Opto‐mechanical interactions in different photonic platforms as optical fibers and optical microresonators are raising great attention, and new exciting achievements have been reported in the last ...few years. Transverse acoustic mode resonances (TAMRs) in optical fibers –which can be excited optically via electrostriction and generate forward Brillouin scattering (FBS)– are being promoted as the physical mechanism for new fiber‐sensing concepts. Here, the study reports a novel approach to detect and characterize opto‐excited TAMRs of an optical fiber based on the interplay with optical surface wave resonances, i.e., optical whispering‐gallery mode (WGM) resonances. TAMRs induce perturbations in the geometry and the dielectric permittivity of the fiber over the entire cross‐section. It is shown that these perturbations couple the acoustic with the optical resonances and affect WGMs in a noticeable way. The study proposes and demonstrates the use of WGMs for probing opto‐excited TAMRs in optical fibers. This probing technique provides the narrowest linewidths ever reported for the TAMRs and demonstrates an optimum efficiency for the detection of low‐order TAMRs. The interplay between sensitivity, bandwidth, and Q factor of the WGM resonance is discussed.
Forward Brillouin scattering (FBS) in optical fibers is being promoted as a physical mechanism for new fiber sensing concepts. It involves two copropagating optical waves and transverse acoustic mode resonances (TAMRs). This study investigates the interaction between opto‐excited TAMRs and the optical whispering‐gallery mode resonances (WGMs) supported by the fiber itself and demonstrates accurate characterization of radial acoustic mode resonances.
A new approach to detect and analyze transverse acoustic mode resonances (TAMRs), responsible for forward Brillouin scattering in optical fibers, is reported using optical whispering gallery modes ...(WGMs). TAMRs generate perturbations in the geometry and the dielectric permittivity of the fiber that couples the acoustic and optical resonances. This interaction is exploited to probe opto-excited TAMRs exhibiting an optimal efficiency for detecting low-order TAMRs.
Tapered optical fibres are well-established devices for different applications, in order to exploit nonlinear effects, manage dispersion, excite azimuthal resonances in microresonators (so-called ...Whispering Gallery Modes). Also, the micro- or nanofibres guide optical-fields with large evanescent fields. In this talk, we will focus on the combination of tapers and Bragg gratings to perform novel optical devices. We will present two applications: the first, the fabrication of single-mode Bragg gratings in commercial multimode or few-mode tapered fibres by means of UV-photoinscription. The result is a grating that exhibits a single-mode reflection band and low insertion loss. The second application is the fabrication of Bio Bragg Gratings in micrometric tapers of single-mode fibres. In this case, the Bragg Grating is formed by a periodic pattern of biomolecules microstamped on the surface of the taper waist. As the molecules binds to its specific antibody, the reflectivity of this Bio Bragg Grating will increase, allowing quantification of the antibody concentration.
Rapid, reliable and low cost techniques to fabricate biosensors is a hot topic nowadays. Here, we present a BIO-grating fabricated by means of local, selective denaturing of molecules using UV ...radiation. A phase-mask is used to generate an interferometric pattern of 1420 nm pitch that, when illuminating a biolayer of BSA molecules lead to its periodic deactivation. After the biorecognition of the specific antibody, aBSA, a BIO-grating is generated due to the height difference between the protein, and the complex protein + antibody. We present the optimization of the fabrication of the BIO-gratings and their AFM characterization. Also, the biosensor performance in terms of limit of detection and limit of quantification will be presented.
Optical fiber characterization using whispering gallery mode resonances of the fiber itself has been demonstrated to be a powerful technique. In this work, we exploit the thermal sensitivity of ...whispering gallery mode resonances to characterize the pump-induced temperature increment in holmium doped and holmium-ytterbium codoped optical fibers. The technique relies on the measurement of the resonances' wavelength shift due to temperature variation as a function of the pump power. Holmium doped fibers were pumped to the second excited level 5I6 of the Ho3+ ion using a laser diode at 1125 nm and ytterbium-holmium codoped fibers to the 2F5/2 level of the Yb3+ ion by a laser diode at 975 nm. Our results demonstrate that pumping ytterbium-holmium codoped fibers at 975 nm results in dramatic thermal effects, producing a temperature increment two orders higher than that observed in holmium doped fibers pumped with a 1125 nm laser diode.
Resonant couplings in U-shaped fibers for biosensing Londero, Carolina; Delgado-Pinar, Martina; Cuadrado-Laborde, Christian ...
