This PDF file contains the front matter associated with SPIE Proceedings Volume 7634, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

In this paper a novel Surface-enhanced Raman Scattering (SERS) sensor combining with fused taper optical fiber (FBTF) and the film coating with silver sols is proposed. This structure is designed to obviously increase the SERS active surface when the radius is reduced and the length of the taper is increased, because the penetration depth is proportional to the taper length and inversely proportional to the taper radius according to the fiber-optic evanescent-wave theory. Based on the SERS sensing principle, the feasibility of FBTF sensor is analyzed in this paper. Actually, the Raman spectrum of R6G is obtained from the taper surface coating with the silver sols in our experiments. The detecting concentration is up to 10-7M. Moreover, this SERS sensing structure is simple and reproducible.

Dynamic optical coherence elastography, an emerging optical technique to measure material mechanical properties using the non-invasive imaging modality of optical coherence tomography is introduced. Dynamic mechanical excitations were applied to the samples while a spectral domain optical coherence tomography system was used for detection. Based on a simple mechanical model, material mechanical properties such as Young's moduli can be extracted from detected phaseresolved signals. Biological tissues and their biomechanical properties are currently the main objects for this technique due to its micron-scale resolution and relatively deep penetration. Quantitative results were achieved by this technique on tissue phantoms and rat tumor tissues. Different excitation approaches and applications for dynamic optical coherence elastography are also discussed.

An original method based on a microfluidic dye laser has been investigated to carry out optical analysis of microfluidic droplets. Droplets that have been the subject of extensive works over the last five years appear as the best tool to manipulate subnanoliter volumes for a lot of applications in both chemistry and biology. We have designed a device that combines a microfluidic dye laser and a droplet generator on the same chip. Intracavity measurement can thus be performed as the droplets pass through the laser cavity. Depending on the droplet shape, whether it is spherical or not, the presence of the droplet inside the optical cavity results in an extinction of the laser signal or in a variation of its intensity. This innovative method can be used for in-situ direct analysis of any event occuring inside the droplet volume. In addition to this work, in order to develop a device allowing optical analysis over the full visible spectrum, we have also developed a new laser that is able to deliver multiple wavelength on-demands. Such improvement in the laser design has several advantages such as reducing the number of equipment around the set-up.

A swept-source optical coherence tomography (SS-OCT) system with a specially designed probe is built for clinical scanning of oral submucous fibrosis (OSF) patients. By analysing 44 OSF cases of SS-OCT scanning results, two indicators, including epithelium (EP) thickness and standard deviation (SD) of A-mode scan intensity in the laminar propria (LP) layer, are found useful for real-time OSF diagnosis. Statistics show that sensitivity and specificity of LP SD can reach 84.1 and 95.5 %, respectively. Also, both sensitivity and specificity of EP thickness can reach 100 %.

A new processing technique called Non-Harmonic Analysis (NHA) is proposed for OCT imaging. Conventional Fourier-Domain OCT relies on the FFT calculation which depends on the window function and length. Axial resolution is counter proportional to the frame length of FFT that is limited by the swept range of the swept source in SS-OCT, or the pixel counts of CCD in SD-OCT degraded in FD-OCT. However, NHA process is intrinsically free from this trade-offs; NHA can resolve high frequency without being influenced by window function or frame length of sampled data. In this study, NHA process is explained and applied to OCT imaging and compared with OCT images based on FFT. In order to validate the benefit of NHA in OCT, we carried out OCT imaging based on NHA with the three different sample of onion-skin,human-skin and pig-eye. The results show that NHA process can realize practical image resolution that is equivalent to 100nm swept range only with less than half-reduced wavelength range.

Fluorescence molecular tomography (FMT) can obtain a sufficient data set and optimal three-dimensional images when projections are captured over 360° by CCD camera. In the Tikhonov regularization-based reconstruction procedure of FMT, the optimal regularization parameter obtained by some parameter-choice methods might miss the accurate result due to the model-mismatch and discretization error. Herein a two-step algorithm was proposed. In the first step, a suboptimal parameter was estimated based on the expected value of the Fourier coefficient of perturbation. Then in the second step, the L-curve criterion was adopted to get the optimal parameter in the permissible region obtained in the first step. With the optimal parameter and permissible region, more accurate reconstruction result was acquired. Experimental results suggested that such technique outperform the traditional L-curve criterion when applying into the FMT reconstruction.

