650-nm GaInP/AlGaInP visible laser diode with buried tapered-ridge structure

A new tapered ridge waveguide structure is employed in GaInP/AlGaInP laser diodes in order to increase (theta) PLL for digital versatile disk optical pick-up application. The dry-etched buried tapered ridge has been fabricated using BCl(subscript 3/Ar plasma in electron cyclotron resonance reactive ion etching system and chemical treatments. The parallel far-field angle was increased up to 9.7 degrees when the width of tapered ridge at the front facet was reduced down to 3.2 micrometers . The threshold current was 60mA and slope efficiency was 0.42W/A, which were comparable to the values of wet-etched lasers. The characteristics temperatures were estimated to be 154K at 25-60 degrees C and 60K at 60-100 degrees C. An operating time of over 1000 hours at the output power of 5mW at 70 degrees C was obtained without significant increase of operating current, which indicates a sufficient reliability for commercial purposes.