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A technique for temperature-insensitive force measurement via strain-induced Gaussian-strain-chirped fiber Bragg grating (FBG) couple and differential optical power detection is proposed and experimentally demonstrated. For a temperature range from -10degC to 80degC , a linear force measurement with thermal fluctuations less than 2.5% full-scale is achieved by simply using cost-effective p-i-n photodiodes without any temperature compensation.

A vector magnetic field sensor based on surface plasmon resonance (SPR) of a 15° tilted fiber Bragg grating (TFBG) and magnetic fluid is proposed and experimentally demonstrated. Both the orientation and the amplitude of the magnetic fields can be determined unambiguously via the wavelength and intensity monitoring of the SPR, which is essentially dominated by the arrayed Fe3O4 nanoparticles over the nanometric-film of fiber surface.

An ultra-thin silver-coated tilted fiber Bragg grating (TFBG) sensor with clear surface plasmon resonance (SPR) together with strong evanescent wave in transmission for "surface" and "bulk" surrounding refractive index (SRI) measurement is proposed and experimentally demonstrated. The thickness of the silver coating over the fiber surface is precisely controlled at 12~16 nm (much thinner than 40~50 nm for traditional SPR excitation). The transmission spectrum of the sensor provides a fine comb of narrowband resonances that overlap with the broader absorption of the surface plasmon and thus provide a unique tool to measure small shifts of the plasmon and identify the "surface" SRI changes with high accuracy. Meanwhile, the ultra-thin nanometric-coating permits part of high-order cladding modes to become leaky modes which have a large sensitivity to variations in the background solution for "bulk" SRI measurement. Experimental results show that above two resonances have an inverse amplitude responses to the SRI changing. Biological solutions (urine of rats with different concentration of Aquaporin) with different RI ranging from 1.3400 to 1.3408 were clearly discriminated in-situ by using the differential amplitude monitoring between “cut-off” cladding resonance and plasmonic resonance, with an amplitude variation sensitivity of ~8100 dB/RIU and a limit of detection of ~10-5 RIU.

A novel fiber-to-fiber tip-reflection sensing configuration for power-referenced refractometry with the capability to measure surrounding refractive index (SRI) as low as 1.33 is proposed and demonstrated. A short D-shaped fiber stub is parallel adjacent to another unshaped fiber containing a weakly tilted Bragg grating (TFBG). Light from the unshaped fiber can be effectively coupled into the adjacent D-shaped fiber through the TFBG which functions as a "bridge" between the core and cladding. Strong "comb" like cladding modes over a broad wavelength range have been recaptured in D-shaped fiber in reflection. These re-coupled cladding modes show different amounts of power as the SRI changes and the sensitivity is much higher than reported in-fiber sensing schemes, especially for low SRI measurement.

A novel refractive index (RI) sensing system with improved resolution based on a microwave photonics filter (MPF) is proposed and experimentally demonstrated. The sensing probe used for RI measurement is a microfiber Bragg grating. We use the frequency interrogation scheme (different from the traditional wavelength demodulation method) for resolution improvement of RI detection. The frequency shift of MPF notch point shows a linear relationship with the surrounding RI change over the range of 1.33 to 1.38 and a RI sensing resolution of 2.63×10−5 RIU has been achieved experimentally. The proposed MPF based RI sensing system provides a new interrogation method over the frequency domain with improved RI sensing resolution, as a good candidate for rapid and highly sensitive detection in chemical and environmental monitoring.

Based on differential intensity measurement between the cut-off and Plasmon resonances of an Au-coated tilted fiber Bragg grating, refractometer with RI sensitivity of 920 dB/RIU over the range of 1.332 to 1.357 has been achieved.

