Device for selectively increasing higher-order mode losses in an optical fiber

A device for selectively increasing higher-order mode losses in a fiber communication system, comprising:

• an optical fiber taper, configured to be connected to a multi-mode fiber of a specific wavelength, the optical fiber taper comprising:
• a first non-tapered region and a second non-tapered region, each having a diameter equal to a diameter of the multi-mode fiber;
• a waist region having a diameter that is smaller than the diameter of the first and second non-tapered regions;
• a first transition region between the first non-tapered region and the waist region having a diameter that transitions from that of the first non-tapered region where the first transition region meets the first non-tapered region to that of the waist region where the first transition region meets the waist region;
• wherein a ratio of taper is defined by a ratio of a difference in diameter between the diameter of the first and second non-tapered regions and the diameter of the waist region over the diameter of the first and second non-tapered regions, and the ratio of taper is at least twenty percent;
• wherein the first transition region and the waist region each have a length of at least 0.5 millimeters;
• a filtering substance covering at least a portion of the optical fiber taper at the waist region, and wherein the filtering substance has at least one of emissive, absorptive, or light attenuating properties;
• wherein the filtering substance is selected from a group including paraffin, petroleum jelly, fatty acids, fatty acid salts, fatty acid esters, graphite, graphene, soot, carbon, polymers dissolved in polystyrene, ethyl cellulose, nitrocellulose, cellulose acetate, methyl cellulose, polyvinyl acetate, methyl methacrylate, polyvinyl chloride, ethylene-vinyl acetate, acrylic, octane-cellulose, butyl-cellulose polymers, polyimides, polyamides, polyolefins, perfluored polymers, R—Si—O organosols, polydimethylsiloxanes, polybutadiene rubber, ultraviolet-hardened polymers, epoxy resins, epoxy-acrylic resins, urethane-acrylic resins, silicone-epoxy resins, silicone-acrylic resins, metallic layers, metal oxides, glycerin, toluene, styrene, carbon tetrachloride, carbon disulfide, silicone oil, concentrated carbohydrate solutions, immersive oil, or mixtures thereof;
• an optical fiber cladding material surrounding the optical fiber taper;
• and
• wherein the filtering substance has a higher refractive index than a refractive index of the optical fiber cladding material.