Finite-cladding fibres: HE12 and local-normal-mode coupling evolution

Abstract

A discussion of the evolution of the HE 12 (LP 02 ) field, and thus the role of the core in H E n -H 1 2 (LP 01 -LP 02 ) local-mode coupling for a tapered 'doubly-clad' lightguide as may be formed by the combination finite-cladding fibre and external medium (i.e. outer cladding) is presented. Consideration of more than one interface injects interesting novel features into the local-normalmode viewpoint: examination of the HE 12 lobe maximum and field evolution leads to the discovery of a core/cladding bounce phenomenon (related to an HE 12 leaky-mode property) as well as an intriguing coupling phase dependence.

Optical Gas Sensor Fabrication Based on Porphyrin-Anchored Electrostatic Self-Assembly onto Tapered Optical Fibers

“…These two modes propagate, with different effective refractive indices, to the end of the tapered waist, and then will couple back to the LP 01 mode of the fiber through the second conical region. Interference between these modes produces a sinusoidal channeled spectrum (Black, Bures, and Lapierre 1991;Kieu and Mansuripur 2006). This effect has been used previously to demonstrate sensors for temperature and surrounding refractive index, based upon the differential response of the two modes of the tapered region (Kieu and Mansuripur 2006).…”

Tapered Optical Fibre Sensors: Current Trends and Future Perspectives

“…Depending on the taper geometry, optical fibre tapers can be divided into adiabatic and non-adiabatic types: if the angle of the taper transition region is small and the cylindrical symmetry of the optical fibre is retained, resulting in most of the optical power remaining in the fundamental mode the tapers are considered adiabatic; if the optical power is coupled into higher order modes the tapers are non-adiabatic tapers. For non-adiabatic tapers of diameter less than 10 μm, the linearly polarised, LP 01 , mode of the single mode fibre generally couples to the HE 11 and HE 12 modes of the tapered waist [35,47], which propagate with different effective indices along the taper waist and interfere when recombine at the second taper transition (Figure 5a). The corresponding channelled spectrum is shown in Figure 5b.…”

Response of the transmission spectrum of tapered optical fibres to the deposition of a nanostructured coating

“…In non-adiabatic tapers the LP 01 mode generally couples to the HE 11 and HE 12 modes of the tapered waist [14,15]. These two modes propagate, with different effective refractive indices, to the end of the tapered waist, and then will couple back to the LP 01 mode of the fibre through the second conical region.…”