Silicon photonics with ultra-broadband operation from 1.2 to 2.4 µm wavelength

Timo Aalto*, Markku Kapulainen, Fei Sun, Mikko Harjanne, Srivathsa Bhat, Katherine Bryant, Yisbel Marin

*Corresponding author for this work

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

1 Citation (Scopus)

Abstract

Single-mode and low-loss operation of optical waveguides is typically limited to a 200-500 nm wide wavelength range. The lower limit is the boundary between single and multi-mode operation, and the upper limit comes from the decreasing confinement of the fundamental mode inside the core, which eventually leads to too large bending radii, waveguide crosstalk and poor integration density. Many interferometric waveguide components, such as grating couplers and multi-mode interference (MMI) couplers, have even narrower wavelength range. This paper demonstrates photonic integrated circuits (PICs) with ultra-broadband operation from 1.2 to 2.4 µm wavelength based on 3 µm thick silicon-on-insulator (SOI) waveguides. Such thick waveguides maintain ultra-high mode confinement for over 1 µm bandwidth, which supports dense integration with low-loss crossings, Euler bends and total internal reflection (TIR) mirrors. While some parts of the PICs are based on multi-moded strip waveguides, mode filters with rib-waveguides allow to keep the PICs effectively single-moded. The focus of the paper is on passive PICs, although the platform also enables active components. Ultra-broadband test results are provided for long waveguide spirals and waveguide-fiber coupling, as well as for echelle gratings, arrayed waveguide gratings (AWGs) and different types of 2x2 couplers. Low-loss operation is demonstrated with continuous transmission spectra measured from 1.25 µm up to 2.4 µm wavelength, i.e. up to 1.15 µm bandwidth. The measured bandwidths are limited by the available measurement setup, rather than the PIC components themselves. Remaining challenges for ultra-broadband operation, such as anti-reflection coatings, are discussed. Applications for broadband operation in communication, imaging and sensing are also presented.

Original languageEnglish
Title of host publicationSilicon Photonics XIX
EditorsGraham T. Reed, Andrew P. Knights
PublisherInternational Society for Optics and Photonics SPIE
ISBN (Electronic)9781510670426
DOIs
Publication statusPublished - 2024
MoE publication typeA4 Article in a conference publication
EventSilicon Photonics XIX 2024 - San Francisco, United States
Duration: 29 Jan 202431 Jan 2024

Publication series

SeriesProceedings of SPIE
Volume12891
ISSN0277-786X

Conference

ConferenceSilicon Photonics XIX 2024
Country/TerritoryUnited States
CitySan Francisco
Period29/01/2431/01/24

Funding

This work has been mostly carried out in PICAP and DYNAMOS projects, which were partly funded by Business Finland (decision 44065/31/2020) and EU (grant 101070342), respectively. It is also part of the Academy of Finland Flagship Programme, Photonics Research and Innovation (PREIN).

Keywords

  • arrayed waveguide grating
  • broadband operation
  • echelle grating
  • silicon photonics

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