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Proceedings Paper

Instantaneous spectral span of 2.85 - 8.40 μm achieved in a Cr:ZnS laser pumped subharmonic OPO
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Paper Abstract

Degenerate (subharmonic) optical parametric oscillators (OPO) show great promise for the generation of broadband mid-infrared (MIR) frequency combs. Their main features are low pump threshold, dramatic extension of the spectrum of the pump laser, and phase locking to the pump frequency comb. Here we report on obtaining instantaneous spectrum ranging from 2.85 to 8.40 μm at -40 dB level from a subharmonic OPO pumped by an ultrafast Cr2+:ZnS laser. Our experimental setup includes a free running Kerr lens mode locked 2.35 μm Cr2+:ZnS laser, with 62-fs time-bandwidth limited pulse duration, 630-mW average power, and 79 MHz repetition rate that synchronously pumps a ring-cavity orientation-patterned (OP-GaAs) based OPO. A 0.5-mm-long OP-GaAs crystal has a quasi-phase-matching (QPM) period of 88 μm and is designed to provide a broadband parametric gain at OPO degeneracy. A 0.3-mm-thick ZnSe wedge inside the cavity was used to minimize group velocity dispersion. Spectral span of 1.56 octaves in the MIR that we achieved can be further improved by fabricating an in-coupling dielectric mirror with (i) broader reflectivity range and (ii) with compensation of the residual group velocity dispersion. The broad spectrum achieved, 2.85 - 8.40 μm (2320 cm-1 wide instantaneous span), overlaps with a plethora of fundamental molecular IR resonances and can be used for frequency comb spectroscopic detection applied to such fields as remote sensing, study of fast combustion dynamics and medical diagnostics, to name a few.

Paper Details

Date Published: 20 February 2017
PDF: 7 pages
Proc. SPIE 10088, Nonlinear Frequency Generation and Conversion: Materials and Devices XVI, 1008809 (20 February 2017); doi: 10.1117/12.2256046
Show Author Affiliations
Qitian Ru, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)
Kai Zhong, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)
Tianjin Univ. (China)
Nathaniel P. Lee, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)
Zachary E. Loparo, Univ. of Central Florida (United States)
Peter G. Schunemann, BAE Systems (United States)
Sergey Vasilyev, The Univ. of Alabama at Birmingham (United States)
Sergey B. Mirov, The Univ. of Alabama at Birmingham (United States)
Konstantin L. Vodopyanov, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)


Published in SPIE Proceedings Vol. 10088:
Nonlinear Frequency Generation and Conversion: Materials and Devices XVI
Konstantin L. Vodopyanov; Kenneth L. Schepler, Editor(s)

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