František Urban

Design of a Pressure Sensor Based on Optical Fiber Bragg Grating Lateral Deformation

This paper describes steps involved in the design and realization of a new type of pressure sensor based on the optical fiber Bragg grating. A traditional pressure sensor has very limited usage in heavy industrial environments, particularly in explosive or electromagnetically noisy environments. Utilization of optics in these environments eliminates all surrounding influences. An initial motivation for our development was the research, experimental validation, and realization of a complex smart pressure sensor based on the optical principle. The main benefit of this solution consists of increasing sensitivity, resistance to electromagnetic interference, dimensions, and potential increased accuracy.

Preparation and measurement of TFBG based vibration sensor

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.

Sensors based on longitudinal fiber Bragg gratings

This paper deals with the fabrication of novel Fiber Bragg Grating structure created in the longitudinal direction of the optical fiber. Basics of the Fiber Bragg Grating manufacturing method and optical fiber sensors using Fiber Bragg Gratings are presented. The role of the phase mask in the manufacturing process is discussed. Potential benefit of the grating writing direction is also analyzed. Next analyses and fabrication of novel longitudinal structures in optical fibers are presented. Experimental measurements using simple measurement setup employing precise LTCC structure for the characterization of the longitudinal fiber gratings are presented as well. The obtained results are discussed. Furthermore, the possibility of the longitudinal fiber gratings real application is discussed and proof of concept is provided.

Development of optical inclinometer in LTCC technology

This paper is focused on the development of the free-standing structures in Low Temperature Co-fired Ceramics (LTCC) using thick film pastes and sacrificial carbon material. There are many ways how to create a free standing thick film structure. One of the methods is using carbon tape with screen printed thick film. Using this method we have created mechanical structures consisting of the thick film bridge suspended between two LTCC parts. These free-standing bridges can act as a mechanical support of a seismic mass. Testing of the suitability of the materials for the manufacturing process was performed. There were three different LTCC substrates and different conductive, resistive and dielectric thick film pastes studied. Mechanical testing of the manufactured free standing bridges was also performed. The optical inclinometer using free-standing thick film structures with seismic mass was designed, manufactured and measured. First tests of the sensor proved the suitability of the free-standing structures for mechanical support of the seismic mass in optical sensors.

Bonding of zero-shrink LTCC with alumina ceramics

Purpose – The purpose of this paper is to focus on a description of reliable bonding technique of zero-shrink low-temperature co-fired ceramic (LTCC) and alumina ceramics. LTCC is widely used for manufacturing electrical systems in 3D configuration. LTCC substrates were so far bonded with alumina ceramics using additional adhesive layers with subsequent firing or curing cycle. With the advent of the zero-shrink LTCC substrates, it is now possible to bond unfired substrates with other fired substrates, for example fired LTCC or alumina substrates. Alumina substrate in combination with LTCC brings advantages of good thermal conductivity for usage in heating elements or packaging. Design/methodology/approach – The test structure contains a thick-film pattern for verification of the compatibility of the bonding process. We have used two methods for bonding the substrates: cold chemical lamination (CCL) and thermo compression method, using a dielectric thick-film paste as the adhesive. Optical microscopy, scan...

Photo-Reflective Layer on Low Temperature Co-Fired Ceramic for Optical Applications

The article deals with photo-reflective layer on Low Temperature Co-fired Ceramic substrate deposition. Measurement of diffusion and specular reflectance and roughness of layer is included. Fabrication process and its optimization is also mentioned. For measurement of deposited layer optical properties, spectrometric method in spherical chamber was used. Further, profile of layers surface was measured by profilometer to acquire dependence between roughness and reflectivity. The main aim of work is to map the possibility of creation of photo-reflective layer on electrical, chemical and thermal resistant substrate in simple way.

Stimulated Brillouin scattering for generating an acoustic wave in optical fibers

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.