Mid-IR Frequency Combs

Mid-IR frequency combs have emerged as a new generation of spectroscopic tools for molecular science due to their ability to quickly acquire a broadband molecular spectrum with high spectral resolution. High average power frequency combs allow for increased sensitivity and shorter acquisition times. Our work on frequency combs focuses on increasing the average output power of mid-IR frequency combs and extending the wavelength coverage further into the mid-IR spectral region. 


Previous Relevant Work:

Three-photon absorption in optical parametric oscillators based on OP-GaAs

O. H. Heckl, B. J. Bjork, G. Winkler, P. B. Changala, B. Spaun, G. Porat, T. Q. Bui, K. F. Lee, J. Jiang, M. E. Fermann, P. G. Schunemann, and J. Ye, “Three-photon absorption in optical parametric oscillators based on OP-GaAs,” Opt. Lett., vol. 41, no. 22, pp. 5405–5408, 2016.

We report on, to the best of our knowledge, the first singly resonant (SR), synchronously pumped optical parametric oscillator (OPO) based on orientation-patterned gallium arsenide (OP-GaAs). Together with a doubly resonant (DR) degenerate OPO based on the same OP-GaAs material, the output spectra cover 3 to 6 μm within ∼3  dB of relative power. The DR-OPO has the highest output power reported to date from a femtosecond, synchronously pumped OPO based on OP-GaAs. We observed strong three-photon absorption with a coefficient of 0.35±0.08  cm3/GW2 for our OP-GaAs sample, which limits the output power of these OPOs as mid-IR light sources. We present a detailed study of the three-photon loss on the performance of both the SR- and DR-OPOs, and compare them to those without this loss mechanism.