Cladding Pumped Amplifier Using Seven-core EDF

Increases on the internet traffic, such as the increase of the mobile network utilization, the start of IoT related services, etc., are still accelerating. Efforts to increase the communication capacity, such as a higher speed of the transmission speed itself, a multiplexing, etc., are under way and the development is accelerating towards the realization of the space-division multiplexing transmission technology which is a new multi axis. The major topic of the space-division multiplexing is a multicore optical fiber and a utilization of the mode-division multiplexing technology. A standard optical fiber has a core arranged in the center portion of the fiber to propagate a signal, whereas a multicore fiber has a plurality of cores arranged in one fiber so that the transmission capacity is physically expanded. The mode-division multiplexing technology is the one that increases the number of modes propagating in one core and can treat each mode independently. In recent years, a lot of research results, such as an ultra large capacity transmission experiment using a multicore fiber and a mode-division multiplexing technology, etc., have been reported and the space-division multiplexing transmission is also beginning to be adopted in practical use. Along with the expansion of the number of cores used in the fiber cable due to the development of the spacedivision multiplexing technology, the avoidance of increasing the load for the repeater apparatus is also required. It can be said that the most common repeater apparatus is an amplifier. Up to now, the multiplexing has been performed on the frequency axis and the time axis of one fiber. Therefore, it was not necessary to increase the number of amplifiers, but for the multicore fiber, one amplifier is required per core. For this reason, the necessity of the space-division multiplexing inside the amplifier as well as in the transmission line cable is also increasing. In other words, it is important to minimize the area for the equipment in the repeater station by performing an integration including the peripheral devices, together with a multicore EDF used in the amplifier. Furthermore, the suppression of the increase in the power consumption due to the increase of the number of cores is also an important issue. In this report, we introduce the size reduction technology of the amplifier with a multicore erbium doped fiber amplifier (MC-EDFA) and the effort to reduce the power consumption corresponding to the request for the expansion of the communication capacity.