Ashworthmagnussen8166

We propose a novel approach based on the inversion method to eliminate interference in the continuous-wave (CW) terahertz (THz) reflection imaging. Through the study on the imaging window of the CW-THz reflection imaging with the interference mechanism, inverse processing is introduced to realize the interference elimination. Based on the theoretical calculation, high resistivity float-zone silicon (HRFZ-Si) with high refractive index is selected as the imaging window to improve the dynamic range of the THz image. The interference elimination method is verified experimentally by a CW-THz reflection imaging system based on a THz quantum cascade laser (QCL) lasing at 4.3THz. The reflectivities of liquid samples of water and ethanol are restored by the interference elimination method, which corresponds well with the theoretical calculation. Moreover, the interference elimination method is performed on THz images of fresh biological tissues. The image contrast of tissue can be greatly enhanced with the accurate reflective information.The state of the quantum system will inevitably be disturbed and changed in the testing process. Using interaction-free measurement (IFM), the information can be extracted without any interaction between objects and photons or particles. Here we present a novel approach that the refractive index can be measured accurately with "no-touch" measurement between testing materials and light beam. The design system is a non-traditional model of interaction-free measurement with an unbalanced Mach-Zehnder interferometer (UMZI), which is combined with the chain quantum Zeno effect and the technique for spatial separation of light field. We select two beams with different intensity distribution in cross-section and different frequency as the transmission source, and the refractive index of samples can be obtained from the contrast degree of two beams under the condition of a few beam splitters existing. The scheme could prevent the damage to the radiation-sensitive optical materials, and provide a new idea for the research and application of precision measurement.The polarization switching and phase generated carrier (PS-PGC) hybrid method is typically adopted to control signal fading induced by fiber birefringence and to precisely demodulate signals in interferometric fiber Bragg grating (FBG) sensor arrays. Unlike simple PGC demodulation, the real-time phase delay between the detected interference and the PGC carrier in the hybrid method has more adverse effects as both demodulation accuracy and background noise can be deteriorated, which may invalidate the polarization switching (PS) method. Aiming at this issue, the real-time phase delay and its compensation method were analyzed in detail in this paper. The features of the real-time phase delay in the PS-PGC hybrid method were summarized and the differences among polarization channels were investigated. Theoretical analysis indicated that the real-time phase delay mainly affected the interference complex synthesis (ICS) procedure, ultimately bringing about errors in the PS-PGC algorithm. The method for demodulating the real-time phase delay from sampled interference was presented, which provided the key compensation parameter. Experimental results showed that the compensation method could greatly improve the stability of the demodulated signal and suppress the sensor background phase noise. The amplitude of the demodulated signal was stabilized with a fluctuation less than ± 0.75dB and a noise suppression of 5dB. The acceptable compensation error was also analyzed.Flight velocity measurement is an important aspect of insect research that can aid insect identification and facilitate studies and monitoring of insect movements. #link# We propose a novel scheme for the 1-D flight velocity measurement of insects, based on a near-IR Scheimpflug lidar system. We implement this new technique and apply it to study insects at the Salter Research Farm, Robertson County, Texas. The resolution property perpendicular to the probing direction of the Scheimpflug lidar system is explored and reveals the capability of retrieving the velocity component normal to the probing direction of insects passing through the field of view of our system. SBI-477 order observe a shift in wingbeat frequency, which indicates the presence of new insect species during the multi-day measurement. The study on 1-D flight velocity reveals a net directional movement of insects, providing supportive evidence of the arrival of a new species.This paper presents a detailed-balance analysis required for the achievement of a high-efficiency spectral selective STPV system utilizing thermodynamic and optical modeling approaches. Key parameters affecting the design and optimization of spectrally selective surfaces that are essential for high-efficiency STPV applications are investigated. A complete GaSb-based planar STPV system utilizing a micro-textured absorber and a nanostructure multilayer metal-dielectric coated selective emitter was fabricated and evaluated. The micro-textured absorber features more than 90% absorbance at visible and near-infrared wavelengths. The selective emitter, consisting of two nanolayer coatings of silicon nitride (Si3N4) and a layer of W in between, exhibits high spectral emissivity at wavelengths matching the spectral response of the GaSb cells. The performance of the STPV system was evaluated using a high-power laser diode as a simulated source of concentrated incident radiation. When operated at 1670 K, an output power density of 1.75 W/cm2 and a system efficiency of 8.6% were recorded. This system