Design of tunable composite spectrums using all-fiber acoustooptical filters subject to strain control

This paper addresses the tunability issue of the all-fiber acoustooptic tunable filter (AF-AOTF) when it is used to design optical filters that are capable of producing tunable complex spectrums. A strain control scheme implemented on a loop-structure AF-AOTF is proposed for the filter design. In this paper, the mathematical model of the proposed scheme is first derived. Based on this model, the tunability of the composite spectrum obtained via the proposed scheme is analyzed and compared with existing AF-AOTF schemes. It is shown in theory that, when compared to existing schemes, the strain control scheme implemented on a loop-structure AF-ATOF has a better capability of maintaining a composite spectrum while the spectrum is being tuned. The theoretical analysis is verified by simulations and experiments.