Acousto-optic_programmable_dispersive_filter
An acousto-optic programmable dispersive filter (AOPDF) is a special type of collinear-beam acousto-optic modulator[1] capable of shaping spectral phase and amplitude of ultrashort laser pulses. AOPDF was invented by Pierre Tournois.[2] Typically, quartz crystals are used for the fabrication of the AOPDFs operating in the UV spectral domain, paratellurite crystals are used in the visible and the NIR (up to 4 μm) and calomel in the MIR (3–20 μm). 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.[5][6] Although sharing a lot in principle of operation with an acousto-optic tunable filter, the AOPDF should not be confused with it, since in the former the tunable parameter is the transfer function and in the latter it is the impulse response.