Murakami Y, Kawana A, Tsuchiya H
Appl Opt. 1979 Apr 1;18(7):1101-5. doi: 10.1364/AO.18.001101.
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. 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.
已经提出了一种用于直接测量截止波长的新技术，在该波长下，第一高阶模消失。它利用由可变波长源激发的光纤近场图案的变化。截止波长的测量精度可达±5纳米。精确测量最合适的光纤长度为10 - 20毫米。此外还发现，在接近截止的条件下，第一高阶模由于波导缺陷而迅速衰减，其中由于纤芯 - 包层边界畸变引起的损耗最为显著。
