power variation range between the maximum to 70%, a temperature tolerance is measured to be 35℃. The results prove that GTR-KTP should be a potential nonlinear crystal for red laser generation.
