We report experimental results on enhanced light transmission through double-layered （Ag/Au） metallic hole arrays within a skin-depth. Zero-order transmission spectrums are characterized as a function of Ag film＇s thickness, which extends from 5/15, 5/6 to approximately 5, where 5 is a skin-depth. In contrast with other reported results （Refs. [11 - 13]） in single-layered metallic hole arrays, our experimental results show much more dramatic properties of transmission process dependent on sub-5 thickness. It is shown that there is no negligible transmission enhancement at 5/15. At 5/6, much higher transmission efficiency can be achieved. With film＇s thickness being close to 5, the transmission efficiency declines contrarily. Simultaneously, the corresponding resonant peak also slightly moves toward the shorter wavelength. It is proposed that the coupling of surface plasmon polaritons （SPPs） at Ag/Au interface within 5 is involved in the process.
