WAVEGUIDE TYPE OPTICAL SWITCH

摘要

PURPOSE:To permit optical switching without making opto/electric signal conversion by providing a nonlinear material whose refractive index changes according to the intensity of the light to be projected to a switching part and providing a loop for positive feedback to part of a waveguide. CONSTITUTION:The coefft. of absorption of the nonlinear material 3 decreases and the refractive index thereof decreases as well when excitation light Pex of the wave length longer than the central absorption wavelength of the material 3 is entered to the waveguide 1. As a result, the refractive index decreases to the index smaller than the refractive index of a circumferential material 6 and part of the excitation light Pex is reflected in the direction of the waveguide 1'. Part of said light is guided to the waveguide 4 for feedback and is positively fed back after the light is amplified by an amplifier 5. The refractive index decreases in the final to cause total reflection. The total reflection is maintained even if the light Pex is cut off. Signal light Ps is totally reflected and is outputted from the waveguide 1' when said light is inputted in this state from the waveguide 1. On the other hand, the reflectivity restores 0 when the injection current Ia to the light amplifier 5 is decreased. In the state, the signal light Ps inputted from the waveguide 1 is outputted from the waveguide 2'.