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The resonance enhanced InAs/GaSb type-II Superlattices (T2SLs) infrared detectors with diffraction rings is designed, and the photoelectric characteristics are calculated and studied in this paper. The diffraction rings are designed on the top surface of T2SLs detector to control the incident light inside the device by forming the resonant cavity. We designed the structure of the conventional PIN InAs/GaSb T2SLs photodetector, calculated the energy band structure of the absorption layer, and analyzed the influence of the thickness of the absorption layer on the photoelectric performance. It is proved that blindly increasing the thickness of the absorption layer cannot effectively improve the device performance. We further studied the quantum efficiency (QE) and electric field distribution of the device after adding the diffraction ring structure. The results show that the structure with diffraction rings can significantly improve the QE of the photodetector without increasing the dark current. The interaction between the diffraction ring and the metal contact layer will enhance the localization of the electric field and further increase the light absorption between the semiconductor layers.

Vortex beams with optical orbital angular momentum have broad prospects in future high-speed and large-capacity optical communication. In this investigation of materials science, we found that low-dimensional materials have feasibility and reliability in the development of optical logic gates in all-optical signal processing and computing technology. We found that spatial self-phase modulation patterns through the MoS2 dispersions can be modulated by the initial intensity, phase, and topological charge of a Gauss vortex superposition interference beam. We utilized these three degrees of freedom as the input signals of the optical logic gate, and the intensity of a selected checkpoint on spatial self-phase modulation patterns as the output signal. By setting appropriate thresholds as logic codes 0 and 1, two sets of novel optical logic gates, including AND, OR, and NOT gates, were implemented. These optical logic gates are expected to have great potential in optical logic operations, all-optical networks, and all-optical signal processing. [ABSTRACT FROM AUTHOR]

Vortex beams with optical orbital angular momentum have broad prospects in future high-speed and large-capacity optical communication. In this investigation of materials science, we found that low-dimensional materials have feasibility and reliability in the development of optical logic gates in all-optical signal processing and computing technology. We found that spatial self-phase modulation patterns through the MoS2 dispersions can be modulated by the initial intensity, phase, and topological charge of a Gauss vortex superposition interference beam. We utilized these three degrees of freedom as the input signals of the optical logic gate, and the intensity of a selected checkpoint on spatial self-phase modulation patterns as the output signal. By setting appropriate thresholds as logic codes 0 and 1, two sets of novel optical logic gates, including AND, OR, and NOT gates, were implemented. These optical logic gates are expected to have great potential in optical logic operations, all-optical networks, and all-optical signal processing.

The resonance enhanced InAs/GaSb type-II Superlattices (T2SLs) infrared detectors with diffraction rings is designed, and the photoelectric characteristics are calculated and studied in this paper. The diffraction rings are designed on the top surface of T2SLs detector to control the incident light inside the device by forming the resonant cavity. We designed the structure of the conventional PIN InAs/GaSb T2SLs photodetector, calculated the energy band structure of the absorption layer, and analyzed the influence of the thickness of the absorption layer on the photoelectric performance. It is proved that blindly increasing the thickness of the absorption layer cannot effectively improve the device performance. We further studied the quantum efficiency (QE) and electric field distribution of the device after adding the diffraction ring structure. The results show that the structure with diffraction rings can significantly improve the QE of the photodetector without increasing the dark current. The interaction between the diffraction ring and the metal contact layer will enhance the localization of the electric field and further increase the light absorption between the semiconductor layers., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

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Synthesis and measurements of third-order optical nonlinearity and optical limiting of conducting copolymers of aniline are presented. Single beam z-scan technique was employed for the nonlinear optical studies. Continuous wave He–Ne laser operating at 633 nm was used as the source of excitation. Copolymer samples exhibited reverse saturable absorption (RSA) process. The nonlinear refraction studies depict that the copolymers exhibit self-defocusing property. The estimated values of β eff , n 2 and χ (3) were found to be of the order of 10 −2 cm/W, 10 −5 esu and 10 −7 esu respectively. Self-diffraction rings were observed due to refractive index change when exposed to the laser beam. A good optical limiting and clamping of power of ∼0.9 mW and ∼0.05 mW was observed. Therefore, copolymers of aniline emerge as a potential candidate for photonic device applications. [ABSTRACT FROM AUTHOR]

