亚10飞秒脉冲的诊断与压缩

采用二次谐波-频谱分辨光闸法对克尔透镜锁模钛宝石激光器输出的飞秒脉冲的振幅和相位 进行诊断，测得其脉冲包络是双曲正割型的，而相位则近似为时间的三次幂形式. 通过对脉 冲频域相位的拟合，诊断出二阶群速度色散是造成脉冲啁啾、导致脉冲展宽的主要原因. 利 用棱镜对补偿二阶群速度色散，进一步将17 fs啁啾脉冲压缩至半高全宽为8.5 fs的近似转 换极限脉冲. 关键词： 飞秒脉冲 二次谐波-频谱分辨光闸法 群速度色散     

在色散渐减光子晶体光纤中产生超连续谱的实验研究

本文利用非线性偏振锁模激光器产生的重复频率50 MHz, 脉宽为1.8 ps的脉冲分别抽运外径均匀和色散渐减两种高非线性光子晶体光纤, 在三阶非线性效应 (自相位调制、交叉相位调制、四波混频和受激拉曼散效应等) 和色散共同作用下得到扩展至蓝光部分的超连续谱. 模拟了光谱在色散渐减光纤和均匀光纤中的展宽过程, 通过对比均匀光纤发现色散渐减光纤在调控色散, 加强拉曼孤子和色散波的群速度匹配条件, 产生超带宽光谱方面具有很大优势. 实验利用20 m长的色散渐减光纤, 得到了406.1至671.8 nm的可见光波段增强的较为平坦的超连续谱. 关键词： 超连续谱 色散渐减光子晶体光纤 群速度匹配 非线性效应     

用于飞秒脉冲锁模激光器中的优化Gires-Tournois反射镜

根据飞秒脉冲锁模钛宝石激光器腔内色散补偿的要求,设定负色散镜的色散目标值,用最优化方法,设计出了负色散Gires-Toumois(G-T)反射镜,计算了光场在优化负色散G－T反射镜不同膜层内的分布,不同波长的光场分量,在优化负色散G－T反射镜内部,穿透深度不同,在720nm-900nm波长范围内,长波分量有较大的穿透深度,因而对长波分量提供较大的时间延迟,将其用于飞秒锁模钛宝石激光器中,取代传统的腔内色散补偿棱镜对,结合半导体可饱和吸收镜（SESAM）自启动锁模,在钛宝石激光器中获得了56fs脉冲。     

直接从钛宝石激光器获得超连续光谱

采用啁啾镜和棱镜对相结合补偿色散的方法在自调Q自锁模钛宝石激光器腔内直接产生了超 过一个倍频程的超连续光谱，光谱范围从460nm到1000nm；这是飞秒激光器输出光谱在短波 波段第一次突破500nm.这将使得脉冲的载波包络偏移频率的测量装置得到大大简化，同时也 提高了光频测量的稳定性. 关键词： 超连续光谱 啁啾镜 自调Q自锁模 钛宝石激光器     

孤子光脉冲的产生及其应用研究

利用非线性偏振旋转技术实现自起振被动锁模.在掺铒光纤环形腔激光器中产生了中心波长为1563.3 nm、重复频率为12.5 MHz、脉冲宽度为352.0 fs、3 dB光谱宽度为7.8 nm的孤子光脉冲.采用该孤子光脉冲作为抽运光源，经掺铒光纤放大器放大后，输入到101 m长的高非线性光子晶体光纤中，获得了20 dB带宽约为240 nm的超连续激光光谱.实验详细观测了光脉冲随抽运功率的变化及超连续激光光谱的形成过程，分析了其形成机理.研究表明：当抽运功率较低时，光谱加宽主要由高阶孤子的分裂引起；随着抽运功率的增加，高阶孤子分裂成基本孤子的数目逐渐增大，光谱进一步加宽；当抽运功率增加到受激拉曼散射的阈值时，受激拉曼散射成为光谱展宽的主要原因；抽运功率进一步增加时，受激拉曼散射、参量四波混频等非线性的共同作用将使光谱进一步加宽且变得光滑. 关键词： 孤子光纤激光器 超连续 光子晶体光纤     

掺锗硅基高非线性光纤超连续光源研究

利用非线性偏振旋转锁模掺铒光纤激光器和1100m长的掺锗硅基高非线性光纤制作了超连续光源，获得了从1150～1750nm的超宽带输出光谱，其中1150～1350nm波段光谱起伏小于3dB，1600～1700nm波段平坦度优于1dB，并有很好的向长波延展空间。光谱展宽的机理为孤子分裂与受激拉曼散射，而四波混频使光谱进一步展宽。     

