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Coupler desing

Tools to optimize devices with python and meep.

Creating geometry - create_geo.py

The first step is to create the computation domain, input and output guides and the device. The create_geo,py tool creates a h5 with the refractive index. The device refractive index is define by a arbitrary matrix (.csv file)

Use example:

Create a 0.6um waveguide to a 1.2um waveguide with SiN/SiO index contrast using a random device with 0.050um resolution.

python create_geo.py --LX 20 --LY 20 --n_low 1.45 --n_high 2.00 -r 0.05 --x_in 0.0 --y_in 8.7 --lx_in 10 --ly_in 0.6 --x_dev 6.5 --y_dev 6.5 --lx_dev 5.0 --ly_dev 5.0 --x_out 10 --y_out 8.4 --lx_out 10 --ly_out 1.200 -o coupler.h5

Create a single 1.2um waveguide

python create_geo.py --LX 20 --LY 20 --n_low 1.45 --n_high 2.00 -r 0.05 --no-in --no-dev --x_out 0 --y_out 8.4 --lx_out 20 --ly_out 1.200 -o output-wv.h5

$ python create_geo.py -h
usage: create_geo.py [-h] [--LX LX] [--LY LY] [--n_low N_LOW]
                 [--n_high N_HIGH] [-r RESOLUTION] [--x_in X_IN]
                 [--y_in Y_IN] [--lx_in LX_IN] [--ly_in LY_IN]
                 [--x_out X_OUT] [--y_out Y_OUT] [--lx_out LX_OUT]
                 [--ly_out LY_OUT] [--x_dev X_DEV] [--y_dev Y_DEV]
                 [--lx_dev LX_DEV] [--ly_dev LY_DEV] [-i DEVICE_FILE]
                 [-o INDEX_FILE]

create computational domain to meep(refractive index map).Positions and sizes
in micro meters.

optional arguments:
-h, --help       show this help message and exit
--LX LX          comp. domain X size
--LY LY          comp. domain Y size
--n_low N_LOW    Low refractive index
--n_high N_HIGH  High refractive index
-r RESOLUTION    resolution
--x_in X_IN      Input wg X position (left corner)
--y_in Y_IN      Input wg Y position (botton corner)
--lx_in LX_IN    Input wg X length
--ly_in LY_IN    Input wg Y length
--x_out X_OUT    Output wg X position (left corner)
--y_out Y_OUT    Output wg Y position (botton corner)
--lx_out LX_OUT  Output wg X length
--ly_out LY_OUT  Output wg Y length
--x_dev X_DEV    Device X position (left corner)
--y_dev Y_DEV    Device Y position (botton corner)
--lx_dev LX_DEV  Device X length
--ly_dev LY_DEV  Device Y length
-i DEVICE_FILE   CVS file mapping the device refractive index
-o INDEX_FILE    H5 file mapping full domain the refractive index

Use example

Creating a h5 file with a straigth waveguide.

Remeber that:

Courant [number] Specify the Courant factor S which relates the time step size to the spatial discretization: cΔt = SΔx. Default is 0.5. For numerical stability, the Courant factor must be at most n_\textrm{min}/\sqrt{\textrm{# dimensions}}, where nmin is the minimum refractive index (usually 1), and in practice S should be slightly smaller.