The invention discloses a method for realizing guided-mode
resonance filtering through a single gradient-material
grating structure, and belongs to the field of an
optical communication and MOEM (micro optical electro mechanical)
system. The method is characterized in that an
optical thin film, the
refractive index of which increases progressively with the thickness, is prepared on a substrate, and by
etching the refractive-index-gradient thin film, a guided-mode resonant
grating structure is obtained, and furthermore, guided-mode
resonance filtering can be realized; on the basis of the above, by selecting different
etching depths, channel position of a filter can be adjusted; and with the
etching depth being kept unchanged, by reducing gradient coefficient, multichannel filtering can be realized. The filtering performance of the guided-mode resonant
grating structure is highly insensitive to change of substrate
refractive index, so that even if the substrate
refractive index is higher than the maximum value of the refractive index of the gradient thin film, the guided-mode
resonance filtering performance keeps excellent; and the method breaks away from the limit that refractive index of a
waveguide layer in a conventional guided-mode resonance filter needs to be higher than the substrate refractive index, and is more advantageous in practical application.