Design and Continuous-Wave Room-Temperature Performance of Ga(AlInAs)Sb DFB Lasers at 2.8 $\mu$ m

We have fabricated continuous-wave GaInAsSb– AlGaAsSb distributed-feedback (DFB) lasers in the 2.8- $\mu$m range, using a DFB concept requiring no subsequent overgrowth steps, by defining first-order Cr-Bragg gratings laterally to a ridge waveguide. We have simulated the confinement factor $\Gamma_{\rm Cr}$ of the optical mode and the Cr-grating for various ridge widths and investigated the effect on laser properties and single-mode yield in order to optimize DFB lasers in this wavelength region. In terms of low threshold current and high output power, we found an optimum ridge width around 7 $\mu$m. These lasers show the smallest average threshold current around 33 mA and a high average output power around 7 mW per facet.