Planar chalcogenide glass device processing
Our in-house glass processing capabilities include thin film deposition and planar device fabrication.
Glass thin film depositions are performed via thermal evaporation or RF magnetron sputtering, using a custom-designed film deposition station. The flexible techniques can be adapted to a wide range of glass film compositions, and are particular suitable for low-cost, high-throughput depositions on large-area substrates [1].
The device fabrication process uses standard UV lithography and a CMOS-backend-compatible lift-off technique we developed at MIT. This etch-free approach presents several benefits: leverages Si-CMOS process compatibility; enables submicron photonic device fabrication; reduces sidewall roughness; and applies to a wide choice of glass compositions [2-3]. Further, a surface tension induced thermal reflow process has been developed to remove as-fabricated device sidewall roughness and reduce optical loss [4].
Several chalcogenide glass photonic devices featuring world-record performance have been created, including high-index-contrast submicron photonic wire waveguides, multi-mode interferometer (MMI) splitters, and micro-ring and micro-disk resonators [5].
Evaporation-Sputtering Deposition Station
Chalcogenide micro-disk resonator patterned by lift-off
Inset shows a reflowed waveguide
Calculated internal pressure in glass melt during thermal reflow
[1] N. Carlie, J. Hu, L. Petit, A. Agarwal, L. C. Kimerling, and K. Richardson, Comparison of the optical and thermal properties and structure of Ge-Sb-S thin films deposited using thermal evaporation and pulsed laser deposition techniques, to be submitted.
[2] J. Hu, V. Tarasov, N. Carlie, N. Feng, L. Petit, A. Agarwal, K. Richardson, and L. C. Kimerling, Si-CMOS-compatible lift-off fabrication of low-loss planar chalcogenide waveguides, Opt. Express 15, 11798-11807 (2007).
[3] J. Hu, V. Tarasov, N. Carlie, L. Petit, A. Agarwal, K. Richardson, and L. C. Kimerling, Exploration of Waveguide Fabrication From Thermally Evaporated Ge-Sb-S Glass Films, Opt. Mater. 30, 1560-1566 (2007).
[4] J. Hu, N. Carlie, N. Feng, L. Petit, A. Agarwal, K. Richardson, and L. C. Kimerling, Optical loss reduction in HIC chalcogenide glass waveguides via thermal reflow, to be submitted.
[5] J. Hu, N. Carlie, N. Feng, L. Petit, A. Agarwal, K. Richardson, and L. C. Kimerling, Design, fabrication and integration of HIC glass waveguides on a silicon platform, Proc. SPIE 6986, 68960Z