Strain effect on the tunability of cascading all-fiber acoustic-optical tunable filters

This paper studies the cascading of several all-fiber acousto-optical tunable filters (AF-AOTFs) to yield a tunable complex transmission. The tunability of the complex transmission, which defines the transmission distortion resulting from asynchronous tuning of the participant notch transmissions, is assessed quantitatively by the phase mismatch coefficients of AF-AOTFs. It is shown explicitly in theory that by applying an axial strain on the acousto-optical interaction section of each participant AF-AOTF, the composite transmission can be maintained better than that with smaller applied strain when the transmission spectrum is being tuned over a wide wavelength range. Simulation results are presented to justify the theoretical analysis.