1School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China 2Department of Civil and Environmental Engineering, West Virginia University, Morgantown, WV 26506, USA 3Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC, Canada H3G 1M8 4Institute of Photonics Technology, Jinan University, Guangzhou 510632, China 5Department of Civil Engineering, Zhejiang University, Hangzhou 310058, China

A technique for temperature-insensitive force measurement using a single fiber Bragg grating (FBG) based on strain-gradient-induced reflection spectrum-bandwidth modulation and optical-power detection is demonstrated. A specially designed bending cantilever beam (BCB) is used to induce axial-strain gradient along the sensing FBG, resulting in a Bragg bandwidth modulation. The broadening of the FBG spectrum bandwidth and reflection optical power linearly change with the applied force, and both of them are insensitive to spatially uniform temperature variations. For a temperature range from 20 degC to 80 degC, a linear response of force measurement up to 20 N with fluctuation less than 0.8% full-scale is achieved without any temperature compensation. The demodulation process is simplified by optical-power detection via a p-i-n photodiode, and the sensing system is potentially cost-effective

A novel method for independent tuning of the center wavelength and the bandwidth of a fiber Bragg grating (FBG) was proposed and demonstrated. An FBG was adhered to the outer surface of a loop thin-wall section beam. The center wavelength and the bandwidth of the FBG can be tuned independently through changing the force while the fiber grating locates at different special positions. Quasi-chirp-free wavelength tuning with 6.706 nm and bandwidth tuning with 5.368 nm under quasi-shift-free center wavelength were obtained experimentally. The experimental results are in good agreement with the theoretical analyses.

Infantile hemangioma (IH) is a benign vascular neoplasm resulting from the abnormal proliferation of endothelial cells and pericytes in infants. Propranolol, a non-selective β-adrenergic blocker, has recently emerged as an effective therapy for IH, causing regression. However, its potential therapeutic mechanism remains largely unknown.An XPTS-1 cell line was established by isolating hemangioma-derived endothelial cells (HemECs) from a specimen of human proliferating IH. Flow cytometer assay was performed to assess the effect of propranolol on cell cycle distribution. Western blot was employed to determine changes of protein expression. Matrigel invasion and tube formation assays were used to measure invasion ability and tube formation ability, respectively. Commercial kits were employed to quantify NO and VEGF levels.Propranolol blocked norepinephrine-induced HemECs cell cycle progression as well as the expression of cyclin A2 and cyclin D2; whereas p21 and p27 proteins were altered conversely. Propranolol inhibited norepinephrine-induced cell invasion by reducing the expression of MMP-9, VEGF, and p-cofilin. NO and VEGF release induced by norepinephrine was decreased by propranolol pretreatment, coincident with alterations in the phosphorylation of Akt, eNOS, and VEGFR-2. Tube formation ability and subsequent levels of NO and VEGF elevated by norepinephrine were distinctively counteracted in HemECs.The current study demonstrated the antiangiogenic properties of propranolol in vitro and that the drug was able to induce the regression of hemangioma cells via the inhibition of cell cycle progression, invasion, and tube formation, concomitantly with decreased NO and VEGF levels through the down-regulation of the PI3K/Akt/eNOS/VEGF pathway.

Broadband-trimming band-rejection filters based on chirped and tilted fiber Bragg gratings (CTFBG) are proposed and experimentally demonstrated. The flexible chirp-rate and wide tilt-angle provide the gratings with broadband filtering functions over a large range of bandwidth (from 10 nm to 150 nm), together with a low transmission loss (less than 1 dB) and a negligible back-reflection (lower than 20 dB). The slope profile of CTFBG in transmission can be easily tailored by adjusting the tilt angle, grating irradiation time and chirp rate-grating factor, and it is insensitive to polarization of launch condition. Furthermore, by coating the CTFBG with a suitable polymer (whose refractive index is close to that of the cladding glass), the cladding modes no longer form weakly discrete resonances and leave a smoothly varying attenuation spectrum for high-quality band rejection filters, edge filters and gain equalizers.

A novel all-fiber temperature-calibrated refractometer based on a compact fiber Bragg grating (FBG) single–multi–single (SMS) structure is proposed and experimentally demonstrated. The sensor head is composed of a FBG combined with a SMS structure, in which the middle multimode fiber (MMF) section is etched by a time-controlled hydrofluoric. The transmission dip of SMS is extremely sensitive to ambient refractive index (RI) variation, whereas the upstream FBG provides the necessary temperature information for RI calibration. All aforementioned functions are performed via a compact FBG-SMS structure not longer than 25 mm. The proposed sensing device provides a linear RI sensitivity over water or waterbased solutions (RI values near 1.33 at optical wavelengths for most biological and many environmental applications), and has temperature-calibration capability. Hence, the said refractometer is a good candidate for sensing in chemical and biological applications.

