Mcgeelehmann4836

A surface plasmon resonance (SPR) temperature sensor on the basis of depressed double cladding fiber (DDCF) is theoretically proposed and experimentally demonstrated for the first time. Simulation analysis implies that the SPR fiber optic structure consisting of a multimode fiber (MMF) inserted into an 8 mm long DDCF is highly sensitive to the refractive index (RI) of the surrounding environment, owing to their mismatched cores, large discrepancy in cladding diameters, and the depressed inner cladding in DDCF. The experimental results further verify that the highest RI sensitivity is 7002 nm/RIU established with a 50nm Au coated DDCF-SPR sensor. Additionally, the temperature sensitivity reaches up to -2.27 nm/°C within a wide working temperature range of -30 to 330 °C by combining polydimethylsiloxane (PDMS) film as the temperature sensitive material with DDCF-Au architecture. The integrated PDMS, Au and DDCF temperature sensor possesses high performance in terms of sensing capability and physical construction, opening a route to their potential applications in other types of sensors.This work presents a description of a polarimetric system for measuring the properties of birefringent media. In our reflection system the applied Stokes polarimeter acts both as a generator of the light's selected polarization states as well as a light analyzer leaving the examined medium. The method is based on six intensity distribution measurements realized in six different configurations of polarizers/analyzers four linear and two circular ones. Thus, we have achieved parallel polariscope for linear polarizers and the crossed polariscope for circular polarizers. Such a setup can be easily applied for linearly birefringent media properties measurements including dichroic ones. This measurement setup and the measurement method were successfully tested in a homogeneous medium and a medium with variable phase difference.Recently, boron arsenide (BAs) has been measured with high thermal conductivity in the experiments, great encouragement for low-power photoelectric devices. Hence we systematically investigate the direct and indirect optical absorptions of BAs and BSb by using first-principles calculations. We obtain the absorption onset corresponding to the value of indirect bandgap by considering the phonon-assisted second-order indirect optical absorption. The temperature-dependent calculations also capture the redshift of absorption onset, enhancement, and smoothness of optical absorption spectra. Moreover, in order to introduce the first-order absorption in the visible range, the doping effect of congeners is studied without the assist of phonon. It is found that the decrease of local direct bandgap derives from either the decrease of bonding-antibonding repulsion of p orbital states by the heavier III group elements or the similar influence of lighter V group elements on the s orbital states. Thus, the doping of congeners can improve the visible optical absorptions.Phase-sensitive optical time domain reflectometry (Φ-OTDR) realizes quantitative measurement of the dynamic strain employing phase demodulation. selleck Unfortunately, it is difficult to measure the large dynamic strain with the conventional Φ-OTDR due to the restriction of the unwrapping algorithm. In this work, an approach based on two-wavelength probe is proposed and demonstrated to improve the measurable range of the dynamic strain in Φ-OTDR. By utilizing the difference between the two phases acquiring with two different lasers, the large dynamic strain can be recovered. In experiments, dynamic strains with peak values from 10.32 uɛ to 24.08 uɛ are retrieved accurately, which cannot be recovered with the conventional Φ-OTDR. Moreover, the tunable sensitivity is also demonstrated through adjusting the wavelengths of the probe. With the increment of the wavelength interval from 9.06 nm to 23.06 nm, the normalized sensitivity increases from 0.4 to 1 accordingly. That agrees well with the theoretical prediction. Foreseeably, the proposed method will extend the scope of application fields for Φ-OTDR, which requires large dynamic strain recognition.Recent studies have shown that quadratic-power-exponent-phase (QPEP) vortex and modified QPEP vortex have some novel properties and potential applications in optical manipulation, orbital angular momentum (OAM) communication, OAM multicasting and so on. In these applications, there may be potential need of processing these kinds of beams by using uniaxial crystals. In this paper, the analytical propagation equations of Gaussian QPEP vortex and modified QPEP vortex propagating in uniaxial crystals are derived and the evolution of the angular momentum via spin-orbital coupling during the propagation is investigated. This may be meaningful for guiding and promoting the applications of the QPEP vortex and modified QPEP vortex.The room-temperature strong plasmon-exciton coupling is first investigated in a metal-insulator-metal (MIM) waveguide-resonator system with WS2 monolayer. Finite-difference time-domain (FDTD) simulated results exhibit that the Fabry-Pérot (F-P) cavity is realized by the MIM plasmonic waveguide with two separated metal bars. When the F-P resonance is tuned to overlap with the A-exciton absorption peak of WS2 monolayer, the strong plasmon-exciton coupling is obtained at visible wavelengths. As a result, the spectral splitting response confirmed by the coupled-mode theory (CMT) appears in the transmission spectrum. Intriguingly, the switching response is handily witnessed by tuning the orientation of WS2 monolayer along the cavity, and the coupling strength is dynamically tuned by changing the position of the WS2 monolayer. Simultaneously, the anticrossing behavior with the Rabi splitting up to 109 meV is achieved by small changes in the length of the F-P cavity and the refractive index of dielectric in the cavity, respectively. The underlying physics is further revealed by the coupled oscillator model (COM). The proposed strong plasmon-exciton coupling can find utility in highly integrated plasmonic circuits for optical switching.