Compact Spot-Size Converters with Fiber-Matched Antiresonant Reflecting Optical Waveguides

We propose a concept for InGaAsP-InP 1.55- (mu)m lasers integrated with spot-size converters based on modal interference between the modes of the structure formed by an active waveguide and an underlying fiber-matched antiresonant reflecting optical waveguide. Simulation results show that the spot-size converters exhibit low transformation loss, and narrowed far-field emission patterns (10(degree) x 20 (degree)) and reduce the coupling loss to standard single-mode fibers from 8 to 2.6 dB over lengths approximately 200 (mu)m shorter than the adiabatic concept. A tolerant design to fabrication variations is also proposed, which could be realized by standard processing techniques.