Correction for ‘Ultrasensitive and in situ DNA detection in various pH environments based on a microfiber with a graphene oxide linking layer’ by Yunyun Huang et al., RSC Adv., 2017, 7, 13177–13183.

We demonstrate multiwavelength fiber lasers by incorporating the micro Michelson interferometer with spatial mode beating phenomenon, which comes from the interferences among cladding modes, into ring cavity for high resolution linear and angular displacement sensing.

High sensitivity biological sample measurements have been achieved by using a 12o tilted fiber Bragg grating (TFBG). Human acute leukemia cells with different intracellular densities and refractive index (RI) ranging from 1.3342 to 1.3344 were clearly discriminated in-situ by using the differential transmission spectrum between two orthogonal polarizations for the last guided mode resonance before “cut-off”, with an amplitude variation sensitivity of 1.8×10 4 dB/RIU and a limit of detection of 2×10 -5 RIU. The technique is inherently temperature-insensitive.

The polarimetric sensing characteristics of multi-mode-fiber based tilted fiber Bragg grating (MMF-TFBG) have been analyzed and experimentally demonstrated. The physical “enlarged” fiber core enables the tilted gratings to excite multi high-order core modes with significantly different polarization dependence and well-defined “comb” profiles which are spectrally separated at different wavelength. Orientation-recognized twist/rotation measurement (-90 o to 90 o ) has been achieved with sensitivity of 0.075 dB/deg by using a cost-effective double-path power detection (power monitoring of two orthogonal-polarimetric odd core-modes, i.e. LP 11 and LP 12 ).

Microfiber Bragg gratings (mFBGs) can be used as cost-effective and relatively simple-to-implement biosensors for monitoring DNA interactions in situ. The sensors are functionalized by a monolayer of poly-L-lysine (PLL) with the specific molecular recognition probe DNA sequences to bind with high specificity to a given target. By recording the wavelength seperation between the two resonant peaks of a single mFBG, the mFBG biosensor is capable of detecting the presence of specific target DNA in situ.

A label-free fiber-optic biosensor with a reflective microfiber Bragg grating (mFBG) configuration for in-situ DNA hybridization detection has been proposed and experimentally demonstrated. A single straight Bragg grating inscribed in the silica microfiber provides two well-defined resonances in reflection, which show different response to external medium refractive index (RI) and present the same temperature sensitivity. By monitoring the wavelength separation between these two resonances, temperature-compensated RI measurement has been achieved. The label-free bio-recognition scheme used demonstrates that the sensor relies on the surface functionalization of a monolayer of poly-l-lysine (PLL), synthetic DNA sequences that bind with high specificity to a given target. In addition to monitoring the surface functionalization of the fiber in real-time, the results also show how the fiber biosensor can detect the presence of the DNA hybridization with high specificity, in various concentration of target DNA solutions, with lowest detectable concentration of 0.5µM.

A label-free and ultrasensitive microfiber interferometer biosensor has been demonstrated for detection of neurotransmitter molecule (5-HT). The surface morphology of the silicon dioxide nanospheres acting as molecule sieve provides an effective mean of gathering 5-HT molecules by designed mesoporous structure. The slight concentration change of 5-HT molecules is translated into a dramatic wavelength shift of the interferometric fringe pattern. The experimental results show that the biosensor has a linear response in concentration range from 100 fM to 1 µM and a detection limit as low as 84 fM.

Tilted fiber Bragg grating (TFBG) biosensors can be used as a cost-effective and relatively simple-to-implement alternative to well established biosensor platforms for high sensitivity biological sample measurements in situ or possibly in vivo. The fiber biosensor presented in this study utilizes an in-fiber 12° tilted Bragg grating to excite a strong evanescent field on the surface of the sensor over a large range of external medium refractive indices. The devices have minimal cross-sensitivity to temperature and their fabrication does not impact the structural integrity of the fiber and its surface functionalization. Human acute leukemia cells with different intracellular densities and refractive index (RI) ranging from 1.3342 to 1.3344 were clearly discriminated in-situ by using the differential transmission spectrum between two orthogonal polarizations for the last guided mode resonance before "cut-off", with an amplitude variation sensitivity of 1.8 × 10(4) dB/RIU, a wavelength shift sensitivity of 180 nm/RIU, and a limit of detection of 2 × 10(-5)RIU. The detection process was precisely controlled with a micro-fluidic chip which allows the measurement of nL-volumes of bio-samples. The proposed in-fiber polarimetric biosensor is an appealing solution for rapid, sub-microliter dose and highly sensitive detection of analytes at low concentrations in medicine, chemical and environmental monitoring.

