An Innovative Gas Sensor with On-Chip Reference Using Monolithic Twin Laser

An innovative gas sensor with on-chip reference using a monolithic twin laser is proposed. In this sensor a monolithic twin laser generates two closer laser beams with slight different wavelengths alternatively, one photodiode is used to catch both absorption and reference signals by time division multiplexing. The detection of nitrous oxide adopting this scheme using a 2.1μm antimonide laser and an InGaAs photodiode has been demonstrated experimentally with detection limit below 1ppm. Using this on chip reference scheme the fluctuations from the optical path and devices can be compensated effectively; the sensor system is simplified distinctly.     

Low-threshold mid-IR MgO:PPLN optical parametric generation with high reflectivity mirror for signal wavelength

A low-threshold middle-infrared(mid-IR)MgO:PPLN optical parametric generation(OPG)pumped by a laser diode(LD)end-pumped Z-type Nd:YLF laser at 1047 nm is realized with high reflectivity(HR) mirror for signal.At repetition rate of 10 kHz,the OPG threshold of 50μJ has been achieved with HR mirror for signal.Compared with the threshold without mirror,the threshold decreases by 17%.Using HR mirror for pump at output side of crystal,the threshold of 40μJ is achieved.The 2.7-4.1μm continuous tunable output is produced with seven grating periods from 28.5 to 31.5μm and temperatures from 30 to 200℃.When the incident average pump power is 3 W,the OPG idler output power is 0.46 W at 3.26μm,which corresponds to optical-to-optical conversion efficiency up to 15.3%.     

Violet to Infraned Multiwavelength Generation in Periodically Poled Lithium Niobate Pumped by a Q—Switched Nd：YVO4 Laser

Six output wavelengths from violet to infrared have been observed simultaneously from an all-solid-state laser pumped optical parametric oscillator in a periodically poled lithium niobate crystal.The output wavelengths can be tuned by varying the quasi-phase matched period and/or temperature.The pump laser is a diode-pumped pasive Q-switched Nd:YVO4 laser operated at 1064nm.Using a crystal with a 29.9μm grating period,we measured six wavelengths at 448,515,532,630,773 and 1546nm and obtained efficient output.We explain the multiwavelength generation by multiwave coupling theory.This phenomenon may have novel applications in photonic devices.     

Low-threshold mid-IR MgO:PPLN optical parametric generation with high reflectivity mirror for signal wavelength

A low-threshold middle-infrared(mid-IR) MgO:PPLN optical parametric generation(OPG)pumped by a laser diode(LDl end-pumped Z-type Nd:YLF laser at 1047 nm is realized with high reflectivity(HR) mirror for signal.At repetition rate of 10 kHz,the OPG threshold of 50μJ has been achieved with HR mirror for signal.Compared with the threshold without mirror,the threshold decreases by 17%.Using HR mirror for pump at output side of crystal,the threshold of 40μJ is achieved.The 2.7-4.1μm continuous tunable output is produced with seven grating periods from 28.5 to 31.5μm and temperatures from 30 to 200℃.When the incident average pump power is 3 W.the OPG idler output power is 0.46 W at 3.26 μm,which corresponds to optical-to-optical conversion efficiency up to 15.3%.     

High-power output from a compact OPCPA laser system

With a tabletop hybrid Nd:YAG-Nd:glass laser as pump source, a compact optical parametric chirpedpulse amplification(OPCPA)laser system with a peak output power of 16.7 TW and a pulse duration of120 fs has been demonstrated.Chirped pulses are amplified from 50 pJ to more than 3.1 J with an energygain of above 6×10~(10)by three LBO optical parametric amplifiers with a pump energy of 12.4 J at 532nm.After compression, a final output of 2.0-J/120-fs pulse is obtained. To the best of our knowledge,itis the highest peak output power from an OPCPA laser so far.In addition, a practical design of 1-PWlaser system based on the technique of OPCPA is also proposed.     

Trends in ultrashort and ultrahigh power laser pulses based on optical parametric chirped pulse amplification

Since the proof-of-principle demonstration of optical parametric amplification to efficiently amplify chirped laser pulses in 1992,optical parametric chirped pulse amplification(OPCPA)became the most promising method for the amplification of broadband optical pulses.In the meantime,we are witnessing an exciting progress in the development of powerful and ultrashort pulse laser systems that employ chirped pulse parametric amplifiers.The output power and pulse duration of these systems have ranged from a few gigawatts to hundreds of terawatts with a potential of tens of petawatts power level.Meanwhile,the output pulse duration based on optical parametric amplification has entered the range of fewoptical-cycle field.In this paper,we overview the basic principles,trends in development,and current state of the ultrashort and laser systems based on OPCPA,respectively.     

