This book emphasizes on the realization, investigation and manipulation of Bragg gratings with external electrical control especially for spectral filtering applications. Volume photorefractive Bragg gratings realized in bulk lithium niobate crystals are manipulated with external electric field in order to demonstrate fast electrically switchable holographic lenses and mirrors. Furthermore, photorefractive Bragg gratings are inscribed in lithium niobate waveguides and a fast electrically tunable integrated optical spectral filter is demonstrated. The most important and interesting part is the introduced concept of phase-shift keying of corrugated waveguide Bragg gratings which was used to dynamically reconfigure the Filter transfer function. This novel concept comprises, for the first time to the best of author's knowledge, the use of external electric field to dynamically inscribe phase-shifts to more than two sections of the already fabricated integrated corrugated Bragg grating. Employing this technique, a fast (< one microsecond) reconfiguration or synthesis of the transfer function into several desirable profiles is demonstrated.