Effect of aberrations in a holographic system on reflecting volume Bragg gratings

Abstract

The effect of aberrations in the recording beams of a holographic setup is discussed regarding the deterioration of properties of a reflecting volume Bragg grating. Imperfect recording beams result in a spatially varying grating vector, which causes broadening, asymmetry, and washed out side lobes in the reflection spectrum as well as a corresponding reduction in peak diffraction efficiency. These effects are more significant for gratings with narrower spectral widths.

Moiré volume Bragg grating filter with tunable bandwidth

“…The small beam diameter was used so that the effect of inhomogeneity in the grating properties across the beam aperture would be minimized. Also with larger beam sizes the aperture of the beam would encircle areas of the tilted grating with phase φ in significant range to produce some convolution of spectrum across the beam aperture such as described in [19] and a small beam minimizes these effects. The tunable laser was incident normal to the fringe planes of the grating structure and, as the wavelength of the incident beam was swept through its range, the transmitted power through the moiré VBG was monitored.…”