Methods for Estimating Modal Bandwidth Spectral Dependence

Abstract

Methods for estimating the Effective Modal Bandwidth (EMB) of laser optimized Multimode Fiber (MMF) at a specified wavelength, λS, based on the measured EMB at a first reference measurement wavelength, λM. In these methods the Differential Mode Delay (DMD) of a MMF is measured and the Effective Modal Bandwidth (EMB) is computed at a first measurement wavelength. By extracting signal features such as centroids, peak power, pulse widths, and skews, as described in this disclosure, the EMB can be estimated at a second specified wavelength with different degrees of accuracy. The first method estimates the EMB at the second specified wavelength based on measurements at the reference wavelength. The second method predicts if the EMB at the second specified wavelength is equal or greater than a specified bandwidth limit.

1 . A method for estimating modal bandwidth of multimode fibers at a set of wavelengths, based on a DMD measurement performed at only one wavelength λ M  comprising performing a DMD measurement at a first wavelength, extracting at least one signal feature, the signal feature bring at least one of a centroid, peak power, pulse width, and skew of the DMD measurement at the first wavelength, and predicting an at least one signal feature for a second wavelength based upon the at least one signal feature of the first wavelength, and using the predicted at least one signal feature of the second wavelength to estimate a modal bandwidth. 
     
     
         2 . A method for estimating the centroids and peaks of multimode fibers at a set of wavelengths, based on a DMD measurement performed at only one wavelength λ M . 
     
     
         3 . A method for estimating the DMD pulses energy position and width of multimode fibers at a set of wavelengths, based on a DMD measurement performed at only one wavelength λ M . 
     
     
         4 . A method to extract features of DMD pulses that describe spectral dependence of modal dispersion. 
     
     
         5 . A method for enabling machine learning of multimode fiber by identifying features and radial-offset regions that relates the EMB at two wavelengths. 
     
     
         6 . A method for predicting if EMB at an arbitrary wavelength, λ S , is equal or greater than a specified bandwidth threshold, EMB th , based on a DMD measurement at a different wavelength, λ M . 
     
     
         7 . A method according to 1 to reduce the testing time for fibers designed to operate at more than one wavelength. 
     
     
         8 . A method according to 2 to evaluate modal-chromatic dispersion properties of a MMF at multiple wavelength based on measurements at only one wavelength. 
     
     
         9 . A method according to 3 to predict differential mode delay, minimum effective modal bandwidth at more than one wavelength with reduced testing time for fibers designed to operate at more than one wavelength. 
     
     
         10 . A method according to  claim 1 - 4  to select MMFs with alpha parameters lower than the alpha optimum function at a desired spectral range. 
     
     
         11 . A method according to  claim 1 - 4  to select MMFs that produce modal-chromatic dispersion compensation at a desired spectral range. 
     
     
         12 . A method according to  claim 1 - 4  to select MMF that have desired modal bandwidth at desired spectral range, i.e 840nm 980 nm. 
     
     
         13 . A method according to  claim 1 - 4  to sort production in order to select standard compliant wideband fibers capable to operate in a desired spectral range, i.e. 840 nm to 1000 nm, without the need to measure the modal bandwidth at all the specified wavelengths. 
     
     
         14 . A method according to  claim 5 - 6  to sort production in order to select standard compliant wideband fibers capable to operate in a desired spectral range, i.e. 840 nm to 1000 nm, without the need to measure the modal bandwidth at all the specified wavelengths. 
     
     
         15 . A method according to  claim 1 - 6  to reduce the number of modal bandwidth measurements during manufacturing or quality test for MMFs. 
     
     
         16 . A method according to  claim 1 - 6  to design MMF that complies with modal bandwidth requirements at specific wavelengths based on the extracted features such as centroid, width, peaks, skews.