The intrinsic cutoff wavelength of the LP11 mode is investigated using three different types of measurement for an ITT single-mode fiber. Characterization of the far-field pattern of the LP01 mode gives a cutoff value ~660 nm, a near-field transmission experiment gives ~690 nm, and a refracted power measurement gives ~830 nm. We conclude that the refracted power technique is the best experimental method for the determination of the intrinsic cutoff wavelength of a fiber sample. The effect of the loss of coupling efficiency into the LP11 mode as cutoff is approached on the transmission and refracted power experiments is noted.
C. C. Wang, C. A. Villarruel, and W. K. Burns, "Comparison of cutoff wavelength measurements for single-mode waveguides," Appl. Opt. 22, 985-985 (1983)