We propose a novel and cost-effective copper-gold planar nanostructure resulting in strong plasmonic enhancement of
the electromagnetic field with a peak at 615 nm and FWHM of 180 nm. The structure consists of aggregates of 20 nm in
diameter gold nanospheres on a thin continuous 50 nm thick copper film. We attribute the strong field enhancement to
the coupling of interparticle plasmon resonances from gold nanospheres to the surface plasmons induced in the copper
film. The high reflectivity of the copper layer increases the collection efficiency in a reflection mode of the scattered
light that would otherwise be transmitted. We achieved the homogeneity and planarity of the copper-gold structure
through the electrostatic attraction between the negative surface charge of gold nanospheres and a lattice of positive
copper ions of copper oxide, formed by ionic bonds during the exposure of copper to air.
We designed a compact optical resonator with two distributed Bragg reflectors (DBR) embedded on single mode
polymer ridge waveguide structure towards micro-scale polymer lasers. Single DBR is made up of alternating layers
with λ/4 thickness of air and polymer. Numerical simulation of the device was carried out with 3D FDTD. We
investigated the reflectance of single DBR as a function of order and number of periods and found a maximum of 97.8%,
achieved for a TE mode with air cladding in material with low refractive index 1.54. Focused ion beam (FIB)
lithography was used to open periodic air gaps on a 3 um wide ridge waveguide consisting of 1 um thick polymer layer
doped with disperse red 1 (n=1.54) structure. Single DBR with five periods are optically characterized by observing the
transmission through the device.
We present a new idea for minimizing temperature sensitivity of a fiber-optic interferometric sensor based on highly birefringent side-hole fibers. The sensing part is composed of a side-hole fiber characterized by a very high pressure-to-temperature sensitivity ratio equal to 25°C/bar, which is about two orders of magnitude higher than in the case of other highly birefringent fibers. We took advantage of this unique property to assure good insensitivity to temperature effects, which are always associated with fast pressure changes. The presented sensor requires no additional temperature-compensating fiber, which has been a normal procedure until now for all fiber-optic pressure sensors. We used a digital demodulation system based on the coherence-addressing principle to decode a differential phase shift introduced by the sensing fiber and the quartz plates, which compensate an optical path delay of the fiber. The demodulation system allows unambiguous measurement of a phase shift with a resolution of 1/8 interference fringe in a range of 40 fringes. In this paper we also show that the side-hole fibers can be applied for measurements of high dynamic pressures at an operating range of 110 bar. We compared the dynamic characteristics of the fiber-optic sensor to the responses of a calibrated and temperature-compensated piezoelectric sensor with a sampling rate up to 200 kHz. The dynamic characteristics of the fiber-optic sensor are in good agreement with the reference piezoelectric sensor, which shows the great utility of the side-hole fibers in accurate measurements of high dynamic pressures.
A fiber-optic sensor for simultaneous measurements of pressure and temperature is presented. The sensor is based on highly birefringent fibers and uses coherent addressing principle to retrieve information about changes of the two parameters. The bow-tie fiber is used as a temperature sensing element while information about pressure changes is decoded from the differential pattern produced by the side- hole and the bow-tie fiber. The sensor characteristic and responses to simultaneous changes of pressure and temperature are demonstrated.
A new type of fiber-optic sensor for measuring fast changes of hydrostatic pressure is presented. The sensor is based on highly
birefringent side-hole fiber and employs the low-coherence interferometric scheme to detect phase shifts induced by pressure
changes. The decoding system is based on a fringe counting method. The sensor is characterized by a resolution of 1/8 of an
interference fringe, counting speed of 5kHz, and a pressure range up to 2. 1 MPa.
A new type of fiber-optic pressure sensor based on highly birefringent fibers is presented. To assure temperature desensitization, the sensing part of the device is composed of specially developed side-hole fiber and elliptical core fiber, which are spliced to each other with polarization axes rotated by 90 degree(s). Such sensor construction assures high sensitivity to pressure and compensation of temperature effects associated with rapid pressure changes. The sensor allows for unambiguous and fast phase-shift measurements in the range from -(pi) /2 to +(pi) /2 with a sampling rate of 5 kHz and resolution of about 0.5% of full scale (2 (DOT) 10-3 atm). The sensor calibration procedure, responses to fast pressure change, and preliminary applications are demonstrated.