SCATTERING IN TWIN-CAVITY NARROW-BAND INTERFERENCE FILTERS ILLUMINATED BY A MONOCHROMATIC BEAM

The scattering behavior of the all-dielectric twin-cavity narrow-band interference filter is studied both in theory and in experiment in two cases, l(1) = l(2) and l(1) not equal l(2), where l(1) and l(2) are t he optical thicknesses of the two cavities. It has been shown that the scattering properties are determined mainly by the spacers in which t he electric-field intensities are large because of the presence of lar ge standing-wave fields. The scattered light cones are found on both s ides of the filter illuminated by a monochromatic light of which the w avelength (lambda(L)) is shorter than the peak wavelength (lambda(0)') of the filter. The scattering angle of each cone is equal to the tilt ed angle of the filter when the peak wavelength of the filter shifts t o the For the case l(1) not equal l(2), the distributions of the scatt ered light on both sides of the The analytical calculations are in goo d agreement with experimental results. The possible applications of sc attering in the twin-cavity filter in determining the bandwidth of the peak transmittance and the optical thicknesses of two spacers are add ressed. (C) 1997 Optical Society of America.