LASER-DIODES WITH INTEGRATED SPOT-SIZE TRANSFORMER AS LOW-COST OPTICAL TRANSMITTER ELEMENTS FOR TELECOMMUNICATIONS

We have realized laser diodes with integrated spot-size transformer to achieve a high-coupling efficiency to a standard single-mode fiber (S MF) without microoptical elements, A coupling loss of about 1 dB has b een achieved with tolerances of +/-2 mu m in both vertical and horizon tal direction, We have fabricated both distributed-feedback (DFB) and Fabry-Perot (FP)-type lasers, In the case of the FP lasers the longitu dinal single-mode emission was stabilized by means of an external fibe r Bragg-grating which was directly butt-coupled to the laser, We have experimentally and theoretically investigated the optical and electric al properties of the devices using a transmission line model.