Velazquezmcclanahan3678

We describe a microscopic setup implementing phase imaging by digital holographic microscopy (DHM) and transport of intensity equation (TIE) methods, which allows the results of both measurements to be quantitatively compared for either live cell or static samples. Digital holographic microscopy is a well-established method that provides robust phase reconstructions, but requires a sophisticated interferometric imaging system. TIE, on the other hand, is directly compatible with bright-field microscopy, but is more susceptible to noise artifacts. We present results comparing DHM and TIE on a custom-built microscope system that allows both techniques to be used on the same cells in rapid succession, thus permitting the comparison of the accuracy of both methods.A high-sensitivity ultralow-frequency fiber optic interferometric seismometer using phase feedback control is proposed and demonstrated. PTC-209 order The principle of sensitivity improvement using feedback is described, and the characteristics of the seismometer, including the ultralow-frequency vibration sensing with Michelson interferometer with and without feedback control, are analyzed in terms of the amplitude response and phase response. The phase feedback control loop is designed and implemented, and higher sensitivity for very low frequency vibration is achieved. The efficacy of the new approach is demonstrated experimentally, showing that the weak vibration signal originally buried in noise can be observed unambiguously.We propose an ultraviolet perfect ultranarrow band absorber by coating a dielectric grating on the monolayer graphene-dielectric-metal structure. The absorber presents an ultranarrow Fano lineshape with quality (Q) factor of 70 and a nearly perfect absorption of over 99.9% in the ultraviolet region, which is ascribed to the near field coupling of the optical dissipation of graphene and guide mode resonance of the dielectric grating. Structure parameters to the influence of the performance are investigated. The structure exhibits the high optical sensitivity (S = 150 nm/RIU, S* = 48/RIU) and figure of merit (FOM = 50, FOM* = 25374) and can also be used to detect the nanoscale analyte layer of sub-nanometer thickness, suggesting great potential applications in ultra-compact efficient biosensors for a much more sensitive detection of small refractive index changes.A tungsten disulfide (WS2) coated surface plasmon resonance (SPR) sensor based on gradient pitch Mach-Zehnder interferometer (GP-MZI) for measuring ethanol vapor concentration is proposed and verified by experiments. Under continuous CO2 laser heating, a MZI based on GP helix structure is fabricated by twisting single mode fiber (SMF), which can excites multi-order cladding modes. A gold film is deposited on the surface of the GP helix structure by a magnetic sputtering coating machine. WS2 film is coated on the gold film of the GP helix structure, which increases the evanescent field strength of the twisted structure surface and enhances the interaction between SPR wave and ethanol molecules. Since the absorption of ethanol molecules by WS2 sheets will cause the change of effective refractive index (RI) of WS2 film, the intensity of transmission signal can be adjusted accordingly. For multi-order cladding modes, the effective RI and the effective thermo-optic coefficient vary with the modal order, so the RI and temperature sensitivity of different modal orders are also different. So, the ethanol vapor concentration, relative humidity (RH), and temperature can be simultaneously measured by monitoring the intensity of those dips with the resolution of ± 0.030 mg/L, ±0.035%RH, and ± 0.010 ℃, respectively. This sensor structure provides a promising platform for multi-parameter sensing applications.In this paper, a localized surface-plasmon resonance (LSPR) biosensor, which uses a U-shaped multi-mode fiber (U-MMF), is introduced and investigated. It is modified with a complex of three-dimensional (3D) gold nanoparticles and multilayer graphene as spacer n*(Au/G)@U-MMF, where n denotes the layer number of gold nanoparticles. The gold nanoparticles were synthesized by reducing chloroauric acid. Graphene films were formed using a liquid/chemical method. The number of gold-nanoparticle layers was found to be critical for the performance of the sensor. Moreover, using the finite-difference time domain, 3D nanostructures, with a wide range of gold-nanoparticle layers, were explored. The sensor showed the sensitivity of 1251.44 nm/RIU, as well as high stability and repeatability; for the measurement-process of time- and concentration-dependent DNA hybridization kinetics with detection concentrations, ranging from 0.1nM to 100 nM, the sensor displayed excellent performance, which points towards a vast potential in the field of medical diagnostics.Er3+ ions doped titanium dioxide (TiO2) thin films have been prepared by sol-gel method. The photoluminescence both in visible light range (510-580 nm and 640-690 nm) and near infrared light range (1400-1700nm) have been observed. The photoluminescence excitation spectra demonstrate that energy transfer from wide band-gap TiO2 to Er3+ ions causes the infrared light emission. It is also found that the post annealing temperature can influence the luminescence intensity significantly. Based on sol-gel prepared TiO2Er3+ thin films, we fabricate light emitting device containing ITO/TiO2Er3+/SiO2/n+-Si/Al structure. Both the visible and near infrared electroluminescence (EL) can be detected under the operation voltage as low as 5.6 V and the working current of 0.66 mA, which shows the lower power consumption compared with the conventional EL devices.Two long-period fiber gratings (LPFGs) used to separately suppress the stimulated-Raman-scattering (SRS) in the seed and amplifier of kW-level continuous-wave (CW) MOPA fiber laser are developed in this paper. A process that combines constant-low-temperature and dynamic-high-temperature annealing was employed to reduce the thermal slopes of 10/130 µm (diameter of core/cladding fiber) and 14/250 LPFGs, used in the seed and amplifier respectively, from 0.48 °C/W to 0.04 °C/W and from 0.53 °C/W to 0.038 °C/W. We also proposed a reduced-sensitivity packaging method to effectively reduce the influence of axial-stress, bending, and environmental temperature on LPFGs. Further, we established a kW-level CW MOPA system to test SRS suppression performance of the LPFGs. Experimental results demonstrated that the SRS suppression ratios of the 10/130 and 14/250 LPFGs exceed 97.0% and 99.6%, respectively.