A VERY NARROW-BEAM ALGAAS LASER WITH A THIN TAPERED-THICKNESS ACTIVE LAYER (T3 LASER)

A very narrow-beam and high-power laser which has a thin tapered-thickness active layer is developed. The property of liquid-phase epitaxy on a ridged substrate is utilized to obtain the thin tapered-thickness (T**3) active layer. In the T**3 laser, the active layer is thinner near the mirror than near the inner region. The main feature of the T**3 laser is the independent control of the beam divergence perpendicular to the junction ( theta // PERPEND ) and the threshold current (I//t//h), i. e. , the narrow beam is obtained with little increase of I//t//h. Thus theta // PERPEND as narrow as 10 degree has been obtained with I//t//h about 60 mA. The large near-field spot size of the laser is also suitable for high-power operation. Maximum output power of 120 mW in the fundamental transverse mode has been realized for a laser emitting at 780 nm. Stable 30-mW operation at 50 degree C has been confirmed over 7000 h.