FIBRE OPTICAL COUPLER SIMULATION BY COMSOL MULTIPHYSICS SOFTWARE

Funding: The research has been supported by the European Regional Development Fund project No.1.1.1.1/18/A/068. The Institute of Solid State Physics, University of Latvia as a Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.The paper presents a simulation model developed for a special optical coupler intended for coupling radiation from signal and pump sources used for the realization of cladding-pumped doped fibre amplifiers. The model is developed in COMSOL Multiphysics and used to assess the pumping efficiency for different side pumping angles and different numbers of electromagnetic modes. The obtained results show that the highest pumping efficiency, above 75 %, is achieved for 5–14 modes when two fibres representing the pump source and the signal source form a 10-degree angle between their central axes. The search for the optimal number of modes corresponds to the development trend in optical coupler technology where the multimode pumping by light-emitting diode (LED) replaces the classical scheme with a single-mode pumping by a laser diode (LD). © 2022 Sciendo. All rights reserved. --//-- This is an open access article Elsts E., Supe A., Spolitis S., Zakis K., Olonkins S., Udalcovs A., Murnieks R., Senkans U., Prigunovs D., Gegere L., Draguns K., Lukosevics I., Ozolins O., Grube J., Bobrovs V. FIBRE OPTICAL COUPLER SIMULATION BY COMSOL MULTIPHYSICS SOFTWARE (2022) Latvian Journal of Physics and Technical Sciences, 59 (5), pp. 3 - 14, DOI: 10.2478/lpts-2022-0036 published under the CC BY-NC-ND 4.0 licence.ERDF No.1.1.1.1/18/A/068; The Institute of Solid State Physics, University of Latvia as a Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2

FPGA-Implemented Fractal Decoder with Forward Error Correction in Short-Reach Optical Interconnects

Forward error correction (FEC) codes combined with high-order modulator formats, i.e., coded modulation (CM), are essential in optical communication networks to achieve highly efficient and reliable communication. The task of providing additional error control in the design of CM systems with high-performance requirements remains urgent. As an additional control of CM systems, we propose to use indivisible error detection codes based on a positional number system. In this work, we evaluated the indivisible code using the average probability method (APM) for the binary symmetric channel (BSC), which has the simplicity, versatility and reliability of the estimate, which is close to reality. The APM allows for evaluation and compares indivisible codes according to parameters of correct transmission, and detectable and undetectable errors. Indivisible codes allow for the end-to-end (E2E) control of the transmission and processing of information in digital systems and design devices with a regular structure and high speed. This study researched a fractal decoder device for additional error control, implemented in field-programmable gate array (FPGA) software with FEC for short-reach optical interconnects with multilevel pulse amplitude (PAM-M) modulated with Gray code mapping. Indivisible codes with natural redundancy require far fewer hardware costs to develop and implement encoding and decoding devices with a sufficiently high error detection efficiency. We achieved a reduction in hardware costs for a fractal decoder by using the fractal property of the indivisible code from 10% to 30% for different n while receiving the reciprocal of the golden ratio