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Struggling with the environment Instability involving Cesium Container Halide Perovskites through Metal Ion Increase.
A novel and effective simultaneous recording method, to the best of our knowledge, is proposed for improving the diffraction efficiency and uniformity of full-color holographic optical elements (HOE) using the Bayfol HX102 photopolymer. To improve the diffraction efficiency of a full-color HOE, it is important to find the optimal recording beam intensity taking into account the initial and late responses of the medium. The range of optimal beam intensity for recording full-color HOE can be found experimentally by analyzing the inhibition period and response characteristics of the recording medium for three wavelengths. Through this method, a full-color HOE with an average diffraction efficiency of about 56.81% and a standard deviation of about 1.7% was implemented in a single layer photopolymer.A scheme for polarization control using two laser beams in a non-linear optical medium is studied using both co- and counter-propagating beam geometries. In particular, we show that under certain conditions it is possible for two laser beams to exchange their polarization states. A model accounting for a more realistic, 2D propagation geometry is presented. The 2D model produces drastically different results (compared to the 1D propagation geometry), creating difficulties for implementing polarization control in a realistic setting. A proposal for overcoming these difficulties by reducing the non-linear optical medium to a thin slab is presented.Guided modes of two-dimensional (2D) material-based plasmonic waveguides are applied in photonic devices because of their strong light-matter interaction within atomically thin layers and unique optical characteristics. Numerical simulations and experiments both play crucial roles in exploring unexpected phenomena at the sub-nanoscale of these materials. To efficiently and precisely compute mode characteristics, a multi-domain pseudospectral method (MPM) exhibiting high accuracy and fast convergence is proposed to study 2D material-based plasmonic waveguides in this study to alleviate the highly computational load of the widely used finite difference time domain or finite element method, as they demand extremely fine grid points or meshes around 2D materials. Models of graphene- and black phosphorus-based waveguides demonstrate that the MPM preserves exponential accuracy at relatively low computational cost, compared with the analytical characteristic equation and FEM, respectively. AZ20 nmr We believe that the proposed MPM offers a highly efficient and accurate approach to the study of 2D material-based photonics devices.Methods for measurement of polarization dependent loss and cross talk of individual few mode fiber components and connected systems are presented. A new method for determining the cross talk of the individual components, from the measurements on the connected system is presented and verified through simulations and measurements. The method is based on Fourier analysis of the wavelength dependent interference of the loss of the system.We describe an approach for realizing a superluminal ring laser using a single isotope of Rb vapor by producing electromagnetically induced transparency (EIT) in Raman gain. We show that by modifying the detuning and the intensity of the optical pump field used for generating the two-photon population inversion needed for generating Raman gain, it is possible to generate a dip in the center of the gain profile that can be tuned to produce a vanishingly small group index, as needed for making the Raman laser superluminal. We show that two such lasers, employing two different vapor cells, can be realized simultaneously, operating in counter-propagating directions in the same cavity, as needed for realizing a superluminal ring laser gyroscope. This technique, employing only one isotope, is much simpler than the earlier, alternative approach for realizing a superluminal Raman laser based on Raman gain and Raman dip in two isotopes [Zhou et. al, Opt. Express27, 29738 (2019)10.1364/OE.27.029738]. We present both an approximate theoretical model based on four levels as well as the results of a model that takes into account all relevant hyperfine states corresponding to the D1 and D2 transitions in 85Rb atom. We also present experimental results, in good agreement with the theoretical model, to validate the approach.The elastic modes of a general circular thin plate (EMCTP), reflecting the natural deformation of the resonance, are applied to the diffraction theory of the optical aberrations in this paper. Our work has shown that the mode shapes of the EMCTP resemble those of the Zernike polynomials. As an application example, the compensations of some low order aberrations of the 2.5 m-wide field survey telescope (WFST) have been performed with the EMCTP. Moreover, a quantitative comparative study of the active optics corrections for the EMCTP and the Zernike polynomials is presented in the numerical analysis. The quantitative analysis results have demonstrated that the efficiency of the EMCTP is superior to the standard Zernike polynomials as well as the annular Zernike polynomials.Over the last few years, optical nanoantennas are continuously attracting interest owing to their ability to efficiently confine, localize resonance, and significantly enhanced electromagnetic fields at a subwavelength scale. However, such strong confinement can be further enhanced by using an appropriate combination of optical nanoantennas and Slanted Bound states in the continuum cavities. Here, we propose to synergistically bridge the plasmonic nanoantennas and