Fabrication and characterization of GaAs-based space-variant inhomogeneous media for polarization control at 10.6μm

Chia Ho Tsai*, Uriel Levy, Pang Lin, Shaya Fainman

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations

Abstract

Approaches to create radially and azimuthally polarized light beams usually suffer from issues of integration difficulty and system complexity. In this research, we apply a compact design of space-variant inhomogeneous media (SVIM), providing an even more compact solution with relatively higher conversion efficiency. The device we utilize to convert linear polarization at the wavelength of 10.6μm to radial/azimuthal polarization is fabricated on a single GaAs substrate, using space-variant subwavelength periodic structure with locally varying form birefringence. Unlike previous approach, this subwavelength periodic structure is designed to be relatively deep in order to introduce a π phase shift between the TE and the TM components of the input light, and therefore to locally rotate the incident linearly polarized light to the radial/azimuthal direction. To realize the deep space-variant form birefringent structure, we utilize standard photolithography on a GaAs substrate, followed by chemically assisted ion beam etching (CAIBE), rendering an etch profile with high aspect-ratio (6:1) as required by the original design. An optical characterization at 10.6μm shows a close match between the measured and the theoretical polarization distribution. With proper control of the etch profile it shows that the subwavelength structure also serves as an anti-reflection coating at the sample surface.

Original languageAmerican English
Article number23
Pages (from-to)142-149
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume5515
DOIs
StatePublished - 2004
Externally publishedYes
EventNanoengineering: Fabrication, Properties, Optics, and Devices - Denver, CO, United States
Duration: 4 Aug 20046 Aug 2004

Keywords

  • Chemically assisted ion beam etching
  • Form birefringence
  • Polarization
  • Space-variant inhomogeneous media

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