Modified optical fiber sensors received increasing attention because of their superior properties over electrical sensors. These properties include their immunity towards electromagnetic interference and the ability to be deployed in corrosive and volatile environment. Several optical fiber platforms have been developed for chemical sensing applications based on modifying optical fiber cladding layer such as etched, tapered, D-shaped and etched-tapered. The modifications purpose is to extend the evanescent wave propagating out of the core physical dimensions. Thus, evanescent wave interaction with analyte is enhanced. Modified optical transducing platforms are integrated in gas sensing applications, such as ammonia. Modified optical fiber sensors coated with nanostructured thin films have been developed and gained popularity as practical devices towards gases with low concentrations. The development and characterization of the modified SMF sensing platforms including etched, tapered and etched-tapered platforms against ammonia will be presented in this chapter. These platforms were coated with PANI nanostructured thin film. The 50 μm etched-tapered SMF coated with PANI produced response, recovery times, and sensitivity of 58 s, 475 s, and 231.5%, respectively, in the C-band range. The limit of detection of the modified fiber sensor was 25 ppm. The developed sensors exhibit good repeatability, reversibility, and selectivity.
Thin films of (Cu2S)100-x( SnS2 )x at X=[ 30,40, &50)]% with thickness (0.9±0.03)µm , had been prepared by chemical spray pyrolysis method on glass substrates at 573 K. These films were then annealed under low pressure of(10-2) mbar ,373)423&473)K for one hour . This research includes , studying the the optical properties of (Cu2S)100-x-(SnS2)x at X=[ 30,40, &50)]% .Moreover studying the effect of annealing on their optical properties , in order to fabricate films with high stability and transmittance that can be used in solar cells. The transmittance and absorbance spectra had been recorded in the wavelength range (310 - 1100) nm in order to study the optical properties . It was found that these films had direct optical band
... Show MoreThis study describe the effect of temperature on the optical
properties of nickel(ii) phthalocyanine tetrasulfonic acid tetrasodium
salt (NiPcTs) organic thin films which are prepared by spin coating
on indium tin oxide (ITO-glass). The optical absorption spectra of
these thin films are measured. Present studies reveal that the optical
band gap energies of NiPcTs thin films are dependent on the
annealing temperatures. The optical band gap decreases with increase
in annealing temperature, then increased when the temperature rising
to 473K. To enhance the results of Uv-Vis measurements and get
more accurate values of optical energy gaps; the Photoluminescence
spectra of as-deposited and annealed NiPcTs thin fi
Nano-structural of vanadium pentoxide (V2O5) thin films were
deposited by chemical spray pyrolysis technique (CSPT). Nd and Ce
doped vanadium oxide films were prepared, adding Neodymium
chloride (NdCl3) and ceric sulfate (Ce(SO4)2) of 3% in separate
solution. These precursor solutions were used to deposit un-doped
V2O5 and doped with Nd and Ce films on the p-type Si (111) and
glass substrate at 250°C. The structural, optical and electrical
properties were investigated. The X-ray diffraction study revealed a
polycrystalline nature of the orthorhombic structure with the
preferred orientation of (010) with nano-grains. Atomic force
microscopy (AFM) was used to characterize the morphology of the
films. Un-do
In this research we prepared CdS thin films by Spray pyrolysis method on a glass substrates and we study its structural , optical , electrical properties .The result of (X-Ray ) diffraction showed that all thin films have a polycrystalline structure , The relation of the transmission as a function of wavelength for the CdS films had been studied , The investigated of direct energy gap of the CdS its value is (2.83 eV). In Hall effect measurement of the CdS we find the charge carriers is p – type and Hall coefficient 1157.33(cm3/c) ,Hall mobility 6.77(cm2/v.s)
Sb2S3 thin films have been prepared by chemical bath deposition on a glas sub Absorbance and transmittance spectra were recorded in the wavelength range (30-900) nm. The effects of thickness on absorption coefficient, reflectance, refractive index, extinction coefficient, real and imaginary parts of dielectric constant were estimated. It was found that the reflectivity, absorption coefficient , extinction coefficient, real part of dielectric constant and refractive index, all these parameters decrease as the thickness increased, while the imaginary part of the dielectric constant increase as the thickness incre
... Show MoreIn this paper, a step-index fiber with core index 1.445 5 1 7 and cladding index 1.443 1 5 7 has been designed and studied. Multimode operation is achieved by using a fiber with core radius 25 μm operating at a wavelength of 1.3 μm. The mode parameters (effective refractive index, phase constant, fractional modal power in the core and cutoff wavelength) were calculated using RP fiber calculator (PRO version 2020). The shapes of the intensity and amplitude distribution of linearly polarized guided modes were shown.
This paper reports a fiber Bragg grating (FBG) as a biosensor. The FBGs were etched using a chemical agent,namely,hydrofluoric acid (HF). This implies the removal of some part of the cladding layer. Consequently, the evanescent field propagating out of the core will be closer to the environment and become more sensitive to the change in the surrounding. The proposed FBG sensor was utilized to detect toxic heavy metal ions aqueous medium namely, copper ions (Cu2+). Two FBG sensors were etched with 20 and 40 μm diameters and fabricated. The sensors were studied towards Cu2+ with different concentrations using wavelength shift as a result of the interaction between the evanescent field and copper ions. The FBG sensors showed
... Show MoreIn this work, a solid core photonic crystal fibre (SC-PCF) has been designed with endlessly single mode of which both centerd core and holes in the cladding are organized by circles. The designed SC-PCF has a single solid centerd core which is ringed by a six rings hexagonal cladding. The computation of SC-PCF is achieved by using the finite element method (FEM) with perfectly matched layer (PML) boundary condition. All the designed factors like dimensions and distance of both core and cladding areas have varied with an optimized structure. After ending the numerical calculation, the results shows that there are a link between the air hols in the cladding , and the different normaliz
... Show MoreThe optical transmission and UV-VIS absorption spectra have been recorded in the wavelength range (200-1100m) for different composition of polyaniline and polyvinyl Alcohol(PVA ) blends thin films. Polyaniline was prepared in acidic medium to enhancement the solubility and processibility, The optical energy gap (Eopt) refractive index and optical dielectric constant real and imaginary part have been evaluated. The effects of doping percentage of prepared polyaniline on these parameters was discussed and the non –linear behavior for all these parameters was investigated.
The pure and Sb doped GeSe thin films have been prepared by thermal flash evaporation technique. Both the structural and optical measurement were carried out for as deposited and annealed films at different annealing temperatures.XRD spectra revealed that the all films have one significant broad amorphous peak except for pure GeSe thin film which annealed at 573 K, it has sharp peak belong to orthorhombic structure nearly at 2θ=33o. The results of the optical studies showed that the optical transition is direct and indirect allowed. The energy gap in general increased with increasing annealing temperature and decreased with increase the ratio of Sb dopant. The optical parameters such as refractive index, extinction coefficient and real and
... Show More