USE OF RADIO-FREQUENCY-PULSE SURFACE-ACOUSTIC-WAVE PROFILOMETRY FOR PASSBAND ENGINEERING OF ACOUSTOOPTIC TUNABLE FILTERS

One can determine the acoustic profile of an acousto-optic tunable fil ter (AOTF) either by measuring the intensity of a laser diffracted off the surface of an AOTF by the surface acoustic wave (SAW) or by measu ring the optical output power of an AOTF as a short burst of rf energy is launched down the device. This rf-burst technique (also called pul se probing) is compared with the established optical diffraction SAW p rofilometry technique. We demonstrate the usefulness of rf-burst profi lometry to measure the acousto-optic coupling as a function of positio n along an AOTF interaction region. Such a probe can be used to make a djustments to the acousto-optic coupling in real time to achieve passb and shape modification in complex AOTF structures. (C) 1996 Optical So ciety of America