Realization of high-power highly efficient GaInP/AlGaInP ridge laser diodes for recordable/rewritable digital versatile discs

Very efficient and reliable GaInP/AlGaInP red multiple-quantum-well laser diodes for recordable/rewritable digital versatile disc (DVD-R/RW) were successfully developed by low-damage fabrication. Because we adopted dry etching instead of conventional chemical wet etching for the steep ridge sidewalls of laser diodes (LDs), devices could be operated at a high output power over 200 mW at 70°C without showing any unstable higher-order transverse modes. In-situ monitoring tools in metal organic chemical vapor deposition (MOCVD) and dry etching were useful for controlling process parameters precisely, which enhances device characteristics and maintains the reproducibility of device fabrication. A very small beam aspect ratio of 1.78 with a very low vertical beam divergence angle of 15.3° at a high output power was achieved by optimizing the two-step n-cladding layer in our LD structures. These low values of the vertical beam divergence angle and aspect ratio are essential for minimizing the coupling loss between the LD and the objective lens in DVD pickups.