We demonstrate, for the first time, a mid infrared silicon Raman amplifier. Amplification of 12 dB is reported for a signal at 3.39 micron wavelength. The active medium was a 2.5 cm long silicon sample that was pumped with 5ns pulses at 2.88 micron. Such a technology can potentially extend silicon photonics' application beyond data communication in the near IR and into the mid-IR world of remote sensing, biochemical detection and laser medicine. Challenges faced in the mid-IR regime such as a higher free carrier scattering rate longer lifetime in mid-IR waveguides are also discussed.

No abstract

Measurement of the Kerr nonlinearity in silicon is reported in the 2350 nm to 2750 nm wavelength range, where three-photon absorption effect is present. The measurements confirm that the Kerr interaction strength is comparable to that in the near-infrared. The measured dispersion trend for the Kerr coefficient is consistent with that obtained using Kramers-Krönig relations. Three-photon absorption was measured, and its effect on the nonlinear figure of merit in silicon appears not to be as restrictive as that of two-photon absorption. The results identify silicon as a promising platform for parametric processes in mid-infrared spectral region.

We revisit recent work on the generation of extreme optical events via nonlinear dynamics in silicon waveguides. The underlying processes, modulation instability and stimulated Raman scattering, are able to reshape normally distributed initial conditions into skewed output statistics whose properties can be tailored by controlling experimental variables. While these are both gain processes, they bear fundamental differences: modulation instability is a broadband parametric process, whereas stimulated Raman scattering is a narrowband inelastic process. As a result, they respond to different forms of input noise. Specifically, the extreme events generated spontaneously by modulation instability evidence a strong sensitivity to a particular input noise component. This sensitivity can be controllably seeded to generate coherent supercontinuum radiation, which also offers a means to alleviate conventional free-carrier limitations to chip-scale spectral broadening.

L-shape probability distributions are extremely non-Gaussian distributions that have been surprisingly successful in describing the frequency of occurrence of extreme events, ranging from stock market crashes and natural disasters, the structure of biological systems, fractals, and optical rogue waves. In this paper, we show that fluctuations in stimulated Raman scattering in silicon, as well as in coherent anti-Stokes Raman scattering, can follow extreme value statistics and provide mathematical insight into the origin of this behavior. As an example of the experimental observations, we find that 16% of the Stokes pulses account for 84% of the pump energy transfer, an uncanny resemblance to the empirical Pareto principle or the 80/20 rule that describes important observation in socioeconomics.