Analytic description of microcylindrical cavity for surface plasmon polariton

We consider the formation of the surface plasmon polariton (SPP) mode in the microcylinder cavity. Developed theoretical model allows to analytically calculate the closed-form expressions for the mode field distributions, resonant frequency, as well as the radiation and dissipative parts of quality factor of the structure in a broad wavelength range. For the conditions when a radius of a metallic cylinder is in order of SPP's wavelength, the highest value of Q-factor is achieved in infrared region of the spectrum where the absolute value of the real part of dielectric permittivity of the metal is much more than both the imaginary part of dielectric permittivity of the metal and the dielectric permittivity of surrounding media. Also, the radiation losses decrease with increasing of radius of cylinder. The obtained results give opportunity to find optimal conditions for having efficient emission in microcylinder cavity and it can serve as practical guidelines to design SPP microcavity for stimulated emission.