CONCENTRATION OF AN OPTICAL-FIELD IN AN OPTICAL COAXIAL LINE

A study is reported of the characteristics of the principal wave in an optical coaxial metal waveguide. The real properties of metals at opt ical frequencies are taken into account. An approximate formula is der ived for the dependences of the eigenvalues of the transverse wave vec tors on the geometric parameters of a coaxial line and on its permitti vity. The exact eigenvalues are determined for several values of the p arameters of practical interest. It is shown that such a coaxial line can concentrate radiation with domains much smaller than the radiation wavelength.