What does SLS (dB) in the test report indicate?

FBGs are optical fibers that have a periodic variation in the refractive index along their length, which causes them to reflect certain wavelengths of light while allowing others to pass through. However, due to the nature of the manufacturing process and the properties of the materials used, the reflection spectrum of an FBG can sometimes exhibit unwanted reflections or side lobes at wavelengths other than the desired reflection peak. These side lobes can interfere with the signal or degrade the performance of the FBG in certain applications.

SLS techniques are used to suppress these side lobes and improve the quality of the FBG’s reflection spectrum. This can be achieved through various methods, such as designing the FBG’s structure with optimized parameters, or by using additional optical elements such as apodization or chirping to modify the FBG’s reflection spectrum. The goal of SLS is to minimize the side lobe level in the FBG’s reflection spectrum, while maintaining a high reflection efficiency and narrow bandwidth for the desired reflection peak.

Is the user-end software installed on the interrogator itself, or intended for installation on a separate monitoring PC/device? Is it OS independent?

One can use either the on-board processing (on the MC of the Interrogator) and just stream the raw, strain and temp data via USB or serial UART interface (in conjunction with e.g. a teensy or arduino) or use the compiled LabView application “BraggSens 1.8” on a separate PC.

Is there an API that can be used?

There is no API, but all serial commands are documented in our manual, as well as a sample C programme.

What are the advantages of 850nm and 1550nm fibre optic sensors respectively?

Advantages of 850nm

Pinpoint Precision:
Only approx. 1mm physical FBG length for highest spatial resolution.

Inherent Felxibility:
Down to 5mm bending radius for tight windings.

Higher Interrogator Cost-Effectiveness:
Silicon-based CMOS technology instead of expensive InGaAs.


Advantages of 1550nm

Higher Connector Cost-Effectiveness:
Connectors, Switches, Couplers and Patch-Chords vastly available.

Long Distances:
10- 20km lengths between sensor and read-out no problem.

Less Insertion Loss:
More Interconnections possible for multi-star installations.