Continuous-wave hybrid index-antiguided and thermal-guided planar waveguide laser

A continuous-wave index-antiguided planar waveguide laser with a 220 -μm Nd:YAG active layer is investigated. Robust fundamental mode oscillation in the antiguided direction is demonstrated with negligible thermal index focusing while in the orthogonal direction the laser is dominantly thermally guided. A maximum output power of 2.25 W is obtained with a slope efficiency of 43% and an optical efficiency of 39%. A model is developed for finding the fundamental mode of laser oscillation with arbitrary index antiguiding and gain guiding in orthogonal directions with simultaneous thermal index guiding. Experimental results are compared to theory with good agreement.