Browsing by Author "Wei, Chengli"
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Item Geometry of Chalcogenide Negative Curvature Fibers for CO2 Laser Transmission(2018-07-16) Wei, Chengli; Menyuk, Curtis; Hu, Jonathan; UMBC Faculty collectionWe study impact of geometry on leakage loss in negative curvature fibers made with As2Se3 chalcogenide and As2Se3 chalcogenide glasses for carbon dioxide (CO2) laser transmission. The minimum leakage loss decreases when the core diameter increases both for fibers with six and for fibers with eight cladding tubes. The optimum gap corresponding to the minimum loss increases when the core diameter increases for negative curvature fibers with six cladding tubes. For negative curvature fibers with eight cladding tubes, the optimum gap is always less than 20 μm when the core diameter ranges from 300 μm to 500 μm. The influence of material loss on fiber loss is also studied. When material loss exceeds 102 dB/m, it dominates the fiber leakage loss for negative curvature fiber at a wavelength of 10.6 μm.Item Increasing the power threshold in fiber amplifiers considering both the transverse mode and Brillouin instabilities(Optica, 2022-05) Young, Joshua T.; Menyuk, Curtis; Wei, Chengli; Hu, JonathanWe study the Brillouin instability and the transverse mode instability in a combined computational model for fiber amplifiers. We find the optimal core diameter, which leads to the highest power threshold and output power.Item Polarization-filtering and polarization-maintaining low-loss negative curvature fibers(Optical Society of America, 2018) Wei, Chengli; Menyuk, Curtis; Hu, JonathanWe propose a polarization-filtering and polarization-maintaining negative curvature fiber in which two nested resonant tubes are added to a standard negative curvature fiber with one ring of tubes. The coupling between the glass modes in the nested resonant tubes and the fundamental core modes is used to increase the birefringence and differential loss for the fundamental core modes in the two polarizations. We show computationally that the birefringence and the loss ratio between the modes in the two polarizations can reach 10−5 and 850, respectively. Meanwhile, the low-loss mode has a loss that is lower than 0.02 dB/m. The relatively simple design of this polarization-maintaining negative curvature fiber will be useful in hollow-core fiber devices that are sensitive to polarization effects, such as fiber lasers, fiber interferometers, and fiber sensors.Item Temperature sensor based on liquid-filled negative curvature optical fibers(Optical Society of America, 2019-06-24) Wei, Chengli; Young, Joshua T.; Menyuk, Curtis; Hu, JonathanWe computationally investigate a novel temperature sensor that uses liquid-filled negative curvature optical fibers. Both the core and cladding tubes are infiltrated with a liquid that has a temperature-sensitive refractive index. The high-loss resonant wavelengths are sensitive to the liquid’s change of the refractive index. The refractive index of the liquid decreases and the resonant wavelengths increase when the temperature increases. The temperature sensitivity is 1.1 nm/ ◦C as the temperature changes from 15 ◦C to 35 ◦C using negative curvature optical fibers that are filled with liquid that has a refractive index of 1.36. The temperature sensitivity rises from 0.82 nm/ ◦C to 2.48 nm/ ◦C when different liquids are used with a refractive index from 1.30 to 1.42, and we use the third resonant peak in the fiber. The temperature sensitivity can be increased by 38% by using the second resonant peak. An analytical formula for the temperature sensitivity is derived, which can give an accurate prediction for the temperature sensitivity of this sensor. The relatively large size of the air core and cladding tubes, on the order of 10 µm, should make the infiltration procedure easier compared to other photonic crystal fibers with smaller holes. With temperature sensors based on liquid-filled negative curvature optical fibers, there is no need for any special post-processing, such as the liquid filling of selected air holes or inscription of fiber gratings.