A novel technique for simultaneous measurement of refractive index and temperature based on power level detection of a weakly tilted fiber Bragg grating (TFBG) is proposed and experimentally demonstrated. Surrounding refractive index (RI) and temperature can be unambiguously determined by the TFBG transmitted and reflected power, respectively, avoiding complex wavelength interrogation. An accuracy approaching 1 x 10-4 in terms of the RI as well as temperature self-calibration is shown for this robust and cost-effective refractometer.

A novel technique for continuous chirp control of a fiber Bragg grating (FBG) based on a double-hole cantilever beam (DHCB) is proposed and experimentally demonstrated. The specifically designed DHCB provides a pressure-position-dependent strain-gradient along an originally uniform FBG and allows a tunable linear and Gaussian chirp modulation over the grating spectrum. Bandwidth and wavelength-independent tuning, under center-applied-pressure effect, is achieved by linear chirp modulation with a symmetrical broadening profile and a temperature-controlled wavelength shift. And intensity-referenced temperature-immune pressure measurement, under side-applied-pressure effect, is accomplished by Gaussian chirp modulation with a single-side-broadening profile and a linear-increasing reflection optical power.

A novel method about force sensing with temperature self-compensated based on a loop thin-wall section beam is proposed and demonstrated. Two identical fiber Bragg gratings are rigidly affixed on the outer surface of the beam with the positional angle difference between the two gratings of 90/spl deg/. The wavelength space between the two reflected peaks of the gratings is proportional to the force and insensitive to temperature when the direction of the force and one of the two gratings are located along a diameter; therefore, the force sensing with temperature self-compensated can be achieved.

We present an L-band all-optical gain-clamped erbium-doped fiber amplifier with a fiber-loop mirror as the ASE reflector. By using the combination of a C/L-band wavelength division multiplexer (WDM) and fiber-loop mirror, the backward C-band amplified spontaneous emission (ASE) is reflected back into the erbium-doped fiber and works as the control light. The static gain level of this amplifier can be adjusted by changing the ASE feedback. The experimental results show that the EDFA gain can be effectively clamped via this ASE reflection technique. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 852–854, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21496

A temperature insensitive fiber Bragg grating (FBG) liquid level sensor based on bending cantilever beam (BCB) is proposed and demonstrated. The BCB induces axial strain gradient along the sensing FBG, resulting in a Bragg bandwidth modulation. The broadening of FBG spectrum bandwidth and the reflection optical power change with the liquid level and they are insensitive to spatially uniform temperature variations. For a liquid level variation of 500 mm and a temperature range from 0/spl deg/C to 80/spl deg/C, the measured liquid level fluctuates less than 2% without any temperature compensation. By optical power detection via a pin photodiode, the liquid-level sensor avoids complex demodulation process and potentially costs low.

A compact fiber-optic vector rotation sensor in which a short section of polarization-maintaining (PM) fiber stub containing a straight fiber Bragg grating (FBG) is spliced to another single mode fiber without any lateral offset is proposed and experimentally demonstrated. Due to the intrinsic birefringence of the PM fiber, two well-defined resonances (i.e. orthogonally polarized FBG core modes) with wavelength separation of 0.5 nm have been achieved in reflection, and they exhibit a high sensitivity to fiber rotation. Both the orientation and the angle of rotation can be determined unambiguously via simple power detection of the relative amplitudes of the orthogonal core reflections. Meanwhile, instead of using a broadband source (BBS), the sensor is powered by a commercial vertical cavity surface emitting laser (VCSEL) with the laser wavelength matched to the PM-FBG core modes, which enables the sensor to work at much higher power levels (~15 dB better than BBS). This improves the signal-to-noise ratio considerably (~50 dB), and makes a demodulation filter unnecessary. Vector rotation measurement with a sensitivity of 0.09 dB/deg has been achieved via cost-effective single detector real time power measurement, and the unwanted power fluctuations and temperature perturbations can be effectively referenced out.

