Wavelength tunable MEMS VCSELs for OCT imaging

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Abstract

MEMS VCSELs are one of the most promising swept source (SS) lasers for optical coherence tomography (OCT) and one of the best candidates for future integration with endoscopes, surgical probes and achieving an integrated OCT system. However, the current MEMS-based SS are processed on the III-V wafers, which are small, expensive and challenging to work with. Furthermore, the actuating part, i.e., the MEMS, is on the top of the structure which causes a strong dependence on packaging to decrease its sensitivity to the operating environment. This work addresses these design drawbacks and proposes a novel design framework. The proposed device uses a high contrast grating mirror on a Si MEMS stage as the bottom mirror, all of which is defined in an SOI wafer. The SOI wafer is then bonded to an InP III-V wafer with the desired active layers, thereby sealing the MEMS. Finally, the top mirror, a dielectric DBR (7 pairs of TiO2 - SiO2), is deposited on top. The new device is based on a silicon substrate with MEMS defined on a silicon membrane in an enclosed cavity. Thus the device is much more robust than the existing MEMS VCSELs. This design also enables either a two-way actuation on the MEMS or a smaller optical cavity (pull-away design), i.e., wider FSR (Free Spectral Range) to increase the wavelength sweep. Fabrication of the proposed device is outlined and the results of device characterization are reported.
Original languageEnglish
Title of host publicationProceedings of SPIE
Number of pages6
Volume10552
PublisherSPIE - International Society for Optical Engineering
Publication date2018
Article number105520I
ISBN (Print)9781510615892
DOIs
Publication statusPublished - 2018
EventVertical-Cavity Surface-Emitting Lasers XXII SPIE Conference - The Moscone Center, San Francisco, United States
Duration: 27 Jan 20181 Feb 2018
Conference number: 22

Conference

ConferenceVertical-Cavity Surface-Emitting Lasers XXII SPIE Conference
Number22
LocationThe Moscone Center
CountryUnited States
CitySan Francisco
Period27/01/201801/02/2018
SeriesProceedings of S P I E - International Society for Optical Engineering
Volume10552
ISSN0277-786X

Keywords

  • MEMS
  • VCSEL
  • OCT
  • Wavelength tunable
  • Low threshold

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