| 摘要 |
<p>The percentage fraction of fundamental mode power located in the cladding holes of different holey fibres (PFholes) is shown as a function of wavelength in microns of the fundamental mode (μ). Properties of two groups of holey fibres are shown. The upper group of three curves shows embodiments of the invention with Μ=0.75 νm and d/Μ=0.6, 0.7 & 0.8 respectively, where d is the hole diameter and Μ the hole spacing or pitch. The lower group of curves, which are almost superimposed on each other, show properties of holey fibres representative of the prior art with Μ=3.2 νm and d/Μ=0.6, 0.7 & 0.8 respectively. A huge improvement in the mode power present in the holes is evident. In the prior art curves, the mode power fraction is generally less than 1%, whereas with the illustrated embodiments of the invention, holey fibres with 10-40% of the fundamental mode power in the holes are achieved. Generally the holey fibre should be structured such that the wavelength of the guided light μ > 2.2Μ. For telecommunications wavelengths, this means that the hole spacing should be smaller than typical in the prior art, i.e. around 1νm or less, and the hole diameter should be as large as possible in relation to the hole spacing, preferably d/Μ > =0.6.</p> |