A compact fiber torsion sensor, in which a short section of polarization-maintaining (PM) fiber stub containing a normal straight fiber Bragg grating (FBG) is spliced to another single-mode fiber without any lateral offset, is proposed and experimentally demonstrated. Two well-defined resonances (orthogonal-polarimetric FBG core-modes) with ~0.5 nm wavelength separation have been achieved in reflection due to the birefringence of the PM fiber, and they exhibit a strong polarization and rotation dependence. Both the orientation and the angle of rotation can be determined unambiguously via dual-path power detection of the orthogonal-polarimetric core reflections. The unwanted power fluctuations and temperature perturbations can be effective referenced out by dual-path power normalization.

To investigate the therapeutic mechanism of Bleomycin A5 on infancy hemangioma.After intralesional injection of Bleomycin A5 into the tumor of animal model of infancy hemangioma, the variation of tumor form was and the variation of tumor structure were observed using light microscope and electron microscope, the variation of tumor gene expression spectra was also tested by DNA microarray technique.After treatment, the tumor gradually shrunk, hardened, disappeared one month later. The tumor lost appearance of infancy hemangioma and replaced by lamellar collagen fibers and cellular nucleus scattered in the fibers, and almost all cells were necrotic and dissolved. Under electron microscope, only large stretches of dissolved cell could be seen without intact cells and blood vessels, but apoptotic cells and bodies could also be found. The results of DNA microarray analysis showed that 9 genes associated with apoptosis (murine double minute 2, heat-labile enterotoxin B subunit, lymphotoxin B receptor, tumor necrosis factor ligand superfamily 7, tumor necrosis factor receptor superfamily 21, tumor necrosis factor receptor superfamily 1A, myeloid cell leukemia-1, caspase3), 13 genes associated with cell proliferation and cell cycle (cell division cycle27, cell division cycle37, CDC28 protein kinase 1B, cycling B1, cullin 2, cullin 3, cullin 4A, growth arrest and DNA damage-inducible 45A, meiotic recombination 11 homolog B, forkhead box M1, minichromosome maintenance 7, antigen identified by monoclonal antibody ki 67, proliferating cell nuclear antigen), and 11 genes associated with cellular stress and toxic reaction (glutathione peroxidase 1, metallothioneins, superoxide dismutase-1, heat shock protein A1A, heat shock protein A2, heat shock protein A4, heat shock protein A5, heat shock protein 9B, heat shock protein CA, macrophage migration inhibitory factor, plasminogen activator inhibitor)were up or down regulated more than 2 folds in tumors treated with Bleomycin A5 compared with controls.The therapeutic effect of Bleomycin A5 on infancy hemangioma is the synthetic results of multiple factors. Bleomycin A5 could not only induce apoptosis and inhibit cell proliferation, but also depressed the ability of cell stress and toxic reaction.

Orientation-recognized two-dimensional vibration sensor based on a polarization-controlled cladding-to-core recoupling is demonstrated experimentally. A compact structure in which a short section of multi-mode fiber stub containing a weakly tilted fiber Bragg grating (TFBG) is spliced to another single-mode fiber without any lateral offset. Several well defined lower-order cladding resonances in reflection show different polarization dependence due to the tilted grating vector excitation. Both orientation and amplitude of the vibration can be determined unambiguously via dual-path power detection of the orthogonal-polarimetric odd-cladding-modes. Meanwhile, the unwanted power fluctuations and temperature perturbations can be definitely removed via core mode monitoring.

