Highly Nonlinear Chalcogenide Glasses for Ultrafast All Optical Switching in Optical TDM Communication Systems

Channel rates exceeding 40 Gbit/s are currently very difficult to achieve with high-speed electronics. Significantly higher channel rates (> 100 Gbit/s) require optical time division multiplexed (OTDM) solutions. Such OTDM systems rely on all-optical switching (AOS) and all-optical processing (or all-optical logic). Ultrafast optical switches require a highly nonlinear material with an extremely fast time response so that switching can be achieved with = 1 pJ pulse energy and = 1 ps pulse width. Typically the Kerr nonlinearity is employed in ultrafast AOS, since its non-resident character results in the required fast time response and in low absorption. On the other hand, the small value of the Kerr nonlinear refractive index n sub 2 often requires excessive switching powers. The goal is to maximize the nonlinearity and thereby to bring switching energies to the pJ regime while keeping the device dimensions small.