Limiting Nature of Continuum Generation in Silicon

Spectral broadening in silicon is studied numerically as well as experimentally. Temporal dynamics of the free carriers generated during the propagation of optical pulses, through the process of two-photon absorption (TPA), affect the amplitude and phase of the optical pulses, thereby determining the nature and extent of the generated spectral continuum. Experimental results are obtained by propagating pico-second optical pulses in a silicon waveguide for intensities that span two orders of magnitude (1-150 GW/cm2). These results validate the conclusions drawn from numerical simulations that the continuum generation has a self-limiting nature in silicon.