Acousto-optical tunable filter is tuned to the laser and, by means of this

摘要

An acousto-optic tunable filter ("AOTF") with a pair of electrodes on opposite sides of the waveguide. A voltage source applies a potential across the electrodes, thereby creating an electric field through the waveguide. The electric field controls an optical property of the waveguide by altering the birefringence of the waveguide. Suitably adjusting the potential applied by the voltage source results in suppression of sidelobes, correction of asymmetric sidelobes, and compensation for physical variations in the waveguide. The AOTF can be tuned very rapidly by a tuning voltage applied to the electrodes. In combination with a thermistor, the control voltage can compensate for changes in temperature. A spatially-varying electric field is generated by using a set of electrodes at different potentials, or by using a resistive element as an electrode, or by shaping the electrodes according to the desired field. A rapidly-varying control voltage can modulate a light beam in the filter. The AOTF finds an application as the tuning element of an external-cavity tunable laser.