| 摘要 |
Apparatus for producing and sourcing two lightwaves having a wavelength-shift known and controllable and suitable to be used as "pump" and "probe" in a stimulated Brillouin analyser in which part of the radiation of frequency f0 from a primary source (70) is first shifted of a frequency Δf1 typically from 200 to1000MHz lower than the Brillouin shift ΔfB,SNS in the sensor, by a first frequency conversion system comprising a Brillouin ring laser (105) and then is shifted of a frequency Δf2 in order to fall inside the Brillouin gain band of the sensor through a further tuneable frequency conversion system (105, 106, 107) in which at least one electro-optical modulator generates modulation side bands (117, 119) of frequency (f0- Δf1+ Δf2) and (f0- Δf1- Δf2), only one of which can fall within a Brillouin gain band of the sensor The apparatus possibly comprises also a feedback stabilization system that acts on Δf2 depending on changes in the value of Δf1 in order to stabilise at least one between | Δf1+ Δf2| and | Δf1 - Δf2|. The apparatus solves the following problems of known solutions: wavelength- shift stability and accuracy, wavelength agility, width of the wavelength-shift tuning range, power consumption, tuning speed and industrial cost. |