高效、高峰值功率蓝光飞秒脉冲产生研究

分析计算了利用棱镜组引进频谱空间啁啾来补偿谐波倍频晶体的相位失配.结果表明,光谱 存在空间啁啾时,选择合适的透镜可在一定程度上补偿由于飞秒光脉冲的宽谱带引起的相位失配.采用此方法在实验上用自制的飞秒自锁模钛宝石激光器和BBO倍频晶体进行了二次谐波 倍频的研究,结果产生倍频蓝光的转换效率高达63%,蓝光平均输出功率达320mW,中心波长 为420nm,光谱带宽达5.5nm,可支持33.6fs的光脉冲.利用钛宝石激光器中的棱镜对进行波 长调谐,可使蓝光脉冲产生404—420nm的调谐范围. 关键词： 飞秒蓝光脉冲 空间啁啾补偿 二次谐波产生 转换效率     

单棱镜色散补偿自锁模钛宝石激光器

分析并描述了单棱镜色散补偿的原理,实验上实验了单棱镜色散补偿的钛宝石自锁模激光器的稳定运转。     

连续自锁模钛宝石激光器

锁模的钛宝石激光器是近红外波段比较可靠的飞秒(fs)超短脉冲光源.用氩离子激光器,实现了连续钛宝石激光器自锁模运转,输出脉宽92fs、谱宽8.5nm、平均功率大于200mW、调谐范围750～850nm.实验中Ti:Al_2O_3自锁模激光器结构如图1所示,谐振腔采用了“Z”形折送四镜象散补偿腔,M_1和M_2为曲率半径150mm高反镜,M_3为耦合输出镜,透过率5%,M_4为平面高反端腔镜,总腔长为1.6m左右,非对称排布M_2M_3相似文献   

钛宝石激光器9.5 fs脉冲输出中的啁啾镜色散补偿

根据钛宝石激光器的要求,实验设计了中心波长800 nm带宽200 nm的啁啾镜,在700—900 nm波长范围内提供约-60 fs²群延迟色散(group delay dispersion,GDD).采用双射频离子束溅射方法进行制备,用实验室搭建的白光干涉仪进行色散性能测试,从测试结果可以看出,制备的啁啾镜的性能和设计值符合得比较好.制备得到的非成对啁啾镜在钛宝石激光谐振腔中进行色散补偿,锁模后分别获得了12 fs和9.5 fs的激光脉冲输出.这是目前报道的使用国产啁啾镜获得的最短的 关键词： 啁啾镜 群延迟色散 色散补偿 钛宝石激光器     

Diode-pumped regenerative amplifier delivering 100-mJ single-mode laser pulses

We report on a side-pumped Nd:phosphate laser regenerative amplifier that delivers laser pulses of as much as 100 mJ in a single TEM mode. The laser beam is mode matched to the amplification medium by an intracavity fused-silica phase plate for mode shaping and a telescope for adjustment of the beam mode to the amplification rod section such that most of the energy stored in the rod is transferred to the laser pulses. As a result of the good overlap and the low loss, an optical-to-optical conversion efficiency of as much as 10% was measured for a pumping current of 80 A and greater than 100-mJ output pulses.     

注入锁定改善大口径稳定腔CuBr激光器的输出特性

报道了在稳定腔中采用注入锁定技术，钭自锁模ＣｕＢｒ激光脉冲成功地进行了注入锁定放大，得到了高平均功率的锁模铜激光脉冲，并且通过这种注入锁定，首次在稳定腔中得到了在２０ｍｍ光斑内空间高度相干的高功率铜激光辐射。     

Passive Q-switching of the diode-pumped Er:YAG laser cavity with the Q-switch based on the Fe<Superscript>2+</Superscript>:ZnSe crystal

Repetitive-pulse generation of the diode-pumped Er:YAG laser (λ = 2.94 μm) in the free mode and in the mode of cavity passive Q-switching was achieved using a Q-switch based on the Fe²⁺:ZnSe crystal. When using pump pulses 3 ms long, the pulse-average output power of the Er:YAG laser in the free generation mode was 0.5W. In the passive Q-switching mode, giant pulses 180 ns long with an energy of 3 μJ were obtained.     

Numerical modeling of generation of few-cycle pulses in a mode-locked laser

We have performed numerical simulation of a laser generating few-cycle pulses in the regime of coherent mode locking. It is shown that such a laser can support generation of pulses with a duration close to the reciprocal of the main laser transition frequency of the gain medium in a wide range of laser parameters.     

