Numerical analysis of a high-resolution fast tunable filter based on an intracavity Bragg grating.

A fast tunable filtering technique is proposed associating a diffraction grating with an intracavity Bragg grating. The bandwidth and the tuning range of this filter can be easily adapted by changing the diffraction grating's orientation, or its period, and its response is uniform over the whole tuning range. A numerical simulation of the filter response to a Gaussian beam has been developed, and it fits the experimental results allowing a calculation of the performances that could be obtained with more specific elements. For example, using a commercial acousto-optic deflector would allow a separation of 500 frequencies. It would then be possible to have a tuning range of 100 nm with a bandwidth of 0.2 nm for optical telecommunications.