However, the core and cladding layers of communication grade multimode optical fiber are composed of fused silica, which is a transparent, hard, brittle, and high band gap (~9 eV) material that could not have been effectively machined by long-pulsed lasers (e.g., CO2 laser, pulse duration at range of ��s). The peak power intensity of selleck bio the long-pulsed laser is not high enough to generate a significant amount of free electrons [3�C5]. Recently, femtosecond laser has been extensively used for microfabrication. The most prominent features of the femtosecond laser over conventional long-pulsed laser are ultra short pulse duration and very strong peak power intensity, which can photoinduce the non-linear Inhibitors,Modulators,Libraries multi-photon absorption of a material during irradiation.

The material vaporizes immediately after absorbing ultra high transient pulse energy from the ultra short pulse of femtosecond Inhibitors,Modulators,Libraries laser [6,7]. It can be used to engrave on transparent, hard and brittle materials very precisely, such as optical fibers, without inducing any micro cracks and heat affected zone [8,9].In this paper, we report a multi-D-shaped optical fiber sensor with a direct write technique by using high-power femtosecond laser pulses. A communication grade multimode optical fiber (Corning 62.5/125 optical fiber) was adopted in the present study. The optical fiber was composed of a silica-based core (62.5 ��m in diameter), and cladding and polymeric jacket with outer diameters of 125 ��m and 250 ��m, respectively. Shown in Figure 1 is an illustration diagram of the fabricated multi-D-shaped optical fiber.

For a single D-shaped zone the depth was 100 ��m measured from the surface of the polymer jacket layer, and the length was 1 mm. The distance between two neighboring D-shaped zones was 1 mm. The number of Inhibitors,Modulators,Libraries D-shaped zones fabricated could range from three to seven, and they were distributed in line along the axis of the optical fiber. The operating principle of sensing is based on attenuated total internal reflection (ATR) via multiple internal reflections along the fiber and the attenuated light intensity of the multi-D-shaped fiber changes linearly with an increase of the surrounding refractive index. The loss of light energy caused by the sensing portion of the fiber is detected by a sensor interrogation system which is used to derive the refractive index of the surrounding media.

In this scheme the fiber plays a role not only as a signal transmission Inhibitors,Modulators,Libraries line but also as a sensing component. The result of the tensile test of the multi-D-shaped fiber is reported. The ability of the multi-D-shape fiber as a high sensitive refractive-index sensor to detect changes in the surrounding refractive index was also Carfilzomib studied.Figure 1.Illustration diagram of the multi-D-shaped optical fiber.2.?Sensor selleck chemicals 17-DMAG FabricationA femtosecond laser micromachining system, as illustrated in Figure 2, was used for engraving the trench on the optical fiber.