Generation of long broadband pulses with a figure-eight fiber laser

In this paper we performed the experimental and numerical study of a passively mode-locked fiber laser that generates packets of sub-picosecond pulses instead of individual pulses. The proposed configuration is a figure-eight fiber laser scheme, which includes a Nonlinear Optical Loop Mirror with polarization asymmetry inserted into a ring cavity. No experimental evidence of self-starting mode locking operation of the laser was observed; however, for proper adjustments of the wave retarders included in the setup, a mechanical stimulation triggers the onset of mode locking. The autocorrelation of the generated pulses shows a narrow sub-picosecond peak riding a large sub-nanosecond pedestal whose intensity is half that of the peak, and the optical spectrum is smooth and wide. We show that contrary to conventional ultrashort pulses, these pulses do not vanish rapidly after propagation through a long dispersive fiber, which makes then attractive for super-continuum generation as well as for applications in metrology. Finally, we study the pulse formation in the laser and present arguments based on experimental data and numerical simulations that the observed pulses are actually sets of a large number of solitons.     

Picosecond pulse generation in a benzene raman generator amplifier system

Picosecond ruby laser pulses generate simultaneously Stokes pulses of the 992 cm^–1 ring breathing mode and of the 3063 cm^–1 CH-stretching mode of benzene in a Raman generator cell by stimulated Raman scattering under self-focusing conditions. The Raman generator light is spectrally filtered, collimated, and amplified in three Raman amplifier cells pumped by ruby laser pulses. Both first Stokes lines have been selectively amplified to short, low divergence, intense light pulses.     

Tunable ultrashort laser pulses generated through filamentation in gases

Tunable and stable ultrashort laser pulses in the visible spectrum are generated with high efficiency by four-wave mixing process during the filamentation of near-infrared and infrared laser pulses in gases. It is shown that these tunable ultrashort pulses have a very low energy fluctuation and an excellent mode quality due to the processes of intensity clamping and self-filtering in the filament.     

Enhanced quadratic photocurrent in commercial light emitting diodes for autocorrelation measurement of ultrashort laser pulses

The quadratic photocurrent in commercial light emitting diodes (LEDs) has been studied in reverse bias mode for autocorrelation measurement of ultrashort laser pulses. It is found that the photocurrent can be greatly enhanced by operating the LED biased just below the reverse bias breakdown threshold. The effect of aging of LEDs on laser exposure in this mode of operation is found to be similar to that for the photovoltaic mode. The large internal gain in LED junction has enabled the recording of the second order autocorrelation signal of ∼200 fs laser pulses from 100 MHz laser oscillator with two orders of magnitude smaller average and peak power product compared to the case of the photovoltaic mode. PACS 42.65.Re; 42.50.Hz; 85.60.Jb     

高重复频率飞秒掺镱光纤放大器

 数值分析了掺镱单模光纤放大器的最佳增益光纤长度，并在实验上对掺镱单模光纤放大器和光栅对压缩器进行了研究。以最大平均输出功率为7 mW、重复频率为25.4 MHz、脉宽为56 ps的被动锁模环形腔掺镱光纤激光器作为种子脉冲，用250 mW的976 nm单模半导体激光器分别泵浦3种不同长度的掺镱单模光纤，对种子光进行放大，并用光栅对压缩器对放大后的脉冲在不同光栅距离上进行了压缩实验研究。当掺镱单模光纤长度为1.2 m时得到了较好的放大效果，种子脉冲被放大到140 mW，相应的增益为13 dB，放大后的单脉冲能量为5.5 nJ。在光栅距离为14.1 cm时获得了最短440 fs的脉冲，压缩后的功率为43 mW，相应的峰值功率为3.8 kW。     

Conditions of the generation of subnanosecond pulses in a THL-100 laser system

The results from the generation and amplification of positively chirped pulses of 0.05 ns duration at a central wavelength of 475 nm in a THL-100 laser system are presented. It is found that the initial complex allows the generation of such radiation pulses with Gaussian intensity profiles and energies of up to 7 mJ. When such pulses with energies of 2–4 mJ are amplified in an XeF(C-A) amplifier, it is possible to achieve a saturation mode and obtain at the output laser beams with energies of up to 3.2 J. The possibility of compressing subnanosecond pulses at a wavelength of 475 nm in a compressor based on diffraction gratings is demonstrated.