用后向SBS压缩电光调Q Cr:LiSAF激光脉冲宽度的研究

在抽运能量一定的条件下，采用强聚焦短焦距透镜提高焦点处的光功率密度，将Cr:LiSAF电光调Q激光器的输出脉冲聚焦于装有CS2介质的受激布里渊散射(SBS)池中，实现了宽线宽、多横模Cr:LiSAF激光脉冲的后向SBS，并观察到对激光脉宽的有效压缩。     

用后向SBS压缩电光调Q Cr∶LiSAF激光脉冲宽度的研究

在抽运能量一定的条件下 ,采用强聚焦短焦距透镜提高焦点处的光功率密度 ,将Cr∶LiSAF电光调Q激光器的输出脉冲聚焦于装有CS2 介质的受激布里渊散射 (SBS)池中 ,实现了宽线宽、多横模Cr∶LiSAF激光脉冲的后向SBS ,并观察到对激光脉宽的有效压缩。     

半导体激光双稳态光信号放大和处理

利用光纤耦合输出反馈泵浦半导体激光双稳装置,实现了微分增益、双稳和零偏等三种工作模式的运转。由此完成了恒定偏置和脉冲偏置光信号放大、光脉宽压缩、限幅、整形和开关等多种光信号处理功能。光信号增益达22.5dB,脉宽可压缩25倍。     

1064nm激光诱导等离子体开关控制355nm脉宽可调输出

为得到脉宽可控的355nm紫外脉冲激光输出,采用1064nm脉冲激光诱导等离子体开关技术,控制355nm激光脉冲宽度,在激光电离Cu小孔内壁表面及空气击穿共同作用下,获得了2.8ns～10ns的脉宽可调输出。讨论了1064nm单脉冲输出能量对脉宽压缩的影响,在无延时情况下得到了脉宽最短达2.8ns的脉冲激光输出。在此基础上,保持1064nm单脉冲输出能量不变,采用延时装置改变两光路间的光程差,以控制等离子体开关相对于355nm激光脉冲的形成时间,最终得到脉宽可调的脉冲激光输出。结果表明,等离子体开关结构简单、操作方便、适用范围广,是一种较好的脉冲整形手段。     

1064nm激光诱导等离子体开关控制355nm脉宽可调输出

为得到脉宽可控的355nm紫外脉冲激光输出,采用1064nm脉冲激光诱导等离子体开关技术,控制355nm激光脉冲宽度,在激光电离Cu小孔内壁表面及空气击穿共同作用下,获得了2.8ns～10ns的脉宽可调输出.讨论了1064nm单脉冲输出能量对脉宽压缩的影响,在无延时情况下得到了脉宽最短达2.8ns的脉冲激光输出.在此基础上,保持1064nm单脉冲输出能量不变,采用延时装置改变两光路间的光程差,以控制等离子体开关相对于355nm激光脉冲的形成时间,最终得到脉宽可调的脉冲激光输出.结果表明,等离子体开关结构简单、操作方便、适用范围广,是一种较好的脉冲整形手段.     

LD泵浦Cr4+,Nd3+:YAG自调Q腔内倍频激光器研究

Cr4 ，Nd3 ：YAG晶体的激光特性得到了系统研究．在LD泵浦下，Cr4 ，Nd3 ：YAG晶体获得了1.064μm的自调Q激光输出．激光平均输出功率达到3．36W，脉宽65ns，重复频率87kHz，光-光效率为15．3％．加入KTP晶体后实现了自调Q腔内倍频，获得了532nm的绿色脉冲激光输出，平均功率达到1W，脉宽210ns，重复频率47kHz，光-光效率为6％．对自调Q激光及其腔内倍频发现的现象进行了讨论．     

宽线宽Cr:LiSAF受激布里渊散射相位共轭激光器

激光聚焦到受激布里渊散射(SBS)介质中所产生的声子光栅的密度对比度对应于叠加光场的强度对比度,据此直观分析了宽线宽激光SBS能量阈值高于窄线宽激光SBS的原因,并对宽线宽SBS相位共轭谐振腔的高启动阈值进行了定性分析.设计并运行了Cr:LiSAF宽线宽SBS相佗共轭激光器,对其静态运行时的输出激光波形,以及自调Q动态运行时的输出激光脉冲波形、能量、光束发散角等进行了测量.结果表明它能有效地产生脉宽约为50 ns的自调Q脉冲激光,光束发散角相对于静态激光压缩了约2倍.     

