Abstract
Generation of continuous wave (cw) orange light at 590-nm by double-pass second harmonic generation (SHG) of a high-power 1180-nm Raman fiber laser with a 20-mm long bulk periodically poled MgO doped lithium niobate (PP-MgO: LN) is presented. The rear end-face of the crystal was polished at a small angle of 5.4 mrad for compensating relative phase shift between the fundamental and SH waves in double-pass configuration. With this technique, 1.2-W of cw orange laser radiation with conversion efficiency of 9.8 % and power stability of ±1.0 % recorded over a one-hour period has been achieved. For the same normalized pump linewidths, approximately 3.5-fold efficiency enhancement over the single-pass efficiency has been obtained with the double-pass SHG configuration.
