Compact, Low-Power, and High-Speed Graphene-Based Integrated Photonic Modulator Technology
Abstract
We developed several approaches to overcome the relative high sheet resistance of undoped graphene. We integrate ion liquid assisted gating mechanism into our device and demonstrate reduced resistance through electric double layer structure. With electro-chemical doping, we significantly reduced the graphene resistance (~5 time), which enables high speed modulation above 25 GHz. To overcome the high loss of graphene and to achieve low-power modulation, we investigated two approaches for fabricating of ultra-high Q devices integrated with 1) graphene and 2) two-dimensional tungsten disulfide (WS2) as an alternative for giant electro-refractive modulation. We demonstrated ultra-high quality (Q) factor (~8M loaded Q) with a newly optimized etching recipe with flowable oxide (FOX) as negative resist mask. We also show integration of WS2 onto high Q cavity with a relative low reduction in Q factor (from 2M to 300k). We also developed a method for planarization of SiO2 on patterned SiN sample using our recently installed commercial CMP machine to make our platform suitable for 2D material integration. We developed a recipe that works effectively for oxide-stop-onnitride, which allow us to have a sample with ÒflatÓ surface for crack-free 2D material integration. More recently, we integrate ion liquid on microdisk resonators fabricated on SOI to demonstrate the feasibility of ion liquid assisted gating on integrated photonic devices. We also reoptimize our Flowable Oxide (FOx) planarization technique on SiN platform to achieve near perfect platform for crack-free graphene integrating while CMP approach is under aggressive development. A final approach would be using FOx as the initial seeding layer for PECVD oxide followed by CMP polishing to guarantee both flatness and smoothness. Finally, we optimized the design of ohmic contacts for our graphene/Si device to further reduce the contact resistance to achieve a better trade-off between resistance (speed) and insertion-loss.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 03, 2020
- Source ID
- W911NF1810142
Entities
People
- Ali Adibi
Organizations
- Army Contracting Command
- Georgia Tech Research Corporation
- United States Army