Compact all-fiber plasmonic Airy-like beam generator is demonstrated. A single slit and a 1D groove array were fabricated by focused ion beam (FIB) milling on the end facet of a single mode optical fiber. The single slit excites the surface plasmonic polaritons (SPPs), which are decoupled into free space by the groove array. The phase of decoupling SPPs is adjusted by the grooves position. Experimental generation of the single Airy-like beam has good consistency with theoretical predictions. The transverse acceleration and nondiffraction properties are observed. The presented plasmonic Airy-like beam generator is of importance to realize all-fiber optical trapping, beam shaping, and fiber integrated devices.
A compact singlemode-photonic crystal fibre-singlemode fibre tip (SPST) refractive index sensor is demonstrated in this paper. A CO2 laser cleaving is exploited to provide a clean-cut fibre tip which is then coated by a layer of gold to increase reflection. An average sensitivity of 39.1 nm/RIU and a resolvable index change of 2.56×10-4 are obtained experimentally with a ~3.2 µm diameter SPST. Because of its compactness, ease of fabrication, linear response, high sensitivity, easy connectivity to other fibreized optical components and low cost, this refractometer could find various applications in chemical and biological sensing.
Plasmonic slot nano-resonators (PSNR) embedded in gold-coated optical fiber tapers, can show strong three dimensional localization when optimized. Here the PSNR is used as a refractometer with small footprint. An average sensitivity of 66.7 nm/RIU and a resolvable index change of 1.5×10-4 for a resolvable wavelength change of 0.01 nm are obtained.
A compact fiber tip refractive index sensor using FIB-milled gold-coated singlemode-multimode-singlemode structure is demonstrated. Focused ion beam (FIB) is exploited to cut the fiber tip to obtain a flat end-face and then a layer of gold is coated on the tip surface, to increase its reflection. An average sensitivity of 265 nm/RIU is obtained experimentally with a ~2.94 μm diameter singlemode-multimode-singlemode fiber tip (SMST). Because of several advantages, including compactness, ease of fabrication, linear response, high sensitivity, easy connection with other fiberized optical components and low cost, this refractive index sensor could find various applications in chemical and biological area.
In this paper, we demonstrate a hybrid plasmonic bottle microresonator (PBMR) which supports whispering gallery modes (WGMs) along with surface plasmon waves (SPWs) for high performance optical sensor applications. The BMR was fabricated through “soften-and-compress” technique with a thin gold layer deposited on top of the resonator. A polarization-resolved measurement was set-up in order to fully characterize the fabricated PBMR. Initially, the uncoated BMR with waist diameter of 181 μm, stem diameter of 125 μm and length of 400 μm was fabricated and then gold film was deposited on the surface. Due to surface curvature, the gold film covering half of the BMR had a characteristic meniscus shape and maximum thickness of 30 nm. The meniscus provides appropriately tapered edges which facilitate the adiabatic transformation of BMR WGMs to SPWs and vice versa. This results in low transition losses, which combined with partially-metal-coated resonator, can result in high hybrid-PBMR Q’s. The transmission spectra of the hybrid PBMR are dramatically different to the original uncoated BMR. Under TE(TM) excitation, the PBMR showed composite resonances with Q of ~2100(850) and almost identical ~ 3 nm FSR. We have accurately fitted the observed transmission resonances with Lorentzian-shaped curves and showed that the TE and TM excitations are actually composite resonances comprise of two and three partially overlapping resonances with Q’s in excess of 2900 and 2500, respectively. To the best of our knowledge these are the highest Qs observed in plasmonic microcavities.
We propose to optically trap nanoparticles utilizing a single nanostructured glass-fiber tip. 3D translation of optically trapped nanoparticles - nano tweezers - presents vast application possibilities and has not yet been shown. The input end of the fibre probe is a standard fibre, providing easy coupling to a light source. The output end is tapered down and covered with gold, with a nanoaperture fabricated on the tip. The nanoaperture provides the strong field gradient necessary for trapping of nanoparticles. We discuss probe geometries supported by numerical simulations. The fabrication procedure for the fibre probe, using a focused ion beam, is described. A set-up for the experiments has been made and preliminary trapping results are presented.
We have carried out a systematic study of the effect of microtaper diameter on the spectral characteristics of bottle microresonators. By increasing the microtaper-diameter (Dt) from 2μm to 10μm results in progressively cleaner spectra. The transmission depth at resonance varies from ~15dB (@Dt=2μm) to >3dB (@Dt=10μm). The loaded Q factors were measured to be >10+6 in all cases. However, with microtaper Dt=10μm clearly-resolved single resonance peaks could be observed and free-spectral ranges could be easily identified. At some transmission resonances, we have observed LP01→LP11 mode transformation at the excitation microtaper waist, for the first time, as the resonance is scanned.
Proc. SPIE. 8421, OFS2012 22nd International Conference on Optical Fiber Sensors
KEYWORDS: Fabrication, Optical fibers, Silica, Fiber Bragg gratings, Reflection, Optical testing, Temperature sensors, Microsoft Foundation Class Library, Electronics engineering, Temperature metrology
A compact fast temperature sensor based on a broadband microfiber coupler tip is demonstrated. The thermometer
dynamic range spans from room temperature to 1511 °C with a response time of tens of ms. This is the highest
temperature measured with an optical fiber device. The resolution of 0.66 °C was achieved for a coupler tip diameter of
An all-fibre refractive index sensor with a simple periodical tapers configuration is proposed and investigated
experimentally. The proposed fibre refractive index sensor consists of a small core singlemode fibre with tapers
periodically fabricated along the fibre using a focused CO2 laser beam, and sandwiched between two standard
singlemode fibres. Such a structure can be used for sensing of refractive index by measuring the dip wavelength shift of
the multimode interference within the small core fibre cladding. A minimum sensitivity of 125 nm/RIU is measured for a
refractive index of 1.33 and a maximum sensitivity of 383 nm/RIU for a refractive index of 1.38. The proposed
refractive index sensor benefits from simplicity and low-cost and achieves a competitive sensitivity compared with other
We theoretically and experimentally investigate a singlemode-multimode-singlemode (SMS) structure based on
chalcogenide (As2S3) multimode fiber and conventional silica singlemode fibers. The experimental results show a general
agreement with the numerical simulation results based on a wide angle-beam propagation method (WA-BPM). The
chalcogenide fiber and silica fibers were mechanically spliced and packaged using a UV cured polymer with a low
refractive index on a microscope slide. Multimode interference variation was observed by photo-induced refractive index
changes resulting from both a localized laser irradiation at a wavelength of 405 nm and a UV lamp. Our result provides a
platform for the development of compact, high-optical-quality, and robust photonic nonlinear devices.
An improved ratiometric wavelength measurement system incorporating two fibre comb filters is presented, which
performs both rough and fine wavelength measurements simultaneously. The resolution of the system is significantly
improved, compared to a single edge filter system, to better than 5 pm while maintaining the potential for high
measurement speed and wide measurable wavelength range.
We demonstrate a technique for tapering periodically an all-solid soft glass fiber consisting of two types of lead
silicate glasses by the use of a CO2 laser and investigate the bend sensing applications of the periodically-tapered
soft glass fiber. Such a soft glass fiber with periodic microtapers could be used to develop a promising bend sensor
with a sensitivity of -27.75 μW/m-1 by means of measuring the bend-induced change of light intensity. The proposed
bend sensor exhibits a very low measurement error of down to ± 1%.