RSoft Application Gallery Note: Reflection Spectrum of Surface-Relief Grating in a Rib Waveguide

Tools Used: GratingMOD

This example will compute the reflection spectrum for a simple rib waveguides with a sinusoidal higher perturbation.

Creating the Structure

The rib waveguide used in this example is typical of those used in DFB design: a substrate index of 3.34, a core index of 3.44, a cover index of 1, a width of 2 μm, a height of 2.5 μm, and a slab height of 1.25 μm. The grating will consist of a height perturbation with a modulation depth of 10%, have a length of 200 μm, and a desired central wavelength of 1.55 μm.

A cross-section of several periods of the refractive index appears as:

Contour Map of Index Profile

Simulation Results

For this simulation, the built-in mode solvers will be used to compute the modes of the structure. One such mode is:

Transverse Mode Profile

The computed reflection spectrum for this grating is:

Grating Spectral Response