Optical grating coupling between low-index fibers and high-index film waveguides

Abstract

Grating couplers between low-refractive-index (n ≈1.5) optical fibers and high-refractive-index (n ≈2.2) electro-optic planar guides have been analyzed and demonstrated. Coupling efficiencies of 6% between single modes of a film and a fiber have been observed. Efficiencies of approximately 86% between single-mode fibers and films using blazed backward-wave gratings are predicted. In addition, low-loss low-optical-aperture multimode fibers may be coupled to single-mode films with efficiencies greater than 50% and angular spreads less than 0.5°.

A Zeroth-Order Modification of Coupled Mode Theory for Waveguide Gratings

“…G RATINGS in waveguides and cavities play an important role in many active and passive integrated optical devices, such as distributed Bragg reflectors (DBRs) and distributed feedback (DFB) lasers [1], optical grating couplers [2], single wavelength microring mirrors [3], and single wavelength ring lasers [4], [5]. For the design and analysis of these periodic devices, the coupled mode theory (CMT) is known to be a fast and relatively accurate method.…”