High-power 660-nm GaInP-AlGaInP laser diodes with low vertical beam divergence angles

We present 660-nm GaInP-AlGaInP ridge multiple-quantum-well laser diodes (LDs) reliably operating at high output power over 200 mW at 70°C not showing unstable higher order lateral modes owing to an adoption of a dry etching method instead of a conventional chemical wet etching for realizing steep ridge sidewalls. Employing an optimized two-step n-cladding layer LDs produced very narrow horizontal and vertical beam divergence angles of 8.6° and 15.3°, respectively. To the best of our knowledge, this vertical beam divergence angle is the lowest value ever reported in high-power 660-nm LDs operating over 200 mW and is expected to play an important role in minimizing the coupling loss between LD and passive optical components in digital versatile disc system.