Integrated-optical add/drop multiplexer for DWDM in lithium niobate

In this contribution, an add/drop multiplexer that uses a mode-selective coupler and a holographically recorded slanted Bragg grating in lithium niobate is demonstrated. A Bragg grating with a bandwidth of 0.1 nm allows for an add/drop efficiency of about 96% with a cross-talk well above 22 dB applicable for wavelengths in the 1.5 μm window. Polarisation-independent operation can be achieved by application of a bias electric field to compensate for the small mismatch of propagation constants of TE and TM modes. The proposed scheme of an integrated-optical lithium niobate based device appears to be an interesting option due to its potential for fast electro-optical switching. PACS 42.40.Ht; 42.65.Hw; 42.70.Ln; 42.82.Cr; 42.82.Et