Resonant intracavity modulator for Q-switching a CO2 laser in a new parameter regime

In this paper we report on the development program of an original intracavity Q-switch for CO2 lasers, called Integrated Mirror Optical Switch (IMOS). The IMOS is based on the optical plasma resonance effect in a GaAs- semiconductor when the refractive index of a tens of nm's thin MBE grown n-GaAs (5-8X1018cm-3) layer is modulated by electronically controlling the electron density in the thin n-GaAs layer. A heterostructure diode is conceived to keep the power dissipation low. 15 to 30% modulation depth can be achieved for a depletion voltage of 15 V at 1 W power dissipation. Switching frequencies of more than 1 MHz were measured. These driving characteristics are very promising to turn a CO2 laser into an easily computer controlled and flexible-machining tool. In order to achieve this, the structure of the Q-switch needs to be adapted for intracavity usage. Q-switches operating in reflection and transmission are compared and discussed. Highly efficient coupling mechanisms are suggested. Special attention will be paid to the design of diffraction gratings.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.