Development of Cavity-Dumped Ti : sapphire Femtosecond Laser and its Amplifier

我们研制了一套腔内倒空飞秒钛宝石激光系统及其多程放大器，获得了足以进行液体溶液三阶非线性光学实验的中等能量短脉冲。目前，市售的飞秒Ti：蓝宝石激光系统是（1）Ti：蓝宝石振荡器（一般价格= 18，000，000日元），其产生具有4 nJ/脉冲的能量的脉冲，或者（2）Ti：蓝宝石振荡器及其放大器（一般价格= 50，000，000日元），其产生具有1 mJ/脉冲的能量的脉冲。为了在诸如瞬态吸收或光子回波的化学系统中进行短脉冲实验，我们需要具有mJ/pulse到sub mJ/pulse的能量的脉冲。因此，需要一种新的短脉冲激光系统来获得中等能量的脉冲。本文采用ABCD矩阵方法计算了腔倒空钛宝石激光器的振荡稳定性。我们对五镜和六镜结构进行了理论和实验研究。腔倒空激光器在4 MHz下产生13 fs的脉冲宽度和67 nJ/脉冲的能量。目前，一个多通（六通）放大器与钛：蓝宝石晶体的设计和建造，以获得更高的能量脉冲。该放大器的目的是在20 kHz下获得能量超过亚微焦/脉冲的脉冲。我们也正在编写一本手册来构建这个激光系统，并计划将其分发给公众。

We have developed an intra-cavity dumped femtosecond Ti : sapphire laser system and its multi-pass amplifier to obtain a moderately high energy short pulse, enough to perform third order optical nonlinear experiment in liquid solutions. Currently, commercially available femtosecond Ti : sapphire laser systems are either (1)Ti : sapphire oscillator (general price = 18,000,000 yen), which yields a pulse with an energy of 4 nJ/pulse, or (2)Ti : sapphire oscillator and its amplifier (general price = 50,000,000 yen), which yields a pulse with an energy of 1 mJ/pulse. In order to perform experiment with a short pulse in chemical systems such as transient absorption or photon echo, we need a pulse with an energy around mJ/pulse to sub mJ/pulse. Therefore, a new short pulse laser system is desirable to get s moderately high energy pulse. In this research project we here calculated stability of oscillation for the cavity-dumped Ti : sapphire laser by the ABCD matrix formalism. We have investigated both the five-mirror configuration and six-mirror configuration theoretically and experimentally. The cavity dumper laser produces a pulse width of 13 fs and energy of 67 nJ/pulse at 4 MHz. Currently, a multi-pass (six-pass) amplifier with a Ti : sapphire crystal is being designed and constructed to get a higher energy pulse. The purpose of this amplifier is to get a pulse with an energy more than sub microJ/pulse at 20 kHz. We are also writing a manual to construct this laser system and are planning to distribute it to public.