CW operation of GaInAsP stripe lasers

A quantitative investigation of the constraints on dc operation of GaInAsP stripe-geometry lasers at room temperature and above has been made. Laser pulse threshold current, its temperature sensitivity, electrical series resistance, and the thermal resistance of the bonded device are critical parameters in this respect. Sets of theoretical curves have been generated that allow expected de thresholds to be determined from the value of the pulsed threshold. Experimental results confirm the accuracy of the expressions. For GaInAsP lasers, the low values of T0reported in the literature (47-80 K) imply that both electrical series resistance and thermal resistance must be minimized in order to obtain stable dc operation over a reasonable temperature range in conventional oxide or proton isolated stripe structures. Both parameters are calculated theoretically for a range of structures. The calculations show that thermal runaway is sensitive to electrical resistance in the range this suggests an area where improvements are possible. To this end, the use of tunneling Schottky contacts to a ternary InGaAs p-capping layer has been developed to minimize contact resistance.