Single polarization fiber and method of evaluating fiber cutoff wavelengths using optical time domain reflectometry

A method for measuring fundamental mode cutoff wavelength of single polarization fiber comprising:

• 1) sequentially launching pulsed light of multiple wavelengths λi into one end of the single polarization fiber;
• 2) sequentially measuring backscattered light intensity corresponding to each of said multiple wavelengths to obtain the backscattered light intensity as a function of fiber position at each wavelength, wherein the backscattered light propagates through the same end of the fiber;
• and
• 3) determining the fundamental mode cutoff wavelengths and the corresponding positions within said fiber for each of the cutoff wavelengths, based on a specified threshold of light intensity level.