Tunable fibre Bragg grating arrays for spectral cross-correlation

Miniaturization of astronomical instruments for high-resolution cross-correlation spectroscopy for exoplanet analysis may be achieved using existing photonic platforms and technologies. Arrays of fibre Bragg gratings (FBGs) may be inscribed into optical fibre to form a target-tailored instrument spectrum offering flexible modulation during instrument operation. This paper presents example spectra of the first such instrument designed for astronomical spectroscopy, fabricated by point-by-point writing with a femtosecond laser in the core of a single-mode telecommunication fibre. First results of spectral modulation and cross-correlation analysis are presented for a strain-modulated FBG array based on infrared molecular gas absorption.