Abstract

Volume Bragg gratings (VBGs) have gained growing interest over the last decades for diverse applications. Typically, they are produced in photo-thermo-refractive glasses using UV light [1]. Later, femtosecond (fs) laser pulses were used to produce refractive-index modifications (Δn), mainly type-1, in various other materials [2]. To obtain more freedom in designing optical systems, it is desirable to inscribe VBGs in glasses exhibiting a much higher Δn, such as silver-containing phosphate glasses. Indeed, a novel type of Δn has been demonstrated in such glasses, denominated Type-A (A from Argentum), which is related to the spatial distribution of the photo-induced silver clusters around the interaction voxel and exhibits two positive Δn peaks at each laser pass [3], reaching a value of up to 2×10⁻² [4]. Recently, we demonstrated the first Type-A VBGs inscribed in silver-containing phosphate glasses with a Gaussian-Bessel beam. The most efficient grating was recorded in ~1 hour at a velocity of 20 μm⁄ for a transverse area of 400×400 μm². Indeed, there is a growing interest in writing high throughput VBGs suitable for industrial manufacturing.

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