Properties of photonic crystal fiber and the effective index model

TLDR

The study reports the waveguiding properties of a new low‑loss optical waveguide. The authors engineer a photonic crystal fiber to support only the fundamental guided mode across silica’s transparency window and use an effective index model to quantify monomode requirements. Experimentally, a robust single mode was observed from 337 nm to beyond 1550 nm, with monomode requirements independent of fiber scale at short wavelengths and spot‑size variation confirming the effective index model predictions.

Abstract

We report the waveguiding properties of a new type of low-loss optical waveguide. The photonic crystal fiber can be engineered to support only the fundamental guided mode at every wavelength within the transparency window of silica. Experimentally, a robust single mode has been observed over a wavelength range from 337 nm to beyond 1550 nm (restricted only by available wavelength sources). By studying the number of guided modes for fibers with different parameters and the use of an effective index model, we are able to quantify the requirements for monomode operation. The requirements are independent of the scale of the fiber for sufficiently short wavelengths. Further support for the predictions of the effective index model is given by the variation of the spot size with wavelength.