Abstract

Various kinds of laser diode based frequency doubling devices have been developed to provide a compact, efficient and visible coherent light source. A diode pumped, intra-cavity doubled solid state laser has advantages in its good spatial and temporal coherence, very low noise and scalability by parallel pumping.¹ These advantages derive from the intrinsic characteristics of a solid state laser. We have reported stabilized second harmonic generation (SHG) by polarization-mode decoupling with a KTiOPO4 (KTP) doubler and a quarter wave plate (QWP) inside a Nd:YAG laser cavity.² Since spatial coherence of the pump source is not necessary, a broad area laser diode (LD) can be used for pumping to generate the several mW green output required for readout of optical disks. A 1W LD allows a several tens of green output, sufficient for recording optical disks.³ A 1W green output was reported using a multimode optical fiber bundle for parallel pumping.4

© 1991 Optical Society of America