Special feature on: Ultrashort pulse Ti: Sapphire lasers and amplifiers

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Special feature on: Ultrashort pulse Ti: Sapphire lasers and amplifiers     

宽带扩展腔产生15飞秒光脉冲实验研究

用３ｍｍ长的钛宝石短棒和改进的非对称Ｚ型折叠腔结构进行自锁模实验，以石英棱镜对作为腔内色散补偿元件，在５Ｗ氩离子激光泵浦下，实现低阈值泵浦自锁模运转。在腔内不加任何调制元件的情况下实现软光阑锁模，获得最短脉冲宽度为１５ｆｓ，光谱宽度为８０ｎｍ，输出平均功率４００ｍＷ。     

脉冲Ti~（3＋）：Al_2O_3激光器的增益长度

脉冲激光束纵向泵浦Ｔｉ￣（３＋）：Ａｌ＿２Ｏ＿３晶体，根据晶体中增益区的分布情况和脉冲运转的特点，从获取高转换效率考虑，可用“损耗平衡”确定晶体长度。单纵向泵浦时晶体的长度１由式选取。式中α＿ｐ是晶体对泵浦光的吸收系数，β是ＦＯＭ值。双纵向泵浦时，“损耗平衡”表示为：是晶体长度。根据实际光路的调整状态，设双纵向泵浦参数基本对称，对高α＿ｐ晶体取Ｌ＝１．５ｌ。若α＿ｐ较低，且泵浦参数并不对称，则Ｌ在ｌ＜Ｌ＜１．５ｌ范围内取值。这一方法与实验系统运转情况相符。     

Temporal intracavity detection of parasitic infrared absorption in Ti:Sapphire lasers

An intracavity technique with temporal sensitivity to optical losses is used to detect parasitic infrared absorption (PIRA) in Ti:sapphire crystals with high active-center concentrations. By means of comparative analysis, re-emission is established of part of the parasitically absorbed energy back into the laser action channel. A method is proposed for approximate quantitative determination of the relative part of re-emitting PIRA-centers with respect to their total number; for the highly-doped crystal described, it is estimated at about 11%.     

钛宝石再生放大器实验研究

分析了啁啾脉冲在钛宝石再生放大器中的能量增益与泵浦光及信号光光束口径的关系。并用不同能量的调Ｑ倍频ＮｄＹＡＧ激光器的５３２ｎｍ光为泵浦光，测量了２ＴＷ钛宝石激光系统中钛宝石再生放大器在无注入信号脉冲时和有注入信号脉冲时的脉冲建立时间及相应的输出能量大小。再生放大器的增益为２×１０７。     

可调谐窄线宽钛宝石激光脉冲的放大和频率展宽

在频域上进行了光参变激光器对钛宝石激光脉冲作选取放大并频率扩展的理论分析和数值模拟。实验上实现了用BBO光学参变振荡器作钛宝石激光脉冲选取、频率展宽为120nm的连续可调谐窄线宽（小于0.02nm）激光输出。     

Erbium fibre amplifiers and lasers

Erbium-doped fibre amplifiers and lasers have been the subject of intense research and development over the last five years. It is hoped that this review will serve as an introduction to the main device concepts and make accessible the rapidly expanding body of literature.     

TW级Ti：Al2O3飞秒激光放大器

报道ＴＷ（１０＾１２Ｗ）级Ｔｉ：Ａｌ２Ｏ３飞秒激光放大器的研究，采用Ｔｉ：Ａｌ２Ｏ３自锁模激光振荡器和脉冲啁啾放大技术，获得了能量为８４ｍＪ，脉宽为７５ｆｓ的放大光脉冲，峰值功率达到ＴＷ量级。     

预脉冲灯泵钛宝石可调谐激光器

利用预脉冲技术,可减小氙灯放电初始阻抗,使主放电电流脉冲前沿变陡,脉冲包络变窄,峰值变高,泵浦能量集中,有利于灯泵钛宝石激光输出。试验证明,在低能量（４７Ｊ）注入时,电光转换效率提高１８％,输出９５０ｍＪ;在高能量（１１６Ｊ）注入时,效率提高５％,输出能量１８１０ｍＪ。该激光器可调谐范围为６９５～９４０ｎｍ。     

