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Proceedings Paper

Dielectric flat lens for the MIR region
Author(s): Maxime Guais; Grégory Maisons; Johan Abautret; Fahem Boulila; Delphine Marris-Morini; Mathieu Carras
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Paper Abstract

The mid-infrared (MIR) molecular fingerprint region has gained great interest in the last past years thanks to development of semiconductor laser source like Quantum Cascade Lasers (QCL). Nevertheless, because of the small size of the waveguide of such devices (≈ 10μm), the beam at the output of such source has an extreme divergence (could be < 45 deg) which makes it difficult to use without specific optics. Several solutions, such as classical lens in chalcogenide glass or parabolic mirror, have been used to shape the laser beam. However, this kind of solution remain expensive and not always usable for small component. This paper present a new kind of lens for the collimation of MIR laser beam, very compact and with a focal length highly adjustable. The fabrication of this dielectric flat lens has the advantages of the semiconductor fabrication techniques and a single etch step on a wafer is sufficient to perform the lens. The main principle is to structure the wafer surface with sub wavelength pattern to induce a local variation of the refractive index. Then the mapping of this local index is the key to control the phase of an input beam and to perform the desired lens function. This works shows simulation results and demonstrate the first prototype of this device for wavelength close to 9μm with a focal length and numerical aperture of almost 150μm and 0, 5. This prototype is disc-shaped with a diameter of 100μm made on InP wafer.

Paper Details

Date Published: 21 February 2020
PDF: 9 pages
Proc. SPIE 11261, Components and Packaging for Laser Systems VI, 1126106 (21 February 2020); doi: 10.1117/12.2547296
Show Author Affiliations
Maxime Guais, mirSense (France)
Grégory Maisons, mirSense (France)
Johan Abautret, mirSense (France)
Fahem Boulila, mirSense (France)
Delphine Marris-Morini, Ctr. de Nanosciences et de Nanotechnologies, Univ. Paris-Sarclay, CNRS (France)
Mathieu Carras, mirSense (France)

Published in SPIE Proceedings Vol. 11261:
Components and Packaging for Laser Systems VI
Alexei L. Glebov; Paul O. Leisher, Editor(s)

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