Abstract: The third order nonlinear optical properties of multi-wall carbon nanotubes (MWNT), single-wall carbon nanotubes (SWNT) dissolved in 1,2-dichlorobenzene and SWNT doped poly(ethylacetylenecarboxylate) polymer have been studied using Z-scan technique. Experiments are performed using a CW diode laser at 635nm wavelength with 26mW power. It has been found that the values of nonlinear absorption coefficient β, nonlinear refractive index n 2, Re χ 3, and Im χ 3 in SWNT are larger than in MWNT. It was noticed that the closed-aperture Z-scan is most effective when the linear transmittance of the aperture “S” is small. Laser-induced diffraction ring patterns were observed only for SWNT. Based on the number of diffraction rings, variation of refractive index Δn and the relative phase shift ∆ϕ (r) have been estimated at different input laser power: 5, 10, 15 and 25mW. [Copyright &y& Elsevier]

Abstract: We report the investigations of thermally induced third-order nonlinear optical and optical limiting characterizations for various concentrations of acid blue 40 dye in N,N-Dimethyl Formamide, studied by employing z-scan technique under cw He–Ne laser irradiation at 633 nm wavelength. The samples exhibited nonlinear absorption and nonlinear refraction under the experimental conditions. For lower concentration, the samples display both saturable absorption (SA) and reverse saturable absorption (RSA); whereas with increase in concentration, RSA behaviour prevails. The estimated values of the effective coefficients of nonlinear absorption β eff, nonlinear refraction n 2 and third-order nonlinear susceptibility χ (3) were found to be of the order of 10−2 cm/W, 10−4 esu and 10−6 esu respectively. Multiple diffraction rings were observed when the samples were exposed to laser beam due to refractive index change and thermal lensing. The effect of concentration and the laser intensity on the self-diffraction ring patterns was studied experimentally. The acid blue 40 dye also exhibited strong optical limiting properties under cw excitation and reverse saturable absorption is found to be the dominant nonlinear optical process leading to the observed nonlinear behaviour. [Copyright &y& Elsevier]

Abstract: We present the synthesis and results on the third-order optical nonlinearity and optical limiting properties of Polyaniline and Poly (o-toluidine) studied in N,N-Dimethyl Formamide solution using a single-beam z-scan technique. Experiments were performed using continuous wave He–Ne laser operating at 633nm wavelength as an excitation source. The samples exhibit absorption and refraction nonlinearities. The negative sign of the nonlinear refractive index n 2 indicates that both materials exhibit self-defocusing optical nonlinearity. The nonlinear refractive index n 2, the nonlinear absorption coefficient β eff and the third-order optical susceptibility χ (3) were determined and found to be of the order of 10−7 cm2/W, 10−2 cm/W and 10−7 esu respectively. The FTIR and UV–visible characterization spectra confirm the expected molecular structure of the polymers. Multiple diffraction rings were observed when the samples were exposed to laser beam. The appearance of rings is due to the refractive index change and thermal lensing. The polymer samples with different concentrations exhibits strong optical power limiting under continuous wave laser at the experimental wavelength. Reverse saturable absorption is the dominating mechanism for the observed absorption nonlinearities. [Copyright &y& Elsevier]

Abstract: A Solid State Nuclear Track Detector (SSNTD) can be used to identify an impinging ion as well as to determine the energy of that ion. The track of the ion is made visible by chemically ‘etching’ the detector after exposure. By finding out the ratio of the track-etch rate (V t ) to the bulk-etch rate (V g ), together with the range of the ion in the detector, the identity and the energy of the ion can be ascertained. The required measurements can be conveniently made with the help of a microscope when the angle of incidence of the ion, with respect to the normal direction to the detector surface, is more than 15°. For normal or near normal incidence, uncertainties plague the measurement of the depth of the etch pit and hence the range of the particle. Through this article we wish to suggest an alternative method of assessment, based on the observation of diffraction rings, of the depth of an etch pit. [Copyright &y& Elsevier]

Abstract: In a context of automation of cryo-electron microscopy, we developed a novel method for improving visibility of diffraction rings in the power spectra of cryo-electron micrographs of vitreous ice (without carbon film or high concentration of diffracting material). We used these enhanced spectra to semi-automatically detect and remove micrographs and/or local areas introducing errors in the global 3D map (drifted and charged areas) or those unable to increase global signal-to-noise ratio (non-diffracting areas). Our strategy also allows a detection of micrographs/areas with a strong astigmatism. These images should be removed when using algorithms that do not correct astigmatism. Our sorting method is simple and fast since it uses the normalized cross-correlation between enhanced spectra and their copies rotated by 90°. It owes its success mainly to the novel pre-processing of power spectra. The improved visibility also allows an easier visual check of accuracy of sorting. We show that our algorithm can even improve the visibility of diffraction rings of cryo-electron micrographs of pure water. Moreover, we show that this visibility depends strongly on ice thickness. This algorithm is implemented in the Xmipp (open-source image processing package) and is freely available for implementation in any other software package. [Copyright &y& Elsevier]