Subpicosecond light pulses induced by Fano antiresonance buildup process

We propose a simple technique of cutting short pulses out of a sharp edge input signal. The technique is based on the Fano antiresonance buildup dynamics. The output pulse duration is inverse proportional to the coupling strength to the resonator. We show that this coupling can be effectively increased by using more than one resonator and exploiting the antiresonance coalescence phenomenon. Analytical calculations for a model of standing-wave resonators and whispering gallery mode (WGM) resonators are performed within the coupled mode theory. We show that the latter can provide better pulse compression. Analytical results for WGM resonators are verified numerically by finite difference time domain method. Ability to generate pulses as short as a few hundreds of femtoseconds at 1.55 μm wavelength has been demonstrated for a potentially CMOS compatible silicon waveguide, which does not require optical nonlinearities to operate.