We present vibration fiber sensor set up based on tilted fiber Bragg grating (TFBG) and fiber taper. The sensor uses the TFBG as a cladding modes reflector and fiber taper as a bend-sensitive recoupling member. The lower cladding modes (ghost), reflected from TFBG, is recoupled back into the fiber core via tapered fiber section. We focused on optimization of TFBG tilt angle to reach maximum reflection of the ghost and taper parameters. Comparative measurements were made using optical spectrum analyzer and superluminiscent diode as broadband light source. We present dependence between intensity of recoupled ghost mode and sensor deflection.
We present our first basic concept of the simulation of stimulated Brillouin scattering (SBS) in this paper. We summarize
basic theories of SBS in standard communication optical fibers. We are using the simulation to recognize effects of using
SBS to generate acoustic waves in fibers. The acoustic waves in the optical fibers can be used to create long period fiber
grating. We present our application of this effect in our concept of fiber spectrometer and optical filters. Basic principle
of these applications is in the interaction of acoustic waves with measured laser beam in the optical fiber. The interaction
of acoustic waves and the measured laser beam in the optical fiber is demonstrated.
At present, photonic technologies boost most areas of both communication and sensing. Coincidently, most applications of the novel technical solutions based on any sort of O1)tiCal elements can be found here. Beside of classic bulk optics, there is a rising importance of planar and diffractive optics which is able not only to take many typical tasks of the conventional optics over but also to open guite a few new applications. For the planar and diffractive optics is based on the structures of the size comparable to or smaller then a wavelength, it utilises a modern technology, very the same as a semiconductor microelectronics does. One of the technology noticeably used here is an electron beam lithography which allows to generate the dielectric structures with the lateral accuracy up to 0. 1 micron or even less. Inventioned originally for conductive materials the EBL brings some limitations and peculiarities to the fabrication of the dielectric structures like trapped charge effects, proximity effect and others which will be briefly discussed. Most dielectric structures produced by direct EBL are composed of ultra fine relief patterns created either onto the flat bulk waffer surface or onto the layered sandwitch substrate. The physical methods of microfabricatiou (plasma etching) allow to get the reliefs of the depth comparable to the wavelength of light.
The present approach to the diffractive element design is based on Kirchhoff scalar theory of diffraction. Predictions made by this theory become unreliable if the diffraction of polarized light is evaluated. The paper presents the 'vector correction' to the Kirchhoff theory and suggest a method for calculating interaction of diffractive optical element and an incident electromagnetic field.
Predictions which are made by the Kirchhoff scalar theory of diffraction are widely used in the diffractive element design but they become unreliable if the diffraction of the polarized light is evaluated. The vector revision of this theory is presented and a novel approach to the diffractive element design is suggested.
This paper presents results of research activities devoted to preparing optical diffraction elements for space waves by use of electron-beam lithography. It is shown that the orthogonal electron-beam drawing can increase irregularities and flaws. Relations between the zone area inaccuracy and properties of the relief binary phase transparent screens are described. From these relations, the demands for setting the necessary edge drawing quality of the electron beam exposition are derived.
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