Pulse compression inside an actively AM mode-locked ND:YAG laser using a liquid Kerr cell

A mode-locked Nd:YAG laser capable of generating pulses substantially shorter than the present limit of 30-50 ps, while retaining the stability of active mode locking, would be a useful development. We present here a simplified theoretical analysis and a preliminary experimental verification of the use of an optical Kerr cell as a passive lossless pulse compressor inside aQ-switched and actively mode-locked YAG laser. The theoretical model indicates possible compression to as short as ∼5 ps in a typical low-power Nd:YAG laser. The preliminary experimental results show substantial pulse compression via the predicted mechanism, though still not below ∼30 ps. The technique appears capable, however, of pulse compression to substantially shorter values without the instabilities, statistical fluctuations, or energy losses associated with saturable-absorber mode locking.     

Compression mechanism of subpicosecond pulses by malachite green dye in passively mode-locked rhodamine 6G/DODCl CW dye lasers

The pulse width compression effect of a malachite green (MG) dye upon subpicosecond pulses has been experimentally investigated in a CW passively mode-locked rhodamine 6G/DODCI dye laser. The pulse width reduces as MG concentration increases, and reaches 0.34 ps at1.5 times 10^{-6}M. By adding the MG dye, good mode locking is achieved in a rather wide pumping-power range. A computer simulation of pulse growth has also been carried out by using simple rate equations, in which the fast-recovery component of loss due to the MG dye is taken into account. The simulated results can explain some experimental results qualitatively such as pulse width compression and pumping-power restriction. The pulse width compression results essentially from the fast recovery of cavity loss caused by the MG dye.     

Narrow-band infrared picosecond pulses tunable between 1.2 and 1.4 µm generated by a traveling-wave dye laser

A novel type of picosecond light source is the traveling-wave dye laser. It consists of a generator and an amplifier cell, both pumped by single pulses. Using the fast switching dye No. 5 with a fluorescence quantum efficiency of5 times 10^{-4}, one obtains an energy conversion of the pump to the IR pulse of up to 10 percent. The spectral width of the IR pulses is 15 cm^-1over the tunability range of1.18-1.4 mum. At 1.33 μm we observe Gaussian shaped pulses of 4.4 ps duration for pump pulses of 4.5 ps generated by a mode-locked Nd:glass laser. The output pulses show a high stability with a jitter of less than 0.2 ps.     

波长可调的ps超短腔染料激光器的研究

本文报道了用锁模磷酸盐玻璃激光的倍频光泵浦若丹明B超短腔染料激光器的实验装置和实验结果,用TPF和OSA的组合装置研究了磷酸盐玻璃激光器的最佳运转条件,得到了脉宽～5ps的锁模脉冲系列,以此ps光源泵浦的染料激光器获得了波长为620.1～641.6nm,脉冲宽度小于4ps的单模可调谐激光输出。     

高峰值功率主动-主动瞬态锁模激光技术研究

研究了主动-主动瞬态锁模技术,腔长调节技术和单一脉冲选取技术。实现了单一脉冲选取率达到100%,单一脉冲能量达到1.087 mJ,能量抖动不超过3%;脉宽小于等于300 ps,瞬态峰值功率高达3.62×106 W。实现了外触发与出光时间抖动±15 ns。     

Picosecond amplification and kinetic studies of XeCl

A 2 ps pulse derived by frequency doubling the amplified output of a CW mode-locked dye laser has been used to probe the gain characteristics of XeCl in the 308 nm region. Energy saturation parameters were measured for the four main laser transition. The gain kinetics of XeCl were investigated by observing the temporal gain recovery after the passage of a saturating picosecond pulse, and the contribution of the various relaxation processes to the XeCl gain dynamics is discussed. Evidence suggests that vibrational relaxation in the upper laser level is incomplete during the effective lifetime of XeCl*. Taken together, these measurements have permitted the determination of a stimulated emission cross section of general utility. To demonstrate the potential of XeCl for high power amplification, a picosecond pulse was amplified to a power of ∼20 GW.     

