Inscription of high contrast volume Bragg gratings in fused silica with femtosecond laser pulses

We present volume Bragg gratings (VBGs) with a period of 1.075 µm inscribed in fused silica using a femtosecond laser and a phasemask. The femtosecond-inscribed VBGs can be used as reflecting elements with reflectivities of about 80% for a 1-mm-long grating. Due to the nonsinusoidal refractive-index shape, higher order Bragg resonances up to the 7th reflection order could be measured. Therefore, the Bragg gratings also reflect light in the visiblewavelength range.