Misalignment Losses Research Articles

Insertion loss reduction between single-mode fibers and diffused channel waveguides

Methods of reducing the insertion loss between single-mode fibers and graded-index channel waveguides, namely, annealing and backdiffusion, are analyzed theoretically and compared. Mode mismatch and misalignment losses are calculated to determine the best method and the optimal conditions for their use. The main result of this paper is that, in the single-mode regime, there is no apparent advantage in using backdiffusion instead of the simpler annealing process, in contrast with the multimode case. In the coupling loss calculation, a numerical simulation of waveguide formation by potassium-sodium ion exchange in glass is used for illustration.

Coupling Between an Abruptly Terminated Optical Fiber and a Dielectric Planar Waveguide

The coupling between an optical fiber and a dielectric planar waveguide is analyzed when both guides are terminated abruptly and are facing each other. Mixed spectrum eigenwave representations of fields are employed inside the waveguides while Fourier integrals are utilized to describe the field in the space between the two guides. A coupled system of integral equations is derived by satisfying the boundary conditions on the terminal planes of both waveguides. A weak guidance approximation is assumed to facilitate the analysis. Numerical results are presented for several coupling geometries. Misalignment losses and coupling optimization phenomena are investigated.

Design and characteristics of a branching component for bunched optical fiber using two graded-index rod lenses

An optical branching component is proposed for coupling bunched optical fiber to mono-core optical fibers and the component loss and crosstalk characteristics are investigated. The component is constructed with two graded-index (GRIN) rod lenses for matching different parameters between bunched and mono-core optical fibers. The method of analyzing mismatching and misalignment losses is based on geometrical optics. Measured losses are found to be in agreement with the calculated results and demonstrate that bunched optical fibers can be branched with low loss. Crosstalk measurements show that crosstalk attenuation greater than 30 dB can be easily maintained in the component.

Misalignment losses at multimode graded-index fiber splices and GRIN rod lens couplers

A geometric optics model to describe transverse offset splice loss in multimode graded-index fiber, which has been adapted to evaluate misalignment losses at a graded-index rod (GRIN rod) lens-to-lens coupler, is reported. In both cases, the model gives close agreement with experimental measurements. Finally, in contrast with fiber splice losses, invariance of the lens coupler loss with the optical launch and receive conditions is shown.