Search results for "Grating"
showing 10 items of 366 documents
Tuning the propagation constant by the anti-crossing bandgap prism coupling technique.
2012
A novel plasmonic structure based on an anticrossing bandgap prism coupling technique is proposed. The study has been carried out using photonic crystals based on diffraction gratings (bounded by dielectrics with identical dielectric functions) together with a high refractive index prism to couple the long-range surface plasmon polaritons to photons. We analyse the structure and demonstrate the ability for tuning the propagation constants of plasmon modes by changing the thickness of the gold grating. The comparison to non-bandgap techniques is studied, and the influence of the plasmonic configuration on the plasmon propagation constant is discussed as well. Experimental measurements were a…
Design and Implementation of Density Sensor for Liquids Using Fiber Bragg Grating Sensor
2022
In this paper, an optical fiber sensor based density sensor is proposed and demonstrated experimentally. The sensor is formed by fiber Bragg grating (FBG) sensor. The proposed sensor design is very simple and versatile for density measurements of liquids. The FBG strain sensor has one end mounted to a 3D printed rigid support, and the other end connected to a 3D manufactured clamp in this sensor design. A metal ball is suspended from this clamp by a non-stretchable cord. When it is completely immersed in liquid, the liquid buoyancy force acts on it. As a result, the strain in FBG varies depending on the force applied to the ball. This results in a wavelength shift in the FBG sensor. The pro…
Abrupt-tapered fiber filter arrangement for a switchable multi-wavelength and tunable Tm-doped fiber laser.
2018
A switchable and tunable multi-wavelength Tm-doped fiber laser is successfully demonstrated using a filter constructed with two tapered fiber elements in the cavity. The proposed system design uses a low-cost simple filter that allows stable dual, triple, quadruple, and quintuple-wavelength emission operation in the region around 1.9 μm. In the dual wavelength regime, the laser is capable of independently tuning each wavelength. For switching and tuning, a curvature is applied to the tapered fibers.
Photoinduced mass transport in low molecular organic glasses and its practical application in holography
2015
Abstract In this paper we present the synthesis and optical properties of amorphous low molecular compound 4-((4-(bis(5,5,5-Triphenylpentyl)amino)phenyl)diazenyl)benzoic acid. The surface relief gratings formation by polarization holography method on these thin films (thicknesses are 200–1700 nm) was shown. The dependence of the surface relief modulation on various parameters: recording exposure dose, the polarization state of the recording beams, the grating period and the film thickness of the material was demonstrated. Values of surface tension at the air-film before and after irradiation of the substance by polarized radiation were measured. The efficiency of surface relief formation in…
<title>Amorphous chalcogenide thin films as a media for holographic recording</title>
2004
The amorphous As2S3 and As40S15Se45 films as a recording media for optical holography and lithography were studied. The results on research of the transmission, surface-relief and Bragg reflection grating holographic recording and readout conditions are presented. The recording of transmission holographic gratings in As40S15Se45 films was performed by He-Ne (0.6328 μm) laser beam, while the redout of the diffraction efficiency was made at Bragg agle using diode (0.805 μm) laser lines. The Bragg reflection gratings in As2S3 films were recorded and studied by Ar+ laser line 0.5145 μm. The surface-relief modulated gratings with a period of 0.15 μm - 1 μm were recorded.© (2004) COPYRIGHT SPIE--…
Doubly active Q switching and mode locking of an all-fiber laser
2009
Simultaneous and independent active Q switching and active mode locking of an erbium-doped fiber laser is demonstrated using all-fiber modulation techniques. A magnetostrictive rod attached to the output fiber Bragg grating modulates the Q factor of the Fabry-Perot cavity, whereas active mode locking is achieved by amplitude modulation with a Bragg-grating-based acousto-optic device. Fully modulated Q-switched mode-locked trains of optical pulses were obtained for a wide range of pump powers and repetition rates. For a Q-switched repetition rate of 500 Hz and a pump power of 100 mW, the laser generates trains of 12-14 mode-locked pulses of about 1 ns each, within an envelope of 550 ns, an o…
A magnetostrictive sensor interrogated by fiber gratings for DC-current and temperature discrimination
2000
A magnetostrictive sensor head with temperature compensation has been developed for measurement of static magnetic fields. The device consists on two different alloys with similar thermal expansion coefficient one of which has a giant magnetostriction, the expansion of both materials produced by heat and magnetism is detected by two fiber gratings. One of the gratings measures the temperature of the sensor and the difference between the wavelengths reflected by the gratings is a measurement of the magnetically induced strain.
Chirped fibre Bragg gratings for phased-array antennas
1997
A variable delay line for phased-array antennas based on a chirped fibre Bragg grating is demonstrated. The time delay of a microwave modulating signal is modified by scanning in wavelength a chirped grating. In this initial experiment, time delay variations up to 556 ps have been achieved using a grating of 0.4 nm bandwidth and 6 cm length and modulating in the frequency range 390 MHz-5.20 GHz.
Acoustically driven arrayed waveguide grating.
2015
We demonstrate compact tunable phased-array wavelength-division multiplexers driven by surface acoustic waves (SAWs) in the low GHz range. The devices comprise two couplers, which respectively split and combine the optical signal, linked by an array of single-mode waveguides (WGs). Two different layouts are presented, in which multi-mode interference couplers or free propagating regions were separately employed as couplers. The multiplexers operate on five equally distributed wavelength channels, with a spectral separation of 2 nm. A standing SAW modulates the refractive index of the arrayed WGs. Each wavelength component periodically switches paths between the output channel previously asi…
Mode locking of an all-fiber laser by acousto-optic superlattice modulation
2009
Active mode locking of an erbium-doped all-fiber laser with a Bragg-grating-based acousto-optic modulator is demonstrated. The fiber Bragg grating was acoustically modulated by a standing longitudinal elastic wave, which periodically modulates the sidebands at twice the acoustic frequency. The laser has a Fabry-Perot configuration in which cavity loss modulation is achieved by tuning the output fiber Bragg grating to one of the acoustically induced sidebands. Optical pulses at 9 MHz repetition rate, 120 mW peak power, and 780 ps temporal width were obtained. The output results to be stable and has a timing jitter below 40 ps. The measured linewidth, 2.8 pm, demonstrates that these pulses ar…