| Project/Area Number |
16560336
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Communication/Network engineering
|
|---|
| Research Institution | Kyoto University |
|---|
Principal Investigator |
NORIMATSU Seiji Kyoto University, Graduate School of Informatics, Kyoto University, Associate Professor, 情報学研究科, 助教授 (20303886)
|
|---|
| Project Period (FY) |
2004 – 2006
|
| Project Status |
Completed (Fiscal Year 2006)
|
| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2006: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥1,500,000 (Direct Cost: ¥1,500,000)
|
|---|
| Keywords | Fiber nonlinearities / WDM / optical fiber transmission / Q-factor / 相互位相変調 / 伝送特性 |
|---|
| Research Abstract |
Recently optical fiber nonlinearities dominantly affect transmission performance of wavelength division multiplexing systems, which are most common configuration for high-capacity optical fiber transmission systems. Among the nonlinearities, self-phase modulation (SPM) and cross-phase modulation (XPM) tend to take place. To assess effect of them on transmission performance numerically, split-step Fourier (SSF) method is usually utilized. Fiber length is divided into a large number of segments in the SSF method; it needs a very long calculation time to simulate long span transmission.
In this research, we develop fast evaluation method of effects of SPM/XPM on WDM transmission systems. We studied intensity modulation (IM) and differential phase modulation (DPSK).
First we studied IM systems. There are many approximations for waveform after nonlinear transmission. We utilized one of them and obtained analytical expression for standard deviation of sampled amplitude. Unfortunately there was
… More
approximation error in the standard deviation. Then we take both second-order SPM accompanied by first XPM and approximated higher-order SPM into account. The final expression for the standard deviation of sampled amplitude offers very good agreement with simulation results.
Secondly we studied DPSK systems, which are brought to international attention. Before studying the SPM/XPM effect on transmission performance, we studied relation between waveform degradation and bit error rate (BER). And we propose an accurate derivation method of Q-factor, which has one-to-one correspondence with a BER, from statistics of each bit in DPSK systems. The method is able to be applied to waveform distorted signals. We show our method can assess the Q-factor more accurately than conventional methods regardless of parameter settings. During this study, we have found occurrences of unusual threshold-BER curves in reception of DPSK signals distorted by SPM/XPM. Such problems have not been found in the case of IM systems. We figure out what is behind the unusual threshold-BER curves of differential binary or quadrature phase-shift keying. Less
|
