Feature

Evanescent Coupling, Part 2

Masud Mansuripur

Last month we began a discussion of electromagnetic coupling between objects that are close enough to sense each other's evanescent fields without making physical contact. This subject has received widespread attention in recent years as manufacturers of optical data storage systems have attempted to increase recording densities by flying a solid immersion lens over the surface of a magnetooptical disk, taking advantage of the evanescent coupling of a focused laser beam into and out of the disk. This month's column is devoted to a description of magneto-optical disks, in general, and the nature of their interaction with the solid immersion lens, in particular.