high optical quality-factor cavities to numerically demonstrate six orders of magnitude local intensity enhancement without critical coupling conditions. The proposed hybrid system paves a new way for applications requiring highly confined fields such as optical trapping, optical sensing, nonlinear optics, quantum optics, etc.A novel fiber Michelson interferometer (FMI) based on parallel dual polarization maintaining fiber Sagnac interferometers (PMF-SIs) is proposed and experimentally demonstrated for temperature sensing. The free spectral range (FSR) difference of dual PMF-SIs determines the FSR of envelope and sensitivity of the sensor. The temperature sensitivity of parallel dual PMF-SIs is greatly enhanced by the Vernier effect. Experimental results show that the temperature sensitivity of the proposed sensor is improved from -1.646 nm/°C (single PMF-SI) to 78.984 nm/°C (parallel dual PMF-SIs), with a magnification factor of 47.99, and the temperature resolution is improved from ±0.03037°C to ±0.00063°C by optimizing the FSR difference between the two PMF-SIs. Our proposed ultrasensitive temperature sensor is with easy fabrication, low cost and simple configuration which can be implemented for various real applications that need high precision temperature measurement.Spectral imagers, the classic example being the color camera, are ubiquitous in everyday life. However, most such imagers rely on filter arrays that absorb light outside each spectral channel, yielding ∼1/N efficiency for an N-channel imager. This is especially undesirable in thermal infrared (IR) wavelengths, where sensor detectivities are low. We propose an efficient and compact thermal infrared spectral imager comprising a metasurface composed of sub-wavelength-spaced, differently-tuned slot antennas coupled to photosensitive elements. Here, we demonstrate this idea using graphene, which features a photoresponse up to thermal IR wavelengths. The combined antenna resonances yield broadband absorption in the graphene exceeding the 1/N efficiency limit. We establish a circuit model for the antennas' optical properties and demonstrate consistency with full-wave simulations. We also theoretically demonstrate ∼58% free space-to-graphene photodetector coupling efficiency, averaged over the 1050 cm-1 to 1700 cm-1 wavenumber range, for a four-spectral-channel gold metasurface with a 0.883 µm by 6.0 µm antenna pitch. This research paves the way towards compact CMOS-integrable thermal IR spectral imagers.We theoretically and numerically investigate the generation and evolution of different pulsed terahertz (THz) singular beams with an ultrabroad bandwidth (0.1-40 THz) in long gas-plasma filaments induced by a shaped two-color laser field, i.e., a vortex fundamental pulse (ω0) and a Gaussian second harmonic pulse (2ω0). Based on the unidirectional propagation model under group-velocity moving reference frame, the simulating results demonstrate that three different THz singular beams, including the THz necklace beams with a π-stepwise phase profile, the THz angular accelerating vortex beams (AAVBs) with nonlinear phase profile, and the THz vortex beams with linear phase profile, are generated. The THz necklace beams are generated first at millimeter-scale length. Then, with the increase of the filament length, THz AAVBs and THz vortex beams appear in turn almost periodically. Our calculations confirm that all these different THz singular beams result from the coherent superposition of the two collinear THz vortex beams with variable relative amplitudes and conjugated topological charges (TCs), i.e., +2 and -2. These two THz vortex beams could come from the two four-wave mixing (FWM) processes, respectively, i.e., ω0+ω0-2ω0→ωTHz and -(ω0+ω0) + 2ω0→ωTHz. The evolution of the different THz singular beams depends on the combined effect of the pump ω0-2ω0 time delay and the separate, periodical, and helical plasma channels. And the TC sign of the generated THz singular beams can be easily controlled by changing the sign of the ω0-2ω0 time delay. We believe that these results will deepen the understanding of the THz singular beam generation mechanism and orbital angular momentum (OAM) conversion in laser induced gas-filamentation.A novel photonic method, to the best of our knowledge, to generate high-frequency micro/millimeter-wave signals based on the optoelectronic oscillator (OEO) with all-optical gain is proposed in this paper. The core device is the monolithically integrated dual-frequency semiconductor laser (MI-DFSL), in which the two DFB laser sections are simultaneously fabricated on one chip. Attributing to the combined impact of the photon-photon resonance effect and the sideband amplification injection locking effect, one widely tunable microwave photonic filter with a high Q value and narrow 3-dB bandwidth can be realized. In this case, the generated microwave signals would largely break the limitation in bandwidth once making full use of the optical amplifier to replace the narrow-band electrical amplifiers in traditional OEO configuration to provide the necessary gain. No additional high-speed external modulator, high-frequency electrical bandpass filters or multi-stage electrical amplifiers are required, highly simplifying the framework and reducing the power consumption. Moreover, this simple and compact structure has the potential to be developed for photonic integration. In the current proof-of-concept experiment, microwave signals with wide tuning ranges from 14.2 GHz to 25.2 GHz are realized. The SSB phase noises in all tuning range are below -103.77 dBc/Hz at 10 kHz and the best signal of the -106.363 dBc/Hz at 10 kHz is achieved at the frequency of 17.2 GHz.
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