Ryo Maruyama

Two mode optical fibers with low and flattened differential modal delay suitable for WDM-MIMO combined system

We propose two mode optical fibers (TMFs) with minimally low differential modal delay (DMD) slope which are suitable for wavelength division multiplexing and multiple input multiple output (MIMO) combined transmission system. We designed and fabricated three different kinds of TMF, nearly zero-DMD (zTMF), positive-DMD (pTMF) and negative-DMD (nTMF) with a graded index core and a depressed inner cladding. We confirmed that the fabricated zTMF has DMD of below 15 ps/km in the C band and the fabricated pTMF and nTMF have the same degree of effective areas. We also confirmed that a DMD compensation line with a length of 100 km composed of pTMF and nTMF can successfully achieve the best properties of low DMD in the C + L band and low mode conversion.

Optimized graded index two-mode optical fiber with low DMD, large A eff and low bending loss

An optimized two-mode optical fiber (TMF) with the graded index (GI) profile is designed and fabricated. We clarify an appropriate region of GI-TMF satisfying DMD = 0 ps/km, the large effective area A(eff), and the low bending loss for LP(11) at 1550 nm. According to our fiber design, GI-TMF is successfully fabricated to have the large effective area A(eff) of 150 μm(2) for LP(01) mode, and low DMD below 36 ps/km including zero in the C-band. We expect that our design GI-TMF is suitable for MDM and can reduce MIMO-DSP complexity.

Experimental investigation of relation between mode-coupling and fiber characteristics in few-mode fibers

We experimentally clarify that relation between mode-coupling coefficient h and effective-index difference Δn_eff in few-mode fibers (FMFs) by impulse response technique and h in our fabricated FMFs with Δn_eff ≥ 1.7 × 10^-3 converges to 7.4×10^-5 1/km.

Experimental Evaluation of Mode Conversion Ratio at Splice Point for Two-Mode Fibers and its Simulated Effect on MIMO Transmission

We evaluate experimentally mode conversion ratio at a splice point (Cs) for two-mode fibers which degrades transmission performance. We confirm the measured results are consistent with the calculated ones by an overlap integral on field distributions of individual modes and clarify the precise connection value with an offset and an end face angle of the fiber which are required for suppressing the degradation due to Cs by MIMO transmission simulation.

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 dispersion compensating optical transmission line composed of two-mode optical fibers

We fabricated mode dispersion compensating optical transmission line composed of two different kinds of two-mode optical fibers with the opposite signs of mode dispersion. Its mode dispersion was successfully controlled within ±700 ps/km at C-band.

Mode-division multiplexed W-Band RoF transmission for higher-order spatial multiplexing

20Gb/s seamless 2×2 MIMO transmission of W-Band millimeter-wave signals over a 30-km modal-dispersion-compensated mode-division multiplexed link and a 2.5-m wireless path, is demonstrated for enhancing the transmission capacity in radio-over-fiber systems.

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.

Longitudinal fiber parameter measurements of two-mode fiber links by using OTDR

A technique is proposed for measuring mode field diameter of LP01 mode and relative-index difference of a fiber link composed of two mode fibers using the OTDR. Longitudinal fiber parameters of the fiber link were successfully estimated by our technique.

Longitudinal fiber parameter measurements of multi-core fiber using OTDR

A novel technique is proposed for measuring the longitudinal fiber parameters of multi-core fiber (MCF). The mode field diameter (MFD)of a fiber link composed of MCF is successfully estimated with a modified optical time domain reflectometer (OTDR). The measurement accuracy of the MFD distribution is revealed by simulation as a function of the mode coupling coefficient. It is also shown that the relative-index difference and chromatic dispersion of MCF can be estimated with the present technique.