Dual-wavelength (λ = 1300–1650 nm) directional coupler multiplexer–demultiplexer by the annealed-proton-exchange process in LiNbO_3

The potential of switching wavelengths by using a directional coupler has been explored. A dual-wavelength (lambda = 1300-1650 nm) directional coupler multiplexer-demultiplexer has been realized by using the annealedproton-exchange process in LiNbO(3). The interaction length of the coupler has been accurately tuned to operate at a desired wavelength by annealing and reannealing the substrate until the desired coupling length is achieved.