Wavelength-Locked 878.6 nm In-Band Pumped Intra-Cavity 2.1 μm Optical Parametric Oscillator

We report herein a high-power folded intra-cavity 2.1μm optical parametric oscillator(ICOPO)which is the first example of an ICOPO that utilizes a wavelength-locked 878.6 nm in-band pumped Nd:YVO_4 laser as the pump source.The thermal effect of PPMgLN crystal and the divergence angle of the incident laser are considered comprehensively to determine the 2128 nm degenerate temperature.In the experiment,the functions of different output coupler transmittances and different repetition rates on the parametric laser output power are studied,respectively.The temperature versus parametric laser output power in an in-band p umped non-wavelength-locked880 nm laser diode(LD)and in a wavelength-locked 878.6 nm LD is compared.A maximum output power of 5.87 W is obtained at the pump power of 56.9 W when the repetition rate is 80 kHz.The corresponding conversion efficiency is 14.55%,with a linewidth of 73.65 nm and pulse width of 3.62 ns.The wavelength-locked 878.6 nm LD in-band pumping technology can stabilize the 2.1μm laser output power of Nd:YVO_4 crystal effectively in the environment of intense temperature change.     

Threshold characteristic of intracavity optical parametric oscillator pumped by all-solid-state Q-switched laser

We derive the threshold pump intensity for a singly resonant intracavity optical parametric oscillator (IOPO)based on a temporal coupled field model.Particular attention is paid to the dependence of the intracavity singly resonant OPO(SRO)threshold intensity on the signal wave output coupling.Meanwhile, a Nd:YAG laser pumped KTiOPO_4(KTP)IOPO for eye-safe laser output is studied experimentally. The experiment is performed with four signal wave output reflectivities of 60%,70%,80%,and 90%, respectively.The measured values are in good agreement with the theoretical results.With an output coupler reflectivity of 80%,a peak power of 70 kW at 1572 nm has been obtained at a repetition rate of 3.5 kHz.The pulse width is 4.9 ns.Such investigation is helpful to identifying suitable operational regime of low pump intensity.     

A periodically poled LiNbO_3 optical parametric generator in wavelength conversion from 2 to 3.88——4.34 μm

A periodically poled lithium niobate(PPLN)optical parametric generator(OPG)pumped by a laser diode(LD)-pumped Q-switched Tm,Ho:GdVO_4 laser operated at 2.048μm with pump pulse of 25 ns and repetition rate of 10 kHz is reported.A continuous tunable middle-infrared(mid-IR)spectrum of 3.88-4.34μm is obtained by changing the crystal temperature from 50 to 124°C.When the incident pump power is 3 W,the total OPG output power is 95 mW,corresponding to optical conversion efficiency of 3.2%.     

Wavelength tunability of tandem optical parametric oscillator based on single PPMgOLN crystal

The theoretical analysis and experimental results of the wavelength tunability of a tandem optical parametric oscillator (TOPO) based on a single nonlinear crystal are presented.TOPO is a configuration wherein the signal laser is used as a pump laser to generate secondary optical parametric oscillator (OPO).The cascaded parametric interactions are achieved synchronously in a single-grating-period MgO doped periodically poled lithium niobate (PPMgOLN).Tunable multiple-wavelength mid-infrared (mid-IR) lasers are obtained by changing the temperature of the crystal.When the PPMgOLN crystal with a grating period of 31.2 μm is operated at 148 ℃,the dual OPOs generate an identical mid-IR laser of 2.83 μm.The secondary OPO transforms into an optical parametric amplifier,in which different frequency mixing from the signal laser results in the amplification of the idler laser in the first OPO.TOPO is a useful configuration for multiple laser output,broad tuning range,and high-efficiency mid-IR lasers.     

宽调谐高效率的BBO光参量振荡器

本文报道用354.7nm泵浦的单共振BBO脉冲光参量振荡器在413～661nm和2513～765nm波段内获得了可调谐的振荡输出,最高总能量转换效率达52％;文中还讨论了输出特性。     

Mid-infrared tunable dual-wavelength generation based on a quasi-phase-matched optical parametric oscillator

We report an efficient optical parametric oscillator (OPO) of dual idler wave output based on periodically poled MgO:LiNbO₃ with a periodically-phase-reversed grating structure, which is pumped by a Q-switched 1.064 μm laser with a repetition rate of 50 kHz. 0.98 W of dual idler-waves at 3.824 μm and 3.731 μm is achieved at room temperature, leading to a 12.9% conversion efficiency. The crystal temperature tuning provides output tunability of the dual idler wavelengths. In addition, the sum frequency generation of the dual signal waves is simultaneously observed in the OPO cavity.     