efficiency is higher than those of previously reported experimental STPV systems. Optical and thermal losses that occurred at multiple stages of the energy transport process were modeled and quantified. Essential guidelines to mitigate these losses and further enhance the system performance are also provided.The phase-sensitive X-ray imaging technique based on the bilens interferometer is developed. The essence of the method consists of scanning a sample, which is set upstream of the bilens across the beam of one lens of the interferometer by recording changes in the interference pattern using a high-resolution image detector. The proposed approach allows acquiring the absolute value of a phase shift profile of the sample with a fairly high phase and spatial resolution. The possibilities of the imaging technique were studied theoretically and experimentally using fibres with different sizes as the test samples at the ESRF ID06 beamline with 12 keV X-rays. link2 The corresponding phase shift profile reconstructions and computer simulations were performed. The experimental results are fully consistent with theoretical concepts and appropriate numerical calculations. Applications of the interferometric imaging technique are discussed, as well as future improvements.In this erratum, the funding section of our paper [Optics Express, 27, 38098- 38108 (2019)] has been updated.An erratum to correct a typo in the author list in [Opt. Express27(14), 19778 (2019)].We demonstrate the thermal bleaching effect on a photodarkened thulium-doped fiber (TDF) in detail. The bleaching effect on visible transmission initiates at 250 °C and a complete recovery is achieved at 550 °C. Prior to the recovery, a post-irradiation heat-induced spectral loss is observed. It indicates that an intermediate energy state is generated in the TDF under exposure to near-infrared (NIR) radiation, exhibiting the spectral attenuation in visible (VIS) and NIR region as driven by color center after thermal activation. And, with thermal treatment, the bleached TDF shows a partial photodarkening (PD) resistance when it is subject to photoirradiation again. In addition, the temperature-dependent spectral broadening and red shift that may distort the measured decay curve of excess loss is observed and discussed.Chip-integrated photonic devices have stimulated development in areas ranging from telecommunications to optomechanics. Racetrack resonators have gained popularity for optomechanical transduction due to their high sensitivity and cavity finesse. However, they lack sufficient dynamic range to read out large amplitude mechanical resonators, which are preferred for sensing applications. We present a robust photonic circuit based on a Mach-Zehnder interferometer (MZI) combined with a racetrack resonator that increases linear range without compromising high transduction sensitivity. Optical and mechanical properties of combined MZI-racetrack devices are compared to lone racetracks with the same physical dimensions in the undercoupled, overcoupled and critical coupled regimes. We demonstrate an overall improvement in dynamic range, transduction responsivity, and mass sensitivity of up to 4x, 3x and 2.8x, respectively. Our highly phase sensitive MZI circuit also enables applications such as on-chip optical homodyning.We demonstrate simple optical frequency combs based on semiconductor quantum well laser diodes. The frequency comb spectrum can be tailored by choice of material properties and quantum-well widths, providing spectral flexibility. We demonstrate the correlation in the phase fluctuations between two devices on the same chip by generating a radio-frequency dual comb spectrum.We introduce a novel probabilistic shaping (PS) scheme based on bit-weighted distribution matching (BWDM) into a discrete multi-tone wavelength division multiplexing passive optical network (DMT-WDM-PON) employing low-density parity-check-coded 16-ary quadrature amplitude modulation (16QAM). Unlike the prevailing arithmetic coding-class PS schemes with target symbol probability, such as arithmetic distribution matching and constant composition distribution matching, the proposed one realizes Gaussian-like symbol probability distribution emulation merely based on simple bit-class processing, having the advantage of much lower computational complexity. As the key operation in BWDM, the bit weight intervention is implemented in the process of PS-16QAM generation for elevated transmission probability of binary data '0' by cascaded operations of weight bit labelling and bit reconstruction. The experimental results show that, compared with uniformly-distributed signal with the same net rate, significantly-improved receiver power sensitivity and system tolerance to optical fiber nonlinear effect can be obtained in the DMT-WDM-PON system. The proposed PS scheme can be considered as one of promising practical solutions for more available optical network units due to enlarged system power loss budget for the optical distribution network.We report the CsPbI3 random lasing at room temperature fabricated by a chemical deposition method. The CsPbI3 thin films with high crystalline quality have intense PL emission and easily achieve the lasing behavior with the Q-factor value over 7000. link3 The lasing behavior of CsPbI3 thin films can be classified as random lasing by measuring lasing spectra at different collective angles. The fast Fourier transform analysis of the lasing spectra is employed to determine the effective cavity length. Most important of all, the lasing stability investigation shows the prolonged lasing stability over 4.8 X 105 laser shots in air.