Recent Progress on 1.55- μm Dilute-Nitride Lasers

We review the recent developments in GaAs-based 1.55-mum lasers grown by molecular beam epitaxy (MBE). While materials growth is challenging, the growth window appears to be relatively broad and is described in detail. The key considerations for producing high-quality GalnNAsSb material emitting at 1.55-mum regime are examined, including the nitrogen plasma conditions, ion removal from the nitrogen flux, surfactant- mediated growth, the roles of various V-II ratios, the growth temperature, the active region thermal budget, proper annealing, and composition. We find that emission may be tuned throughout the 1.55-mum communications band without penalty to the optical quality varying only one parameter - the total growth rate. This powerful result is validated by the demonstration of low-threshold edge-emitting lasers throughout the 1.55-mum regime, including threshold current densities as low as 318 A/cm² at 1.54 mum. Additional characterization by Z-parameter techniques, cavity length studies, and band offset measurements were performed to better understand the temperature stability of device performance. Lasing was extended as far as 1.63 mum under nonoptimized growth conditions. The GaAs-based dilute-nitrides are emerging as a very promising alternative to InP-based materials at 1.55-mum due to their high gain, greater range of achievable band offsets, as well as the availability of lattice-matched AlAs-GaAs materials and native oxide layers for vertical-cavity surface-emitting lasers (VCSELs). Indeed, this effort has enabled the first electrically injected C-band VCSEL on GaAs.