超快、超短、超强激光脉冲

正如激光的发明引起了科学技术领域的一场巨大的革命一样，超快、超短、超强激光脉冲的产生使人类探索许多未知领域及发现新的物理规律成为可能．自然界中存在着许多以前受测量手段的时间分辨率限制而无法认识的超快现象，如分子尺度上的运动，单分子的振动及转动，液体或晶格的振动及转动，     

超短脉冲掺Yb3+光纤放大器实验研究

通过采用不同类型和不同长度掺Yb3+光纤进行被动锁模光纤放大器的实验研究.获得了最大输出功率为140 mW,单脉冲能量为5.5 nJ的超短脉冲.实验分析表明:掺杂光纤绿色荧光的产生和自吸收是影响放大器光转换效率的主要原因.绿色荧光的产生为Yb3+离子间相互作用引起合作能量转移过程,这种能量转移过程将降低光纤放大器的量子效率.     

载波相位对超短正弦高斯脉冲的影响

在时间域中研究了载波相位对超短正弦高斯脉冲的影响.给出了超短正弦高斯脉冲的脉冲能量和时间重心的解析表达式和数值模拟结果.结果表明载波相位和正弦函数的参数对超短正弦高斯脉冲的脉冲能量和时间重心有很大的影响.当载波相位等于nπ和2n+1π/2时,超短正弦高斯脉冲的脉冲能量分别达到最小和最大值;当载波相位等于2n+1π/4时,载波相位对超短正弦高斯脉冲的脉冲能量没有影响.当载波相位等于4n+3π/4和4n+1π/4时,超短正弦高斯脉冲的时间重心分别达到最小和最大值;当载波相位等于nπ/2时,超短正弦高斯脉冲的时间重心不发生变化.     

Model studies of THz-range generation via down conversion of the radiation of Ti:Sapphire lasers in LBO crystals

Results from model studies of the possibility of creating a source of high-power picosecond pulses of terahertz radiation via optical rectification and phase-matched down conversion of femtosecond pulses of Ti:Sapphire lasers in a nonlinear LBO crystal are presented. Modified Sellmeier equations are used in calculations. It is shown that the lengths of coherence for the generation of THz radiation at frequencies higher than 0.5 THz are more than 0.5 mm, allowing the technologically simple production of periodic structures. The maximum length of coherence is achieved for s–s type interactions in the XY plane. Phase-matched s–f type down conversion is possible only in the XY plane, including noncritical spectral matching conditions. Maximum efficiency can be expected for three-wave interactions with the polarization of interacting waves parallel to Z axis.     

Planar Er- and Yb-doped amplifiers and lasers

New results in erbium-doped planar waveguide amplifiers and lasers are presented. The waveguides are produced in silica-on-silicon technology using plasma-enhanced chemical vapor deposition. Waveguide propagation losses outside the erbium absorption band are improved to values below 0.05 dB/cm for a core–cladding index step of around 1.4%. Amplifier arrays show a net gain of more than 12 dB over the entire C-band. Received: 13 June 2001 / Published online: 23 October 2001     

Ultrafast ytterbium-doped bulk lasers and laser amplifiers

We review recent achievements with ultrafast bulk lasers and amplifiers based on Yb:YAG and Yb:glass. Special attention is paid to those aspects of the quasi-three-level nature of these gain media that are important for short-pulse generation. The potential of Yb-doped media for efficient short-pulse generation and amplification is compared to their Nd-doped counterparts. Received: 4 January 1999 / Revised version: 15 March 1999 / Published online: 26 May 1999     

可单向和双向运转的自锁模掺钛蓝宝石环形激光器

首次报道了采用六镜环形腔结构的掺钛蓝宝石激光器，该激光器既可以实现自锁模的单向运转，也可以实现自锁模的双向同时运转。     

自锁模钛宝石激光器多脉冲运转特性研究

对自锁模钛宝石激光器中多脉冲的特性和成因进行了较详细的分析，提出了腔内脉冲周期性散射减弱了腔内自振幅调制的理论模型。据此所作的数值模拟结果，很好地解释了实验现象。     

双预燃闪光灯泵浦钛宝石激光输出的实验研究

对强预燃闪光灯泵浦的钛宝石激光器进行了研究。实验采用双直流预燃电路，研究强预燃对激光输出的影响。