Single-mode fibre optic directional coupler

UV inscribed long period gratings with femtosecond ablated axial fibre slots for polarization control

“…Currently, there are three main approaches for polarisation control in optical fibres; i) side polished D-shaped optical fibre coated with a thin metallic layer; the core mode of the optical fibre selectively couples to the polarisation dependent surface plasmon mode 1 ; ii) D-shaped optical fibre embedded in birefringent crystals, where the core mode interacts with the polarisation dependent crystals allowing for the extinction of one polarisation mode and the propagation of the orthogonal state 2 ; iii) the UV laser inscription of Bragg grating structures tilted at 45 o from the fibre core axis; the tilt strongly out couples the S polarised light to the radiation modes, whilst the P polarised light remains bound in the fibre core 3 . These techniques are efficient but have disadvantages, such as the weakness of the D-shaped fibre and the consistency and repeatability of the inscription of the tilted grating structures in hydrogen loaded fibre.…”

Estimating Performance of Fiber Optic Modulators/Switches with Multimode Electrooptic Overlay/Interlay Waveguide

“…In-line fiber components [1,2], based on evanescent coupling of a single-mode side-polished fiber (SPF) [3] to a highly multimoded active or passive overlay, have attracted a considerable amount of R & D interest in recent years [4,5]. Such a ''continuous fiber'' component [5] overcomes the severe interfacing problems between the signal fiber and the existing components encountered in bulk and integrated optics.…”

An Optical Routing Switch Using Coupled Erbium Doped Fibres

“…This is the basis of the fused fibre coupler [1] and of polished couplers [2] . In this letter we consider the effect of asymmetric loss or gain on the properties of linear couplers and show how these can be used to design an all-optical cross-bar switch .…”