1.55-MU-M INGAASP-INP LASER ARRAYS WITH INTEGRATED-MODE EXPANDERS FABRICATED USING A SINGLE EPITAXIAL-GROWTH

We report on two techniques for the realization of expanded-mode laser arrays with a single epitaxial growth step and conventional fabricati on techniques. Laser arrays with integrated adiabatic-mode expanders ( AME) based on a tapered active region and an underlying passive coupli ng waveguide are demonstrated at the 1.55-mu m wavelength, These laser s butt couple to standard cleaved single-mode fibers (SMF's) with a lo ss of only 3.6 dB, This coupling efficiency compares with a theoretica l calculation of 3.2 dB, We also propose a novel realization of a lase r with an integrated-mode expander based on resonant coupling between a tapered active waveguide and an underlying coupling waveguide, Three -dimensional (3-D) beam propagation method (BPM results are presented which show that compact, efficient mode expanders with a mode transfor mation loss of only 0.36 dB can be realized using this method, putt-co upling efficiencies of 2.6 dB are possible to standard cleaved single- mode fibers.