Nobutomo Hanzawa

Demonstration of mode-division multiplexing transmission over 10 km two-mode fiber with mode coupler

We realized mode-division multiplexing(MDM) transmission by using orthogonal LP modes with negligible modal crosstalk, for the first time. A 2×10Gbps MDM transmission was achieved over a 10km two-mode fiber with sufficiently low power penalty.

Two-mode PLC-based mode multi/demultiplexer for mode and wavelength division multiplexed transmission

We proposed a PLC-based mode multi/demultiplexer (MUX/DEMUX) with an asymmetric parallel waveguide for mode division multiplexed (MDM) transmission. The mode MUX/DEMUX including a mode conversion function with an asymmetric parallel waveguide can be realized by matching the effective indices of the LP(01) and LP(11) modes of two waveguides. We report the design of a mode MUX/DEMUX that can support C-band WDM-MDM transmission. The fabricated mode MUX/DEMUX realized a low insertion loss of less than 1.3 dB and high a mode extinction ratio that exceeded 15 dB. We used the fabricated mode MUX/DEMUX to achieve a successful 2 mode x 4 wavelength x 10 Gbps transmission over a 9 km two-mode fiber with a penalty of less than 1 dB.

Mode-Division Multiplexing Transmission System With DMD-Independent Low Complexity MIMO Processing

We propose a mode-division multiplexing (MDM) transmission system with differential mode delay (DMD) independent low computational complexity MIMO processing. We adjusted the delay time of the delay units in the equalizer in accordance with the DMD value of the fiber, and the functional imperfection of the mode MUX/DEMUX can be compensated for with low computational complexity by using this technique. Finally, we investigated the crosstalk characteristics of the PLC-based MUX/DEMUX and achieved an experimental WDM-MDM transmission over the C-L band with low MIMO processing complexity even when using a few-mode fiber with a high DMD.

PLC-based LP 11 mode rotator for mode-division multiplexing transmission

A PLC-based LP11 mode rotator is proposed. The proposed mode rotator is composed of a waveguide with a trench that provides asymmetry of the waveguide. Numerical simulations show that converting LP11a (LP11b) mode to LP11b (LP11a) mode can be achieved with high conversion efficiency (more than 90%) and little polarization dependence over a wide wavelength range from 1450 nm to 1650 nm. In addition, we fabricate the proposed LP11 mode rotator using silica-based PLC. It is confirmed that the fabricated mode rotator can convert LP11a mode to LP11b mode over a wide wavelength range.

Mode-division multiplexed transmission with fiber mode couplers

We describe the mode-division multiplexing (MDM) transmission using a conventional fiber coupler with negligible modal crosstalk. A 2×10 Gbps MDM transmission was achieved over a 10 km two-mode fiber without any signal processing.

Optical Fiber Amplifier Employing a Bundle of Reduced Cladding Erbium-Doped Fibers

We propose a novel optical amplifier that employs a bundle of reduced cladding erbium-doped fibers (EDFs) for multicore fiber transmission and successfully demonstrate the amplification of seven independent signals by employing a bundle of 60-μm cladding EDFs and a planar lightwave circuit integration technique. Average gains of 23 dB with low noise figures of less than 5.1 dB in the C-band were achieved for seven individual EDFs. We also confirmed that low crosstalk characteristics can be achieved for a multicore optical fiber amplifier by using bundled EDF.

Experimental Demonstration of Optically Phase-Shifted SSB Modulation with Fiber-Based Optical Hilbert Transformers

Optically phase-shifted SSB modulation is demonstrated using the third-order optical Hilbert transformer of Mach-Zehnder interferometers. The results verify the principle of the optically phase-shifted SSB scheme which is applicable for high-speed transmission with bandwidth efficiency.

Transmission over large-core few-mode photonic crystal fiber using distance-independent modal dispersion compensation technique

We propose a transmission distance-independent technique for modal dispersion compensation over few-mode fiber that uses a single-input multiple-output configuration and adaptive equalization. Our technique can compensate for the modal dispersion of a signal with 1-tap FIR filters regardless of the amount of modal delay difference, and enables us to utilize fiber with a large core and few modes as a long-haul transmission line. We also show numerically the advantage of few-mode photonic crystal fiber (PCF) for realizing a larger effective area (A(eff)), and finally we report a transmission over a large-core two-mode PCF with A(eff)>280 μm(2).

Observation of a propagation mode of a fiber fuse with a long-period damage track in hole-assisted fiber.

We examined the fiber-fuse propagation characteristics in hole-assisted fibers (HAFs) when the diameter of an inscribed circle linking the air holes was almost the same as the diameter of the melted area caused by the fiber fuse. We observed a new propagation mode for the fiber fuse in HAF with a damage track whose period was approximately 30 times longer than that in conventional single-mode fiber. We also made the first observation of a new threshold power (upper threshold) for the fiber fuse.

PLC-Based Four-Mode Multi/Demultiplexer With LP 11 Mode Rotator on One Chip

We propose a PLC-based mode multi/demultiplexer (MUX/DEMUX) for mode-division multiplexing. We show numerically that the PLC-based mode MUX/DEMUX with a uniform height on one chip can multi/demultiplex four modes (LP₀₁, LP₁₁a, LP₁₁b, and LP₂₁a) by using our proposed LP₁₁ mode rotator and a parallel waveguide. We successfully multi/demultiplex the four modes and achieve a relatively low-wavelength dependence over the C-band by using our fabricated four-mode MUX/DEMUX.