An over 2200-km coherent transmission experiment at 2.5 Gb/s usingerbium-doped-fiber in-line amplifiers

A 2223 km transmission distance was achieved with a 2.5-Gb/s heterodyne detection system that used erbium-doped-fiber in-line amplifiers and dispersion-shifted single-mode fibers. Twenty-five amplifiers, placed at approximately 80-km intervals, offered a total gain of more than 440 dB. Receiver sensitivity was -42.0 dBm, with only a 4.2-dB penalty from the initial sensitivity achieved by the back-to-back configuration     

Synthesis and luminescence properties of Pr3+ doped CaxBa1?xTiO3 (0.3?x<1) fine particles

Ca _x Ba_1−x TiO₃ (CBT) fine particles doped with red luminescence center of Pr³⁺ ions (Pr: CBT) were successfully synthesized by salt assisted spray pyrolysis (SASP) process. Scanning electronic microscope (SEM) and laser scattering analysis demonstrate that salt can be removed from the surface of particles by washing with Milli-Q water and the particles can be further separated by ball-milling to get well-dispersed Pr³⁺ ions doped CBT fine particles. The luminescence properties, such as photoluminescence (PL) and mechanoluminescence (ML), of as-synthesized Pr: CBT particles were investigated. For Pr: CBT fine particles with different Ca molar ratios, all the samples show one emission at 612 nm, with increasing Ca molar ratio, PL intensity of Pr: CBT fine particles become stronger and stronger. When pressure was loaded on the Pr: CBT pellet, mechanoluminescence(ML) emission was measured. The results show that the ML intensity is proportional to the applied pressure.     

Some characteristics of a sparged agitated vessel under foaming — Mechanical control of foaming —

Foam-breaking with a rotating disk mechanical foam-breaker (MFRD) was studied for a foaming system containing a diluted detergent solution in a laboratory sparged agitated vessel. The change of the foam-breaking capacity of the MFRD by varying the air sparge rate, the working volume and the impeller speed or the disk diameter was measured. Based on these measurements, empirical equations are presented for predicting the critical foam-breaking regions of the MFRD fitted with the agitated vessel. The operational range where foam-breaking with the MFRD can be carried out effectively and economically is also discussed.     

Organic–Inorganic Nanohybrids as Novel Thermoelectric Materials: Hybrids of Polyaniline and Bismuth(III) Telluride Nanoparticles

Thermoelectric materials have received much attention recently from the viewpoint of global environmental issues and effective utilization of energy resources. Especially those effective at relatively low temperature, such as below 100°C, which are usually abandoned without use, have become noteworthy recently. From this point of view, organic thermoelectric materials are most attractive, because they could be prepared at low cost and applied in various locations due to their flexibility. We have investigated the thermoelectric properties of organic conducting polymers such as polyaniline, polypyrrole, and polyphenylenevinylene, and succeeded in increasing the thermoelectric performance by selecting dopants, stretching conducting films, etc. Recently we have focused on new systems of organic–inorganic hybrid thermoelectric materials. Herein we present the preparation of a novel system of hybrids of polyaniline and bismuth(III) telluride nanoparticles, starting from bismuth(III) chloride and tetrachlorotellurium by using polyvinylpyrrolidone as a protecting reagent, as well as their thermoelectric properties. The hybrids prepared by this particular method showed much higher thermoelectric performance than the starting organic conducting polymer.     

Photoluminescence measurements on undoped CdZnTe grown by the high-pressure bridgman method

The low temperature photoluminescence of Cd_0.91Zn_0.09Te grown by the high-pressure Bridgman (HPB) method exhibits a neutral donor bound exciton emission (D⁰X) at 1.65603 eV with its excited state (D⁰X^*) at 1.65798 eV and neutral acceptor bound exciton emissions (A⁰X) at 1.64566 eV and 1.65201 eV. Assuming a direct generation and subsequent relaxation of excitons at the D⁰X^* state, we demonstrate that the temporal evolution of the above emission bands is well reproduced by a set of rate equations. The resultant radiative-lifetime of 1.4 ns for the D⁰X and 1.5 and 2.0 ns for the A⁰Xs are compared with various CdZnTe's (CZTs) grown by the other methods to demonstrate the particular nature of the HPB CZT.     

Efficient electron transport in 4,4′-bis[N-(1-napthyl)-N-phenyl-amino] biphenyl and the applications in white organic light emitting devices

The electron transport capability of 4,4′-bis[N-(1-napthyl)-N-phenyl-amino] biphenyl (α-NPD) was investigated by fundamental physical measurements named as current–voltage (I–V) electrical property evaluation and displacement current measurement (DCM). In electron-dominated devices, the I–V characteristics of α-NPD were similar as that of (8-hydroxyquinolino) aluminum (Alq₃) owing to their same order of electron mobilities. The interface of Al/LiF and α-NPD was proven to be an Ohmic contact through the evaluation of I–V characteristics at low bias regime (<3 V). And an electron injection barrier, 0.21 eV, at Al/LiF/α-NPD was obtained by extrapolating the temperature dependent I–V curves. The electron transport behavior in α-NPD film was further confirmed by DCM evaluations. Furthermore, an efficient white organic light emission device was successfully fabricated by using α-NPD as hole transport layer and electron transport layer, respectively.     

WDM upgrading of an installed submarine optical amplifier system

This paper describes the WDM upgrading of a submarine optical amplifier system installed for single-channel transmission in commercial use. The key technologies used include 10-Gb/s high-speed forward error correction, preemphasis to overcome the optical passband-width constraint, optimized signal pulse format that leads to partial return-to-zero (PRZ) signaling, and dispersion compensation to suppress the degradation caused by fiber nonlinearity and dispersion. It also reports field experimental results on upgraded system performance. The results confirm that simply upgrading the terminal equipment allows the transmission capacity of a submersed line consisting of submarine repeaters and cables to be flexibly increased from 10 Gb/s to 40 Gb/s per fiber pair     

HDR satellite codec with concatenated multilevel codes

The performance of a high data rate (HDR) codec based on a multidimensional modulation code derived from multilevel codes is evaluated for a satellite channel. The codec reliably supports HDR transmission for broadband ISDN over a 72 MHz satellite transponder and is designed to be used with an 8 PSK modem. Results show that significant coding gain with higher spectral efficiency can be achieved compared to uncoded QPSK     

A promising application for broadband ISDN: Hypermedia teleconference

The optimum BISDN teleconference service for business, called hypermedia teleconference, is designed based on research into typical business activities and ATM, the most promising BISDN architecture. Service characteristics are determined by analysing the daily work practices of a large set of businessmen. It is shown that communication tasks occupy 44 per cent of the working day. The analysis further shows that some 60 per cent of all communication tasks could be performed through an advanced digital teleconference service. Hypermedia teleconference is designed to satisfy the needs of business through personal communication terminals and ATM public networks. The terminals effectively allocate the BISDN's high-speed transmission capability between a number of subchannels that realize distributed multipoint connection links and multimedia paths. The terminals use a new variable-bit-rate ATM codec created to realize high quality video. Users can easily create full featured teleconferences without a centralized connection facility. Terminals allow the synergistic combination of video, voice, telewriting, telepointing and document transmission services.