Polarization-selective grating excitation of plasmons in cylindrical optical fibers

Abstract

We show that the tilted-grating-assisted excitation of surface plasmon polaritons on gold coated single-mode optical fibers depends strongly on the state of polarization of the core-guided light, even in fibers with cylindrical symmetry. Rotating the linear polarization of the guided light by 90 degrees relative to the grating tilt plane is sufficient to turn the plasmon resonances on and off with more than 17 dB of extinction ratio. By monitoring the amplitude changes of selected individual cladding mode resonances we identify what we believe to be a new refractive index measurement method that is shown to be accurate to better than 5 x 10(-5).

Light Polarization-Assisted Sensing with Tilted Fiber Bragg Gratings

“…(11) depicts the relative wavelength shifts and relative mode loss variations for selected resonances when the SRI is varied in a range of 1.2 10 -3 RIU. The results confirm the already established finding that the SPR mode is the most sensitive with a wavelength shift computed equal to 194 nm/RIU [12]. However, its strong attenuation prevents its proper use in practice.…”

“…When TFBGs are covered by a nanoscale noble metal layer, the cladding modes whose effective refractive index and polarization state are equal or close to those of a Plasmon wave transfer energy to it across the metallic surface. An unambiguous SPR signature appears in the TFBG amplitude spectrum, as reported in [11,12]. It is strongly sensitive to surrounding refractive index (SRI) changes [12][13][14][15], which yields an implementation of SPRbased (bio-)sensors easy to fabricate and to use.…”

“…It has also been recently demonstrated that the addition of a nanoscale gold coating overlay on the TFBG outer surface considerably enhances the refractometric sensitivity through the generation of surface Plasmon resonances (SPR) [11,12]. Plasmon waves result from collective excitations of electrons at the boundary between a metal and a dielectric [26,27].…”

Wavelength Interrogator Based on Closed-Loop Piezo-Electrically Scanned Space-to-Wavelength Mapping of an Arrayed Waveguide Grating

“…Finally, the interrogation under large-scale wavelength range is tested by reconstructing the transmission spectrum of a tilted-FBG (TFBG) sensor, a 18-nm wavelength range is achieved by setting the travel range of the piezo motor to 540 m. A TFBG sensor is one kind of short-period grating with the grating planes slanted or blazed with respect to the fiber axis [9]. Due to the tilt of the grating, multiple resonances within a large-scale wavelength 0733-8724/$26.00 © 2010 IEEE range are generated which are sensitive to the refractive index of surrounding medium and make it ideal for biomedical applications [10]. However, these multiple resonances require a wavelength interrogation technique to have a high bandwidth with light weight and miniaturized size.…”

Combining physical micro-machining and direct UV writing to fabricate novel planar tilted Bragg grating refractometers

“…Discrimination can usually be made in this way as the external refractive index is not in direct contact with the core mode. Such technology has been primarily exploited in optical fibre [1][2][3], with some recent progress demonstrating multiplexed multi-point sensing networks [2], and the employment of enhancement layers to increase external refractive index resolution [3]. Despite significant developments made in fibre, relatively few reports have been made for such components in a planar geometry, which have the added advantage of compact integration and offers ready integration with microfluidics.…”