Measurement of the relaxation time of the Eastman 9740 bleachable dye

An upper limit of between 25 and 35 ps has been determined for the relaxation time of the Eastman 9740 bleachable-dyeQ-switch solution. The measurement was made by determining the time dependence of the transmission of the dye cell inside a mode-locked Nd:glass laser, using a delayed, attenuated pulse from the same laser as a probe.     

用互相关法测定锁模Ar~+激光脉冲的形状与宽度

使宽度约为5ps的锁模染料光脉冲与锁模Ar~+光脉冲柱KDP晶片内互相关,可以确定514.5nm与488.0nm Ar~+光脉冲宽度约为210ps,型状为高斯型。     

主动锁模和调Q Nd:YAG激光倍频同步泵浦染料激光器特性研究

本文介绍一种主动锁模和调Q Nd:YAG激光倍频同步泵浦可调谐染料激光器。由此激光器已获得脉冲宽度为70ps,脉冲能量为0.1μJ,调Q重复率达7kHz,调谐范围为580～610nm的微微秒脉冲,本文还研究了这一激光器的时间和频谱特性,分析了腔长失配对脉宽和中心波长的影响。     

1.3 μm高脉冲能量锁模皮秒再生放大器

报道了激光二极管抽运工作波长为1.3 μm的高能量皮秒再生放大器,种子源为重复频率65 MHz、平均输出功率140 mW的被动锁模皮秒激光振荡器。通过优化再生放大器,获得了重复频率为1 kHz、脉宽小于20 ps、单脉冲能量大于1 mJ的高脉冲能量皮秒脉冲激光,脉冲能量稳定性均方根值小于0.3%,其倍频光束671 nm的质量因子M2小于等于1.1,这表明再生放大器输出激光具有很好的光束质量。     

Picosecond stimulated Raman generation, pump pulse fragmentation, and fragment compression in single-mode optical fibers

Pump pulse depletion has been examined for high peak power (∼ 100 kW) 90 ps pulses from aQ-switched and mode-locked Nd:YAG laser in 4 m of single-mode optical fiber. Fragmentation of the fundamental and low Stokes Raman orders has been observed for this cascading process. Pulse compression using an interferometric technique has been carried out, obtaining compression ratios of up to times five, on these fragments which exhibited a negative frequency chirp.     

Simultaneous determination of the spectral and temporal properties of tunable, single, picosecond pulses from a short cavity dye laser

We report simultaneous quantitative spectral and temporal measurements of the output pulses from a single-axial mode rhodamine 6G short cavity (1-8 mum) dye laser. The dye laser was pumped at 10 Hz with single second harmonic (532 nm) pulses from a mode-locked Nd⁺³:YAG laser. Spectral measurements made with a high resolution spectrograph and temporal measurements made with an ultrafast streak camera indicate the production of Fourier transform limited pulses for near threshold operation. Output pulses of 7-14 ps (FWHM) are observed from the short cavity dye laser when pumped with 15-30 ps duration 532 nm pulses. The output pulse delay and jitter are also investigated. A theoretical model for the temporal evolution of the pulses is presented and compared with the experimental results.     

一种新型皮秒脉冲激光器

一种新型皮秒脉冲激光器由序列脉冲激光的产生、单脉冲激光的选取、放大和倍频等部分组成,激光器工作物质选用Nd∶YAG晶体,用两个格兰棱镜分别作为起偏器和检偏器,激光器的振荡级利用被动锁模染料产生的锁模序列脉冲激光,经过单脉冲选择器选取出其中的一个单脉冲激光,再经激光器放大部分的放大和倍频晶体的倍频后,激光器最终输出能量为120mJ,脉冲宽度为100ps,波长为532nm的单脉冲激光,其功率约为1.2×109W,功率密度约为4.2×109W/cm2,系统的外触发同步精度优于2μs。     

