Experimental Evaluation of Recovery From Multiple Failures in Multicore Fiber Links Using FPGA-Based Optical Switch Units

We developed a novel failure recovery system utilizing a multicore fiber (MCF) link consisting of field programmable gate array (FPGA)-based optical switch (SW) units. A failure recovery scheme for managing the MCF link by means of monitoring signals (FRS-MS) was devised wherein the proprieties of the path usage are verified before the switching operation. It uses laser light signals to monitor protection paths in the MCF and selects the most available path as a protection path. Signal transmission experiments in point-to-point structures connected by an MCF link based on FRS-MS demonstrated that by switching in the event of multiple failures in the link, the path could be recovered within a short time period (approximately 8 ms). Performing a second (consecutive) switching after no signal was detected in the first switching in the event of other failures in the MCF link also led to recovery within a short time period (approximately 25 ms). These times are sufficiently less than that required by ITU-T. The results indicate that the MCF link and the FRS-MS operations embodied in FPGA-based SW units are useful for increasing the reliability of optical networks.