When Ebbesen et al. first reported in a now famous paper that a thin metal film perforated with an array of subwavelength-sized holes can transmit much more light than expected, they immediately suggested the involvement of surface plasmons. Surface plasmons are electromagnetic surface waves that propagate at the interface between a metal and a dielectric by the collective motion of electrons. Unlike most guided modes, the electric fields associated with surface plasmon modes are evanescent, and decay exponentially with distance from the interface. But once excited by an optical field at a hole in a metal film, they can travel several micrometers along the films surface before eventually being absorbed. However, they can turn back into a freely propagating optical wave when they are scattered at another hole or groove. This interplay between light waves and surface plasmons apparently enables enhancement of transmission. More importantly, the realization that surface plasmons can give rise to potentially useful phenomena has given birth to an entire new field, known as plasmonics. Recently however, the explanation of enhanced optical transmission through nano-holes in terms of plasmons has been challenged. In this dissertation, light transmission enhancement through metallic subwavelength holes and emission of a dipole antenna inside the cavity has been studied to understand the coupling mechanism of the transmission behaviors, as well as the limiting role of the cavity on emitting antennas inside the cavity. In our experimental research with various aperture sizes, the transmission and emission resonances have been measured and characterized for the relationships between the holes geometry and transmission as well as the quantum efficiency of the emission inside the cavity. Throughout this work, we have achieved several outstanding breakthroughs in the study of light transmission enhancement which consist of the following: 1) Photoluminescence effects with optically thin metal film. 2) The relationship between the transmission behaviors and aperture size. 3) The quantum efficiency of cavities with regards to dipole position and cavity size. 4) The significant role of cavity geometry in fluorescence excitation spectrum inside the cavity.