Open AccessImproved broadband performance of an adjoint shape optimized waveguide crossing using a Levenberg-Marquardt update
Author(s) -
Galen Hoffman,
Christina Dallo,
Andrew Starbuck,
Dana Hood,
Andrew Pomerene,
Douglas C. Trotter,
Christopher T. DeRose
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.024765
Subject(s) - levenberg–marquardt algorithm , extinction ratio , bandwidth (computing) , optics , waveguide , smoothing , gradient descent , insertion loss , broadband , figure of merit , physics , computer science , materials science , telecommunications , artificial neural network , artificial intelligence , wavelength , computer vision
We derive an adjoint shape optimization algorithm with a compound figure of merit and demonstrate its use with both gradient descent and Levenberg-Marquart updates for the case of SiO 2 -buried SOI coplanar waveguide crossings. We show that a smoothing parameter, basis function width, can be used to eliminate small feature sizes with a small cost to device performance. The Levenberg-Marquardt update produces devices with larger bandwidth. A waveguide crossing with simulated performance values of > 60 dB cross power extinction ratio and > -0.08 dB through power over the 1500-1600 nm band is presented. A fabricated device is measured to have a maximum of -0.06 dB through power and a 50 dB cross power extinction ratio.