基于多层薄板的全固态高能量飞秒激光脉冲非线性压缩技术

基于掺Yb³⁺光纤和掺Yb³⁺晶体的飞秒激光器输出的飞秒激光脉冲具有较高的脉冲能量和平均功率,被广泛应用于科研和工业生产;但受Yb³⁺增益介质增益带宽的限制,输出脉冲宽度很难小于300 fs。利用飞秒激光脉冲在多层薄板中的自相位调制效应,分别对基于掺Yb³⁺光纤和掺Yb³⁺晶体的飞秒激光器输出的飞秒激光脉冲进行非线性压缩。通过优化非线性压缩装置的各项参数,实现了对低能量、窄脉宽和高能量、宽脉宽脉冲的非线性压缩,分别获得了脉冲能量为64μJ、脉冲宽度为42 fs和脉冲能量为315μJ、脉冲宽度为79 fs的飞秒激光脉冲输出,第一级非线性压缩效率均超过80%,整体压缩效率分别为53%和65%。     

调Q Nd：YAG脉冲激光－光纤耦合与传输特性的研究

研究了调ＱＮｄ：ＹＡＧ脉冲激光－光纤耦合效率与传输特性，测量了激光损伤阈值，研究了入射激光束参数对激光损伤阈值和耦合效率的影响，在此基础上设计了耦合光学系统，对１０ｎｓ的激光脉冲，从光纤输出的激光脉冲的能量密度达１２Ｊ／ｃｍ￣２，对准静态Ｎｄ：ＹＡＧ（脉宽ｍｓ量级）脉冲激光，从光纤输出的激光脉冲的能量达３．５Ｊ可以满足激光刻字和激光焊接的要求。     

高功率窄谱宽1 915 nm掺铥光纤激光器研究

开展了1 915 nm高功率、高效率、窄谱宽输出的掺铥光纤激光器（TDFL）研究。基于全光纤主振荡功率放大（MOPA）结构,采用40 W的793 nm半导体激光器泵浦纤芯直径25 m的双包层大模场面积（LMA）掺铥光纤,获得了最高功率12.1 W的1 915 nm窄谱宽连续种子激光输出。将8 W种子光注入掺铥光纤放大器,在793 nm激光泵浦功率为142.9 W时,获得了平均功率90 W的激光输出,其中心波长为1 915.051 nm,3 dB谱宽仅为94 pm,斜率效率为60.2%,光-光转换效率达63.0%。该系统在40 min运行考核时间内输出激光稳定性良好。     

540 fs light pulses at 1.5 μm with variable repetition rateusing a tuneable twin guide laser and soliton compression in adispersion decreasing fiber

A novel and simple method to generate ultra short light pulses with variable repetition rate is demonstrated. A wavelength modulated tuneable twin guide laser, emitting blue-chirped light, together with pulse compression in a standard single mode fiber is used to generate light pulses of 3 ps width. Amplification and further compression in a dispersion decreasing fiber leads to Fourier transform limited pulses of 1.87 ps width or to 540 fs pulses with a small pedestal     

Simultaneous mode selection and pulse compression of gain-switchedpulses from a Fabry-Perot laser using a 40-mm chirped optical fibergrating

Simultaneous pulse compression and mode selection of gain-switched pulses from a Fabry-Perot semiconductor laser are demonstrated using a chirped optical fiber Bragg grating, which has transformed initially chirped 60-ps pulses from an inexpensive multimode laser into a train of 12-ps single-mode pulses with a side-mode suppression ratio of 15.2 dB     

High-order soliton pulse compression and splitting at 1.32 µm in a single-mode optical fiber

The optically compressed pulses from a CW mode-locked Nd:YAG laser operating at 1.32 μm have been further compressed through a high-order soliton generation effect in a 40 m length of single-mode dispersion-shifted optical fiber. Two- and three-fold splitting of the soliton pulses have been demonstrated. Experimental compression factors and spectra forN = 3, 5, 7, 9, 11, and 13 solitons have been shown to agree qualitatively with theory. In shorter fiber lengths pulses as short as 33 fs have been generated, corresponding to an over-all compression factor of X2700, the largest reported so far.     

