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Proceedings Paper

Spectral line narrowing in PPLN OPO devices for 1-µm wavelength doubling
Author(s): Brian J. Perrett; Jonathan A. C. Terry; Paul D. Mason; David A. Orchard
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Paper Abstract

One route to generating mid-infrared (mid-IR) radiation is through a two-stage non-linear conversion process from the near-IR, exploiting powerful neodymium lasers operating at wavelengths close to 1 μm. In the first stage of this process non-linear conversion within a degenerate optical parametric oscillator (OPO) is used to double the wavelength of the 1 μm laser. The resultant 2 μm radiation is then used to pump a second OPO, based on a material such as ZGP, for conversion into the 3 to 5 μm mid-IR waveband. Periodically poled lithium niobate (PPLN) is a useful material for conversion from 1 to 2 μm due to its high non-linear coefficient (deff ~ 16 pm/V) and the long crystal lengths available (up to 50 mm). Slope efficiencies in excess of 40% have readily been achieved using a simple plane-plane resonator when pumped at 10 kHz with 3.5 mJ pulses from a 1.047 μm Nd:YLF laser. However, the OPO output was spectrally broad at degeneracy with a measured full-width-half-maximum (FWHM) linewidth of approximately 65 nm. This output linewidth is significantly broader than the spectral acceptance bandwidth of ZGP for conversion into the mid-IR. In this paper techniques for spectral narrowing the output from a degenerate PPLN OPO are investigated using two passive elements, a diffraction grating and an air spaced etalon. Slope efficiencies approaching 20% have been obtained using the grating in a dog-leg cavity configuration producing spectrally narrow 2 μm output with linewidths as low as 2 nm. A grating-narrowed degenerate PPLN OPO has been successfully used to pump a ZGP OPO.

Paper Details

Date Published: 23 December 2004
PDF: 9 pages
Proc. SPIE 5620, Solid State Laser Technologies and Femtosecond Phenomena, (23 December 2004); doi: 10.1117/12.577521
Show Author Affiliations
Brian J. Perrett, QinetiQ (United Kingdom)
Jonathan A. C. Terry, Univ. of St. Andrews (United Kingdom)
Paul D. Mason, QinetiQ (United Kingdom)
David A. Orchard, QinetiQ (United Kingdom)

Published in SPIE Proceedings Vol. 5620:
Solid State Laser Technologies and Femtosecond Phenomena
Jonathan A. C. Terry; W. Andrew Clarkson, Editor(s)

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