Kobayashi M, Terui H, Egashira K
Appl Opt. 1978 Feb 1;17(3):486-90. doi: 10.1364/AO.17.000486.
Novel optical-waveguide mode filters, based on mode-selective coupling between nonidentical waveguides and attenuation in a lossy waveguide, are proposed and demonstrated. Both TE(0) and TM(0) mode filters were fabricated from glass compositions by rf-sputtering. For both the TE(0) and TM(0) mode filters, insertion losses were 2.1 dB and 1.1 dB, respectively, and attentuations for undesirable modes were 16.8 dB and 21.6 dB, respectively.