We present results of transmittance measurements on periodic layers of
Ag/MgF2 at optical and microwave frequencies. These one-dimensional,
photonic band gap materials exhibit transparency bands at optical freq
uencies and a huge stop band that extends throughout the near-IR to mi
crowave frequencies and beyond. A unique feature of these metal/dielec
tric photonic band gap (MD-PBG) materials is that the overall transmit
tance in the pass band may increase as more periods are deposited. The
center frequency, width, and sharpness of the pass bands are adjustab
le and generally depend on the thickness of the layers and the number
of Ag/MgF2 periods. These simple periodic structures have applications
as sensor and eye protection devices, heat reflecting windows, ultrav
iolet blocking films, and transparent electrodes for light emitting di
odes and liquid crystal displays. (C) 1998 American Institute of Physi
cs. [S0003-6951(98)03214-8].