Design and optimization of a waveguide/fibre coupler in the visible Range

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

1 Citation (Scopus)

Abstract

When engineering photonic integrated structures, there will be a time that one must consider coupling out the electromagnetic field to an external device. Often, this coupling is made through a single mode optical fibre. Due to the mismatch in mode field diameters between waveguide and fibre modes, the propagating mode inside the dielectric waveguide must undertake a spot-size conversion. It requires to be radially expanded, often laterally by a tapered waveguide and longitudinally through other means, to match the radial profile of the optical fibre mode. Then, the energy must be coupled out of its propagating path into the plane of the optical fibre, through a structure that possesses such functional purpose. In this work, we describe the design steps and optimization of a silicon nitride waveguide/fibre coupler operating in the visible range. To this end, we start by designing an optimized 3D taper waveguide, using Beam Propagation method, that performs as the spot-size converter. Next, through the Eigen Mode Expansion method, a 2D subwavelength grating is designed and optimized regarding substrate leakage and propagating plane energy coupling out, thus vertically validating the energy distribution of the outgoing profile. The required subwavelength grating apodization is accomplished, once more through the Eigen Mode Expansion method, and by carefully engineering a metamaterial that performs accordingly. The obtained diffraction grating is then expanded horizontally to create a 3D structure and laterally validated through Beam Propagation method. Finally, the whole 3D structure is optimized and validated through Finite Differences Time Domain simulations regarding energy profile coupling out, and overlap integral matching is established with the fibre mode profile

Original languageEnglish
Title of host publicationPhysics and Simulation of Optoelectronic Devices XXIX
EditorsBernd Witzigmann, Marek Osinski, Yasuhiko Arakawa
PublisherSPIE-International Society for Optical Engineering
ISBN (Electronic)9781510641952
DOIs
Publication statusPublished - 2021
EventPhysics and Simulation of Optoelectronic Devices XXIX 2021 - Virtual, Online, United States
Duration: 6 Mar 202111 Mar 2021

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume11680
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferencePhysics and Simulation of Optoelectronic Devices XXIX 2021
Country/TerritoryUnited States
CityVirtual, Online
Period6/03/2111/03/21

Keywords

  • Beam propagation method
  • Eigen mode expansion method
  • Finite differences time domain
  • Graded index
  • Inverted taper
  • Metamaterial
  • Resonant waveguide grating
  • Waveguide/fibre coupler

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