We demonstrate gas detection based on evanescent-wave photoacoustic (PA) spectroscopy with tapered optical fibers. Evanescent-field instead of open-path absorption is exploited for PA generation, and a quartz tuning fork is used for PA detection. A tapered optical fiber with a diameter down to the wavelength scale demonstrates detection sensitivity similar to an open-path system but with the ad...

Drawing single mode fibers over a flame generates tapered fibers with waist diameters of approximately 1–3 micrometers and waist lengths of up to 90 mm. We demonstrate how the profile of such tapered fibers can be determined. We then characterize the white light that is generated in a variety of such fibers, showing its dependence on waist length and waist diameter and demonstrating its depende...

In this work, we propose a new concept of optical tactile pressure sensing applied to flexible gold/PDMS nanocomposite material. We develop an optical tapered fiber force sensor based on electromagnetic (EM) coupling effect. The light coming from a tapered multimode Si fiber is coupled to a PDMS-Au polymer film. The formed gold nanoparticles increase the effective refractive index of the PDMS a...

Wide Band CPW-fed Circular Patch Antenna with Tapered Ground Plane Maryam MAJIDZADEH* Changiz GHOBADI Electrical Engineering Department, Urmia University, Urmia, IRAN [email protected] A novel Co-Planar Waveguide (CPW)_ fed antenna is presented for Ultrawide Band (UWB) applications. The main body of the antenna comprises of a simple circular patch and a ground plane with tapered ste...

To optimize the tool geometry (Pin profile) and process parameters for the FSW process. In the present investigation, an attempt has been made to understand the effect of rotational speed, welding speed and there different pin profiles on the nugget zone formation in AA 6063-T4 aluminum alloy. Three different tool pin profiles (tapered cylindrical, tapered square and square) have been used to f...

Diffraction-limited high-power narrow-spectrum red diode lasers are attractive for many applications, such as photodynamic therapy, laser display, and as a pump source to generate UV light by second harmonic generation (SHG). High-power, diffraction-limited diode lasers can be realized by the technology of lasers with a tapered gain-region (Kintzer et al., 1993; Donnelly et al., 1998; Wenzel et...

in order to achieve educational purposes and having better spiritual power in an education institute, the authorities must try to keep and support their human recourses. this study is conducted to determine the affective motivation factors on retension of faculty members at hormozgan university of medical sciences (hums). for this purpose, the view points of 71 faculty member’s (hums) through a...

We present a large-core fiber (LCF) with a reduced nonlinear property for a single-mode beam delivery of intense ultrashort pulses. A tapered-fiber mode filter was fabricated in an LCF with the core diameter decreased from 20 μm to 6 μm at the tapered waist region surrounded by index-matched liquid. By the tapered geometry, the high-order mode was rejected so that our mode-filtered LCF acted as...

In order to improve material flow behavior during friction stir welding and avoid root flaws of weld, a tool with a half-screw pin and a tool with a tapered-flute pin are suggested. The effect of flute geometry in tool pins on material flow velocity is investigated by the software ANSYS FLUENT. Numerical simulation results show that high material flow velocity appears near the rotational tool a...

A tapered coplanar waveguide (CPW) transition is proposed in order to facilitate the connection between a slot antenna and coaxial connector. The broadband bow-tie slot antenna is considered as an example in this design. The tapered transition is utilized to optimize the connection of two 50 CPW lines with different widths. A narrow CPW line is connected to the slot-antenna feed point and the w...