Good things in small packages

摘要

Starting with the principal of total internal reflection, which guides light through optical fiber, the fundamentals of optics have led to some very successful telecommunications products. Such products are needed now to bring on the full-fledged deployment of optical networking in metro and access markets. And surely the simple, innovative application of optical design principals to components will play a critical enabling role. High on the list of fundamental optical principals is diffraction. As light travels, it constantly interferes with itself-if it encounters no objects, it moves along without bending. But objects such as apertures or edges modify the interference, causing the light to bend, or diffract. It's a phenomenon first discovered by the Italian Jesuit priest and astronomer Francesco Grimaldi (1618-63) and defined by French civil engineer and physicist Augustin Jean Fresnel (1788-1827). Over the subsequent years, clever design of diffractive optics has led scientists and engineers to control optical wavefronts in many ways, including products such as laser pointers, DVD players, digital cameras, laser welding equipment, and medical diagnostic devices. Diffracting light in optical-networking components is a relatively old story, too, but some recent creative thinking may result in very-low-cost components aimed at the metro and access markets.