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Efficient volume Bragg gratings in various transparent materials induced by femtosecond laser pulses

Volume Bragg gratings (VBGs) are optical devices that consist of a periodic refractive index structure in a bulk and have a wide range of applications such as frequency stabilizer of semiconductor lasers or as beam combiner for fiber or solid state lasers. Furthermore, chirped VBGs can be used for pulse compression in CPA laser systems. Typically, VBGs are fabricated in photo-thermo-refractive glass by exposure to an interference pattern of an UV-laser ([1]). Due to the restriction to this special glass the method is very limited in its application with respect to monolithic integration of VBGs. This can be overcome by making use of femtosecond laser pulses for the inscription of VBGs in non-photosensitive glass. Due to the high intensity of focused fs pulses a refractive index change can be obtained even in non-photosensitve glass through the process of nonlinear absorption. This process is additionally the cause for higher reflection orders one can see although a single period grating was inscribed ([2]) and opens the door for using one grating at different wavelengths without the need to turn the grating for wavelength adaption.