Monolithic 2.1 Gbit/s decision circuit with a decision threshold ambiguity width of less than 10 mV

An Si bipolar monolithic decision circuit for practical use is developed using an improved circuit technique and super self-aligned process technology with the reliable 1.25 ?m rule. The circuit consists of a slice amplifier, a master-slave D flip-flop and an output buffer. This circuit is capable of operating up to 2.1 Gbit/s with a decision threshold ambiguity width of less than 10 mV. In addition, a clock phase margin of 250 degrees and power dissipation of 640 mW at VEE=?6 V can be achieved.     

OA&M framework for multiwavelength photonic transport networks

Photonic networks based on wavelength division multiplexing (WDM) and optical path technologies are expected to realize flexible, transparent, and cost-effective transport networks with a large transmission capacity. This paper explores the design framework of photonic transport networks taking into consideration the operation administration and maintenance (OA&M) functions required for the successful introduction of WDM systems based on the optical path concept. From the view point of network maintenance, clear distinction is made between the optical path layer and the optical section layer to facilitate accurate and smooth failure localization. The digital multiplexing span between physical multiplexing interfaces at the end-to-end digital nodes should have the same maintenance span as the corresponding optical path. We argue that cooperative maintenance by OA&M functions at both the digital and optical layers can be a practical way of network supervision. A supervisory (SV) signal transfer method and a configuration that is suitable for the terrestrial trunk network are also indicated. As an example, a practical SV system design methodology and an actual procedure developed for a single channel optical transmission system based on optical in-line amplifiers are introduced. Furthermore, application of the developed SV system and network restoration schemes is discussed for future WDM-based photonic networks. The OA&M aspects introduced will be valuable for creating future photonic network systems     

Ultrahigh-speed driverless MQW intensity modulator, and 20 Gbit/s, 100 km transmission experiments

An InGaArInAlAs MQW modulator with the low voltage of 1.5 V for 10 dB extinction ratio and 16 GHz bandwidth has been developed. This ultrahigh-speed modulator enables the modulator driver to be eliminated from the transmitter. 100 km transmission experiments have been carried out using either a 1 V peak to peak output monolithic-IC-driven modulator at 15 Gbit/s or a 2 V peak to peak output multiplexer-driven modulator at 20 Gbit/s. This is the first report on multigigabit operation of MQW modulators to the authors' knowledge.<>     

20 Gbit/s long distance transmission using a 270 photon/bit opticalpreamplifier receiver

A 200 km nonrepeatered transmission experiment and a 400 km transmission experiment using three in-line amplifiers are carried out at 20 Gbit/s by using a simple but highly sensitive optical preamplifier receiver based on a 0.98 μm LD-pumped EDFA. High sensitivity of -31.6 dBm (270 photon/bit) at 20 Gbit/s is obtained     

Very high speed intra-office optical link experiments for 0.4- and 1.6-Gbit/s trunk lines

Very high speed optical links are studied. Applicable areas for systems using light-emitting diodes (LED'S) or laser diodes (LD's) with short transmission length are clarified. A new type differential mode inversion (DMI) decoder is proposed and it is shown that the DMI code is suitable as the line code for very high speed intra-office optical links. By using DMI code. a 400-Mbit/s information rate optical transmission experiment employing a 1.3-μm InGaAsP LED and a 0.5-km graded-index multimode optical fiber (GIF) as well as a 1.6-Gbit/s information rate optical transmission experiment using a 1.3-μm InGaAsP/InP Fabry-Perot-type LD and a 10-km single-mode optical fiber (SMF) are carried out. These results show that the feasibility of a 400-Mbit/s intra-office optical link using the LED and GIF, as well as a 1.6-Gbit/s intra-office optical link using the LD and SMF, are confirmed and this optical transmission technology has high-speed performance up to 3.2 Gbit/s.     

1.5 μm transmission experiment with distributed feedback laser

The paper reports an experiment which demonstrates the possibility of error-free transmission over 100 km without repeater, by using a single-mode fiber and a laser diode with distributed feedback emitting a single longitudinal mode at the wavelength 1.5 μm.     

All-optical discrimination based on nonlinear transmittance of MQWsemiconductor optical gates

This paper proposes an all-optical regenerator utilizing a novel all-optical discriminator. The impacts of nonlinearity of optical gates on discrimination performance are estimated. The evaluation of discrimination performance shows that amplified spontaneous emission noise and wave form distortion in optical signals can be effectively suppressed. We experimentally demonstrate the suppression using a low-temperature-grown optical switch up to 10 Gb/s     

Effects of freezing pretreatment and hygroscopicity of fluidizing particles on drying characteristics of carrots in fluidized bed under reduced pressure

Abstract

A method for low-temperature drying with high drying rate was developed for heat-sensitive foods and agricultural products. A freezing pretreatment was combined with fluidized bed drying under reduced pressure. Cylindrical carrot samples were frozen and then placed without thawing in a fluidized bed of hygroscopic porous silica gel particles that adsorbed water from the sample during the drying process. The effects of the freezing pretreatment and hygroscopicity of fluidizing particles on the drying characteristics of carrots were examined. A higher drying rate was achieved when carrots samples were subjected to freezing pretreatment than without it. At 12?kPa, the volume change was smaller in carrots subjected to freezing pretreatment than in untreated samples. A larger amount of water was absorbed during rehydration by carrots dried at 12?kPa than at 101?kPa within 120?min. The properties of dried carrots were affected not only by freezing pretreatment but also by the pressure applied during the drying process.     

Transmission line with distributed erbium-doped fiber amplifier

We show the advantages of distributed erbium-doped fiber amplifiers (EDFAs) over lumped EDFAs. Using the distributed EDFA for 50%-100% of the transmission line lessens the signal degradation compared to the conventional transmission line. We also show the feasibility of the gain-flattened d-EDFA transmission line. An experiment shows that the gain peak is shifted and flattened at low pump powers     

Long-span repeaterless transmission systems with optical amplifiersusing pulse width management

This paper proposes pulse width management in order to extend the repeater spacings of repeaterless transmission systems with optical amplifiers. First, the dependency of receiver sensitivity on duty ratio, receiver response, and fiber dispersion is clarified by numerical analysis. Next, the calculation results of sensitivity as a function of signal format and receiver basedband response are verified experimentally. Moreover, we show that pulse width management which uses return-to-zero (RZ) format with large duty ratio (~0.7) at the transmitter and pulse compression at the receiver increases the repeater gain by ~4.5 dB compared to conventional systems employing nonreturn-to-zero (NRZ) format. Record repeater spacing of 300 km is realized at 10 Gb/s by utilizing pulse width management