Results in Optics最新文献

The laws of interaction of electromagnetic wave radiation with pyridine molecules and atoms were studied using Raman light scattering spectra of light, and it was shown that the spectra appearing in the lower frequency range (0 ÷ 1031 cm⁻¹) are related to the rotational-rocking movement of molecules. Based on quantum-chemical calculations, a structural model of the pyridine molecule was created. The possibility of determining the bond lengths and angles between the atoms in the pyridine molecule was suggested. Based on the obtained results, the frequency values of the Raman scattering spectra of light from the pyridine molecule were determined by theoretical calculations and compared with the experimental results. Based on the analysis of the results of the research, it was found that the intensity of the Raman scattering spectrum of the light generated by the rotational-rocking laws of the pyridine molecule is significantly smaller than the intensity of the spectra corresponding to other frequencies.

Fluoro-perovskite compounds are important and auspicious materials according to their properties in photovoltaic anti-reflective coating and optoelectronics. In this study, the structural, mechanical, and optoelectronic properties of Cesium Lead Fluoride CsPbF₃ were investigated using first principle calculations with generalized gradient approximations. The effect of stress on the crystal structure of CsPbF₃ was examined at 0, 20, 40, and 59 GPa. It was found that the lattice constant is decreased with increasing stress, and the elastic, electronic, and optical properties of the material were significantly affected. The density of states and band gap of CsPbF₃ were also calculated, and the band gap was found to be zero at 59 GPa. The cubical structure of CsPbF₃ is distorted at 58 GPa. The various mechanical characteristics such as the bulk modulus, shear modulus, Young’s modulus, and Poisson ratio were derived and discussed. The results indicate that CsPbF₃ exhibits ductile behaviour and anisotropic nature under stress, and the increase in refractive index, absorption, reflectivity, and conductivity at high stress make it a promising material for optoelectronic devices.

In this article, an incoherent beam combination of higher-order Gaussian beams through atmospheric turbulence is studied. An analytical expression of the combined intensity and spot size of higher-order Gaussian beams such as Hermite Gaussian (HG), Laguerre Gaussian (LG), and Bessel Gaussian (BG) are derived. The performance of these higher-order Gaussian beams is analyzed in various modes including the effect of beam wander, jitter, bore-sight error, Strehl ratio, and Visibility. A series of analytical simulations shows the intensity variation of 19 higher-order combined beams. Spot size, peak, and average intensity comparisons are made between various modes of higher-order Gaussian beam combinations. It is seen that the spot size of the combined beam increases rapidly in a higher mode of HG and LG beam. We evaluate the efficiency of combining beams at different distances, noting that it increases with higher mode orders and reaches its maximum with the $H{G}_{22}$ mode. Additionally, we explore the performance of higher-order Gaussian beam combinations under varying ground turbulence conditions. We observe that higher modes such as $H{G}_{22}$ and $L{G}_{22}$ are more susceptible to strong turbulence compared to lower modes.

Perovskite solar cells (MAPbI₂Br or CH₃NH₃I₂Br) are the subject of this thorough examination of their optical, structural, and photovoltaic properties. These MAPbI₂Br cells were prepared by the sol–gel spin-coating process to make films of both undoped and Mn²⁺-doped materials. In addition, the band gap energy (E_g) exhibited a steady downward trend as doping levels increased. The largest drop was observed at 4 % Mn²⁺ doping, when UV–Vis spectroscopy measured an E_g value of 1.88 eV. This decrease in band gap energy is essential to improving MAPbI₂Br's functionality. Furthermore, when compared to cells that used pure MAPbI₂Br perovskite solar cells, the efficiency of the manufactured MAPbI₂Br cells shown a significant improvement. Analyzing the current–voltage (J-V) characteristics revealed that the MAPbI₂Br produced with a 4 % Mn²⁺-doped MAPbI₂Br film had dramatically improved properties. These cells showed an open-circuit voltage of 1.02, a fill factor of 0.74, a short-circuit current density of 8.10 mA/cm², and an impressive power conversion efficiency of 6.14 %.

Orthogonal time–frequency space (OTFS) is a multicarrier modulation technique for high-speed data transfer in wireless communications. In an OTFS system, many subcarriers are used to send the modulated symbols. This makes OTFS signals have a high peak-to-average power ratio (PAPR). We suggest a partial transmit sequence (PTS) approach based on the Centre Phase Sequence Matrix (CPSM) to lower the high PAPR. Furthermore, the suggested method effectively searches for the best possible combination of phase rotation factors to reduce computing complexity. We examine the outcomes regarding bit error rate (BER), power spectral density (PSD), and PAPR to validate the competing transforms in the OTFS system. Along with non-orthogonal multiple access (NOMA), filter bank multi-carrier (FBMC), universal filter multi-carrier (UFMC), and orthogonal frequency division multiplexing (OFDM), the PAPR, BER, and PSD performance of OTFS were also compared. According to the data, the suggested PTS + CPSM reduces PAPR more effectively than the current PTS. It is also mentioned that by increasing the number of sub-blocks (s = 2 and 4), the suggested PTS + CPSM can achieve an even better PAPR rate. According to the experimental results, the suggested approach has dramatically decreased the PAPR while maintaining the BER and PSD performance with the least amount of computational complexity.

In this paper, we propose a novel scheme for an all-reflective FROG device using a near-90° retro-reflecting mirror for the complete single-shot measurement of intensity and phase of ultra-short laser pulses. The proposed device has several advantages, such as (1) it is an all-reflective setup, hence no added material dispersion; (2) it is simple and free from alignment disturbances; and (3) the temporal resolution and temporal range of the device can be tuned as per requirement. The proposed device was set up to measure mode-locked ultra-short laser pulses generated from a Ti:Sapphire laser oscillator. Dispersion-broadened laser pulses, obtained by passing the oscillator pulses through a 30 cm long Nd:glass rod, were also characterized, and the group velocity dispersion parameter value of the glass rod was estimated.

This study considers the generation and evolution of chirp-free soliton trains in a focusing cubic-quintic nonlinear optical fiber media (by utilizing experimental parameters), under the influence of weak nonlocal nonlinearity. Analysis of modulational instability (MI) reveals that the MI gain exist only in the anomalous dispersion regime, with the quintic nonlinear term increasing the maximum gain and sideband frequencies. The nonlocal nonlinearity parameter generally suppresses the impact of MI, because the maximum gain is greatly reduced with increase in nonlocality. By using the subsidiary ordinary differential equation method, stationary periodic soliton trains are obtained; with the intensity of the optical beam greatly reduced and frequency increased as nonlocality is gradually stepped up. However, an increase in nonlocality instead reduces the frequency of the traveling optical signals; derived via an efficient transformation method. Our results strongly suggest that nonlocal nonlinearity has potential applications in the control of laser beams; as nonlinear periodic optical signals can be easily transformed to very weak quasi-plane waves.