Suppression of brillouin scattering in lightwave transmission system
US5420868A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 20, 1994 |
| Grant date | May 30, 1995 |
| Priority date | — |
| Expiry date | Oct 20, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F1/225
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Optical nonlinear effects, such as stimulated (Brillouin) scattering, cause disproportionate attenuation of transmitted optical signals and usually occurs only when the optical power exceeds a certain level. One of the most important types of nonlinear scattering which occurs in an optical fiber as the power of the optical signal is increased above a certain level is stimulated Brillouin scattering. Brillouin scattering limits the power density of an optical signal that can be injected into an optical fiber. This invention suppresses Brillouin scattering and, by so doing, permits the power density of the optical signal which is injected into an optical fiber to be increased approximately threefold before the Brillouin scattering threshold is reached. More specifically, in a lightwave AM-VSB CATV transmission system having an external modulator, the optical beam which is amplitude modulated with the CATV signals is also phase modulated with a sinusoidal signal having a frequency which is not less than twice the frequency of the highest CATV signal. The phase modulation of the optical beam suppress Brillouin scattering. With this invention the power density of the CATV signal can be …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.