Broadened waveguide, low loss 1.5 /spl mu/m InGaAsP/InP and 2 /spl mu/m InGaAsSb/AlGaAsSb laser diodes

We demonstrate that free carrier absorption in cladding layers of long wavelength (/spl lambda/=1.5 /spl mu/m and /spl lambda/=2 /spl mu/m), separate confinement quantum well laser diodes limits the differential efficiency and output power for such lasers if their waveguide thickness is designed from the considerations of the maximum optical confinement factor for quantum wells. Broadening of the waveguide up to 1 /spl mu/m considerably increases laser efficiency and does not increase threshold for the lasers with low and moderate output losses. Broadened waveguide design provides the record output powers at continuous and quasi-continuous operation regimes.