High-power 660-nm laser diodes for recordable dual layer DVDs

The light output power versus the operation current P-I characteristics of 660-nm laser diodes (LD) were investigated, focusing on cavity length dependence. It was revealed that the kink in P-I curves occurs at the same slope efficiency regardless of the cavity length. This indicated that higher kink power is realized if the slope efficiency at low power is increased by using a certain method. An LD without an etching-stopping layer whose internal loss was reduced, unlike one with the layer, showed the P-I curves with no kinks up to 350 mW even at a high temperature of 75°C. This is the highest power recorded for narrow stripe LDs with a wavelength of 660 nm. This LD is suitable for the next generation of high speed (8×) recordable dual layer digital video disk (DVD) drives necessitating 350 mW class LDs.