Continuous-wave hybrid index-antiguided and thermal-guided planar waveguide laser with large mode area

We present lasing experiments in index-antiguided (IAG) planar waveguides made of Nd: YAG (refractive index = 1.820) sandwiched by Terbium Gallium Garnet (refractive index = 1.954). For a core width of 220 mu m, we observe fundamental mode oscillation with maximal 2.62 W output power and 0.109 slope efficiency. An analytical model is developed taking into account simultaneous index-antiguiding, gain guiding and thermal induced refractive focusing. For a core width of 400 mu m, fundamental mode oscillation is only observed near the lasing threshold, suggesting that the maximally core width in IAG waveguides for fundamental mode operation depends on the strength of index antiguiding.