All-fiber architecture for high speed core-selective switch for multicore fibers

Introduction

Optical fibers are essential for modern high-speed communication systems, with an ubiquitous presence in access, metropolitan and inter-continental networks. To satisfy the increasing demand for data transmission, optical fibers need to increase their information carrying capacity, and to do so, space division multiplexing (SDM) has been acknowledged as one of the potential solutions to the impending capacity crunch of optical fiber links and networks^{1, 2, 3–4}. The main idea behind SDM is to employ specially designed fibers that can support multiple optical spatial modes, thus providing new transmission channels within the fiber that can increase the multiplexing capabilities. Nonetheless, several challenges still need to be resolved for the deployment of high-capacity SDM optical networks^3,5. For instance, the development of devices such as optical amplifiers, multiplexers and optical switches is crucial for their integration with the actual telecommunication infrastructure.

Among the candidate technologies for SDM, multicore fibers (MCF)-fibers with multiple cores in a single cladding with standard fiber diameter - have shown potential to transmit large data rates for short- and long-reach links. In this case, each available core mode is used as an extra and independent transmission channel, each one being compatible with standard wave-division multiplexing (WDM) techniques. Recently, throughputs of 10.66 Pbps over a distance of 13 km⁶, and 10.16 Pbps over 11 km⁷, were demonstrated using few-mode multicore fibers (FM-MCF). For long reach systems, transmission of up to 120 × 100 Gbps channels in 4-core MCFs was performed over 2768, 4014, and 5350 km^8,9, while using 7-core MCFs, as many as 201 × 100 Gbps channels were transmitted over a transatlantic link of 7326 km¹⁰.

Despite the aforementioned breakthroughs, operating an optical network requires the network manager to successfully allocate resources for each of the users. To do so, the selection of a core to transmit a given signal and devices capable of performing this operation will be a critical part of operating an MCF optical network. Depending on the property used to switch a signal in an optical node, four switching granularities have been identified as requisites for multi-dimensional SDM nodes¹¹, namely: independent spatial mode/wavelength channel switching; spatial mode switching across all wavelength channels; wavelength switching across all spatial modes; and, wavelength switching across spatial mode subgroups.

For MCFs,...