A new class of composite materials has emerged which provides a means
to control and manipulate light. These materials, known as photonic cr
ystals, are periodic arrays of dielectric scatterers in homogeneous di
electric matrices. They affect the properties of photons in much the s
ame way a semiconductor affects the properties of an electron. Consequ
ently, photons can have band structures, localized defect states, surf
ace states, etc. The ability to mold and guide light will lead to many
applications in the control of spontaneous emission and in the fabric
ation of novel optoelectronic devices. (C) 1997 Published by Elsevier
Science Ltd.