Thermal behavior of tensile-strain InGaAsP-InP lasers with varying ridgewidth

The thermal behavior of tensile-strain InGaAsP-InP laser diodes with varying ridgewidth is investigated experimentally. The temperature rise during continuous-wave (CW) operation was determined by comparing CW light-current (L-I) curves with short-pulsed (L-I) curves at different substrate temperatures. It is shown that the thermal impedance R depends strongly on the width w of the ridge and that this effect is different before and after threshold. In the first case, R decreases with increase of ln(w) and in the second case, R increases with increase of 1/w. However, the wider the ridge, the lower the CW maximum operating temperature because of the higher temperature dependence of dl/sub th/(T)/dT.