Acousto-optic programmable dispersive filter

Recently introduced lithium niobate crystals allow for high-repetition rate operation (> 100 kHz) owing to their high acoustic velocity.

The AOPDF is also used for the active control of the carrier-envelope phase of few-cycle optical pulses,[3] as a part of pulse-measurement schemes[4] and multi-dimensional spectroscopy techniques.

Traveling acoustic wave induces variations in optical properties, thus forming a dynamic volume grating.

From signal processing point of view, the AOPDF corresponds to a time-variant passive linear transversal filter with a programmable finite impulse response.

In the limit of low diffraction efficiency the AOPDF behaves as a linear filter and the small value of the α (typically 10−7) allows for the quantitative control of optical signals with frequencies of tens to hundreds of terahertz with electrical signals of tens of megahertz, which are readily produced by commercial waveform generators.