| Budget Amount *help |
¥16,470,000 (Direct Cost: ¥15,300,000、Indirect Cost: ¥1,170,000)
Fiscal Year 2007: ¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000)
Fiscal Year 2006: ¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2005: ¥8,100,000 (Direct Cost: ¥8,100,000)
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| Research Abstract |
We aimed at the realization of all-optical error detection scheme operating at 40Gbps and beyond to overcome the technical issues of the conventional electronic circuits such as operation speed limit and increase of power consumption.
Firstly, we selected the suitable error detection code and optical circuits for the all-optical scheme. On the basis of encoding and decoding error detection symbols processed during passing through optical circuits without buffering and complicated serial-to-parallel and parallel-to-serial conversions and so on, convolutional code and recirculating codes are selected.
In case of convolutional code, check-symbols are generated by processing XOR function between the original information-symbols and the one-bit-delayed information-symbols. And the information and check-symbols are WDM transmitted. In the decoder, the information and check-symbols are WDM demultiplexed, and then XOR function are processed between them, and the original information-symbols are
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regenerated in case of no errors. After XOR function is processed between the regenerated information-symbols and the transmitted information-symbols, the syndrome is generated. If no "1"'s are included, there are no errors, and if there are "1"'s, errors are detected.
To evaluate the capability of the error detection of the proposed scheme, we simulated the frame error rate, and the improvement of the received optical power of about 2dB could be obtained.
Next, we investigated the performance of the all-optical XOR gate consisting of the SOA-MZI all-optical switch and an optical push-pull circuit, which is one of the most significant components in the error detection circuits. By simulating the rate equation of the semiconductor optical amplifier (SOA) in the all-optical XOR gate, optimized condition for input optical power, power split ratio and time delay of the push-pull optical circuit were derived. Then, 10 and 40Gbps operation of the all-optical XOR gate was performed. Clear eye opening was achieved at 10Gbps, but large degradation of extinction ratio was observed at 40Gbps due to the slow carrier recovery time of the SOA's relative to bit rate.
After that, all-optical error detection operation was investigated analytically and experimentally. In simulations, rate equation and the derived optimized conditions for all-optical XOR gate were used, and the error detection could be verified at 40Gbps. In experiments, 10Gbps operation was performed because of carrier recovery time of 130ps, and extinction ratio of 6dB was achieved in the syndrome for the first time. Less
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