Fabrication and Properties of Monolithic Laser Diode Arrays

Monolithic arrays of planar diffused GaAs injection lasers have been fabricated using diffusion masking and photolithography to delineate the junction area. After contact metallization, the arrays are soldered to a sapphire wafer which serves as a heat sink and carries the contacts for each junction. The diodes operate cw at 78 K and the threshold current density. J
th
= 700 to 1100 A cm
⁻²
. The dc power output is linear at least to 5 × J
th
and the power efficiency, η
P
is about 40%. Threshold and power output are quite uniform across the array but the beam polarization varies at random from one unit to the next.