Black phosphorus (BP) is a very promising two-dimensional material as a saturable absorber for ultrashort pulse generation especially in telecommunication bands due to its ultrafast dynamic response and strong resonant absorption in the near-infrared wavelength range. However, the current fabrication methods of BP saturable absorbers are very complex and not suitable for practical large-scale production. We have successfully deposited BP with a thickness of ∼25 nm onto the fiber end facet as a saturable absorber by a simple optically driven deposition method. The BP saturable absorber shows excellent mode-locking performance with a stable pulse train repetition of 1.843 MHz and pulse duration of 117.6 ns.
Fiber Bragg Grating (FBG) sensors have been extensively used for strain and temperature sensing. However, there is still
a need to measure multiple environmental parameters with a single sensor system. We demonstrate a multiplexed FBG
sensor with various nano materials (polyallylamine-amino-carbon-nanotube, carbon nanotubes, polyelectrolyte and
metals) coated onto the surface of the core/cladding FBG for sensing multiple environmental parameters such as pH
(64 pm/pH), protein concentration (5 pm/μg/ml), temperature (15 pm/oC), humidity (31 pm/%RH), gas concentration
(7 pm/1000 ppm), and light intensity (infrared: 33 pm/mW, visible: 12 pm/mW and UV: 1 pm/mW) utilizing the same
FBG based platform.
Detection of petroleum leakages in pipelines and storage tanks is a very important as it may lead to significant pollution of the environment, accidental hazards, and also it is a very important fuel resource. Petroleum leakage detection sensor based on fiber optics was fabricated by etching the fiber Bragg grating (FBG) to a region where the total internal reflection is affected. The experiment shows that the reflected Bragg’s wavelength and intensity goes to zero when etched FBG is in air and recovers Bragg’s wavelength and intensity when it is comes in contact with petroleum or any external fluid. This acts as high sensitive, fast response fluid optical switch in liquid level sensing, petroleum leakage detection etc. In this paper we present our results on using this technique in petroleum leakage detection.
In this paper we report a novel hydrogel functionalized optical Fiber Bragg Grating (FBG) sensor based on chemo-mechanical-
optical sensing, and demonstrate its specific application in pH activated process monitoring. The sensing
mechanism is based on the stress due to ion diffusion and polymer phase transition which produce strain in the FBG.
This results in shift in the Bragg wavelength which is detected by an interrogator system. A simple dip coating method to
coat a thin layer of hydrogel on the FBG has been established. The gel consists of sodium alginate and calcium chloride.
Gel formation is observed in real-time by continuously monitoring the Bragg wavelength shift. We have demonstrated
pH sensing in the range of pH of 2 to 10. Another interesting phenomenon is observed by swelling and deswelling of
FBG functionalized with hydrogel by a sequence of alternate dipping between acidic and base solutions. It is observed
that the Bragg wavelength undergoes reversible and repeatable pH dependent switching.