Pulse train generation using a Fabry–Pérot cavity with an integrated optical amplifier and its application to parametric wavelength conversion

Abstract

Improving the repetition rate of a pulsed laser is an important issue in measurement and processing, as it leads to increased average power. However, in general, the heat generated by high-power lasers that use Q-switches cannot be ignored as the repetition rate increases, limiting the repetition rate. Therefore, in this study, we propose a new method of constructing a cavity in which an optical amplifier is inserted separately from the laser resonator, for generating a laser pulse train inside that cavity. By injecting a single laser pulse into this cavity, we were able to create a pulse train of up to ∼50 pulses. In addition, we confirmed that using the generated pulse train as the pump beam for a terahertz parametric source is useful to achieve a high average output. By selecting the appropriate amplifier inside the cavity, it is possible to create a pulse train from any wavelength or pulse width of the laser beam. This method makes it easier to achieve high average power from lasers when increasing the repetition rate is difficult and will contribute to the expansion of laser applications.