Pockels Cells for Laser
The pockels cells employed in CRYLINK’s equipment use protective window with a high-quality AR coating, resulting in an increased transmission rate and greater equipment lifespan.
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Longitudinal electro-optic modulation is difficult to realize because the half wave voltage of the longitudinal electro-optic effect is independent of crystal size. BBO pockels cells operate based on the transverse electro-optic effect. BBO crystal’s size alters the half wave voltage. Crylink can offer various pockels cell aperture and length configurations that are ideal for a variety of conditions. Due to the low ringing effect and high laser-damaged threshold, Crylink’s BBO pockels cells are capable of operating at a maximum frequency of 1MHz.
Póckels cells are divided into two main groups, depending on this factor. When an electric field is applied to a long light beam, higher apertures and Q-switches are commonly used. smaller apertures and smaller switching voltages can be used with transverse devices, which utilize an electric field that passes perpendicularly to the light beam. For the group who must operate with half-wave voltage, the electrodes separation and aperture are both important. The standard voltage unit is the half-wave voltage, a voltage necessary to create a phase shift of π. Half-wave voltage in an amplitude modulator means the system can either have minimal transmission or maximum transmission. A typical half-wave voltage for longitudinal and transverse devices is in the range of tens of thousands of volts.
Pockels cells are electro-optic crystals through which a light beam can propagate that are supported by electrodes. The Pockels effect can be made variable by applying an adjustable voltage. In contrast to a waveplate, the Pockels cell provides a voltage-controlled wave plate. The basic building blocks of electro-optic modulators and optical switches are the Pockels cells, such as are used in Q switching lasers. Electrical voltages can also be used as sensors.
The electric field is in the direction of the light beam, meaning longitudinal devices have been designed to do that. While holes in the electrodes may be used for light to travel through, transparent electrodes are used less frequently because of their lower light transmittance. A large aperture can be easily realized due to the independent voltage requirement. In the figure to the left, the electrodes are metallic rings, and in the figure to the right, the electrodes are metallic layers on the end faces with metallic contacts. Longitudinal electric field applied to Pockels cells. Electrodes can be made out of either small ring-shaped appendages on the end faces or smaller ring-shaped appendages placed on the outer sides.
Instead of the electric field being parallel to the light beam, transverse devices have it oriented perpendicular to the beam. The crystal is filled with electrodes, which are used to apply the field. When using smaller apertures, the switch voltages can be reduced. The bulk modulator to the left has a larger loop, and the waveguide modulator to the right has a smaller loop. Ammonium hydrogen phosphate (NH4H2PO4) is commonly used in linear Pockels cells (NH4H2PO4, ADP). Special materials like cadmium telluride (CdTe) are required for mid-infrared applications.
