Talbot Effect in Embedded Gratings Inscribed with Femtosecond Laser in Transparent Media

Since the first refractive index modification of transparent materials was achieved via femtosecond laser micromachining [1], the fabrication of bulk inscribed 3D optical elements has been insistently pursued. This method has been extensively used to generate a variety of photonic devices such as waveguides, couplers or amplifiers, which enabled a large number of technological breakthroughs [2]. In particular, the fabrication of glass embedded volume-phase gratings (VPG) has been studied in detail by many authors [3]. Currently, the process for manufacturing VPGs involves the use of dichromated gelatin hologram recording, which is accomplished sealing the gelatin between two layers of glass. Using femtosecond laser inscribing technique, VPGs can be fabricated in a more direct, robust and environmental friendly way.