Infrared Fiber for Conversion & Routing

We propose to use nano-structured Silicon photonic crystal fiber to convert near infrared (NIR) to Mid infrared using parametric amplification. Silicon has intrinsic properties that lend itself to this application. Silicon has very low loss in the Mid IR, high damage threshold, and high environmental stability. However, NIR pumps experience strong loss in bulk silicon crystal due to two-photon absorption (TPA), which prevents high-efficiency and high-power applications. Nano-structured silicon increases the bandgap through quantum confinement. Experiments show that no TPA occurs in nano-structured silicon beyond 1 micron. The benefits of nano-structured silicon also include enhanced third-order nonlinearity, which is 4 orders of magnitude bigger than that of lithium niobate. Nano structure makes silicon even more attractive for parametric conversion to Mid IR. Of Course, parametric interactions also require phase matching. We propose to use photonic crystal structure to provide dispersion engineering. We take advantage of the mature silica photonic crystal fiber (PCF) technology to fabricate silicon PCF, allowing phase matching and high power generation. The Silicon PCF Mid IR sources have many military applications such as LIDAR, remote biochemical sensing and IR countermeasures.