We demonstrate a high sensitivity all­fiber Mach–Zehnder interferometer (MZI) based on radial­aligned liquid crystal (LC) in a hollow optical fiber (HOF). The transmission spectrum of the liquid crystal­filled fiber MZI (LCF­MZI) was measured at different temperatures, and the thermal­induced wavelength shift of the interference spectrum probed. The experimental results indicate that the LC ali...

We report an optical refractive index sensor system based on a planar Bragg grating which is functionalized by substituted γ-cyclodextrin to determine low concentrations of naphthalene in solvent vapor. The sensor system exhibits a quasi-instantaneous shift of the Bragg wavelength and is therefore capable for online detection. The overall shift of the Bragg wavelength reveals a linear relations...

We propose a novel optical delay interferometer (ODI) with an optically controllable phase shifter. The proposed interferometer is implemented by using a phase shifted fiber Bragg grating and an Yb(3+)/Al(3+) co-doped optical fiber. The phase of the delayed optical signal is linearly controlled by adjusting the induced pumping power of a laser diode at 976 nm. Polarization dependent loss, polar...

A photon’s observed wavelength tells an astronomical detector about the amount of position information obtained by observing that photon. This amount of position information appears to depend on time in a way which, to first order over distances small compared to the size of the universe, may account for the cosmological red shift. Interpretation of cosmological red shift as due to rapid recess...

We propose and demonstrate a tunable photonic radio frequency notch filter. The filter has a single delay line architecture and incorporates a new wavelength-selective true-time-delay. The time delay in the feed-forward ioop can be varied by simply changing the optical wavelength resulting in a shift of the null of the filter response. Application in radar systems is discussed.

Dissolved hydrogen is a symbol gas decomposed by power transformer oil for electrical faults such as overheat or partial discharges. A novel D-shaped fiber Bragg grating (D-FBG) sensor is herein proposed and was fabricated with magnetron sputtering to measure the dissolved hydrogen concentration in power transformer oil in this paper. Different from the RI (refractive index)-based effect, D-FBG...

The fluorophore in green fluorescent protein (GFP) is localized in a highly constrained environment, protected from the bulk solvent by the barrel-shaped protein matrix. We have used the wavelength-selective fluorescence approach (red edge excitation shift, REES) to monitor solvent (environment) dynamics around the fluorophore in enhanced green fluorescent protein (EGFP) under various condition...

We present in-depth discussion of the design and optimization of a nanomechanical sensor using a silicon cantilever comprising a two-dimensional photonic crystal (PC) nanocavity resonator arranged in a U-shaped silicon PC waveguide. For example, the minimum detectable strain, vertical deflection at the cantilever end, and force load are observed as 0.0133%, 0.37 mum, and 0.0625 muN, respectivel...

Zebrafish and goldfish are both diurnal freshwater fish species belonging to the same family, Cyprinidae, but their visual ecological surroundings considerably differ. Zebrafish are surface swimmers in conditions of broad and shortwave-dominated background spectra and goldfish are generalized swimmers whose light environment extends to a depth of elevated short wavelength absorbance with turbid...

A novel all-fiber laser based on a highly GeO2-doped dispersion-shifted Tm-codoped fiber, pumped at 1.56 µm wavelength and lasing at 1.862 µm wavelength with a slope efficiency up to 37% was demonstrated. The single-mode Tm-doped fiber with the 55GeO2-45SiO2 core was fabricated for the first time by MCVD technique. The laser produces spectral side bands, resulting from the four-wave mixing owin...