All optical bypass-exchange switch based on anisotropic-diffraction of photorefractive holograms

In this paper, a scheme using anisotropic diffraction to implement the 2 x 2 switching element in a one-block Fe:LiNbO3 photorefractive crystal is sug gested. To decrease the crosstalk among the four individual photorefractive holograms, a thermal fixing scheme by a CO2 laser is quoted. Based on the Kogelnik diffraction efficiency equation, the relation between the optimal incident intensity ratio and the writing angles is analysed. It is seen tha t the switch proposed has the properties of normal input, output and progra mmability.