High-Power Tapered Photonic Crystal Lasers With Slots for Narrow Spectral Width

High-power low-divergence tapered lasers with slots in the ridge waveguide section and near the front facet are demonstrated and compared. Both devices can achieve a narrow spectral width. Tapered lasers with slots in the ridge waveguide deliver an output power of 2.15 W with a wall-plug efficiency of 43%. The maximum side mode suppression ratio (SMSR) is 28.8 dB and the vertical far-field angle is around 11°. For tapered lasers with slots near the front facet, the output power and the wall-plug efficiency are 1.87 W and 37%, respectively. An SMSR of 36.8 dB and a vertical beam divergence of 7° are obtained. High beam quality is achieved for both devices.

I. Introduction

High-power edge-emitting diode lasers are key components for a wide range of applications, such as material processing, optical frequency conversion [1], pumping for fiber amplifiers and solid-state lasers [2]. Most of these applications require a nearly diffraction-limited beam quality, a low divergence, and a narrow spectral width. Tapered lasers have received much attention for their easy fabrication and capability of maintaining a good beam quality at an output power of several watts [3]. Tapered lasers with photonic crystal structure can achieve a low vertical divergence [4]. However, the spectral width of conventional tapered lasers is the same as that of typical broad-area lasers, which usually ranges between 2 and 6 nm [4], [5].