High-tech equipment using a laser beam in its work is increasingly used in a wide variety of areas of industrial, medical and research activities. The main task of the creators is to form a light beam according to the required parameters:
- Capacities.
- Phase.
- Polarization.
To achieve them, optical modulators are used in devices, which are based on the so-called principle of operation of the Pockels cell used in laser solutions for business. (Pockels is a German physicist who studied the refractive indices of rays of light directed at certain materials in an electric field.)
What is an electro-optical modulator
In 1893, by the method of laboratory research, the scientist established the regularity of the change in the refractive indices of rays from certain materials when exposed to a constant electric field, which is proportional to its power (strength) with a coefficient from 10 −10 to 10 −12. It is called the Pockels effect and is widely used today in the production of optical modulators.
The scheme of operation of the devices consists in using a cell, which is a crystal with certain refractive parameters of a light beam placed in a polarizing device between 2 nicols (materials that do not transmit light, in the absence of voltage supply to them). In this case, the external electric field of action on the device in relation to the direction of the light flux can be:
- Transverse - Perpendicular
- Longitudinal - parallel layout.
This effect is especially well manifested when crystals of niobate, lithium, gallium arsenide are used as starting materials. The main condition is that they should not have a center of symmetry, since when the direction of the electric field is changed, its polarity (sign) changes.
Electro-optical modulators, as a rule, include at least 2 Pockels cells in their device and are widely used to control the polarization, phase and output power of a laser beam due to the possibility of changing the parameters of an electrical signal acting on crystals.
