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Go to Editorial ManagerThe aim of this work is to use Fiber Bragg Grating (FBG) to detect the breast cancer at its earliest stages based on the Photoacoustic (PA) hybrid technique. The fiber Bragg gratings sensitivity to acoustic wave, effect of grating length, effect of grating refractive index modification, and ultrasonic frequency on the wavelength sensitivity and intensity sensitivity of the ultrasonic sensor (FBG) for ultrasonic waves were investigated using a simulation programs. A wavelength for the photoacoustic (PA) excitation laser was chosen with respect to a high absorption by the tumor and with low absorption to the surrounding tissue (normal tissue); for higher contrast absorption between them. Fiber Bragg can be used as a sensor to detect the acoustic wave emitted from the tumor (depending on the photoacoustic principle). In this study, k-wave a MATLAB toolbox was used to simulate photoacoustic wave which is detected with fiber Bragg grating simulation, using Optisystem program. The acoustic wave was transferred to FBG by using Optisystem-MTLAB communication programs to detect tumors.
Photonic crystal fibers (PCFs) are generally divided into two categories: solid-core photonic crystal fibers and hollow-core photonic crystal fibers. In this paper, a long-period fiber Bragg grating (LPFBG) was experimentally fabricated in a hollow-core photonic crystal fiber (HC-PCF) using a CO₂ laser and based on the point-by-point technique. Proper LPFBGs were inscribed using laser powers of 0.9 W and 1.4 W, with grating parameters (grating period, length of each pitch, and depth of each pitch) equal to (136 µm, 48.042 µm, 16 µm) and (142 µm, 74.027 µm, 22.09 µm), respectively, for two samples. The Bragg wavelengths and full-width at half-maximum (FWHM) were (1529.274 nm, 1.34 nm) and (1529.629 nm, 5.11 nm), respectively, for the two samples fabricated using CO₂ laser powers of 0.9 W and 1.4 W. From these results, it was recognized that the optimal LPFBG-HC-PCF was the one fabricated using 0.9 W laser power. The unique structure of hollow-core photonic crystal fibers, which enables light propagation within the air core and provides a large internal surface area, has attracted significant research interest for various sensing و communication applications, Environmental and Biological Monitoring, and medical applications.
In this work, four fiber Bragg gratings are fabricated by infiltration different volumes of liquids (star line Glass Mechanix optical adhesive material, olive oil diluted with ?ethanol) into the hollow core photonic crystal fibers (HC19-1550 (Thorlab Company)). The amplitude splitting interferometric technique with a high resolution specially designed translation stage was used for the fabrication process. This stage is capable of moving the fibers in micrometer ?resolution steps. The fabrication was carried out using blue laser operated at wavelength of 405 nm. The infiltrated four photonic crystal fibers were exposed to the blue laser beam of 405 nm forming periodic fringes for Bragg grating generation. These fringes were generated from the interference of two splitted laser beams. All fabricated fibers have the same Bragg length of 3.8 cm and average gratings periods of 0.224 ?m. The four fibers were analyzed by an optical microscope which displayed the areas that were cured using blue laser. The fabricated fibers also were tested by putting laser beam at one end of the fiber and determining the transmittance at the other fiber end by optical signal analyzer? (Thorlabs-CCS200). The resulted Bragg grating fibers have 653.3 nm Bragg reflected wavelength. The results also showed that fiber with higher volume of olive oil has the highest reflection peak about ?96.09647 %? with the greatest FWHM (full width at a half maximum) ?about 0.74 nm.In addition, three of the fabricated fibers (B, C and D) that contained olive oil were prepared for testing magnetic field sensor. The results show that all the fibers shifted to near infrared range. The results also showed that fiber with higher concentration of olive oil has the greatest magnetic wavelength shift about 653.4 nm, the highest fiber sensitivity about ??0.000494623656 nm/ Gauss?, the highest reflection peak about 96.91827? %, and the greatest FWHM ?about 0.98 nm.