A very narrow-beam AlGaAs laser with a thin tapered-thickness active layer (T 3 laser)

A very narrow-beam and high-power laser which has a thin tapered-thickness active layer is developed. The property of LPE on a ridged substrate is utilized to obtain the thin tapered-thickness active layer. In the T3laser, the active layer is thinner near the mirror than in the inner region. The main feature of the T3laser is the independent control of the beam divergence perpendicular to the junction ( \theta_{\perp} ) and the threshold current ( Ith ). That is, the narrow beam is obtained with little increase of Ith . Thus \theta_{\perp} as narrow as 10° has been obtained with Ith about 60 mA. The large near-field spot size of the laser is also suitable for high-power operation. The 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°C has been confirmed over 7000 h.