Abstract

Low cost fabrication of photonic integrated circuits for future subscriber systems require efficient coupling of the single mode fiber to the chip as well as large alignment tolerances. This can be achieved by increasing the laser or amplifier spot size to the mode size of the fiber using an integrated spot size transformer [1-3]. A simple and efficient way to realize such a waveguide taper is to gradually change the waveguide dimensions which leads to an adiabatic mode expansion. New technologies such as selective area growth of MQW structures enable simultaneous increase of the spot size and the band gap energy so that the active waveguide core of the laser can be changed into a transparent waveguide core with an enlarged spot size [2].

© 1995 Optical Society of America