R.J. Standish

Bio: R.J. Standish is an academic researcher from University of Southampton. The author has contributed to research in topics: Fiber laser & Optical fiber. The author has an hindex of 9, co-authored 21 publications receiving 333 citations.

Cladding pumped few-mode EDFA for mode division multiplexed transmission.

Abstract: We experimentally demonstrate a few-mode erbium doped fiber amplifier (FM-EDFA) supporting 6 spatial modes with a cladding pumped architecture. Average modal gains are measured to be >20dB between 1534nm-1565nm with a differential modal gain of ~3dB among the mode groups and noise figures of 6-7dB. The cladding pumped FM-EDFA offers a cost effective alternative to core-pumped variant as low cost, high power multimode pumps can be used, and offers performance, scalability and simplicity to FM-EDFA design.

MCVD in-situ solution doping process for the fabrication of complex design large core rare-earth doped fibers

Abstract: We report on the fabrication and characterization of rare-earth doped silica fibers manufactured using an in-situ solution doping technique, which is compatible with conventional modified chemical vapor deposition equipment. The in-situ technique permits significantly more doped layers to be deposited, compared to conventional solution doping, and is directly applicable for the fabrication of large core rare-earth doped fibers suitable for high-power fiber sources. Ytterbium-doped aluminosilicate fibers fabricated using the new in-situ doping technique are reported and the results are compared to fibers fabricated using a conventional solution doping method.

First Demonstration of Cladding Pumped Few-moded EDFA for Mode Division Multiplexed Transmission

Abstract: We report the first experimental demonstration of a cladding pumped FM-EDFA supporting 4 mode groups. The modal gains are measured to be >20dB between 1540nm-1570nm with a modal differential gain of ~4dB among the mode groups.

Linearly polarized ytterbium-doped fiber laser in a pedestal design with aluminosilicate inner cladding

Abstract: Ytterbium-doped polarization-maintaining fiber in a pedestal geometry is demonstrated using MCVD and a novel in-situ doping technique. The aluminosilicate pedestal layers minimize the thermal expansion mismatch against the silica outer cladding and permits complete freedom of location for the stress-applying parts in the fiber. A birefringence of 2.4×10-4 is experimentally determined. The fiber delivers linearly polarized laser exhibiting 79% slope efficiency with a polarization extinction ratio of 12 dB.

High power fiber lasers: current status and future perspectives [Invited]

Abstract: The rise in output power from rare-earth-doped fiber sources over the past decade, via the use of cladding-pumped fiber architectures, has been dramatic, leading to a range of fiber-based devices with outstanding performance in terms of output power, beam quality, overall efficiency, and flexibility with regard to operating wavelength and radiation format. This success in the high-power arena is largely due to the fiber’s geometry, which provides considerable resilience to the effects of heat generation in the core, and facilitates efficient conversion from relatively low-brightness diode pump radiation to high-brightness laser output. In this paper we review the current state of the art in terms of continuous-wave and pulsed performance of ytterbium-doped fiber lasers, the current fiber gain medium of choice, and by far the most developed in terms of high-power performance. We then review the current status and challenges of extending the technology to other rare-earth dopants and associated wavelengths of operation. Throughout we identify the key factors currently limiting fiber laser performance in different operating regimes—in particular thermal management, optical nonlinearity, and damage. Finally, we speculate as to the likely developments in pump laser technology, fiber design and fabrication, architectural approaches, and functionality that lie ahead in the coming decade and the implications they have on fiber laser performance and industrial/scientific adoption.

Space-division multiplexing: the next frontier in optical communication

Abstract: Space-division multiplexing (SDM) uses multiplicity of space channels to increase capacity for optical communication. It is applicable for optical communication in both free space and guided waves. This paper focuses on SDM for fiber-optic communication using few-mode fibers or multimode fibers, in particular on the critical challenge of mode crosstalk. Multiple-input–multiple-output (MIMO) equalization methods developed for wireless communication can be applied as an electronic method to equalize mode crosstalk. Optical approaches, including differential modal group delay management, strong mode coupling, and multicore fibers, are necessary to bring the computational complexity for MIMO mode crosstalk equalization to practical levels. Progress in passive devices, such as (de)multiplexers, and active devices, such as amplifiers and switches, which are considered straightforward challenges in comparison with mode crosstalk, are reviewed. Finally, we present the prospects for SDM in optical transmission and networking.

Survey and Evaluation of Space Division Multiplexing: From Technologies to Optical Networks

Abstract: Single-mode fiber's physical capacity boundaries will soon be reached; hence, alternative solutions are much needed to overcome the multiplying and remarkably large bandwidth requests. Space division multiplexing (SDM) using multicore fibers (MCFs), multielement fibers, multimode fibers, and their combination; few-mode MCFs; or fibers based on orbital angular momentum are considered to be the propitious stepping-stones to overcome the capacity crunch of conventional single-core fibers. We critically review research progress on SDM fibers and network components, and we introduce two figures of merit aiming for quantitative evaluation of technologies such as amplifiers, fan-in/fan-out multiplexers, transmitters, switches, and SDM nodes. Results show that SDM fibers achieve a 1185-fold (18-fold) spectral–spatial efficiency increase compared with the 276-SMF bundle (single-core fiber) currently installed on the ground. In addition, an analysis of crosstalk in MCFs shows how SDM concepts can be further exploited to fit in various optical networks such as core, metro, and especially future intra-data center optical interconnects. Finally, research challenges and future directions are discussed.

Sapphire-derived all-glass optical fibres

Abstract: Optical fibres heavily doped with alumina are shown to exhibit an exceptionally low Brillouin gain coefficient and an athermal Brillouin frequency response. Such fibres could prove useful for applications that employ fibre sensing or require high-power fibre laser systems.