Transverse-Mode Characteristics of InGaAs/GaAs Vertical-Cavity Surface-Emitting Lasers Considering Gain Offset

Abstract
We have fabricated InGaAs/GaAs vertical-cavity surface-emitting lasers with modulation-doped graded distributed Bragg reflectors (DBRs) grown by metal-organic chemical vapor deposition (MOCVD). The threshold current was 3.2 mA. By observing the spontaneous emission through DBRs, we found that transverse mode behavior depends on gain characteristics. Single fundamental transverse-mode lasing is achieved at a negative gain offset and multiple transverse-mode lasing is achieved at a positive gain offset.