Laser output power stabilization for direct laser writing system by using an acousto-optic modulator

Abstract

We present experimental results on the output power stabilization of an Ar+ laser for a direct laser writing system. (LWS). Instability of the laser output power in the LWS cause resolution fluctuations of being fabricated diffractive optical elements or computer-generated holograms. For the purpose of reducing the power fluctuations, we have constituted a feedback loop with an acousto-optic modulator, a photodetector, and a servo controller. In this system, we have achieved the stability of ±0.20% for 12 min and the relative intensity noise level of 2.1 × 10-7 Hz-1/2 at 100 Hz. In addition, we applied our system to a 2 mW internal mirror He-Ne laser. As a consequence, we achieved the output power stability of ±0.12% for 25 min. © 2007 American Institute of Physics.