1030nm皮秒级光参量啁啾脉冲放大抽运源

利用低温工作状态下Yb∶YAG再生放大器,对1030nm光纤锁模激光器输出的250pJ的种子光进行放大。电光开关门宽控制种子光在放大器内20程往返,最大单脉冲能量为217μJ,输出频率10Hz,同时由于其增益窄化效应光谱宽度由8.9nm减小到0.3nm,相应的脉宽由18.0ps被压缩到5.5ps,这与理论模拟结果的0.4nm,4.2ps基本吻合。实验结果论证了采用窄增益带宽的再生放大器可以同时实现亚皮秒光参量啁啾脉冲放大(OPCPA)对抽运脉冲宽度和光谱宽度的要求,避免使用光纤光栅对光谱滤波带来的高阶非线性效应。     

Tunable, high-power, subpicosecond blue-green dye laser system witha two-stage dye amplifier

A two-stage dye amplifier design has been developed to amplify tunable, blue-green, subpicosecond dye laser pulses which are generated from a hybrid synchronously mode-locked dye oscillator directly (800 fs) or shorter to 200 fs by a fiber compressor stage. This system has achieved single pulse energies of 2 mJ, with an amplified spontaneous emission content of less than 0.1%. Using 40 mJ of the third-harmonic output of an Nd:YAG regenerative amplifier to pump the dye amplifier system, these pulse energies represent an energy extraction efficiency of ~5%. The tunability, stability, and spatial and temporal quality of the output pulses from the system have also been characterized     

重复率光泵染料锁模的研究

采用短谐振腔结构,利用分辨率10ps时间扩展器研究了染料浓度、流速与泵浦能量对锁模脉宽的影响。在重复率10～20次/S下,得到稳定的锁模脉冲输出。没有观测到卫星脉冲与失锁现象。脉冲幅度起伏优于10％。     

Feedback stabilized actively mode-locked Nd:phosphate glass laser

An electrooptic, actively mode-locked Nd: phosphate glass laser system is described employing a novel single-step feedback system to stabilize the pulse buildup time. Single output pulses of ∼100 ps duration with energies of up to 1 mJ could be reliably generated with a standard deviation in thesim3.2 mus pulse buildup time of ±40 ns allowing synchronization with pulses from laser systems at other wavelengths. Evidence of pulse broading due to self-phase modulation was observed together with wide tunability of the output wavelength from 1.054 to 1.068 μm.     

双棱镜扩束、光栅调谐的ps染料激光器

用重复率脉冲锁模YAG激光同步泵浦双棱镜扩束的光栅染料激光腔,对于R-6G激光染料,获得脉冲列重复率为20Hz、脉冲峰值功率为7.6MW、平均功率为9.5mW的30ps可调谐激光,其谱线宽度为0.04nm,接近变换极限宽度。激光输出稳定,调谐方便。     

550～689nm重复率YAG激光同步泵浦染料激光器

用重复率脉冲锁模YAG激光同步泵浦四种激光染料,获得脉冲重复率20Hz、峰值功率MW级、平均功率mW级、脉宽30ps染料激光。波长复盖范围为550.0～689.0nm,谱线宽度0.05nm。实验比较了L_D=1/2L_PF和L_D=L_P两种匹配腔的输出特性。     

110-pJ and 410-fs pulse at 10 GHz generated by single-stage external fiber compression of optically injection-mode-locked semiconductor optical amplifier fiber laser

We demonstrate the high-power amplification and single-stage fiber-based pulse compression of a traveling-wave semiconductor optical amplifier (TWSOA) fiber ring laser (SOAFL), which is optically mode-locked by backward injecting the TWSOA with a dark-optical-comb at repetition frequency of 10 GHz. A negatively chirped SOAFL pulsewidth of 5.4 ps is compensated and shortened to 3.9 ps by a 75-m-long dispersion compensating fiber. With a single-stage pulse compression in a single-mode-fiber spool, the SOAFL pulses with input average power of 1.7 W can further be compressed to a pulsewidth of 410 fs, corresponding to a pulse compressing ratio of nearly ten. The maximum average output power of the amplified SOAFL pulse is up to 1.1 W, corresponding to the peak power and pulse energy of >0.27 kW and 110 pJ, respectively.