# LCML - Grating coupler based on experimental data | lcml_gc_tm_1550_exp

#1

This grating coupler model is built by using experimental data.

## Example Test File

grating_coupler_tm.icp (186.2 KB)

User Guide

lcml_gc_tm_1550_exp (gc)

LCML: grating coupler for TM mode based on experimental data.

Ports

Name Type
opt_1 Optical Signal
opt_2 Optical Signal

## Reference

Y. Wang, et al., "Apodized focusing fully etched subwavelength grating couplers," IEEE Photonics Journal, 2015.

## Model Development

1.In INTERCONNECT, create a compound element.

2.Add two bidirectional optical ports namely “opt_f1” and “opt_2”, and arrange their positions. Set the “model” of the compound element to be “lcml_gc_tm_1550_exp” and the “prefix” of it to be “gc”.

3.Expand the compound element, drag and drop an Optical S-Parameter element to the schematic editor and connect the relays and ports accordingly.

4.The text file gc_exp.txt records the TM mode grating coupler experimental data based on the Reference paper. The text file can be found in the LCML_resource folder in the download page.

5.Edit the setup script of the compound element. Copy and paste the following scripts to the Setup script under the Scripts tab. This setup script will convert the experimental data in the text file to S parameters, which will then be loaded into the Optical S-Parameter element.

filename = %local path% + '/lib_data/grating_coupler/gc_exp.txt';
N=size(Data);
N=N(1);
# plot(Data(1:N,1),Data(1:N,2),'wavelength (nm)','transmission (dB)','Experimental result');
wavelength=Data(1:N,1)*1e-9;
T_dB=Data(1:N,2);    # transmission spectrum
R_dB=-21;            # back reflection
S=matrix(N,5);
S(1:N,1)=c/wavelength;
S(1:N,2)=sqrt(10^(R_dB/10));
S(1:N,4)=sqrt(10^(T_dB/10));
setnamed("SPAR_1","s parameters", S);


6.Back to the compound element and set icon.

## Test

Download the simulation file grating_coupler_tm.icp from the top of this page. In this simulation file, the compact model of the grating coupler is connected to and measured by an Optical Network Analyzer (ONA). The ONA’s output is set to the fundamental TM mode. Click on the “run” button and the ONA will be populated with measurement data. To view the simulation results, user can right click on the results and select “Visualize”.

Lumerical Compact Model Library (LCML)