TY - JOUR
AU - Mason, Paul D.
AB - 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 ॖm. 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 ॖm laser. The resultant 2 ॖm radiation is then used to pump a second OPO, based on a material such as ZGP, for conversion into the 3 to 5 ॖm mid-IR waveband. Periodically poled lithium niobate (PPLN) is a useful material for conversion from 1 to 2 ॖm due to its high non-linear coefficient (d eff ~ 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 ॖm 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 ॖm output with linewidths as low as 2 nm. A grating-narrowed degenerate PPLN OPO has been successfully used to pump a ZGP OPO.
TI - Spectral line narrowing in PPLN OPO devices for 1-ॖm wavelength doubling
JO - Proceedings of SPIE
DO - 10.1117/12.577521
DA - 2004-12-23
UR - https://www.deepdyve.com/lp/spie/spectral-line-narrowing-in-ppln-opo-devices-for-1-m-wavelength-Bimw90WsaD
SP - 275
EP - 283
VL - 5620
IS - 1
DP - DeepDyve
ER -