[Design of a high-throughput and wide-bandwidth near-infrared acousto-optic tunable filter]

The acousto-optic tunable filter (AOTF) is the most outstanding progress of near-infrared spectrometer since the 1990s. Restriction in working range and performance of the device exists due to the traditional single-transducer structure. The design of a near-infrared acousto-optic tunable filter with high-throughput and wide-bandwidth adopting a dual-transducer structure is reported in the present paper. By calculation and simulation based on the wave vector diagram which satisfies the parallel-tangents condition, the optimal cutting direction and cutting angle of the acousto-optic crystal, the length of the transducers and other best parameters were obtained. The tuning range of the filter is improved significantly while the resolution, diffraction efficiency and other parameters satisfy the requirements by making two transducers working at the high-frequency part and low-frequency part respectively. According to the testing results of the designed filter, the spectrum resolution is better than 15 nm and the diffraction efficiency is reaches to 41% with the tuning range of 900-2 400 nm.