High-power constricted double-heterojunction AlGaAs diode lasers for optical recording

In this letter we describe a new type of constricted double-heterojunction injection laser especially designed for optical disk recording. The laser is capable of steady operation in a stable fundamental spatial mode at powers of 80 mW/facet at 20% duty cycle (25-MHz repetition rate, 8-nsec-wide pulses) and 50 mW/facet at 50% duty cycle (10-MHz repetition rate, 50-nsec-wide pulses). Such devices have been used in high-data-rate optical recording and preliminary results indicate operating life in excess of 103 h at 40 mW/facet and 50% duty cycle. The laser employs a very thin active region (500–800 Å) and a nearly planar structure to provide as large a source size as possible while remaining in fundamental spatial mode operation. Single longitudinal mode cw operationwas recorded up to 21 mW/facet. It is also found that an antireflection coating on the emitting facet not only raises the overall efficiency and facet damage limit, but also can simplify the modal pattern.