Hideyuki Iwamura

Experimental study on time-spread/wavelength-hop optical code division multiplexing with group delay compensating en/decoder

10-Gb/s time-spread/wavelength-hop optical code generation and decoding were performed by group delay compensating fiber Bragg grating (FBG) en/decoder pair. A 10-km single-mode fiber (SMF) transmission of 10-Gb/s optical code division multiplexing (OCDM) was experimentally demonstrated.

First Demonstration of Coexistence of Standard Gigabit TDM-PON and Code Division Multiplexed PON Architectures Toward Next Generation Access Network

World-first coexistence trial of TDM and CDM giga-bit passive optical networks (PONs) was successfully completed. A very shallow minimum isolation of 7 dB between G- and CDM-PON at OLT and ONU in the ITU-T G.984.5 enhancement band was demonstrated. The feasibility of bidirectional transmission on the same wavelength was confirmed. The backscattering optical noise does not seriously affect the maximum reach of CDM-PON. Adding the CDM-PON onto GPON can provide following technical and economical impacts: low-cost coexistence, minimum service outage, and combination of best-effort and guaranteed-bandwidth for efficient and high-quality network services due to CDM feature.

42dB Loss Budget Hybrid DWDM-CDM-PON without Optical Amplifier

First time, an unprecedented 42 dB loss budget was realized by using hybrid DWDM-CDM (code division multiplexing)-PON without optical amplifier. We experimentally demonstrated 100 km 16lambda-DWDM-CDM-PON bidirectional transmission with 62.5 Mbps times 32 users/lambda symmetry guaranteed bandwidth. Long reach PON is expected to reduce CapEx and OpEx cost.

Demonstration of 10 Gbit/s-Based Time-Spreading and Wavelength-Hopping Optical-Code-Division-Multiplexing Using Fiber-Bragg-Grating En/Decoder

We studied 10Gbit/s-based time-spreading and wavelength-hopping (TS-WH) optical code division multiplexing (OCDM) using fiber Bragg gratings (FBGs). To apply it to such the high bit rate system more than ten gigabit, two techniques are adopted. One is encoding with the maximum spreading time of 400 ps, which is four times as data bit duration, to encode without shortening chip duration. Another is encoder design. The apodized refractive index profile to the unit-gratings composing the encoder is designed to encode the pulses with 10-20ps width at 10Gbit/s rate. Using these techniques, 2 × 10Gbit/s OCDM is demonstrated successfully. In this scheme, transmission distance is limited due to dispersion effect because the signal has wide bandwidth to assign a wavelength-hopping pattern. We use no additional devices to compensate the dispersion, in order to construct simple and cost-effective system. Novel FBG encoder is designed to incorporate both encoding and compensating of group delay among chip pulses within one device. We confirm the extension of transmission distance in the TS-WH OCDM from the demonstration over 40 km-long single mode fiber.

Demonstration of 1.25 Gb/s

In this letter, 1.25 Gb/s × 8-channels simultaneous multiplexing using 8-chip electrical codes is experimentally demonstrated for the downlink of a 10-Gb/s electrically code-division-multiplexing passive optical network (ECDM-PON) system. For electrical encoding and decoding, 10-Gb/s multilevel signal generation and 10 Gchip/s correlator as a decoder are utilized. We demonstrate 10-Gb/s ECDM error-free optical transmission over 20 km of single-mode fiber.

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This paper presents the worlds first field trial of a 40-km reach and over 512-split symmetric-rate 40-Gbit/s λ-tunable time and wavelength division multiplexing passive optical network (TWDM-PON) that utilizes our newly developed high-speed λ-tunable optical network unit transceivers and automatic gain controlled semiconductor optical amplifier-based PON extender for repeater and central office use. The upstream signals for C-band and downstream signals for L+-band in our developed λ-tunable TWDM-PON comply with the wavelength plan of ITU-T G.989 series. In a field trial, we successfully demonstrate error free λ-tunable transmission for the 40-km reach and 1024-split (maximum number) symmetric-rate 40-Gbit/s λ-tunable TWDM-PON over installed standard single-mode fiber links, and advanced network functions such as dynamic load balancing, incremental system upgrade, optical subscriber unit protection, and OLT equipment power saving are also confirmed.

8-Channels ECDM Using Eight-Chip Electrical Coding

We improved the receiver sensitivity of WDM/TDM-PON system to split over 64 users and transmit 80km distance. Compact EDFA suppressing the impact of optical power surge and equalization technology enabled the receiver sensitivity up to ×40dBm.

Field Trial of Long-Reach and High-Splitting λ-Tunable TWDM-PON

First demonstration of asymmetric PON system (10 Gbps × 16 ch downstream) using OTDM and OCDM technologies is presented. We accomplished a transmission over 20 km SMF with optimized dispersion tolerance.

Power budget enhancement of WDM/TDM-PON system by utilizing compact EDFA suppressing power surge impact and equalization technology

Next generation long reach hybrid WDM-CDM-PON based on Code Division Multiplexing presented here. We describe system configuration, key merits such as bidirectional transmission (on same wavelength), extend the reach by coding gain and simplified network solution. We show initial experimental results over 100km bidirectional, multi-channels CWDM transmission without an optical amplifier.

A Study of 160Gbps PON System Using OTDM and OCDM Technologies

We evaluate correlation characteristics for phase-coding scheme utilizing fiber-Bragg-gratings as encoder/decoder. From the results, we confirmed that channel discrimination is sufficiently capable with the enlarged pulse width 4 times longer than chip duration.