CuBALL graded index optical fiber
In recent years a number of optical fiber sensors have been developed where the sensing element is the fiber itself. Distributed temperature sensors and strain sensors using fiber are having a big impact on industrial measurements.The maximum and minimum operating temperatures of the sensors are usually determined by the fiber and in particular the fiber coating. By using Cuball fibers the span of usable temperatures ranges from close to absolute zero right up to 500-700ºC*.
Loss vs Wavelength for CuBALL G150-200CU| G150-125CB | G150-200CB | |||
| Core diameter µm | 50 | 50 | ||
| Cladding diameter µm | 125 | 200 | ||
| Coating diameter µm | 165 | 260 | ||
| Attenuation dB/km | 12-15 | <1.5 | ||
| N.A. | 0.15 | 0.15 |
A metal coating applied to small diameter (125 µm) increases the attenuation of the fiber (i.e. single mode or 50-125 graded index types). The thicker the coating the higher the loss.
By control of coating thickness we can make a 50-125 µm grade index fiber with attenuation of 10-15dB/km (at 1300 nm). This allows the use of fiber lengths up to about 1km.
By increasing the cladding diameter of the fiber to 200 µm we can make a graded index fiber with an attenuation approximately 10 times lower (<1.5dB/km). This means that much longer length fiber sensors can be used than was previously possible. This 50-200 µm fiber can be connected to the industry standard 50-125 fiber using connectors (with a 200 µm bore) or the fiber can be supplied with a 50-125 pigtail (fusion spliced).
*By operating the fiber in an inert atmosphere, temperatures up to 700ºC can be tolerated indefinitely.
The combination of high temperature operation, high strength, low
loss, low cost, and availability in long lengths, make this fiber the only choice for high
performance sensors.
