This article presents simultaneous data and power transmission systems using a double-clad fiber (DCF). In future radio-over-fiber (RoF) networks, a large number of remote antenna units (RAUs) will be required to provide various kinds of mobile communication services. Power-over-fiber (PWoF), which delivers electrical power to drive the RAUs in optical fibers, is an attractive technique that offers cost-effective installation, operation, and maintenance of RAUs, and achieves the power savings across the entire RoF networks. In particular, the use of double-clad fibers (DCFs), which consist of a single-mode (SM) core and an inner cladding that surrounds the SM core, are useful for much higher power transmission than conventional PWoF techniques. Along the DCF link, optical data signals are transmitted into the SM core, whereas high-power feed light for optical powering is transmitted into the inner cladding, which has a core area that is approximately 240 times larger core area than that of conventional SM cores. In this article, we experimentally demonstrate a PWoF feed with up to 150-W of power using a 1-km DCF. To show the feasibility of the PWoF system, we investigate the bend performance and temperature characteristics of the DCF link. We also evaluate data and power transmission performance under the 150-W PWoF feed in the DCF link. Index Terms-Double-clad fibers (DCFs), mobile communications, optical power delivery, power-over-fiber (PWoF), radioover-fiber (RoF), remote antenna units (RAUs).
I. INTRODUCTIONO PTICAL transmission systems are expected to play an important role in supporting multiple wired and wireless internet services in future communication networks [1], [2]. In particular, radio-over-fiber (RoF) is an essential technology for transmitting radio-frequency (RF) signals into fiber links between a central office (CO) and remote antenna units (RAUs), as well as for providing broadband mobile communications [3]- [5]. A reduction in the cell size of RAUs is required to