The Integrated acousto-optic tunable filter have the potential to perform the OADM or OXC functions, which play significant role in WDM optical network. The characteristic of the acousto-optic mode conversion is sinc2-like functions with high sidelobe intrinsic. The high sidelobe level lead to serious crosstalk in the WDM optical network. The theory of weighted coupling for IAOTF has been presented. And the filter response using four suggested weighted functions has been calculated with the matrix methods. Significant suppression of sidelobe level has been achieved by employing the techniques of weighted coupling. It is a valid approach to reduce the sidelobe of IAOTF by chosing propriety weighted function and a realized way.

MEMS Fabry-Perot tunable filter is obviously notable because of its mass production and easy integration. Membrane is the key portion of the filter as its structure directly affects the filter's performance and fabricating difficulty. In this paper, some typical membrane structures with different dimensions are simulated. Through making finite element analysis to these simulations and comparing of the results, we find out useful information such that foldaway and spiral cantilevers can achieve longer length in the same membrane area; the longer cantilevers are, the smaller electrostatic force is needed, accordingly the bias voltage is lower and the membrane curvature is smaller, etc. Then we use the information to analyze some important factors affecting membrane's physical and optical performance and make an optimization design.

The acousto-optic tunable filter (AOTF) for wavelength division multiplexing (WDM) applications has attracted much attention. The important reason is that it may realize the multi-wavelength optical cross-connect. This enables the AOTF to become a promising optical component in the future intelligent optical communication networks. The TeO2 AOTF has a specific structure with the capability of both functions of wavelength division and space division. This feature will lead to TeO2 AOTF's lower crosstalk. In this paper, the coupling equations with multiple acoustic waves traveling simultaneously are presented. The analytic solution of the diffraction efficiency for the two acoustic frequencies is given, and its impact on the device performances is analyzed. The crosstalk of the TeO2 AOTF as an OADM in WDM system is discussed, which shows that it is superior to the IAOTF on crosstalk.

In the coming new general optical network, tunable filter is one of important optical devices, and can be used to compose dynamically optical add/drop multiplexer (OADM). Polarization independent integrated acousto-optic tunable filter (IAOTF) is one of devices which have most potential to perform the function[1][2]. Mode splitting and merging are realized by using two symmetrically directional couplers in the IAOTF. Mode polarization is converted by the acousto-optic mode converter when the condition of phase matching is met at the specifically light wavelength. The light wavelength passing the filter can be easily adjusted by changing the frequency of acoustic wave. The Ti diffused technology is adopted to fabricate the device on the X-cut Y propagation LiNbO3 slice. The relation of index difference in the X-cut Y propagation LiNbO3 waveguide with different diffusion conditions is computed in this paper. And the theory of coupling mode is utilized to analyze and design the directional coupler, in which TE/TM mode splitting can be realized. The designed structure is simulated by using BPM software. The extinction ratio of TE/TM mode can be reached 25.1 dB and 24.9 dB respectively.