ABSTRACT
Gamma rays, as hazardous nuclear radiation, necessitate effective and rapid detection methods. This paper introduces a low-cost, fast, and simple fluorescence method based on CdTe/CdS core/shell quantum dots for gamma-ray detection. CdTe/CdS quantum dots, subjected to gamma irradiation from a 60Co source under various conditions, were investigated to assess their fluorescence sensor capabilities. The obtained results showed that an increase in CdTe/CdS nanoparticle size was associated with decreased sensitivity, while a reduction in CdTe/CdS concentration correlated with increased sensitivity. To further validate the practicality of CdTe/CdS core/shell quantum dots in gamma-ray detection, the structural properties of the quantum dots were meticulously studied. Raman spectroscopy, X-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) analysis were conducted before and after gamma-ray radiation. The results demonstrated the crystalline stability of CdTe/CdS core/shell quantum dots under gamma irradiation, highlighting their robust structural integrity. In conclusion, the experimental findings underscore the exceptional potential of CdTe/CdS quantum dots as an off-fluorescence probe for simple, low-cost, fast, and on-site detection of gamma rays. This research contributes to the advancement of efficient and practical methods for gamma-ray sensing in various applications.
ABSTRACT
Microring tower resonators, which are a chain of microring resonators stacked on top of each other, are of great interest for nonlinear optics due to their unique features such as very high compactness, coupling efficiency and quality factor. In this research, we investigate the optical bistability in microring tower (MRT) with Kerr nonlinearity by using the coupled mode theory, and demonstrate how a proper defect into the structure can lead to low threshold bistability. In particular, we observed optical bistability in nonlinear defect modes with switching power as low as 165 µW through numerical calculations in a structure with a overall loss on the order of 0.01 mm. In addition, we also develop an analytical model that excellently gives the position of defect modes in linear regime.
Subject(s)
Computer-Aided Design , Models, Theoretical , Optical Devices , Transducers , Computer Simulation , Equipment Design , Equipment Failure Analysis , Nonlinear DynamicsABSTRACT
The linear characteristics of a vertically stacked multiring resonator (VMR) that can support a photonic bandgap with a defect located at the middle of the structure are investigated numerically. Initially, the spectral transfer characteristics of the uniform structure are studied. Then, the transmission properties of the VMR structure possessing a defect are investigated. The defect is realized by varying the waveguide width of one of the rings in the VMR chain. Finally, the existence of defect modes in the linear periodic array is numerically demonstrated by solving the corresponding coupled wave equations. Numerical results predict a high quality factor (Q) of up to 1.6x10(5) for this microcavity. We also show that our microcavity has a good insensitivity of quality factor to geometric imperfections.