Improvement in Threshold Voltage of 1.55-µm Buried-Heterostructure Vertical-Cavity Surface-Emitting Laser

We report on 1.55-µm vertical-cavity surface-emitting lasers (VCSELs) with a buried heterostructure (BH) fabricated on an undoped GaAs/AlAs distributed Bragg reflector (DBR). These BH VCSELs exhibit a low threshold voltage of 1.3 V due to both our improved p-InP/InGaAsP DBR design and the introduction of an intracavity structure for an n-contact. Our BH VCSEL also shows a single transverse mode with a side-mode suppression ratio of more than 40 dB even at high injection currents under cw operation, and the potential to achieve a maximum modulation bandwidth of 4.7 GHz.