A new technique has been proposed for direct measurement of the cut-off wavelength, at which the first higher-order mode disappears. It uses a change of a near-field pattern of a fiber, which is excited by a variable wavelength source. The cut-off wavelength can be measured with +/-5-nm accuracy.
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The most suitable fiber length for precise measurement is 10-20 mm. It is found, furthermore, that the first higher-order mode under the condition near cut-off rapidly attenuates because of waveguide imperfections, in which the loss due to core-cladding boundary distortions is the most dominant.
Scope This information describes the reference method for measuring the fiber cutoff wavelength (λCF) and the cable cutoff wavelength on uncabled fiber. Cut-Off Wavelength. Cut-Off Wavelength is a term used to denote the wavelength at which the transmission decreases to 50% throughput in a shortpass filter. Cut-off wavelength is indicated by λ cut-off in Figure 6.
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ByOctober 18,2017The CUTOFF WAVELENGTH of a single mode fiber is the wavelength above which the fiberpropagates only the fundamental mode. Below cut-off, the fiber will transmit more than onemode.
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An optical fiber that is single-moded at a particular wavelength may have two or moremodes at wavelengths lower than the cutoff wavelength.The effective cutoff wavelength of a fiber is dependent on the length of fiber and itsdeployment and the longer the fiber, the lower the effective cutoff wavelength. Or the smallerthe bend radius of a loop of the fiber is, the lower the effective cutoff wavelength will be. If afiber is bent in a loop, the cutoff is lowered. The cutoff wavelength of a fiber is reduced when itis cabled. Sudipta Bhaumik is an Associate General Manager – Application Engineering in Sterlite Technologies Limited and located at Sterlite’s Center of Excellence, Aurangabad, India. He joined Sterlite in 1998 as process development engineer in Optical Fiber Plant. He holds a B.Tech degree in ceramic technology from Calcutta University, India and M.Tech degree in ceramic technology from IIT-BHU.
He has been engaged with research on quality, reliability and applications related issues of optical fiber and fiber optics cable and worked in various functions in optical fiber and cable manufacturing like Quality Assurance, Quality Control, Reliability Engineering, Process Engineering, Management Systems, Business Development and Application Engineering. He is American Society for Quality (ASQ) certified Six-Sigma Black Belt, Manager of Quality/ Business Excellence and Quality Auditor and IRCA approved Lead Auditor of Business Continuity Management System. He serves as a member of panel of examiners for national award on business/ manufacturing excellence. He is an expert member of IEC, ITU-T and BIS technical committees and actively participating in developing national and international Telecom standards. He has been representing India in IEC meetings.A frequent author of technical papers, white papers and application notes, he twice won the Urbain J.H.Malo award (by Wire Association International, USA) for most meritorious technical paper.
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