Reconfigurable wavelength add-drop filtering based on a Banyan network topology and ferroelectric liquid crystal fiber-optic switches

This paper presents a modular optical implementation of a Banyan network by using the physical flexibility of the optical fiber to form the interconne ctions between compact switching stages based on bulk polarization optics. Specifically, these switching stages use total internal reflection (TIR) pr isms with ferroelectric liquid crystal (FLC) polarization rotators to form compact modules. Using this Banyan network implementation, a reconfigurable multiwavelength add-drop filter for wavelength division multiplexed (WDM) applications is proposed, Experimental results for our fiber connected 2 in -2 out FLC-based bulk-optic switching stage gives a similar to 6.7 dB optic al insertion loss and a similar to -40 dB optical interchannel crosstalk le vel. A low 2 dB optical insertion loss design number is expected with optim ized components, realizing high (e.g., 35 mu s) switching speed and low cro sstalk switching networks.