Optical coherence tomography (OCT) is an emerging medical imaging technology that can generate high resolution cross-sectional imaging (1-2 mm in depth) of tissue microstructure in situ and in real time. Fluorescence imaging provides tissue biochemical, metabolism, and molecular information by measuring fluorescence intensity or spectroscopy of either intrinsic fluorophores or exogenous contrast agents. The combination of these two modalities provides complementary morphological, functional and molecular information to comprehensively assess tissue status. There is a great interest to further extend the fluorescence imaging into tomography in order to provide depth-resolved molecular function that can be coregistered with 3-D tissue morphology provided by OCT. In this paper, we present a combined OCT and line-scanning fluorescence laminar optical tomography (FLOT) system for simultaneous 3-D morphological and molecular imaging with 10-100 μm resolution and millimeter-scale imaging depth. Co-registration on a capillary phantom with fluorescence dye Cy5.5 using the system has been demonstrated.

Autofluorescence imaging has shown high sensitivity for early diagnosis and detection of cancer in humans. However, it has a limitation in diagnostic specificity due to high false positive rates. In this work, we apply an integrated fluorescence spectroscopy and endoscopic imaging technique for real-time tissue measurements. The results show that the combined autofluorescence imaging and spectroscopy has the potential for improving laryngeal cancer diagnosis and detection.

In vivo small animal imaging is a cornerstone in the study of human diseases by providing important clues on the pathogenesis, progression and treatment of many disorders. Molecular tomographic imaging can probe complex biologic interactions dynamically and to study diseases and treatment responses over time in the same animal. Current imaging technique including microCT, microMRI, microPET, microSPECT, microUS, BLT and FMT has its own advantages and applications, however, none of them can provide structural, functional and molecular information in one context. Multi-modality imaging, which utilizes the strengths of different modalities to provide a complete understanding of the object under investigation, emerges as an important alternative in small animal imaging. This article is to introduce the latest development of multimodality systems for small animal tomographic imaging. After a systematic review of imaging principles, systems and commerical products for each stand-alone method, we introduce some multimodality strategies in the latest years. In particular, two dual-modality systems, i.e. FMT-CT and FMT-PET are presented in detail. The end of this article concludes that though most multimodality systems are still in a laboratory research stage, they will surely undergo deep development and wide application in the near future.

We explore an NIR autofluorescence imaging technique for cancer diagnosis and detection. A set of tissue images including NIR white light images, autofluorescence (AF) images and fluorescence polarized images (FPI) (parallel-, and perpendicular- polarization) were acquired in tandem on human colonic tissues. The results show that NIR fluorescence intensity of normal tissue is significantly higher than that of cancer tissue. The perpendicular-polarization image yields the highest diagnostic accuracy 93% compared to other imaging modes. This work demonstrates that Fluorescence polarization imaging (FPI) technique has great potential for cancer diagnosis and detection in the colon.

Indocyanine green (ICG) is a fluorescent probe widely used in recent years, and it is also the fluorescent dye that can be clinical used, in both imaging and treatment. So it is important to study its biodistribution and metabolism in mammalian organs, but the accuracy and sampling speed is limited by the traditional in-vitro methods. Now we present a design of an in-vivo multi-channel fluorescence intensity measurement system and an algorism of data processing, to achieve the accurate measurement of fluorescence intensity, continuous sampling, real time monitoring and curve fitting. This system design is based on customized fiber bundles and the principle of reflective fluorescence microscopy. We also present a mouse experiment using this system to study the Indocyanine green (ICG) biodistribution in small mammalian liver, in order to demonstrate the potential applications of this system and also present a new experiment method in the study of dye biodistribution and metabolism.

