2006 Fiscal Year Final Research Report Summary
Studies on optical noise reductions in distributed optical fiber amplifiers using optical nonlinear effects
| Project/Area Number |
16560349
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Communication/Network engineering
|
|---|
| Research Institution | Osaka Electro-Communication University |
|---|
Principal Investigator |
MURAKAMI Yasuji Osaka Electro-Communication University, Faculty of Information and Communication Engineering, Professor, 情報通信工学部, 教授 (30330153)
|
|---|
| Project Period (FY) |
2004 – 2006
|
| Keywords | Optical fiber Raman amplifier / Polarization dependency / Multiple reflection optical noise |
|---|
| Research Abstract |
The purpose of the project is to propose a method of suppressing optical noises, which are generated in optical signal amplifications, using the stimulated Raman scattering effect that is one of optical fiber nonlinear optical effects. Summary of research results is as follows :
1. Polarization dependency on optical fiber Raman amplification gains
Distributed amplification experiments are carried out using 50km of DSF (Dispersion shifted optical fibers) and 100 km of SMF (Standard single-mode fibers).
(1) Gain deviations are within 0.5 dB when input polarization states of signal light and pumping light are changed and both lights propagate more-than-10 km long fiber.
(2) In the above experiments, the degrees of polarization states of signal light and pumping light remain through 50-km long fiber, but the angle difference between the polarization planes of both light changes randomly. This fact causes the suppression of the polarization dependency of the Raman gains.
(3) Fiber refractive ind
… More
ex birefringence due to fiber bending, when the fibers are winded up round reels, causes rotation angle differences of polarization planes between signal light and pumping light of different wavelengths. This fact seems to be the reason why the polarization angles change randomly.
2. Multiple reflection optical noise in optical fiber Raman amplifier
The generations of optical noise due to multiple reflections between optical connectors are investigated both theoretically and experimentally.
(1) From numerical calculations, it is found that the power of optical noises due to multiple reflections is permitted to be more than 16 dB compared to signal power when the Raman gain is 6.5 dB, but is limited within 27 dB when the gain is 20dB.
(2) Raman amplifications experiments show that multiple reflection noise powers are under detection limits when optical reflection powers from connectors are up to be 13.7 dB. This fact seems clarify the numerical results. More studies are needed to propose a method of suppressing optical noises, using more-than 20 dB gain amplifier. Less
|
