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Title: Efficient dielectric metasurface collimating lenses for mid-infrared quantum cascade lasers

Light emitted from single-mode semiconductor lasers generally has large divergence angles, and high numerical aperture lenses are required for beam collimation. Visible and near infrared lasers are collimated using aspheric glass or plastic lenses, yet collimation of mid-infrared quantum cascade lasers typically requires more costly aspheric lenses made of germanium, chalcogenide compounds, or other infrared-transparent materials. We report mid-infrared dielectric metasurface flat lenses that efficiently collimate the output beam of single-mode quantum cascade lasers. The metasurface lenses are composed of amorphous silicon posts on a flat sapphire substrate and can be fabricated at low cost using a single step conventional UV binary lithography. Mid-infrared radiation from a 4.8 μm distributed-feedback quantum cascade laser is collimated using a polarization insensitive metasurface lens with 0.86 numerical aperture and 79% transmission efficiency. The collimated beam has a half divergence angle of 0.36° and beam quality factor of M² =1.02.
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [1]
  1. California Institute of Technology, Pasadena, CA (United States). T. J. Watson Laboratory of Applied Physics
  2. California Institute of Technology, Pasadena, CA (United States). Jet Propulsion Laboratory
Publication Date:
Grant/Contract Number:
SC0001293
Type:
Published Article
Journal Name:
Optics Express
Additional Journal Information:
Journal Volume: 23; Journal Issue: 26; Journal ID: ISSN 1094-4087
Publisher:
Optical Society of America (OSA)
Research Org:
California Institute of Technology, Pasadena, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
subwavelength structures; semiconductor lasers, quantum cascade; metamaterials; diffraction and gratings
OSTI Identifier:
1234066
Alternate Identifier(s):
OSTI ID: 1239526