Stimulant abuse enhances dopamine release, thereby causing increased excitation. Any extent of stimulant abuse can considerably harm the user. Thus, methods of detecting stimulants must be precise, accurate, and reliable. A novel terahertz (THz) photonic crystal fiber with a Topas substrate is designed and rigorously investigated for detecting liquid amphetamine, cocaine, and ketamine. The fiber structure has a pentagonal shape and comprises circular air holes in the core and cladding spatial extents. As shown in finite element simulation, the proposed fiber yields a high relative sensitivity of approximately 80 % when any of the liquid stimulants is infiltrated in the core air holes. At 1 THz operating frequency, the proposed fiber produces a large effective mode area, negligible confinement loss, and extremely low bending and effective material losses. Other THz waveguiding properties, such as core power fraction and total loss, are also studied. Lastly, a positive and negative 2 % fabrication tolerance is set to ensure seamless potential practical realization of the fiber.
To increase the sensitivity of biosensor a new approach using an optical fiber Bragg grating (FBG) coated with a suitable nanostructured metal oxide (NMO) is proposed which is costly effective compared to other biosensors. Bragg grating was written on a D-shaped optical fiber by phase mask method using a 248 nm KrF excimer laser for a 5 min exposure time producing a grating with a period of 528 nm. Titanium dioxide (TiO2) nanostructured metal oxide was coated over the fiber for the purpose of increasing its sensing area. The etched D-shaped FBG was then coated with 312 nm thick TiO2 nanostructured layer to ensure propagating the radiation modes within the core. The final structure was used to sense deionized water and saline. The etched D-shaped FBG original sensitivity before coating to air-deionized water and to air-saline was 0.314 nm/riu and 0.142 nm/riu, respectively. After coating the sensitivity became 1.257 nm/riu for air-deionized water and 0.857 nm/riu for air-saline.
In this study, a simulation analysis of 40-Gb/s long-haul (120 km) dense wavelength-division multiplexer system (DWDM) of 32 channels with 50 GHz spacing is conducted for duobinary return-to-zero modulation formats. Pre- and post-dispersion compensation schemes utilizing dispersion compensating fiber (DCF) and fiber Bragg grating (FBG) are analyzed to compare these schemes at high bit rate. Quality factor (Q) and bit error rate (BER) values are used to measure the response of the system as a function of input power for both compensation schemes. The pre-FBG scheme shows a better performance in terms of Q-factor that reached 11.5 at 0 dBm input signal power.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.