A scheme using anisotropic diffraction to implement the 2×2 switching element in a one block Fe∶LiNbO 3 photorefractive crystal is suggested. To decrease the crosstalk among the four individual photorefractive holograms, a thermal fixing scheme by a CO 2 laser is quoted. Based on Kogelnik diffraction efficiency equation, the relation between the optimal incident intensity ratio and the writing angles is analyzed. It is shown that the switch proposed has the properties of normal input, output and miniaturization.