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Modes of Photonic Crystal Fibers

Simulation of photonic crystal fibres and micro-structured fibres with FIMMWAVE

A photonic crystal fiber (or PCF, also called microstructure fiber, holey fiber or hole-assisted fiber) is an optical fibre which obtains its guiding properties from an arrangement of air holes creating a photonic bandgap structure. Photonic crystal fibres were first introduced in the 1990s, and remain to this day a very active field of research.

FIMMWAVE allows you to explore the large variety of possible configurations for PCFs and to model accurately the properties of each resulting structure.

Design of a photonic crystal fibre in FIMMWAVE
Modes of a Photonic Crystal Fibre
Bend modes of a Photonic Crystal Fibre
Propagation in Photonic Crystal Fibres

Design of a Photonic Crystal Fibre in FIMMWAVE

FIMMWAVE comes packed with a flexible pre-defined shape which allows you to design a large variety of PCFs in just a few clicks, for both hollow-core and solid-core geometries.

Photonic Crystal Fibres designed with FIMMWAVE
Photonic Crystal Fibres designed with FIMMWAVE
with a hollow core (left) and a solid core (right)

Modes of a Photonic Crystal Fibre

FIMMWAVE was used to model a photonic crystal fibre with a band gap centred on 500nm using the FEM Solver, whose triangular mesh is ideal to render such cross-sections. The guiding region was created by "removing" the central hole. The mesh of the structure and the parameters of the design are given below.

Good results can also be obtained with the FDM Solver - the two methods are fully independent, which offers you an easy way to check your results.

Photonic Crystal Fibre and FEM mesh in FIMMWAVE
Photonic crystal fibre with the superimposed mesh of the FEM Solver;
the mesh only needs to describe a quarter of the cross-section thanks to the symmetries

lattice geometry hexagonal
bulk material silica
hole material air
lattice constant  0.3 um
hole diameter 0.2um

Parameters of the photonic crystal fibre

The FEM Solver found the fundamental TE-like and TM-like modes in a few seconds. The mode profile for the fundamental TM-like mode is given below, showing the confinement of the mode to the centre of the PCF. The FEM Solver provides you with extensive information regarding your modes, which includes the effective index, effective core area and dispersion.

Photonic Crystal Fibre mode profile
Intensity and Ey-field profiles near the core for the fundamental TM-like mode at 500nm

Photonic crystal fibre mode data
Mode data for the fundamental TM-like mode, including propagation constant and effective index,
effective core area, polarisation, group index and dispersion.

Bend Modes of a Photonic Crystal Fibre

You can see how the bend modes of this photonic crystal fibre were calculated with the FEM Solver here.

Bend modes of a photonic crystal fibre
Contour plot of the Ex-field profiles for the fundamental TE-like mode at 500nm
with no curvature (left) and a radius of curvature of 100um (right)

Propagation in Photonic Crystal Fibres

You can study light propagation in photonic crystal fibers using FIMMPROP, the propagation tool associated with FIMMWAVE. FIMMPROP will allow you to study the coupling between photonic crystal fibers and other waveguides, as well as propagation in tapered PCFs.

You can find here a simulation of a multicore photonic-crystal fiber used as 1x4 power splitter.

More publications 

Click here to find publications that include FIMMWAVE simulations of photonic crystal fibres on Google Scholar.