{"id":346922,"date":"2024-01-29T04:36:00","date_gmt":"2024-01-29T04:36:00","guid":{"rendered":"\/forum\/forums\/topic\/how-to-set-the-group-index-in-this-example-bragg-grating-initial-design\/"},"modified":"2024-01-29T04:36:00","modified_gmt":"2024-01-29T04:36:00","slug":"how-to-set-the-group-index-in-this-example-bragg-grating-initial-design","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/how-to-set-the-group-index-in-this-example-bragg-grating-initial-design\/","title":{"rendered":"how to set the group index in this example, ‘Bragg grating initial design’?"},"content":{"rendered":"
Hello, everyone.<\/div>\n
 <\/div>\n
I’m trying to follow the example, so-called bragg grating initial design(https:\/\/optics.ansys.com\/hc\/en-us\/articles\/360042304394-Bragg-grating-initial-design-with-FDTD), and would like to change some structure parameters.<\/div>\n
 <\/div>\n
In this example, the group index is set in the model script.<\/div>\n
I thought that it meant the group index of the center wavelength for the Si waveguide with averaged width. When I compared two data, 4.3874 and my calculation value from the MODE group index calculation, there is a bit gap.<\/div>\n
<\/p>\n<\/div>\n
Therefore, I would be grateful if anyone could explain the conditions of the group index in the example. I cannot be certain that it is a group index with the averaged Si waveguide.<\/div>\n
 <\/div>\n
Thank you.<\/div>\n","protected":false},"template":"","class_list":["post-346922","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t