Tapered Simplified Modal Method for Analysis of Non-rectangular Gratings

TL;DR

This paper introduces the Tapered Simplified Modal Method (TSMM), an improved analytical approach for analyzing non-rectangular gratings at any incidence angle, accounting for reflection effects with validated simulations.

Contribution

The paper develops a novel TSMM that extends SMM to non-rectangular gratings at arbitrary angles, including reflection, which was not previously possible.

Findings

TSMM accurately models non-rectangular gratings at various angles.

The method accounts for reflected light effects.

Numerical simulations validate the analytical development.

Abstract

The Simplified Modal Method (SMM) provides a quick and intuitive way to analyze the performance of gratings of rectangular shapes. For non-rectangular shapes, a version of SMM has been developed, but it applies only to the Littrow-mounting incidence case and it neglects reflection. Here, we use the theory of mode-coupling in a tapered waveguide to improve SMM so that it applies to non-rectangular gratings at arbitrary angles of incidence. Moreover, this new 'Tapered Simplified Modal Method' (TSMM) allows us to properly account for reflected light. We present here the analytical development of the theory and numerical simulations, demonstrating the validity of the method.