MINIMUM TEMPERATURE SENSITIVITY OF 1.55 MU-M VERTICAL-CAVITY LASERS AT -30 NM GAIN OFFSET

Double-fused vertical-cavity surface-emitting lasers (VCSELs) have dem onstrated the highest temperature performance of any 1.5 mu m VCSEL, b ut further optimization is needed to reduce their temperature sensitiv ity, We present and analyze threshold current measurements of these de vices between -90 degrees C and 30 degrees C stage temperature, Despit e a zero gain peak offset from the emission wavelength at room tempera ture, the pulsed threshold current has its minimum near -50 degrees C corresponding to about -30 nm gain offset, This is in contrast to a co mmon VCSEL design rule. Temperature effects on the optical gain of the strain-compensated InGaAsP/InP active region are found to be the main cause for the disagreement. A design rule modification is proposed. N umerical simulation of an optimized 1.55 mu m VCSEL shows that gain of fset improvements are counteracted by loss mechanisms, (C) 1998 Americ an Institute of Physics.