Journal of lightwave technology,
07/2023, Letnik:
41, Številka:
13
Journal Article
Recenzirano
Odprti dostop
U-shaped tight curvatures in optical fibers lead to resonant couplings between the fundamental and higher order modes that are sensible to different parameters, such as strain or temperature, for ...example. The optical response of the sensor consists on the shift of the resonant wavelength of the coupling. In the case of singlemode fibers, the coupling involves a so-called "cladding mode" and, due to its evanescent field, the curved region will be sensible to changes in the external medium, as well. In this paper, we present the fabrication and characterization of a robust, easy-to-make, U-shaped fiber sensor based on singlemode telecom fiber and its application for biosensing. The resonant nature of the sensing mechanism presents the advantage of large dynamic ranges for RI variations without the ambiguity of other techniques such as interferometry. We studied the performance of the U-shaped fiber sensor for different bending radii, to optimize its sensitivity and detection limit at 1550 nm operation wavelength, as well as the effect of temperature on its response. The shift of the resonant wavelength was measured in detail as a function of the external RI within the range 1.33-1,37; the detection limit was established in (3.71±0.03)×10 -5 RIU. Furthermore, the device was successfully tested as a proof of concept biosensor, using a system model antigen-antibody (BSA-aBSA.)
Discovering nanoscale phenomena to sense biorecognition events introduces new perspectives to exploit nanoscience and nanotechnology for bioanalytical purposes. Here we present Bio Bragg Gratings ...(BBGs), a novel biosensing approach that consists of diffractive structures of protein bioreceptors patterned on the surface of optical waveguides, and tailored to transduce the magnitude of biorecognition assays into the intensity of single peaks in the reflection spectrum. This work addresses the design, fabrication, and optimization of this system by both theoretical and experimental studies to explore the fundamental physicochemical parameters involved. Functional biomolecular gratings are fabricated by microcontact printing on the surface of tapered optical microfibers, and their structural features were characterized. The transduction principle is experimentally demonstrated, and its quantitative bioanalytical prospects are assessed in a representative immunoassay, based on patterned protein probes and selective IgG targets, in label-free conditions. This biosensing system involves appealing perspectives to avoid unwanted signal contributions from non-specific binding, herein investigated in human serum samples. The work also proves how the optical response of the system can be easily tuned, and it provides insights into the relevance of this feature to conceive multiplexed BBG systems capable to perform multiple label-free biorecognition assays in a single device.
•Diffractive bioreceptor nanostructures on optical waveguides to quantify label-free assays.•New transduction phenomenon demonstrated by experimental and theoretical results.•Functional protein assemblies patterned on optical microfibers by microcontact printing.•Minimized non-specific binding signal contributions, assessed in human serum samples.•Tunable optical response and multiplexing perspectives in miniaturized biosensors.
•PhoXonic Resonators.•Chaos transfer.
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We report the activation of optomechanical chaotic oscillations in microbubble resonators (MBRs) through a blue-side excitation of its optical ...resonances. We confirm the sequence of quasi-periodical oscillation, spectral continuum and aperiodic motion; as well as the transition to chaos without external feedback or modulation of the laser source. In particular, quasi periodic transitions and a spectral continuum are reported for MBRs with diameters up to 600 µm, whereas only an abrupt transition into a spectral continuum is observed for larger microbubbles.
Nanometric narrowband long period gratings (LPGs) are investigated for the implementation of improved fiber optic biosensors. The reduction of more than one order of magnitude in the linewidth of the ...LPG with respect to standard LPG at 1500 nm leads to the improvement of the resolution of the sensor. By selecting the proper fabrication parameters (high numerical aperture, relatively high order mode, and large length), LPGs with a 3-dB bandwidth of 1.5 nm were fabricated. The sensitivity of the LPG as a refractometer was calculated and experimentally characterized in detail. In particular, the LP 0,17 and LP 0,18 resonances were investigated in order to select the most suitable one for the bioexperiments. The surface of the LPG was functionalized and the detection of the hybridization of DNA is demonstrated. When the biosensor was immersed in a 2 μM solution of the complementary DNA strand, the resonances of the LPG shifted in wavelength. When measuring the response of the sensor in terms of variation of its transmittance as the resonance shifted in wavelength, the sensitivity was ~10%/μM for both resonances. The detection limit was estimated in 10 nM.
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