The performance parameters of an acousto-optic tunable filter (AOTF) determine its application range. In order to further expand the application field of the AOTF, a system is built based on a single crystal. In this system, the difference between single filtering and double filtering with a single crystal tellurium dioxide (TeO2), including spectral bandwidth and side lobe, is studied using a broadband light source. The experimental results indicate that single crystal double filtering has the advantages of a narrow spectral bandwidth and side lobe suppression. In addition, the diffraction efficiency of single crystal double filtering is measured experimentally. © 2019 IOP Publishing Ltd.