Fabrication of distributed Bragg reflectors to reduce coupling losses of photonic circuits

Volume
105
Start Page
123
End Page
126
Citation
9th GMM-Workshops on Mikro-Nano-Integration (2022)
Contribution to Conference
9th GMM-Workshops on Mikro-Nano-Integration 2022
Scopus ID
2-s2.0-85190713201
ISSN
14323419
ISBN
[9783800759910]
In moving away from the SOI platform to a variety of substrates such as quartz glass or lithium niobate, the coupling efficiency generally reduces significantly. The coupling efficiency can be improved by introducing a reflecting layer below the photonic systems, which reduces the losses towards the substrate. In this work, a distributed Bragg reflector consisting of 2, 4 and 6 layers is designed using the transfer matrix method. The designs are fabricated on top of a silicon and quartz glass substrate and the layer characteristics are determined using ellipsometry. The reflection of the 6-layer DBR on top of silicon and quartz glass is measured using FTIR to be > 98% and > 96%, respectively. The designs are elaborately tested in a FEM model including a grating coupler, where a reflection improvement from 51% to 86% was observed for the 6-layer DBR with respect to an SOI substrate.