In this paper, we demonstrate a high-damage-resistant tungsten disulfide saturable absorber mirror (WSsub2/sub-SAM) fabricated by magnetron sputtering technique. The WSsub2/sub-SAM has an all-fiber-integrated configuration and high-damage-resistant merit because the WSsub2/sublayer is protected by gold film so as to avoid being oxidized and destroyed at high pump power. Employing the WSsub2/sub-SAM in an Erbium-doped fiber laser (EDFL) with linear cavity, the stable Q-switching operation is achieved at central wavelength of 1560 nm, with the repetition rates ranging from 29.5 kHz to 367.8 kHz and the pulse duration ranging from 1.269 μs to 154.9 ns. For the condition of the maximum pump power of 600 mW, the WSsub2/sub-SAM still works stably with an output power of 25.2 mW, pulse energy of 68.5 nJ, and signal-noise-ratio of 42 dB. The proposed WSsub2/sub-SAM configuration provides a promising solution for advanced pulsed fiber lasers with the characteristics of high damage resistance, high output energy, and wide tunable frequency.

We propose two schemes for achieving tungsten disulfide (WS2)-based saturable absorber (SA) and saturable absorber mirror (SAM). By utilizing the pulsed laser deposition method, we grow the WS2 film on microfiber to form an evanescent field interaction SA device. Incorporating this SA device into a common ring-cavity erbium-doped fiber (EDF) laser, stably passive mode-locking can be achieved with pulse duration of 395 fs and signal-to-noise ratio of 64 dB. We also produce a fiber tip integrated WS2-SAM by utilizing the magnetron sputtering technique (MST). This new type of SAM combines the WS2 layer as SA and gold mirror as high reflective mirror. By employing the WS2-SAM, we construct the linear-cavity EDF lasers, and achieve passive mode-locking operation with pulse duration of ∼1 ns and SNR of ∼61 dB. We further achieve stably passive Q-switching operation with pulse duration of ∼160 ns and pulse energy of 54.4 nJ. These fiber-integrated SAs and SAMs have merits of compactness and reliability, paving the way for the development of new photonic devices such as SAs for pulsed laser technology.

A compact fiber-optic vector magnetometer based on directional scattering between polarized plasmon waves and ferro-magnetic nanoparticles is demonstrated. The sensor configuration reported in this work uses a short section of tilted fiber Bragg grating (TFBG) coated with a nanometer scale gold film and packaged with a magnetic fluid (Fe3O4) inside a capillary. The transmission spectrum of the sensor provides a fine comb of narrowband resonances that overlap with a broader absorption of the surface plasmonresonance (SPR). The wavelength of the SPR attenuation in transmission shows high sensitivity to slight perturbations by magnetic fields, due to the strong directional scattering between the SPR attenuated cladding modes and the magnetic fluid near the fiber surface. Both the orientation (2 nm/deg) and the intensity (1.8 nm/mT) of magnetic fields can be determined unambiguously from the TFBG spectrum. Temperature cross sensitivity can be referenced out by monitoring the wavelength of the core mode resonance simultaneously.

To investigate the effect of bleomycin A5 on the hemangioma-derived endothelial cell line XTPS-1.Hemangioma-derived endothelial cell line XTPS-1 was cultured with different concentration of bleomycin A5 (1000, 100, 10, 1, 0 mg/L), and then the survival rate was measured by methyl thiazolyl terazolium (MTT), the variation of cell morphology was observed using inverted phase contrast microscope and electron microscope, the variation of cell cycle and apoptosis rate were measured using flow cytometry.After 24 hours culture the cell survival rate was (92.96 ± 3.66)% and (99.86 ± 0.12)% in lower saturation group (10 and 1 mg/L), but (34.08 ± 3.11)% and (43.28 ± 2.88)% in higher saturation group (1000 and 100 mg/L). The difference between them was more significant (P0.01). Lower saturation of bleomycin A5 (10 and 1 mg/L)could induce apoptosis but had almost no cytotoxic effect. Higher saturation of bleomycin A5 (1000 and 100 mg/L) not only induced apoptosis, but also had strong cytotoxic effect, which was concentration dependent.bleomycin A5 could induce apoptosis, inhibit cell proliferation and has direct cytotoxic effect.

A novel optimizing technique for small-world network model is proposed and demonstrated. The effects of the key parameters to the synchronization of complex networks are investigated theoretically, including the characteristic path length, distribution degree, clustering coefficient and betweenness. It is found that the networks present a significant synchronization different with the equal characteristic path length and clustering coefficient. Simulation results show that neither the characteristic path length nor the clustering coefficient of complex networks can independently demonstrate the synchronization of the complex network. The heterogeneity of the distribution degree essentially suppresses the synchronization of complex networks, while the maximal betweenness is an effective indicator for synchronizability.

