Hitoshi Uemura

Mode-selective optical packet switching in mode-division multiplexing networks

A novel mode-selective optical packet switching, based on mode-multiplexers/demultiplexers and multi-port optical micro-electro-mechanical systems (MEMS) switches, has been proposed and experimentally demonstrated. The experimental demonstration was performed using the LP(01), LP(11a) and LP(11b) modes of a 30-km long mode-division multiplexed few-mode fiber link, utilizing 40 Gb/s, 16-QAM signals.

Mode-Unbundled ROADM and Bidirectional Mode Assignment for MDM Metro Area Networks

A mode-unbundled reconfigurable add/drop multiplexer (ROADM), composed of a fiber-based mode-multiplexer/demultiplexer pair and a multiport microelectromechanical systems switch, is proposed and experimentally characterized for higher data granularity in mode-division multiplexing (MDM) deployment of future metro area networks (MAN). For enabling mode-unbundling transmission, crosstalk reduction through bidirectional mode assignment is adopted. Finally, a 62-km MDM-MAN ring, composed of two mode-unbundled ROADMs and few-mode fiber spans, is experimentally demonstrated by taking advantage of bidirectionally mode assigned 40 Gb/s, 16-QAM signals.

Multicore-fiber cable with core density of 6 cores/mm 2

An Ultra-high density cable with 12-core MCF was presented. A fabricated cable realized core density of 6 cores/mm2. The change of crosstalk behavior before and after cabling was moderate thanks to adequate cable design.

Multicore fibre-based mode multiplexer/demultiplexer for three-mode operation of LP 01 , LP 11a , and LP 11b

A mode multiplexer/demultiplexer with a fused-fibre fan-in/fan-out device for three-mode operation of LP₀₁, LP_11a, and LP_11b is demonstrated using a partially elongated multi-core fibre. A fabricated mode multiplexer/demultiplexer exhibited a coupling efficiency greater than 79% over the C band.

Multicore fiber-based mode multiplexer/demultiplexer

A multicore fiber (MCF)-based mode multiplexer/demultiplexer (MUX/DEMUX) that can overcome the alignment issue of the fiber-based mode MUX/DEMUX is proposed. Design concept and fabrication results of the MCF-based mode MUX/DEMUX for two-spatial-mode operation (LP01 and LP11) (2M-MUX/DEMUX) and for three-spatial-mode operation (LP01, LP11a, and LP11b) (3M-MUX/DEMUX) are presented. The fabricated 2M-MUX/DEMUXes for C-band or L-band, using the same MCF with different elongation ratios demonstrate a coupling efficiency of greater than 90% over each band. Finally, a 3M-MUX/DEMUX with a fan-in/fan-out device is presented. The selective excitation of LP01, LP11a, and LP11b modes depending on input ports is experimentally demonstrated.

Multi-core to 7 single-core-fibers fan-out device with multi-core fiber pigtail connector

Multi-core to 7 single-core-fibers fan-out device with multi-core fiber pigtail connector is demonstrated to apply various types of multi-core fiber based sensor. Fused taper type fan-out device and SC type multi-core fiber connector are separately fabricated on each process. The fan-out device and the pigtail multi-core fiber are spliced each other by a specialty fiber fusion splicer. Comparatively low average insertion loss of 0.95 dB and sufficiently low reflectivity of less than -60 dB are achieved.

OTDR technique for measuring crosstalk and fiber parameters in multi-core fibers

We review OTDR technique for measuring a crosstalk (XT) and longitudinal fiber parameters such as mode field diameter (MFD), and relative-index difference in multi-core fibers.

Theoretical Investigation of Six-Mode Multi/Demultiplexer Based on Fused-Type Multicore Fiber Coupler

A six-mode (LP₀₁/LP₁₁ab/LP_21ab/LP₀₂) multi/demultiplexer based on a fused-type multicore fiber coupler is proposed, and the coupling characteristics are investigated. The multi/demultiplex operation is achieved by a phase matching between the desired mode of center core and the LP₀₁ mode of the outer core in the elongated region of the fused-type multicore fiber coupler. From the numerical results based on the beam propagation method, it is found that the coupling efficiencies between the LP₀₁ and LP₁₁/LP₂₁/LP₀₂ modes are more than -0.1 dB, and the crosstalk is lower than -20 dB at the wavelength of 1550 nm.

Novel mode-selective packet switching

A novel mode-selective packet switching, based on mode-multiplexers/demultiplexers and multi-port optical MEMS switches, has been proposed and experimentally demonstrated over a 30-km long few-mode fiber link using 16-QAM signals without serious signal impairments.

Mode-unbundled ROADM for MDM networks: Characterization of Uni- and Bi-directional mode assignment

A mode-unbundled ROADM, composed of fiber-based mode-mux/demux and a multi-port MEMS switch, is proposed for MDM networks. The experimental demonstration was performed in single- and two-node configurations, for uni- and bi-directionally mode assigned QPSK and 16-QAM signals, without MIMO DSP.