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arXiv · 1510.03744

Cascaded half-harmonic generation of femtosecond frequency combs in mid-IR

Alireza Marandi·Kirk A. Ingold·Marc Jankowski·Robert L. Byer
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Abstract

For the growing demand of frequency combs in mid-infrared (mid-IR), known as the "molecular fingerprint" region of the spectrum [1], down conversion of near-IR frequency combs through half- harmonic generation offers numerous benefits including high conversion efficiency and intrinsic phase and frequency locking to the near-IR pump [2]. Hence cascaded half-harmonic generation promises a simple path towards extending the wavelength coverage of stable frequency combs. Here, we report a two-octave down-conversion of a frequency comb around 1 μm through cascaded half-harmonic generation with ~64% efficiency in the first stage, and ~18% in the second stage. We obtain broadband intrinsically-frequency-locked frequency combs with ~50-fs pulses at ~2 μm and ~110-fs pulses at ~4 μm. These results indicate the effectiveness of half-harmonic generation as a universal tool for efficient phase- and frequency-locked down-conversion, which can be beneficial for numerous applications requiring long-wavelength coherent sources.

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Alireza Marandi, Kirk A. Ingold, Marc Jankowski, Robert L. Byer. 2015-10-13. Cascaded half-harmonic generation of femtosecond frequency combs in mid-IR. https://arxiv.org/abs/1510.03744

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