A directional vibration sensor based on polarization-controlled cladding-to-core recoupling is demonstrated. A compact structure in which a short section of multi-mode fiber (MMF) stub containing a weakly tilted fiber Bragg grating (TFBG) is spliced to another single-mode fiber without any lateral offset. Multiple core modes of the MMF are coupled at the junction and appear as well defined resonances in reflection from the TFBG. Some of those resonances exhibit a strong polarization and bending dependence. Both the orientation and the amplitude of the vibrations can be determined unambiguously via dual-path power detection of the orthogonal-polarimetric lowest order LP(1n) modes. Meanwhile, the unwanted power fluctuations and temperature perturbations can be referenced out by monitoring the fundamental LP(01) mode resonance.

A novel reflective refractometer based on a thin-core fiber (TCF) sandwiched between a leading single-mode fiber (SMF) and a fiber Bragg grating (FBG) imprinted SMF stub was demonstrated. The reflection from the fiber stub occurs in two well-defined wavelength bands, corresponding to the Bragg core mode and cladding modes. The TCF section functions as a tailorable bridge between the FBG core mode reflection and the surrounding refractive index (SRI). Linear response with enhanced sensitivity of 133.26 dB/refractive index unit for temperature-immune SRI measurement within the biologically desirable sensing range of 1.33–1.41 has been achieved via cost-effective power detection.

Plasmons based optical-fiber biosensors created from gold coating tilted Bragg gratings have been demonstrated. Plasmon resonances in the transmission are used to detect the banding of single stranded DNA (aptamer) and the further banding of target DNA (matched one).

High sensitivity biological sample measurement has been achieved by using a 10° tilted fiber Bragg grating. Human acute leukemia cells with different intracellular densities were clearly discriminated by identifying their slight refraction index (RI) perturbations in the range from 1.3342 to 1.3344, combining with a temperature self-calibration property.

In situ bio-sensing system based on microwave photonics filter (MPF) interrogation method with improved resolution is proposed and experimentally demonstrated. A microfiber Bragg grating (mFBG) is used as sensing probe for DNA hybridization detection. Different from the traditional wavelength monitoring technique, we use the frequency interrogation scheme for resolution-improved bio-sensing detection. Experimental results show that the frequency shift of MPF notch presents a linear response to the surrounding refractive index (SRI) change over the range of 1.33 to 1.38, with a SRI resolution up to 2.6 × 10(-5) RIU, which has been increased for almost two orders of magnitude compared with the traditional fundamental mode monitoring technique (~3.6 × 10(-3) RIU). Due to the high Q value (about 27), the whole process of DNA hybridization can be in situ monitored. The proposed MPF-based bio-sensing system provides a new interrogation method over the frequency domain with improved sensing resolution and rapid interrogation rate for biochemical and environmental measurement.

We propose a novel optical coupling technique based on evanescent field coupling between a singlemode- multimode-singlemode (SMS) fiber structure and a long period fiber grating (LPFG). By parallel placement of the two fiber sections in close proximity to each other, the excited multi-cladding modes from the SMS fiber section can be selectively coupled to the guided mode in the LPFG, and vice versa. A theoretical analysis based for such a structure is undertaken and the simulated results are verified by experiments demonstrating a maximum coupling efficiency of up to 1.66% (which could be improved to 27.5% in theory) over a broadband resonance (42 nm with a 3 dB bandwidth).

