Optical feedback effects in cw injection lasers

Liquid-phase, epitaxially grown Al(x)Ga(1-x)As double-heterojunction laser diodes designed for room temperature CW operation are used to evaluate optical feedback effects. It is noted that increased optical feedback reduces the gain required to reach the lasing threshold and thus the threshold current. Power output is increased with the reflecting surface in place with a given current in the laser. A decrease is found in the diode potential drop when the diode current is fixed. This is caused by the smaller density of the carriers in the active region. An increase in the diode current is found when the reflecting surface is introduced and the bias voltage is fixed.