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Proceedings Paper

Subwavelength engineered fiber-to-chip silicon-on-sapphire interconnects for mid-infrared applications (Conference Presentation)
Author(s): Carlos Alonso-Ramos; Zhaohong Han; Xavier Le Roux; Hongtao Lin; Vivek Singh; Pao Tai Lin; Dawn Tan; Eric Cassan; Delphine Marris-Morini; Laurent Vivien; Kazumi Wada; Juejun Hu; Anuradha Agarwal; Lionel C. Kimerling

Paper Abstract

The mid-Infrared wavelength range (2-20 µm), so-called fingerprint region, contains the very sharp vibrational and rotational resonances of many chemical and biological substances. Thereby, on-chip absorption-spectrometry-based sensors operating in the mid-Infrared (mid-IR) have the potential to perform high-precision, label-free, real-time detection of multiple target molecules within a single sensor, which makes them an ideal technology for the implementation of lab-on-a-chip devices. Benefiting from the great development realized in the telecom field, silicon photonics is poised to deliver ultra-compact efficient and cost-effective devices fabricated at mass scale. In addition, Si is transparent up to 8 µm wavelength, making it an ideal material for the implementation of high-performance mid-IR photonic circuits. The silicon-on-insulator (SOI) technology, typically used in telecom applications, relies on silicon dioxide as bottom insulator. Unfortunately, silicon dioxide absorbs light beyond 3.6 µm, limiting the usability range of the SOI platform for the mid-IR. Silicon-on-sapphire (SOS) has been proposed as an alternative solution that extends the operability region up to 6 µm (sapphire absorption), while providing a high-index contrast. In this context, surface grating couplers have been proved as an efficient means of injecting and extracting light from mid-IR SOS circuits that obviate the need of cleaving sapphire. However, grating couplers typically have a reduced bandwidth, compared with facet coupling solutions such as inverse or sub-wavelength tapers. This feature limits their feasibility for absorption spectroscopy applications that may require monitoring wide wavelength ranges. Interestingly, sub-wavelength engineering can be used to substantially improve grating coupler bandwidth, as demonstrated in devices operating at telecom wavelengths. Here, we report on the development of fiber-to-chip interconnects to ZrF4 optical fibers and integrated SOS circuits with 500 nm thick Si, operating around 3.8 µm wavelength. Results on facet coupling and sub-wavelength engineered grating coupler solutions in the mid-IR regime will be compared.

Paper Details

Date Published: 27 July 2016
PDF: 1 pages
Proc. SPIE 9891, Silicon Photonics and Photonic Integrated Circuits V, 98911J (27 July 2016); doi: 10.1117/12.2229350
Show Author Affiliations
Carlos Alonso-Ramos, Univ. Paris-Sud (France)
Zhaohong Han, Massachusetts Institute of Technology (United States)
Xavier Le Roux, Institut d'Électronique Fondamentale (France)
Hongtao Lin, Massachusetts Instute of Technology (United States)
Vivek Singh, Massachusetts Institute of Technology (United States)
Pao Tai Lin, Massachusetts Institute of Technology (United States)
Dawn Tan, Singapore Univ. of Technology & Design (Singapore)
Eric Cassan, Institut d'Électronique Fondamentale (France)
Delphine Marris-Morini, Institut d'Électronique Fondamentale (France)
Laurent Vivien, Institut d'Électronique Fondamentale (France)
Kazumi Wada, Massachusetts Instute of Technology (United States)
The Univ. of Tokyo (Japan)
Juejun Hu, Massachusetts Institute of Technology (United States)
Anuradha Agarwal, Massachusetts Institute of Technology (United States)
Lionel C. Kimerling, Massachusetts Institute of Technology (United States)

Published in SPIE Proceedings Vol. 9891:
Silicon Photonics and Photonic Integrated Circuits V
Laurent Vivien; Lorenzo Pavesi; Stefano Pelli, Editor(s)

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