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

我们研制了一种腔内倾倒飞秒钛蓝宝石激光系统及其多通放大器，以获得中等高能量的短脉冲，足以在液体溶液中进行三阶光学非线性实验。目前，商业上可用的飞秒Ti：蓝宝石激光系统是：(1)Ti：蓝宝石振荡器（一般价格= 1800万日元），它产生的脉冲能量为4 nJ/脉冲，或(2)Ti：蓝宝石振荡器及其放大器（一般价格= 5000万日元），它产生的脉冲能量为1 mJ/脉冲。为了在瞬态吸收或光子回波等化学系统中进行短脉冲实验，我们需要一个能量在mJ/脉冲附近的脉冲来低于mJ/脉冲。因此，需要一种新的短脉冲激光系统来获得中等高能量的脉冲。在本研究项目中，我们用ABCD矩阵的形式计算了腔倾倒Ti：蓝宝石激光器的振荡稳定性。我们从理论上和实验上研究了五镜构型和六镜构型。空腔转储激光器在4mhz时产生的脉冲宽度为13 fs，能量为67 nJ/脉冲。目前，一个多通（六通）放大器与Ti：蓝宝石晶体正在设计和构造，以获得更高的能量脉冲。该放大器的目的是在20khz时获得能量超过亚微j /脉冲的脉冲。我们也正在编写一个手册，以建立这个激光系统，并计划分发给公众。

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.