We experimentally isolate and directly observe multimode solitons in few-mode graded-index fiber. We rely on Raman frequency shifts to spectrally isolate these multimode solitons. By varying the input energy and modal composition of the launched pulse, we observe a continuous variation of multimode solitons with different spatiotemporal properties. They exhibit an energy-volume relation that is...

We report on a class of high-rate dc-free codes, called multimode codes, where each source word can be represented by a codeword taken from a selection set of codeword alternatives. Conventional multimode codes will be analyzed using a simple mathematical model. The criterion used to select the “best” codeword from the selection set available has a significant bearing on the performance. Variou...

A standard multimode optical fiber can be used as a general purpose spectrometer after calibrating the wavelength dependent speckle patterns produced by interference between the guided modes of the fiber. A transmission matrix was used to store the calibration data and a robust algorithm was developed to reconstruct an arbitrary input spectrum in the presence of experimental noise. We demonstra...

A 120o optical hybrid based on 3x3 multimode interference coupler is reported. The device exhibits less than 10o phase deviation over 55 nm in the Cand L-band. Keywords—120-degree hybrid; multimode interference coupler;

Speckle in optical coherence tomography (OCT) images originates in the high spatial coherence of incident light that enables interference of light backscattered from spatially heterogenous tissue specimens. We report results of a numerical simulation and an experiment to test speckle reduction using a partially spatially coherent source. A Gaussian-Schell model for a partially spatially coheren...

While ray optics is a valid model for many multimode optical systems, it cannot capture diffraction and interference phenomena which may be required, for example, in calculating speckle propagation in multimode fiber. Wave optics includes the effect of interference and diffraction, but it is usually much more costly computationally. We show how to bridge the gap between ray and wave optics by u...

Intersymbol interference (ISI) caused by intermodal dispersion in multimode fibers is the major limiting factor in the achievable data rate or transmission distance in high-speed multimode fiber-optic links for local area networks applications. Compared with optical-domain and other electrical-domain dispersion compensation methods, equalization with transversal filters based on distributed cir...

A low delay and low complexity speech coder based on Multimode Tree Coding is proposed. In our Multimode Tree Coder, a simple mode classification method along with frame energy are used to classify the input speech frames into five different modes. Each mode is coded at a suitable bit-rate using a Tree coder with computationally efficient perceptual error pre-weighting and post-weighting filter...

Radio over Fiber (RoF) is a promising technology for short range transmission applications within multimode optical fiber. Typically, the RoF link employs a single mode fiber. But the signal power at the remote antenna become small due to the power loss in the electrical to optical and optical to electrical conversion process. Coupling efficiency of an electrical to optical converter can be imp...

1 EIAiTIA 455-54A, ‘Mode scrambler requirements for overfilled launching conditions to multimode fibres’ 2 RADDATZ, L., WHITE, I.H., CUNNINGHAM, D.G., and NOWELL, M.c.: ‘Influence of restricted mode excitation on bandwidth of multimode fibre links’, ZEEE Photonics Technol. Lett., 1998, 10, (4), pp. 534-536 3 RADDATZ, L., WHITE, I.H., CUNNINGHAM, D.G., and NOWELL, M.c.: ‘An experimental and theo...