非临界相位匹配KTP光学参量振荡器的研究

对电光调Q(Ce,Nd):YAG激光抽运内腔非临界相位匹配(NCPM)光参量振荡器(IOPO)进行了实验研究,实验发现IOPO输出光波长为532 nm、632 nm、1 064 nm、1 100 nm和1 571 nm 5种。OPO输出镜对信号光反射率较大时,信号光出现多脉冲,可以通过控制信号光反射率,使信号光为单脉冲。信号光能量随着抽运能量增加到一定值后出现饱和。     

High-repetition-rate femtosecond optical parametric chirped-pulse amplifier in the mid-infrared

We discuss a dual-stage optical parametric chirped-pulse amplifier generating sub-100-fs pulses in the mid-infrared at a repetition rate of 100 kHz. The system is based on a 1064 nm pump laser and a 3–4 μm difference frequency generation seed source derived from the output of a femtosecond fiber laser amplifier. Both lasers are commercially available, are diode-pumped, compact, and allow for turn-key operation. Here, we focus our discussion on the design and dimensioning of the optical parametric chirped-pulse amplifier. In particular, we review the available gain materials for mid-infrared generation and analyze the impact of different stretching scenarios. Timing jitter plays an important role in short-pulse parametric amplifier systems and is therefore studied in detail. The geometry of the amplifier stages is optimized through a full 3-dimensional simulation with the aim of maximizing gain bandwidth and output power. The optimized system yields output pulse energies exceeding 1 μJ and an overall gain larger than 50 dB. The high repetition rate of the pump laser results in an unprecedented average power from a femtosecond parametric system at mid-infrared wavelengths. First experimental results confirm the design and the predictions of our theoretical model.     

受激布里渊散射相位共轭腔及腔内光学参量振荡器

利用受激布城渊散射相位共轭特性和Ｑ开关特性组成Ｎｄ：ＹＡＧ激光谐振腔,代替传统激光器全反镜和调Ｑ装置,获得能量１００ｍＪ,脉宽１３ｎｓ的线偏振相位共轭激光输出,相应的激光器总体转换效率为０．４７％,同时将单共振ＫＴＰ光学参量振荡器置入腔内,得到波长１．５７μｍ、能量１５ｍＪ的参理振荡激光,实验证实了受激布城渊散射相位共轭腔内光学参量振荡器运行的可行性。     

高峰值功率1．57μm脉冲激光器的研究

KTP非线性频率转换技术是实现人眼安全激光的有效方法,为了获得高峰值功率人眼安全激光,设计了一种级联式1．06μm泵浦非临界相位匹配环形腔KTP光参量振荡器一光参量放大器,并对其激光输出进行了测试,结果证明该光参量振荡器输出激光波长1．571μm,激光峰值功率42MW,光光转换效率35％,能量稳定度2．5％。该技术已用于计量检测标准光源,并在远程人眼安全激光测距仪、激光雷达等装备中具有应用前景。     

基于MgO:APLN的1.57μm/3.84μm连续波内腔多光参量振荡器研究

报道了一种基于MgO:APLN实现1.57 μm和3.84 μm跨周期参量光连续输出的内腔抽运多光参量振荡器. 采用1064 nm谐振腔与多光参量振荡腔折叠型复合结构, 综合考虑高功率抽运下谐振腔的热稳定性及多光参量振荡过程的光斑模式匹配, 通过对两个子腔谐振结构的数值模拟分析, 确定了最佳腔型参数. 在此基础上, 进一步研究了谐振参量光透过率对振荡阈值、抽运光下转换效率、输出功率稳定性的影响, 最终实现了3.13 W的1.57 μm和0.85 W的3.84 μm参量光输出, 对应斜效率为6.8%和1.9%, 输出功率稳定性分别达到了1.8%和3%.     

Continuously wavelength-spacing-tunable and idler-output multiwavelength fiber optical parametric oscillator

We demonstrate a continuously wavelength-spacing-tunable and high-power multiwavelength fiber optical parametric oscillator based on the multiwavelength idler-output technique. The laser cavity for multiwavelength idler outputs is constructed by a pumped highly-nonlinear dispersion-shifted fiber as parametric gain medium, two highly-reflective chirped fiber Bragg gratings (CFBGs) and a superimposed CFBG as comb-like filter. At a pump power of 1.1 W, the idler output of 10 wavelengths around 1.56 μm is achieved with a wavelength spacing of 0.39 nm. The wavelength spacing can be continuously tuned from 0.39 to 1.0 nm by utilizing a cantilever beam-based chirp tuning method to change the FSR of the superimposed CFBG. Our experimental results show that the designed multiwavelength idler-output scheme can significantly increase the multiwavelength output power with a total output power of 98 mW and each idler-channel power of 16.3 mW.     

高功率宽调谐输出的多周期极化铌酸锂晶体光学参量振荡器

利用掺杂浓度为5 mol%的掺氧化镁多周期极化铌酸锂晶体实现了高效单谐振的准相位匹配光参量振荡器,所使用的周期极化铌酸锂晶体有6个周期,且以1 μm为间隔,从26.5~31.5 μm. 该光参量振荡器以脉宽为150 ns,重复频率为10 kHz的声光调Q Nd∶YAG激光器为泵浦源,且泵浦光波长为1.064 μm. 通过控制晶体的温度（50~200℃）以及改变晶体的极化周期（26.5~31.5 μm）,可由该光参量振荡器获得2.83~2.89 μm,3.10~3.38 μm,3.57~3.78 μm,3.95~4.12 μm, 4.28~4.46 μm,4.65~4.79 μm的闲频光连续调谐输出. 且当泵浦功率为8.15 W时,在闲频光输出波长为3.33 μm处,获得了最大输出功率2.17 W.