High-power side-pumped passively mode-locked Er-Yb fiber laser

A side-pumped double-clad Er-Yb fiber laser passively mode-locked with a saturable absorber is demonstrated for the first time. Pumped with a power of 1 W from a broad-stripe diode laser, an environmentally stable cavity design produces positively chirped 3-ps pulses at a repetition rate of 30 MHz with an average output power of 50 mW. The pulses can be linearly compressed to 330 fs in a length of negative dispersion fiber, whereas nonlinear compression in standard telecom fibers yields 130-fs pulses with pulse energies of 1.2 nJ     

光子晶体光纤中基于交叉相位调制的脉冲压缩

为了研究飞秒双脉冲在光子晶体光纤不同色散区的非线性传输过程,采用分步傅里叶方法求解耦合的非线性薜定谔方程组,并进行了理论分析。讨论了不同抽运功率、不同抽运脉冲啁啾参量以及不同脉宽比对信号脉冲压缩的影响。结果表明,基于交叉相位调制效应,弱信号脉冲不仅能够被压缩,而且光纤存在最佳压缩长度。增大抽运脉冲输入功率,选取正啁啾抽运脉冲,可以得到更大的信号脉冲压缩因子,同时最佳光纤长度减小。另外,不同的脉冲宽度对信号脉冲的压缩产生大的影响,较窄脉宽的抽运脉冲易于产生较短的压缩信号脉冲。这一结果对用光子晶体光纤压缩弱信号脉冲提供了理论参考。     

Color center lasers passively mode locked by quantum wells

Using multiple-quantum-well (MQW) saturable absorbers, a NaCl color center was passively mode locked to produce 275-fs transform-limited, pedestal-free pulses with a peak power as high as 3.7 kW. The pulses are tunable from λ=1.59 to 1.7 μm by choosing MQWs with different bandgaps. The output pulses from the laser were shortened to 25 fs using the technique of soliton compression in a fiber. The steady-state operation of the laser requires the combination of a fast saturable absorber and gain saturation     

基于色散平坦光纤的二阶孤子压缩

将再生锁模光纤激光器(RMLFL)输出的约5.8 ps脉宽的高质量无啁啾双曲正割脉冲,通过掺铒光纤放大器(EDFA)放大后注入4.28 km长的色散平坦光纤(DFF)中,利用二阶孤子压缩效应成功地将脉冲压缩到1.74 ps,压缩比为3.3,与理论计算结果完全一致。与基于色散渐减光纤(DDF)的绝热孤子压缩(ASC)方案相比,该方案在同样的孤子阶数下大大降低了入射功率,而且色散平坦光纤的非色散渐减特性决定了它对于不同波长、不同脉宽的输入都可以通过调整输入脉冲功率和选取合适的光纤长度来配合满足压缩条件。虽然压缩因子不大,但基本能满足需求。     

Fiber-grating-based self-matched additive-pulse mode-locked fiberlasers

Fiber-grating-based self-matched additive-pulse mode-locked (APM) fiber lasers were investigated both theoretically and experimentally. With three fiber gratings to form the linearly coupled cavities, such a fiber laser system could generate stable mode-locked output without critical cavity length control. It was shown that the wavelength dependence of the effective penetration length of a fiber grating led to the self-matching of the cavity lengths of the coupled cavities. A millimeter-order cavity-length mismatch could be tolerated. In a similar laser structure using chirped fiber gratings with a designated arrangement of the grating polarities, the APM fiber laser could have the advantages of higher tolerance of cavity-length mismatch and stretched-pulse amplification. After pulse compression with a piece of single-mode fiber, output pulses with full-width at half-maximum pulsewidths of 930 fs were obtained