A very narrow-beam AlGaAs laser with a thin tapered-thickness active layer (T3laser)

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 T
³
laser, the active layer is thinner near the mirror than in the inner region. The main feature of the T
³
laser 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.