SU527973A1 - Electrooptikal switching device - Google Patents

Description

(54) ELECTROOPTICAL COMMUTING DEVICE

one

This invention relates to integrated optics, in particular, to devices for switching a light beam. It can be used in optical computing machines and optical fiber technology, where high speed and high switching capacity are required.

An optical switching device is known, which contains a thin layer of an electro-optical crystal with electrodes made in the form of several parallel rows of conductor strips, the length and period of which determine the period of the phase diffraction grating on which the light diffraction 1 occurs. The efficiency of such a diffraction grid, even if it is located at the Brgga angle to the incident light beam, is relatively small due to the small length of light interaction with the medium portion having a modified refractive index.

Claims (2)

The prototype of the proposed electro-optical switching device is an electro-optical variable phase diffraction grating designed to modulate optical radiation 2. This grating — a film modulator — is a thin-film optical waveguide formed on the surface of an electro-optic crystal, with comb-shaped electrodes deposited on its surface, the teeth of which are located along the propagation direction of the light. When an electric voltage is applied to the comb electrodes, the intensity vector of the electric field changes its direction in adjacent pairs of teeth. In accordance with changes in the direction of the intensity vector of the electric field, the refractive index of the crystal also changes. Thus, a volume phase diffraction grating is formed in the waveguide with a modulation depth of the refractive index proportional to the applied voltage. The light propagating in the waveguide, passing through the diffraction grating, diffracts, and the intensity of the deflected beam is modulated in accordance with changes in the electrical voltage. With some electrical voltage falling on the device, the radiation diffracts with 1% efficiency, the light switches from one angular position to another. Along with undoubted advantages (the most important of which is a small control voltage, the described device has a narrow disadvantage: the beam of light can deflect only in two angular positions. The purpose of the invention is to increase the number of angular positions of the combining beam This goal is achieved by the fact that the comb-shaped electrodes deposited on the surface of the waveguide are arranged in series, the angle between the teeth of the adjacent electrodes being equal to the double Bragg diffraction angle. a device that commutes a light beam at a yi fishing position.The device consists of a substrate 1, an optical thin-film waveguide 2 made of an electro-optical material, for example, L NbO, j, and combed electrodes deposited on the surface of the waveguide 3. The tooth of two adjacent comb electrodes is rotated relative to each other at an angle equal to twice the Bragg diffraction angle determined by the relation: 2 (cf is the period of the comb electrodes; wavelength of switched optical radiation in air; And - the index prelokvcheny waveguide material. The operation of the device is as follows. The switched beam of light propagated in the waveguide falls at an oegg angle in a diffraction grating formed by the first comb electrode of the device. Depending on whether or not an electrical voltage is applied to the electrode, the light beam either deviates by an angle of 2 volts or expands without changing the direction. The teeth of the adjacent comb-shaped electrodes are rotated by an angle of 20 the diffraction grating beam of light falls on the diffraction grating formed by the next comb electrode, also at the Bragg angle 0. The remaining electrodes of the device work in a similar way. After any comb electrode, the number of possible angular applications of the beam increases by one. The entire sequence of K electrodes deflects the beam in K / K +1 angular positions. The proposed electro-optical switching device, while maintaining the speed characteristic of the Prototype (reaching frequencies of several gigahertz), allows switching the beam of light to N K + 1 angular positions. With the achieved level of photolithography technique, the device reaches a maximum deviation step of the light beam of about 2 in air for, 6 μm. It should be noted that when applied to the surface of a waveguide grab-shaped electrodes with different periods, it is possible to build a switching device with a given switching law. The small size, manufacturability and low voltages (5-20 V) controlling the operation of the device constitute the advantages of the device. Formula in the shadow image Electro-optical switching device containing a thin-film optical waveguide with comb-type electrodes applied to its surface, characterized in that, in order to increase the number of angular positions of the switched light beam, the comb-shaped electrodes are arranged in series, electrodes is equal to twice the Bragg diffraction angle. Sources of information accepted for examination: 1. French Patent No. 2103124, cl. G 02 T 1 / OO, 12.05.72. 2. US patent number 3813142, CL 350. 96, 05/28/74.