High average-power self-starting Nd:YAG laser with cavity completed by self-induced refractive index gratings

Abstract

Summary form only given. We present new results of our experimental and theoretical investigation of the lasers with the cavity completed by the holographic population gratings and their capability to generate high average power beams with near-diffraction limited quality. Principles of cavity formation were studied theoretically taking into consideration both gain and refractive index gratings in laser crystals. Analytical investigation and numerical calculation of generation conditions indicate a key role of the refractive index gratings (accompanying the population grating) which provide the positive distributed feedback in the cavity. Transverse and longitudinal mode analysis of the laser oscillator demonstrates high stability of the fundamental mode of the cavity with the self-induced dynamic mirrors. The lasers based on Nd:YAG crystals including LiF:F/sub 2//sup -/ saturable absorber were studied experimentally. Different architectures of the self-starting laser oscillators were examined. Self-adaptive properties of the system for compensation of intracavity thermal-induced distortions of the spatial structure and polarization of the generated beams were tested. The multi-loop schemes with holographic population gratings induced both in the laser crystals and in the saturable absorbers demonstrate a capability for generating high-average power beams with near-diffraction quality, high pointing stability and long coherence length. The generation of a beam with average power up to 150 W and high quality was achieved.