BBO is the electro-optic material of choice for high average power Pockels cell applications.

BBO has significant advantages over other materials in terms of laser power handling abilities, temperature stability, and substantial freedom from piezoelectric ringing. Because it relies on the electro optic effect, switching time — aided by the low capacitance of the Pockels cell — is very fast. The wide transparency range of BBO allows it to be used in diverse applications.  
 

Electro-optic Pockels cells are used in applications that require fast switching of the polarization direction of a beam of light. These uses include Q-switching of laser cavities, coupling light into and out from regenerative amplifiers, and, when used in coniunction with a pair of polarizers, light intensity modulation. Pockels cells are characterized by fast response, since the Pockels Effect is largely an electronic effect that produces a linear change in refractive index when an electric field is applied, and are much faster in response than devices based on acoustic changes in a material, for example.

Because of crystal symmetry and the desire for the light beam to experience no birefringence in the absence of an electric field, BBO Pockels cells are transverse-field devices.

The quarter-wave voltage is V/4 = d / (4 r22 no3 l). The quarter-wave voltage is proportional to d/l, the electrode spacing divided by the crystal length, is inversely proportional to the electro-optic coefficien r22, and decreases when operated at shorter wavelengths.

Piezoelectric ringing in BBO is small, as evidenced by comparison to KD*P and LiNbO3 Pockels cells. Transmission of a test laser beam at 633 nm, with the Pockels cell placed between parallel polarizers, is shown in the following oscilloscope traces. Application of the quarter-wave voltage for each cell caused the transmitted light intensity to decrease to one-half. Operation at the quarter-wave voltage accentuates the appearance of acoustic ringing. In the traces, the 1 indicates ground or zero light intensity. Plots are shown using KD*P, LiNbO3, and BBO as the Pockels cell material.

KD*P BBO LiNbO3
 
Clearly, ringing associated with use of BBO is much less than when either KD*P or LiNbO3 is used. The last trace shows the transmission with BBO in the typical double-pass configuration at the quarter-wave voltage, switching at 5 kHz — the maximum rate allowed by the high voltage driver that was used. In this last trace, intensity is a maximum when voltage is applied; the bottom trace was taken with the laser beam blocked.

Advanced:

  High Repetition Rate

  Low Acoustic Noise

  Damage Resistant Ceramic Apertures

  High Average Power Applications

  Compact Design

  Lower Voltage Requirements Than Other BBO Cells

  Suitable for Q-switch and Regen-amp Applications

  
BBO Pockels Cell Specifications: