A new type of photodetector called "photosensitive floating field emitter, (PFFE)" has been proposed. The PFFE device combines an n-type cone-shaped triode field emitter with a-Si p-i-n photodiode film. However, a PFFE cannot detect two-dimensional distributions of light intensity. In this paper, we propose a novel structure to overcome the above this problem of the PFFE. The device was fabricated on a silicon-on-sapphire substrate to permit irradiation from the backside. p-n photodiodes were constructed within a field emitters, the n+ region being separated by p+ regions to permit detection of two- dimensional light distributions. The emission current of the PFFE/SOS was found to be proportional to the illumination intensity, but the quantum efficiency was only about 2%. This quantum efficiency is lower than that expected. Under irradiation, the emission current increased, but the gate-leakage current increased. This gate-leakage current was several orders of magnitude larger than the emission current. Almost photo-generated electrons lost in the gate electrode.

The first results of a field trial held in November 2000, of 1 Tbit/s (25 43 Gbit/s) unidirectional Wavelength Division Multiplexing (WDM) transmission, are presented. The field trial used a 43 Gbit/s/channel Optical Transport Network (OTN) interface prototype and standard Single Mode Fibers (SMFs) installed in the Nara area network of NTT West Corporation. The features of this field trial include the accommodation of multiple services such as GbE, STM-16 and OC-48. Error free operation of 25 channels with 100 GHz spacing over a 91 km standard SMF with Forward Error Correction (FEC) is verified for STM-16. A DV stream over IP over Ethernet as a tributary channel was also successfully transmitted.

This paper describes the design concept and realized functions of the first Optical Transport Network (OTN) based 43 Gbit/s line terminal. The system requirements of new generation networks are provided, and the functions needed in this line terminal are obtained from the requirements. The line terminal deploys Time Division Multiplexing (TDM) to handle client signals, and provides transparent high quality multiple services such as SONET/SDH and Gigabit Ethernet. The configuration and features of the actually fabricated system are described.

A 1.6-Tb/s dense WDM signal was successfully transmitted over 480 km using the carrier-suppressed return-to-zero (CS-RZ) modulation format. The CS-RZ format was chosen because it exhibited better transmission performance over a wide fiber-input power window than the NRZ and RZ formats in a 40-Gb/s-based WDM transmission experiment with 100-GHz channel spacing, confirming its nonlinearity-insensitive nature in dense WDM systems. With the wide power window of CS-RZ, we achieved stable transmission of 4040-Gb/s WDM signals over a 480-km (680 km) standard SMF line with only the C-band, in which a spectral ripple remained during transmission. Distributed Raman amplification and forward error correction were not used, providing a margin for already installed transmission lines.

This paper proposes a statistical design approach for Non-Return-to-Zero (NRZ) 40 Gbit/s systems with Forward Error Correction (FEC); the approach considers Polarization Mode Dispersion (PMD). We introduce a fluctuating PMD emulator to experimentally clarify FEC performance in PMD-limited systems. By using the proposed design approach, and considering the FEC relaxation effect on PMD, the maximum transmission distance of an NRZ 40 Gbit/s system without PMD compensation is estimated as several hundreds of km depending on the number of cable concatenations per link and the probability threshold of system acceptance.