Gain characteristics of gain‐guided II–VI laser diodes

We have studied the gain characteristics of gain‐guided quantum well II–VI laser diodes by measuring the amplified spontaneous emission spectra under several pulsed conditions. The temperature rise during one current pulse affects the gain characteristics and the L‐I characteristics. The net modal gain at constant peak current increases with the pulse width. The peak gain for long pulses shows a superlinear dependence on injection current. In this case, the L‐I curve is very steep above threshold and sometimes shows an internal quantum efficiency of more than unity. This leads to an underestimation of the internal cavity loss giving a value inconsistent with the one obtained from the gain spectra. With short pulse currents (