KEYWORDS: Microwave radiation, Signal detection, Reflection, Optoelectronics, Oscillators, Microwave photonics, Signal generators, Tunable filters, Single mode fibers, Laser frequency
We can achieve a high frequency with a low-phase-noise microwave photonics signal with the help of an optoelectronic oscillator (OEO). In this paper, we propose an OEO based on an external modulator and a dispersive component that provides frequency selection properties similar to those of the photonic filter, i.e. π phase-shifted fiber Bragg grating (π PS-FBG), which has a fixed center frequency of 1550nm. By changing the wavelength of an optical carrier signal, we can tune the oscillating frequency of the OEO. The π PS-FBG reflected signal was passed through parallelly connected single-mode fibers of 0.1 Km, 0.2 Km, and 0.4 Km length. An extra delay in the loop is provided for locking the oscillating frequency. we use π PS-FBG filters designed for the wavelengths 1550 nm to 1555 nm and the corresponding frequency of oscillation was observed between 4.63 GHz and 40.17 GHz. We make observations of the oscillating frequency. With the help of simulated results, the overall model has been theoretically analyzed and verified.
Creatinine is a metabolite of human muscles that can be used to infer whether part of the kidneys is functioning properly. In this paper, a taper-in-taper fiber (TITF) based fiber optic biosensor is proposed for detecting the concentrations of creatinine solution and helps to diagnosis of kidney failure. The TITF structure used in this study is formed by fabricating a taper shape again in the tapered region of a normal taper optical fiber. This allows the fiber to produce more higher-order modes and thus improve its ability to sense changes in refractive index of the external environment. The sensitivity of the sensor was increased by coating the tapered region of the TITF fiber with a gold nanoparticles and zinc oxide nanomaterials. Creatinase enzyme is used to increase the specificity of the sensor for creatinine. The experimental results show that the sensor can detect the creatinine solution with the concentrations of 300-2000 μM and the sensitivity is 0.17 a.u./μM. It provides a good choice for biomedical applications.
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