All-optical full logic unit with femtosecond switching

We report on the realization of an all-optical full logic unit switching with a response time on the order of one femtosecond. The device is based on instantaneous transient gratings induced in a thin slide of barium fluoride by up to three femtosecond laser beam. The interference pattern from every two of the non-collinear beam is, via optical Kerr effect, translated into a transient index grating which reacts within one optical cycle on the input since the applied light frequency is far from resonance in the material. As one consequence of the grating two strong beams of self phase matched third harmonic are generated, emerging in the middle between the two transmitted fundamentals. By introducing a third femtosecond beam we are able to emulate a demultiplexer, a decoder and a simple adder. Since the output consists of the third harmonic of the input beam, the system works with uniquely high contrast.