Tapered active stripe for 1.5-μm InGaAsP/InP strained multiple quantum well lasers with reduced beam divergence

We propose and demonstrate the application of an intracavity horizontally tapered (in width) active stripe to adiabatically reduce the output beam divergence of a 1.48-μm InGaAsP/InP strained quantum well laser. We achieve far-field full width at half-maximum divergences as low as 13° together with 100 mW emitted power into stable single transverse mode and 400 mA driving current. Maximum coupling efficiency to lensed single mode fiber of 73% is obtained.