Broadband tunable optical delay based on real-time Fourier transformation and ramp-type phase modulation

A new tunable optical delay scheme based on real-time Fourier transformation and ramp-type phase modulation is proposed and experimentally demonstrated. A linearly chirped fiber Bragg grating is adopted to implement the real-time Fourier transformation, and tunable delay is realized by changing the ramp-type modulating signal’s period. Experimental results agree well with the theory. The signal distorts little after the delay, and a 18 ps delay is achieved for a 2-ps-wide optical pulse.