OPTICAL MULTILAYER FILTER Russian patent published in 2008 - IPC G02B5/28 

FIELD: fibre-optic communication, optical multilayer filters.

SUBSTANCE: optical multilayer filter (OMLF) consists of an input optical transformer (In. OT 1), a selective part (SP 2), and output optical transformer (Out. OT 3) and substrates 5, 6. The In. OT 1, SP 2, and Out. OT 3 consist of N_In=2s, N_sp=4k and N_out=2r alternating layers 7 and 8, respectively, with high n_h and low n_l values of refractive indices of materials they are made of. The thickness of every layer d=0.25λ, where λ is the mean OMFL bandwidth wave length. Refractive indices of adjoining layers of the In OT and SP, and those of SP and Out.OT are equal. Note that the SP alternating layers are made from materials with refractive indices mirror-symmetric relative to the SP centre. The first layer of In. OT and the last layer of Out. OT are connected to substrates. Proposed are the relations to calculate the parameters of claimed arbitrary type OMLF.

EFFECT: reduction of signal distortion to preset magnitude in a wide frequency range of the filter attenuation in the preset bandwidth and increase in attenuation to the preset magnitude that allows wider application of the aforesaid filters.

3 cl, 7 dwg