Tadayoshi Kitayama

All-fiber add/drop multiplexing of 6/spl times/10 Gbit/s using a photo-induced Bragg grating filter for WDM networks

Summary form only given. In conclusion, the Mach Zehnder grating fiber filter was successfully applied to add/drop multiplexing experiments used in a 6 x 10 Gbit/s WDM network demonstration. The wavelength offset scheme was useful for avoiding interference cross talk.

An ultra-broadband GaAs MESFET preamplifier IC for a 10 Gb/s optical communication system

An ultrabroadband GaAs MESFET preamplifier IC was developed for a 10-Gb/s optical communication system. A high transimpedance of 44 dB- Omega has been obtained from DC to 12 GHz. A receiver has also been fabricated by using this preamplifier IC and a photodiode. The receiver operated with an extremely low equivalent input noise current of 12.6 pA/ square root Hz from DC to 7.8 GHz. The circuit design and the high-frequency characteristics of the preamplifier IC and the receiver are described. >

Frequency stabilized 622-Mb/s 16-channel optical FDM system and its performance in 1.3/1.55-/spl mu/m zero-dispersion fiber transmission

A study has been conducted on a densely multiplexed 16-channel optical FDM system. A transmitter contains 16 two-section MQW DFB-LDs and a star coupler. An automatic optical multi-frequency controller stabilizes each LD of 10 GHz spacing within /spl plusmn/100-MHz accuracy. A receiver consists of heterodyne-delay-demodulators using a polarization diversity. Any desired channel can be tuned by a novel frequency discriminator with no insensitive frequency region. The system has successfully transmitted 622 Mb/s-16-channel HDTV signals through 110 km long 1.3 /spl mu/m-zero-dispersion fiber. We have also studied error rate degradation due to four-wave mixing in a 1.55 /spl mu/m-dispersion-shifted-fiber. Experimental results have revealed the allowable total input power to be +2 dBm for dispersion-shifted fibers. >

Investigation of the effect of injection locking between pump lasers on a redundant pumping scheme for erbium-doped fiber amplifiers

The stability of the redundant pumping scheme for an erbium-doped fiber amplifier is investigated. It is shown experimentally that an unstable operation occurs in the redundant pumping configuration and that the instability stems from the injection locking due to coupling between pump lasers. Two countermeasures for reducing the interaction between pump lasers are proposed for practical use-by using optical isolators and by using fiber gratings to obtain coherence collapse phenomenon. A theoretical model for the redundant pumping scheme is investigated, and the requirement for the isolation between the pump lasers to suppress the instability is verified.

10 Gbit/s repeaterless transmission over 258 km employing 24 ps RZ pulses

Summary form only given. A 10 Gbit/s RZ transmission system with large loss budget is described and the repeaterless transmission employing short pulses of 24-ps-wide over 258 km is also discussed. The configurations of a 10 Gbit/s RZ transmitter and a receiver are depicted. At the transmitter, a monolithically integrated MQW-DFB-LD/MQW-EA modulator produced 24-ps-wide transform-limited pulses at 10-GHz repetition rate. The signal power was boosted to + 22 dBm by a booster EDFA. No SBS-suppressing circuits were employed, because the SPM-induced spectral broadening could suppress the SBS effectively. At the receiver, a low-noise optical pre-amplifier was followed by a wide-band optical filter.

Fiber optic packet LAN based on the combination of CSMA/CD and FDDI access method

A fiber-optic local-area packet communications system, developed for an office system, is presented. The system consists of a 10-Mb/s token-ring backbone-network. Up to 64 fiber-optic CSMA/CD (carrier-sense multiple access with collision detection) subnetworks are interconnected with the token-ring backbone-network using a bridge over a total length of 128 km. The fiber-optic CSMA/CD subnetwork can support up to 1024 fiber-optic medium-attachment-units (FOMAUs) and a network diameter of 3 km using 33-port passive star couplers, FOMAUs compatible with ISO 8802/3 attachment-unit interface (AUI), and fiber-optic repeater units (FORUs). The implementation and characteristics of the fiber-optic equipment of the CSMA/CD subnetwork and the token-ring backbone-network are described.<<ETX>>