Electro-OpticsA Pockels cell alters the polarization state of light passing through it when an applied voltage induces birefringence changes in an electro-optic crystal such as KD*P and BBO. When used in conjunction with polarizers, these cells can function as optical switches, or laser Q-switches. Frequently, laser cavities incorporate Q-switches to shorten the output pulse, resulting in a light beam with enhanced peak intensity.
Pockels cells come in two electrical configurations; transverse and longitudinal.
- Transverse cells operate with the electric field perpendicular to the light beam. Because the light does not pass through the electrodes, these cells often employ opaque metal electrodes and the operating voltage is geometry dependent. G&H LiNbO3, BBO and CdTe Pockels cells utilize this design. (Lithium Niobate, LightGate and IRX series cells.)
- Longitudinal cells orient the electric field parallel to the light beam. Some designs use face electrodes of transparent, conductive indium tin oxide (ITO), wire grids, metallic electrodes with a hole in the middle for the beam to pass through, or even conductive plasmas. An alternate approach positions the electrodes on the barrel of the cylindrical crystal, near the polished faces. This removes the electrodes from the beam path and, if properly designed, does not degrade the performance. G&H uses this approach in the product of its KD*P Pockels cells. (QX, CQX, IMPACT, and TX series cells.)
Lithium Niobate Q-Switches
Lithium niobate Q-switches are used in military and commercial applications.
Pockels Cell Drivers
Preferred for high-average power and high repetition rate applications.
QX series Pockels cells set the standard for KD*P electro-optic Q-switches.