Area: OpticsOptical element with Braggs 
phase grating that consists of electro-optical material or is embedded in an additional layer. The Braggs 
phase grating is designed as a series of periodically applied elevations and indentations of the 
waveguide's surface, coated with one layer of the compensating material and one layer of the electrically isolating material, along the propagation of light. The 
phase grating is equipped with a means of generating a spatially inhomogeneous, aperiodic, external electrical field.Area of the InventionThe invention belongs to the physical area of 
optics and, in fact, to the 
optics methods and facilities for 
spectral filtering of 
optical radiation. This is based on electro-optical crystals and is to be used to produce narrow-band filters with a broad wave spectrum of 
changeover to 
wavelength, and for production of selective optical attenuators and modulators of light and optical equalisers.Description of the InventionThe object of the invention is, on the one hand, the production of optical elements in an integral optical design that have a multifunctional use (tuneable optical filters, selective optical attenuators and modulators, optical switches and optical equalisers), and which possess a high spectral selectivity, a broad 
wavelength band of tuneability, great dynamics, and a low tendency toward cross-talk. A further aim of this invention was to develop a process for control of the aforementioned filters that makes it possible to electrically control the profile of the 
transfer function, the location of the 
transfer function's maximum, the number of channels to be selected, and compensation of 
phase distortion, while using a relatively low control 
voltage, and with a high tuneability and switching speed.The task in hand is resolved by a large number of inventions that are related by one joint intention.