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Published December 28, 2015 | Published
Journal Article Open

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. Here 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 M^2=1.02.

Additional Information

© 2015 Optical Society of America. Received 31 Aug 2015; accepted 11 Dec 2015; published 17 Dec 2015. This work was supported by the Caltech/JPL Presidents and Directors Fund (PDF). R.M.B gratefully acknowledges support from the NASA PICASSO program. Y.H. was supported as part of the U.S. Department of Energy "Light-Material Interactions in Energy Conversion" Energy Frontier Research Center under grant DE-SC0001293 and a Japan Student Services Organization (JASSO) fellowship. The device fabrication was performed in the Kavli Nanoscience Institute at Caltech. The measurements were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

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August 20, 2023
August 20, 2023