Generation of a green astro-comb using tapered photonic crystal fibers

POSTER

Abstract

Searches for exoplanets using precision stellar radial velocity (PRV) measurements are approaching Earth-like planet sensitivity. Astro-combs, which consist of a laser frequency comb, coherent wavelength shifting mechanism (such as a doubling crystal or photonic crystal fiber), and a mode-filtering Fabry-Perot cavity, provide a promising route to increased accuracy and long-term stability of the astrophysical spectrograph wavelength calibration.~To find an Earth-like exoplanet around a Sun-like star requires astro-combs that cover the visible spectral bands in which there is maximal stellar photon flux and rich high-quality spectral features for high-sensitivity PRV measurements. However, currently no comb lines are available directly from mode-lock lasers in the visible band. Here, we report generation of a green astro-comb from an octave spanning Ti:Sapphire laser, spectrally broadened by a custom tapered PCF to the visible band via fiber-optic Cherenkov radiation for frequency shifting, and filtered by a broadband Fabry-Perot cavity constructed by a pair of complementary chirped mirrors.

Authors

  • David Phillips

    • Harvard-Smithsonian

  • Alexander Glenday

    • Harvard-Smithsonian

  • Chih-Hao Li

    • Harvard-Smithsonian

  • Gabor Furesz

    • Harvard-Smithsonian

  • Nicholas Langellier

    • Harvard-Smithsonian

  • Matthew Webber

    • Northeastern University

  • Guoqing Chang

    • Massachusetts Institute of Technology

  • Li-Jin Chen

    • Massachusetts Institute of Technology

  • Hung-Wen Chen

    • Massachusetts Institute of Technology

  • Jinkang Lim

    • Massachusetts Institute of Technology

  • Franz Kaertner

    • Massachusetts Institute of Technology

  • Andrew Szentgyorgyi

    • Harvard-Smithsonian

  • Ronald Walsworth

    • Harvard-Smithsonian