Tunable fibre Bragg grating arrays for photonic spectral cross-correlation

Photonic platforms and technologies can facilitate the miniaturization of astronomical instruments for high-resolution cross-correlation spectroscopy. Cascaded fibre Bragg grating (FBG) arrays, inscribed into optical fibres using direct femtosecond laser writing, form a target-tailored instrument spectrum. Flexible modulation of spectral features is achievable during instrument operation via strain tuning of the FBG arrays. We present a prototype astrophotonic fibre instrument based on this concept for cross-correlation spectroscopy. Experimental laboratory results of spectral modulation and cross-correlation analysis are presented for infrared molecular gas absorption. Additionally, efforts toward the on-sky integration of the instrument on a 1-meter-class telescope are demonstrated for targeted near-infrared spectral features.