QBY GaN Pockels cell drivers

QBY-4001, QBY-4010-C, QBY-4010-P and QBY-4010-A are Pockels cell drivers by OEM Tech based on GaN transistors, which provide bipolar voltage pulses (3-4 ns rise/fall) on the outputs to control the birefringence of an electro-optical crystal to change the polarization state of light passing through. The QBY-4001 was designed as a very compact model with fast switch to obtain short pulses starting from 10 ns.

The QBY-4010-C requires a customer’s heatsink, the QBY-4010-A is equipped with cooling fans and the QBY-4010-P has a heatsink case, which made it possible to increase the max. rep. rate in ten times at the maximum voltage in comparison with QBY-4001, however the dimension of the system is slightly greater. There are also QBY-BT GaN Pockels cell drivers in a case with a comfort user interface.

It is possible to adjust pulse amplitude by analog input signal and pulse repetition rate and width by external TTL signals J1 and J2 (see the picture below). Output voltage is up to 4 kV, max. rep. rate strongly depends on selected output voltage value and on load capacitance (we recommend therefore to use the shortest possible cables and choose a Pockels cell with lower capacitance).

The module requires +24 V DC power supply and a pulse generator to set an operating frequency and pulse width.

Please, note that by bipolar device an output pulse voltage U is formed by applying +U/2 to positive output wire and –U/2 to negative.

The module was designed to work in set-reset scheme when a base voltage level equals to zero. Non-periodic pulses are also possible, set by pulse generator.

The GaN Pockels cell drivers are very sensitive to load capacitance. In order to keep their performance close to datasheet values, one needs to minimize the load capacitance, numbers less than 5 pF are appreciated.

Performance

The table below contains maximum repetition rate in dependence on output voltage and cooling conditions. Other setup parameters – total load capacitance 5 pF, ambient temperature 25 °C:

Higher load capacitance and higher ambient temperature result in derated performance.