TAPERED WAVE-GUIDE INGAAS/INGAASP MULTIPLE-QUANTUM-WELL LASERS

We propose and demonstrate the application of ultra-thin etch-stop fabrication techniques to adiabatically expand the vertical optical mode size in 1.5 µm InGaAs/InGaAsP MQW lasers using a tapered-core passive intracavity waveguide structure. We achieve 30% differential quantum efficiency out the tapered facet, far-field FWHM of ~ 12°, and a butt-coupling efficiency into a cleaved fiber of -4.2 dB, with -1 dB alignment tolerances of ~ ± 3 ¼m. © 1990 IEEE