Edge interference filter for optical communication transmission in wavelength-division multiplex

Claim 1

In a glued edge interference filter for optical communication transmissions in a wave-division multiplex, said filter comprising a layer sequence arranged between adjacent outer substrates, said layer sequence being composed of alternately arranged layers having a high index of refraction and a low index of refraction, the two outer layers of the layer sequence, which are adjacent to the outer substrates, having the high index of refraction, the improvements comprising said layer sequence being composed of a total of 21 layers with each of the layers of the high index of refraction being composed of a material having an index of refraction of 2.08±0.05 and each of the layers having a low index of refraction being composed of a material having an index of refraction of 1.45±0.05, each of the individual layers having a standardized, optical layer thickness of 3/4 wavelength of an attenuation band center wavelength of 823 nm obtained at 20° angle of incidence, said layer thicknesses having an allowable deviation of at most 2% with the first and twentyfirst layers having a thickness of 0.241 of the standardized thickness, the second and twentieth layers being of a thickness 0.914 of the standardized thickness and the third through the nineteenth layers having a thickness of one standardized thickness.