| Budget Amount *help |
¥10,100,000 (Direct Cost: ¥10,100,000)
Fiscal Year 2001: ¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 2000: ¥3,100,000 (Direct Cost: ¥3,100,000)
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| Research Abstract |
Enabling technologies for ultra-high capacity backbone networks are divided into two categories ; the high-capacity transmission technology and the optical switching technology at network nodes. As for the data transmission, the recent progress in the wavelength-division multiplexing (WDM) technique has achieved the drastic growth of the transmission capacity up to tera-bit/sec.
The transmission capacity of WDM systems is expressed by the product of the bit-rate per wavelength and the number of wavelengths. The recent increase in the transmission capacity has been provided mainly by the increase in the number of wavelengths. Even in the optical region, however, the frequency resources are limited, and the excessive increase in the number of wavelengths leads to the complicated supervision and maintenance of optical systems. In order to cope with these difficulties, we have to increase the bit-rate per wavelength, but it is not easy because the various effects in optical fibers disturb t
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he pulse propagation as the pulse width becomes short. The transmission capacity of WDM systems is expressed by the product of the bit-rate per wavelength and the number of wavelengths. The recent increase in the transmission capacity has been provided mainly by the increase in the number of wavelengths. Even in the optical region, however, the frequency resources are limited, and the excessive increase in the number of wavelengths leads to the complicated supervision and maintenance of optical systems. In order to cope with these difficulties, we have to increase the bit-rate per wavelength, but it is not easy because the various effects in optical fibers disturb the pulse propagation as the pulse width becomes short.
In this study, we have investigated the transmission technique using dispersion-managed soliton (DMS) which can withstand the dispersion, nonlinear optical effects, and higher-order dispersion, and pursued the ultimate limit of the transmission speed. For this purpose, we've investigated the fundamental properties of DMS's and the design guideline of DMS transmission systems. The results are summarized as follows; (1) we numerically studied the influence of the dispersion, the polarization-mode dispersion, and higher-order dispersion on DMS pulses and found that the stable transmission of optical short pulse was possible by optimizing the pulse energy. (2) On the basis of the numerical study, we constructed a 40-Gbit/s long-distance transmission system, and demonstrate the error-free transmission over several thousands of kilometer by using DMS pulses. (3) we proposed and demonstrated novel techniques for dispersion monitoring and dispersion compensation technique, which are key technologies required for practical high-bitrate DMS transmission systems. Less
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