Open AccessMonolithically integrated asymmetric graded and step-index couplers for microphotonic waveguides
Author(s) -
A. Delâge,
Siegfried Janz,
B. Lamontagne,
A. L. Bogdanov,
Dan Dalacu,
DanXia Xu,
K.P. Yap
Publication year - 2006
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/opex.14.000148
Subject(s) - optics , silicon on insulator , waveguide , materials science , coupled mode theory , refractive index , optoelectronics , photonic integrated circuit , power dividers and directional couplers , coupling (piping) , silicon photonics , photonics , silicon , physics , metallurgy
A monolithically integrated asymmetric graded index (GRIN) or step-index (GRIN) mode converters for microphotonic waveguides are proposed and described. The design parameters and tolerances are calculated for amorphous silicon (a-Si) couplers integrated with silicon-on-insulator waveguides. The GRIN and step-index couplers operate over a wide wavelength range with low polarization dependence, and the lithographic resolution needed is only +/-1 microm. Finally, experimental results are presented for a single layer 3 microm thick step-index a-Si coupler integrated on a 0.8 microm thick SOI waveguide. The measured variation of coupling efficiency with coupler length is in agreement with theory, with an optimal coupling length of 15 microm for this device.