Mode scrambler

About: Mode scrambler is a research topic. Over the lifetime, 896 publications have been published within this topic receiving 13595 citations.

Polarization scrambler unit and multi-repeater transmission system incorporating the same

Abstract: The present invention minimizes trouble and loss caused by a failure polarization scrambler. A polarization scrambler unit 201 of the invention is provided with: two polarization scramblers 2 - 1 and 2 - 1 ; a switching unit for coupling either one of the polarization scramblers 2 - 1 and 2 - 1 to a transmission line fiber 4 ; a detection unit for detecting an output signal from the polarization scrambler 2 - 1 (or the polarization scrambler 2 - 2 ) coupled to the transmission line fiber 4 ; and a controlling unit for switching, via the switching unit, between the polarization scramblers 2 - 1 and 2 - 2 whenever a false output signal is detected by the detection unit. Thus, the polarization scrambler unit 201 has a redundant structure.

Fourier-domain low-coherence interferometry for differential mode delay analysis of an optical fiber.

Abstract: We propose a novel mode analysis and differential mode delay measurement method for an optical fiber using Fourier-domain low-coherence interferometry. A spectral interferometer based on a Mach-Zehnder interferometer setup was used with a broadband source and an optical spectrum analyzer to detect relative temporal delays between the guided modes of a few-mode optical fiber by analyzing spectral interference signals. We have shown that experimental results of the proposed method agree well with those results obtained by using a conventional time-domain measurement method. We have demonstrated that this new mode analysis technique has high sensitivity (<60 dB) and very good resolution (<1 ps/m).

Acoustooptic Generation and Characterization of the Higher Order Modes in a Four-Mode Fiber for Mode-Division Multiplexed Transmission

Abstract: We demonstrate a highly efficient acoustooptic mode converter for selective excitation of the higher-order modes in a four-mode fiber which guides the LP01, LP11, LP21, and LP02 modes at telecommunication wavelengths. The coupling efficiency and the mode extinction ratio are measured by analyzing the output far-field patterns. The acoustic resonance frequencies and the operating bandwidths are compared with the theoretical results, by which the modal characteristics, the core diameter, and the core-cladding index difference are estimated.

Mode control in multimode optical fibre and its applications

Abstract: This thesis describes an investigation into methods for controlling the mode distribution in multimode optical fibres. The major contributions presented in this thesis are summarised below. Emerging standards for Gigabit Ethernet transmission over multimode optical fibre have led to a resurgence of interest in the precise control, and specification, of modal launch conditions. In particular, commercial LED and OTDR test equipment does not, in general, comply with these standards. There is therefore a need for mode control devices, which can ensure compliance with the standards. A novel device consisting of a point-load mode-scrambler in tandem with a mode-filter is described in this thesis. The device, which has been patented, may be tuned to achieve a wide range of mode distributions and has been implemented in a ruggedised package for field use. Various other techniques for mode control have been described in this work, including the use of Long Period Gratings and air-gap mode-filters. Some of the methods have been applied to other applications, such as speckle suppression and in sensor technology. A novel, self-referencing, sensor comprising two modal groups in the Mode Power Distribution has been designed and tested. The feasibility of a two-channel Mode Group Diversity Multiplexed system has been demonstrated over 985m. A test apparatus for measuring mode distribution has been designed and constructed. The apparatus consists of a purpose-built video microscope, and comprehensive control and analysis software written in Visual Basic. The system may be fitted with a Silicon camera or an InGaAs camera, for measurement in the 850nm and 130nm transmission windows respectively. A limitation of the measurement method, when applied to well-filled fibres, has been identified and an improvement to the method has been proposed, based on modelled Laguerre Gauss field solutions.