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Mid-infrared frequency comb generation via cascaded quadratic nonlinearities in quasi-phase-matched waveguides

Published

Author(s)

Abijith S. Kowligy, Alexander J. Lind, Daniel D. Hickstein, David R. Carlson, Henry R. Timmers, Nima Nader, Flavio Caldas da Cruz, Gabriel G. Ycas

Abstract

We demonstrate mid-infrared (MIR) frequency comb generation in periodically poled lithium niobate (PPLN) waveguides pumped by nanojoule pulses from a 1.5 um mode-locked Er:fiber laser. The cascaded-c(2) nonlinearity in PPLN yields a nearly octave-spanning supercontinuum in the near infrared (NIR) and phase-matched intra-pulse difference-frequency generation (DFG) results in mid-infrared (MIR) frequency comb generation. We experimentally demonstrate (i) narrow-band mid-IR generation, tunable from 4—5 um with a single chip and (ii) broadband mid-IR combs in aperiodically poled waveguides. We further show that theoretical models can reliably predict the broadband, multi-octave experimental spectra, and can be used to inform waveguide designs to tailor mid-infrared spectra. Our results identify a path to a simple single-branch approach to mid-infrared frequency comb generation in an integrated platform using commercial Er:fiber technology. Abstract:
Citation
Optics Letters

Keywords

Frequency comb, integrated photonics, mid-infrared, spectroscopy
Created April 5, 2018, Updated February 21, 2019