High reflectivity small aperture resonant grating filters for laser diode spectral stabilisation

Resonant grating filters are new optical components of high interest for optical reinjection in a laser diode as they provide simultaneously high reflectivity and high spectral selectivity. However, their usefulness is limited by a low angular tolerance that requires the use of collimated beams. Following the proposal from Ura et al. [1], we demonstrated small aperture resonant grating filters with a high modal reflectivity (larger than 60%), a narrow linewidth (1.5 nm at 850 nm) and a large angular tolerance (larger than 9, FWHM) [2]. In this paper, we discuss the design and performance properties of such filters, and demonstrate spectral stabilization of a laser diode with resonant grating filters.