Bistable optical systems based on Pockels cells (A)

P. W. E. Smith

Albert Feldman

The performance of a bistable intensity modulator based on a Pockels cell can be optimized if a voltage proportional to a linear combination of input and output intensities is applied to the Pockels cell. The bistable response can more closely approximate a step function. The output-optical-power regulation can be improved at levels close to the input-power level. The operating point of an ultralinear modulator can be maintained at the most linear portion of the response curve. Some of the above features are demonstrated experimentally. Analogous modifications can be made to advantage on other bistable optical systems.

Daniel F. Walls, P. D. Drummond, K. J. McNeil

Albert Feldman

An optical device utilizing optical feedback has been constructed with a Pockels cell and polarizing components. Two modes of operation of the device are demonstrated. Both modes exhibit optical bistability. It is demonstrated that in one mode of operation the nonlinear dependence of the output intensity as a function of an input optical or electrical signal can be made arbitrarily small compared to the linear dependence.

Shenping Li, Zhonghong Yan, Yizhou Zhang

Yu Xu, Wei Chen, Hao Liang +5 more

A high voltage pulse generator is presented to drive Pockels cell. The Pockels cell behaves like a capacitor which slows the rise/fall time of the pulse and restrains the repetition rate of the generator. To drive the Pockels cell applied in quantum communication system, it requires about 1 MHz repetition rate with the rise/fall time of the pulse less than 50 ns, adjustable amplitude up to 800 V and an adjustable duration. With the assistance of self-designed transformers, the circuits is simplified that a pair of high current radio frequency (RF) MOSFET drivers are employed to switch the power MOSFETs at a high speed, and the power MOSFETs shape the final output pulse with the requirements. From the tests, the generator can produce 800 V square pulses continously at 1 MHz rate with 46 ns in risetime and 31 ns in falltime when driving a 51 pF capacitive load. And the generator is now used to drive Pockels cell for encoding the polarization of photons.