ABSTRACT
In GaAs-AlGaAs S ingle and M ultiple Q uantum W ell (SQW and MQW) ridge lasers, grown by molecular beam epitaxy, the temperature dependence of the threshold current, expressed by the characteristic temperature T 0 , is investigated as a function of the cavity length (L) at different temperatures. SQW lasers, in contrast to MQW’s, show a strong decrease in T 0 from 250 K to about 100 K when the length is reduced from 400 μm to 200 μm. We found that by further reducing L to about 130 μm, a strong increase in T 0 up to 250 K takes place and T 0 decreases again to 80 K for 60 μm SQW lasers. This T 0 behavior is directly correlated to the gain saturation of the n=1 transition and the change of the laser emission to the n=2 transition.