To establish an immortalized human infancy hemangioma-derived endothelial cell line (HemEC) and animal model of human infancy hemangioma.Hemangioma-derived endothelial cells from specimen of human infancy hemangioma were cultured in vitro and monocloed, and then its growth curve was made, karyomorphism of chromosome analyzed, morphologic characteristics observe, factor VIII related antigen identified by immunohistochemical method.Vascular endothelial growth factor receptor 2 (VEGFR-2) was detected by flow cytometry. HemEC were inoculated subcutaneously in athymic mouse to establish animal model of infancy hemangioma. The animal model was observed closely and its pathological characteristic was also studied.The cultural cells grew active, and immortalized spontaneously when they were subcultured on sixteenth generation. This cell line was cultivated for more than 70 times within one year and in good condition after freezing and resuscitating once and again, and had the morphologic character of HemEC. The cell population doubling time was 22 h. Factor VIII and VEGFR-2 were expressed positively. Karyo type analysis of the cell line showed abnormal diploid with the modal chromosomal number varying between diploid and triploid. The cell line was then named XPTS-1. The animal model of infancy hemangioma was successfully established and its character of histopathology was similar with that of infancy hemangioma.The cell line of HemEC was successfully established and immortalized spontaneously, and had the morphologic and biological character of HemEC. The animal model of infancy hemangioma was successfully established and showed the character of histopathology similar with that of infancy hemangioma.

A compact low-beat-frequency dual-polarization distributed Bragg reflector (DBR) fiber laser for high-frequency ultrasound detection has been demonstrated. The laser was fabricated in high germanium concentration, small-core erbium-doped fiber with very small birefringence. Induced birefringence to the fiber during the UV inscription process is small (~10-7) because of the small fiber core (4.2-μm) and consequently the laser beats at a low frequency of ~20 MHz, making frequency down-conversion unnecessary. The beat frequency can be adjusted by controlling the side-exposure time of the UV light irradiating the gain cavity, providing a simple approach to multiplex a large number of DBR fiber lasers of different frequencies in series using frequency division multiplexing (FDM) technique.

Power-referenced in-fiber edge filters based on a linearly chirped and weakly tilted fiber Bragg gratings (TFBG) are proposed and experimentally demonstrated. A strongly chirped TFBG with a polymer coating provides a smooth transfer function with up to 0.7 dB/nm of discrimination over the C-band. The slope profile of UV-induced chirped TFBG can be easily tailored by adjusting the tilt angle using only one chirped phase mask. Interrogators based on chirped TFBG can provide temperature-self-compensated, broadband, robust and cost-effective in-fiber demodulation for FBG sensing applications.

A compact low beat-frequency dual-polarization distributed Bragg reflector (DBR) fiber laser whose beat frequency can be varied, for high-frequency ultrasound detection has been proposed and experimentally demonstrated. The laser was fabricated in small birefringent commercial erbium-doped fiber. It operated in a robust single-longitude mode with output power of more than 1 mW and high signal-to-noise ratio better than 60 dB. Induced birefringence to the fiber during the UV inscription process is small (~10(-7)) and consequently the laser beats at a low frequency of ~20 MHz which is at least one order of magnitude smaller than previously reported results, making frequency down-conversion unnecessary. The beat frequency can be adjusted by controlling the side-exposure time of the UV light irradiating the gain cavity, providing a simple approach to multiplex a large number of DBR fiber lasers of different frequencies in series using frequency division multiplexing (FDM) technique. The proposed DBR fiber laser is also temperature insensitive, making it a good candidate for hydrophone applications.

Fiber-optic vibration sensing system using a tilted fiber grating and a vertical-cavity surface-emitting laser (VCSEL) has been demonstrated. Dynamic vibration measurement up to 200 Hz with improved signal-to-noise ratio better than 40 dB was achieved.

A compact tip-reflection fiber-optic vibration sensing system that uses a lateral-offset tilted fiber grating (TFBG) as sensor head and a vertical-cavity surface-emitting laser (VCSEL) as light source has been demonstrated. Dynamic mechanical vibration measurement up to 200 Hz with signal to-noise ratio better than 40 dB has been achieved.

A power-referenced fiber-optic accelerometer is proposed by using a weakly tilted fiber Bragg grating (TFBG) combined with a lateral-misaligned splice structure. The recoupling of lower-order cladding modes (ghost modes), excited by the TFBG, to the fiber core via a slightly lateral-offset slice is sensitive to vibration and can be unambiguously determined by monitoring the power change in reflection, avoiding complex wavelength interrogation. However, the Bragg resonance is virtually unaffected by fiber bending and it can be used as a power reference to cancel out any light source fluctuations. Combining with a polymer tube package, the novel sensing configuration presents a linear and reproducible response for acceleration measurement.