Pockels Cell Alignment Guide
Learn how to align your Pockels cell in a Q-switched laser.Click to read how
G&H are a leading crystal grower with decades of electro-optic device design experience. We manufacture a comprehensive range of Pockels Cells for applications in wavelengths from the UV to the IR. Factors such as average power, repetition rate and the design configuration determine the recommended type of device.
Utilizing proprietary crystal growth, fabrication, and polishing techniques, we manufacture both longitudinal and transverse electrode configuration Pockels cells in beta barium oxide (BBO), cadmium telluride (CdTe), potassium dihydrogen phosphate (KDP) and potassium dideuterium phosphate (KD*P).
These operate by virtue of the Pockels effect, also known as the linear electro-optic effect.
KD*P Pockels Cells
A 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.)
G&H offers the industry-standard QX series KD*P Pockels cells, economical IMPACT series KD*P Pockels cells, LightGate series BBO Pockels cells, IRX series CdTe Pockels cells, and large-aperture TX series KD*P Pockels cells.
Widely accepted as the industry-standard KD*P Pockels cell, G&H has manufactured and continually refined the QX series Pockels cell since the 1980s. It is not uncommon to find a QX series Pockels cell still operating well over decades after installation.
Small-aperture KD*P Pockels Cells
G&H small-aperture KD*P Pockels cells include the IMPACT, CQX and QX series. Which small-aperture KD*P Pockels cell to use involves matching the clear aperture required and the repetition rate of operation to the appropriate device.
For operation at 1 kHz repetition rate or less, the unique construction of the IMPACT series enables OEM incorporation into applications such as medical and aesthetic laser systems. It delivers reliable performance at high contrast ratios.
The CQX series employs manufacturing techniques similar to those of the IMPACT series, yet with external dimensions identical to those of the QX series. This makes the CQX cell a suitable retrofit/replacement for a QX series cell in cases where the repetition rate remains below 1 kHz.
Large-aperture KD*P Pockels Cells
Designed to function as optical isolators, our TX series large-aperture KD*P Pockels cells protect the beam line by blocking back reflections in large scale laser platforms such as Petawatt lasers and/or laser fusion programs. We produce the crystals necessary to manufacture the devices required for this very demanding application in-house.
BBO Pockels Cells
For high-average power and high repetition rate applications, our LightGate BBO Pockels cells are the preferred alternative to KD*P Pockels cells . The LightGate series BBO Pockels cell employs transverse electric field geometry with dual crystals to minimize drive voltage (~2.9 kV quarter-wave voltage @ 1064 nm for the 4 mm aperture LightGate 4).
BBO Pockels cells operate from approximately 0.2 - 1.65 µm and are not subject to tracking degradation. BBO, which we have grown since the 1980s, exhibits low piezoelectric response, good thermal stability, and low absorption. Due to the low piezoelectric coupling coefficients of BBO, LightGate cells function at repetition rates of hundreds of kilohertz.
LightGate series BBO Pockels cells are available in numerous configurations to address a diverse range of applications. These Pockels cells work in regenerative amplifiers, high pulse repetition rate micro-machining lasers and high-average power lasers for material processing and metal annealing.
We also provide single crystal cells, longer cells requiring 50% less voltage, and cells with water-cooled apertures for high average power operation.
Mid-Infrared Pockels Cells
Initially designed to address the Q-switched CO2 laser market at 10.6 µm, G&H’s cadmium telluride - based IRX Q-switch may be configured to operate from ~3 - 12 µm. Its high electro-optic coefficient and non-hygroscopic nature makes CdTe well-suited for this purpose. Through more than 40 years of electro-optic device design experience, we are able to provide IRX Pockels cells with application specific AR coatings in apertures ranging from 3 -10 mm.
The IRX Pockels cells are able to address applications beyond the spectral range of traditional Pockels cells constructed of oxide based crystals. Water-cooled designs feature packaging with reduced ambient light sensitivity to increase the average power handling capacity. Optional patent-pending designs for environmental protection and high average power are available.
|Wavelength of operation||Electro-Optic Material|
|Maximum Repetition Rate (Pulse repetition frequency)||Electro-optic material|
*For microsecond length pulses, shorter pulses can raise the repetition rates.
**CdTe good to 100 kHz, upper bound unknown.
***Currently design limited by RF heading, R&D investigating solution.
Average power (for small aperture KD*P cells, i.e. < 13 mm)
|Average Power||Electro-Optic Material|
|< 10 W||KDP/KD*P, BBO, CdTe|
|> 10 W||BBO, low absorption KD*P (in specific cases), CdTe|
Recommended HV Drivers
Choice of HV driver for a Pockels cell depends primary upon the application. Contact us for assistance selecting a matching driver, or to discuss your needs further.
|Pockels cell model||Application||Recommended driver|
|IMPACT, QX (1064 nm)||Quarter-wave Q-switching||Q-Drive™, OEM Q-Drive™|
|IMPACT, QX (1064 nm)||Half-wave Q-switching||HVR-Drive™, HVR-System™|
|LightGate (1064 nm)||Regenerative amplifier||HVR-Drive™, HVR-System™|
|TX series (1064 nm)||Low rep rate optical isolation||HVR-Drive™, HVR-System™|
|IRX series (10.6 µm)||Quarter-wave Q-switching (<5mm clear aperture)||Q-Drive™, OEM Q-Drive™|
|IRX series (10.6 µm)||Quarter-wave Q-switching (>5mm clear aperture)||HVR-Drive™, HVR-System™|
|IRX series (10.6 µm)||Half-wave Q-switching (<5mm clear aperture||HVR-Drive™, HVR-System™|
|IRX series (10.6 µm)||Half-wave Q-switching (>5mm clear aperture)||N/A|
Applications of Pockels Cells
Amplifiers, CO2 lasers, laser fusion, materials processing, medical and aesthetic laser systems, metal annealing, micro-machining, optical switching, petawatt lasers, regenerative amplifiers.
|Product||Wavelength||Voltage Contrast Ratio||Active Aperture||Optical Material|