Abstract: In order to provide price information to customers quickly a fast reflector switch is used. This helps to ensure that price information provided to customers is as up-to-date as possible. To determine a price for use of a particular route in a communications network, the available resources at each node in that route are assessed. The most congested node in that route is selected and a price determined on the basis of the available capacity at that node. This price is then delivered to the customer via the fast reflector switch. In another example, the average amount of available resources at each node in the route is determined over a specified time period. The standard deviation of the resource level values at each node over the specified time period is also determined. A price is then set on the basis of the sum of the average amounts and the sum of the standard deviations. In this way a price which takes into account recent variation in traffic levels as well as average traffic levels is provided.

Abstract: A launcher for waves of selected mode in an optical dielectric waveguide having a core surrounded by cladding, in which the launcher includes a prism of refractive index greater than that of the waveguide and preferably greater than that of the core of the waveguide which is placed against the waveguide either before or alongside an outwardly tapering portion of the waveguide. Light from a laser is directed through the prism on to the waveguide to induce the waves in the waveguide. A matching fluid, which may set to a solid, improved the coupling of the prism to the waveguide. A detector of similar construction is also described, the tapering of the waveguide being inward.