SINGLE MODE OPTICAL FIBER STRUCTURE HAVING HIGH-ORDER MODE EXTINCTION FILTERING FUNCTION

摘要

The present invention relates to the field of optical fibers and optical communication using the same transmitting the light, the longitudinal axis of the waveguide When viewed sequentially incident light, is input by a plurality of modes from the input optical fiber, the size or the refractive index of the core cross-section transition zone (transition region) and gradually decreasing, single mode region to support only a single mode in a short wavelength (single-mode region) and, again, has a structure consisting of a further cross-sectional size or the refractive index transition zone to recover the core, light in the light of the short wavelength of the higher mode in a single mode region by passing through the cladding to prevent high-order mode not return back to the core removing power, and provides a higher-order mode optical fiber filter for removing light of a fundamental mode that is not removed again, characterized in that the output to the optical fiber. This is particularly the diameter of the core and cladding in the longitudinal direction of the optical fiber was reduced again, and the taper waist to recover (tapered waist) the structure and the cladding and the refractive index of the cladding is equal to or outside of the form shell is easily implemented by giving a high cladding. According to the present invention, in the wavelength band other than the single mode to single mode transmission given the characteristics of the optical fiber provides gain in the transmission of optical signals, especially the shorter wavelength of the optical signal mode-dispersion (modal dispersion) without transfer in a high-speed modulation can be.