Steps to Design a Mode Blocking Filter

Theory
Design Steps
Reference

Theory

$n_{SWG}^2 = \delta*n_{Si}^2 + (1-\delta)*n_{Clad}^2$

(1)

where:

$\delta$ is the duty cycle (Si Part).

$n_{Si}$ and $n_{Clad}$ can be derived from Lumerical MODE Simulation.

Then, the phase matching condition:

$n_{bus} + n_{SWG} = \frac{\lambda}{\Lambda}$

(2)

where:

$\lambda$ is the operation wavelength.

$\Lambda$ is the grating period.

$n_{bus}$ is the effective indices of the target mode in bus waveguide.

Design Steps

$n_{bus}$ is known and can be derived from MODE simulation.
decide $\lambda$ .
decide side waveguide width, then $n_{Si}$ and $n_{Clad}$ is decided, and can be derived from MODE.
select a $\delta$ , then calculate $\Lambda$ .

Reference

[1] Yu He, Yong Zhang, Hongwei Wang, and Yikai Su, “On-chip silicon mode blocking filter employing subwavelength-grating based contra-directional coupler,” Opt. Express 26, 33005-33012 (2018)

Steps to Design a Mode Blocking Filter

Theory

Design Steps

Reference

Comments