Pockels Cells


Pockels Cells

  • Voltage-Controlled Wave Plate
  • KD*P Electro-Optic Crystal
  • Ideal for Q-Switching


  • 3 Wavelength Range Options:
    • 425 - 700 nm
    • 700 - 1000 nm
    • 1064 nm
  • Longitudinal Pockels Cell
  • Wedged Windows for 0° Offset and Minimal Back Reflection

Thorlabs' Pockels Cells offer fast, precise control of the output light's polarization direction as a function of applied voltage. They can be thought of as voltage-controlled wave plates. Our family of Pockels cells uses a potassium di-deuterium phosphate (KD*P) crystal with the electric field applied in the longitudinal direction. Using the longitudinal orientation causes the drive voltage to be independent of aperture size, thus allowing for larger apertures than can be realized in a transverse Pockels cell. Since the response is much faster than standard acousto-optic or liquid crystal devices, Pockels cells are ideal for Q-switching lasers. Our Pockels cells utilize wedged windows to ensure 0° offset and to minimize back reflections. The windows are AR coated for 425 - 700 nm, 700 - 1000 nm, or 1064 nm.

The Pockels cell is an electro-optic device (much like an electro-optic modulator) that consists of an electro-optic crystal through which light is transmitted. The polarization direction of the light is controlled by the voltage applied to the crystal. The Pockels Effect explains the behavior of the Pockel cell: an applied constant or variable voltage (electric field) to the crystal produces linear changes in the birefringence of the crystal (in contrast to the Kerr Effect, which is quadratic with E). Applying a constant voltage allows the Pockels cell to operate as a voltage-controlled wave plate. By applying a variable voltage, one can use a Pockels cell to vary the phase delay through the crystal. Pockels cells are essential components in various optical devices such as Q-switches for lasers and electro-optical modulators.

We recommend a drive voltage no greater than 6 kV, as excessive voltage can damage the crystal. These Pockels cells can be modulated up to a frequency of 5 kHz. For general use, a power supply capable of up to 5 kHz modulation and 5 - 6 kV output is recommended. For applications such as Q-switching, fast rise times (on the order of 50 ns) are desired and the user should ensure that his or her power supply is capable providing such fast rise times. To create the electrical connections, these Pockels cells have two electrical sockets for 1 mm pins. Please note that Thorlabs does not currently offer Pockels cell drivers.


Item #EO-PC-550EO-PC-850EO-PC-1064
Wavelength Range 425 - 700 nm 700 - 1000 nm 1064 nm
Design Wavelength 532 nm 785 nm 1064 nm
Aperture Ø9.5 mm
Clear Aperture Ø9.0 mm
Transmission >99%
Half-Wave Voltage 3.3 kV @ 532 nm 5 kV @ 800 nm 6.6 kV @ 1064 nma
Extinction Ratiob >250:1 >550:1 >1000:1
Capacitance 8 pF
  • We do not recommend applying a voltage greater than 6 kV. If half-wave retardance is desired, we recommend setting the Pockels cell to act as a quarter wave plate in a double-pass beam geometry.
  • Specified at the design wavelength.


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