Ultra-low loss waveguide platform in silicon photonics

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

10 Citations (Scopus)


Silicon photonics is the most promising technology for applications ranging from large-bandwidth, low power consumption datacom transceivers, to wearable health monitoring devices, or optical data-bus for quantum processors. To bring silicon PIC based products to the market, ultra-low loss waveguides would be preferred. In the conventional submicron silicon platforms, higher propagation loss (in the order of ∼1 dB/cm) induced by the roughness of the etched sidewalls, as well as higher fiber-to-waveguide coupling loss due to its sub-micron dimensions impose challenges for its deployment in many products. VTT's thick-SOI technology offers a promising alternative, owing to its lower propagation loss (∼0.1 dB/cm), reduced polarization sensitivity, and capacity to handle higher optical power without exciting nonlinear losses. Its micron-scale cross-section enables efficient edge coupling. Exploiting its ultra-low loss, we have demonstrated unprecedented level of integration such as, a 40-channel array waveguide grating (AWG) based mux/de-mux, or a Faraday rotator based on silicon spirals, without employing any magneto-optic material. Now we reduced the propagation loss further, down to record-low 4 dB/m, by controlled annealing of waveguides in 100% pure H2 environment. In our optimized, MPW-compatible annealing process, the atomic mobility of Si smoothens the scallops from etching, without causing any structural deformation of the waveguides. This substantially reduced loss enabled us to develop ultra-high Q ring resonators on our thick-SOI platform, as well as sidewall smoothening for the active components, thereby making our platform a bedrock for the emerging applications such as, quantum computing, biosensors, and 3D imaging.

Original languageEnglish
Title of host publicationSilicon Photonics XVII
EditorsGraham T. Reed, Andrew P. Knights
PublisherInternational Society for Optics and Photonics SPIE
Number of pages6
ISBN (Electronic)978-1-5106-4883-8
Publication statusPublished - 5 Mar 2022
MoE publication typeA4 Article in a conference publication
EventSilicon Photonics XVII - Virtual, San Francisco, United States
Duration: 20 Feb 202224 Feb 2022

Publication series

SeriesProceedings of SPIE - The International Society for Optical Engineering


ConferenceSilicon Photonics XVII
Country/TerritoryUnited States
CitySan Francisco


  • Hydrogen annealing
  • Low-loss waveguide
  • MPW run
  • Silicon Photonics
  • SOI waveguide


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