Very Low-Threshold 1.55-μm Dilute-Nitride Lasers

Abstract

The initial discovery of anomalous bowing in GaInNAs by Kondow and coworkers [1] has prompted great interest in developing high-performance GaAs-based lasers in the 1.2-1.6 pm range to replace InP-based sources. Nitrogen reduces the bandgap almost exclusively in the conduction band, naturally reducing the effects of carrier leakage and increasing the laser stability with ambient temperature. Moreover, the GaAs-based device structure can leverage the GaAs/AlAs material system for distributed mirrors in vertical-cavity surface-emitting lasers (VCSELs). Great strides in growth techniques have produced low-threshold edge-emitting lasers 300 A/cm2 and VCSELs at 1 .3-pm [2], [3]. However, device performance has lagged substantially in the 1.55-pm region (see Fig. 1) due to the growth difficulties associated with the high indium and nitrogen contents required. We present substantially improved 1.55-pm edgeemitting lasers with thresholds comparable to their 1.3-pm counterparts and competitive to their InP-based devices.