In the laser induced interstitial thermotherapy (LITT), real-timely detecting the temperature distribution of the cured tissue is a bottleneck. In this paper, a fully distributed chirped Fiber Bragg grating (FBG) sensor, which is of small size, immune from electromagnetic interference (EMI) and high sensitivity, is proposed to solve this problem. An experiment simulation of LITT is set up, and only one chirped FBG is used to detect the dynamic spectral variation with different laser power. Meanwhile, a high-efficiency spectra inversion algorithm named MSAE of FBG is utilized to demodulate the system and obtain the temperature distribution. The spatial resolution is 0.25mm and the running time of demodulation is tens of seconds, which can help doctors control the laser parameters such as the laser power and the treatment time to guarantee the security of the therapy.

A novel two-dimensional tilt sensor with a large measurement range is demonstrated by using four fiber Bragg gratings (FBGs) attached on a cylindrical cantilever-based pendulum. Experimental results show that tilt accuracy of ±0.2° and resolution of 0.013° have been achieved in the range of -40° to 40°. The temperature effect is automatically eliminated without additional temperature compensation elements.

A fiber-optic strain sensor is demonstrated by using a short length of highly birefringent photonic crystal fiber (PCF) as the sensing element inserted in a fiber loop mirror (FLM). Due to the ultralow thermal sensitivity of the PCF, the proposed strain sensor is inherently insensitive to temperature. When a DFB laser passes through the FLM, the output power will only be affected by the transmission spectral change of the FLM caused by the strain applied on the PCF. Based on intensity measurement, an optical power meter is adequate to deduce the strain information and an expensive optical spectrum analyzer (OSA) would not be needed.

A novel fiber optic accelerometer is proposed and demonstrated. The sensing mechanism is based on the measurement of bandwidth and optical power of a strain-chirped fiber Bragg grating (FBG). An initially-uniform FBG is glued with a slanted direction onto the lateral surface of a simply-supported beam. Two masses are fixed on the top and bottom surfaces in the middle of the beam respectively, which can transfer the vertical acceleration to the deflection of the beam. Therefore, deflection induced nouniform strain is applied along the sensing FBG and makes it chirped. Experimental results show that 3-dB bandwidth and reflected optical power of the strain-chirped FBG responds to acceleration sensitively. The achieved sensitivities are up to 0.4 nm/g and 4.57 μW/g respectively in the linear range. Furthermore, this sensor is very cost-effective and inherently insensitive to temperature due to the simple demodulation method.

Primary liver cancer (hepatocellular carcinoma, or HCC) is associated with liver cirrhosis 60-80% of the time. Liver cancer is one of the most common malignancies in the world, with approximately 1,000,000 cases reported every year. About 80% of people with primary liver cancer are male. Although two-thirds of people have advanced liver disease when they seek medical help, one third of the patients have cancer that has not progressed beyond the liver. HCC may metastasize to the lung, bones, kidney, and many other organs. Surgical resection, liver transplantation, chemotherapy and radiation therapy are the foundation of current HCC therapies. However the outcomes are poor: the survival rate is almost zero for metastatic HCC patients. Molecular mechanisms of HCC metastasis need to be understood better and new therapies must be developed to selectively target to unique characteristics of HCC cell growth and metastasis. We have developed the "in vivo microscopy" to study the mechanisms that govern liver tumor cell spread through the microenvironment in vivo with real-time confocal near-infrared fluorescence imaging. A recently developed "in vivo flow cytometer" and optical imaging are used to assess liver tumor cell spreading and the circulation kinetics of liver tumor cells. A real- time quantitative monitoring of circulating liver tumor cells by the in vivo flow cytometer will be useful to assess the effectiveness of the potential therapeutic interventions.

Conventional bead-based micro immunoassays do not guarantee high reliability and repeatability due to the trapping mechanisms of the systems which cause inconsistency in trapping of cytometric beads. This paper presents a new beadbased micro immunoassay system for semicontinuous assays with high reliability and accuracy in cytometric bead trapping by using the hole-patterned microstructures. Trapping test showed the assembly of single layer of bead array in ordered fashion. In addition that, the μ-immunoassay exhibits that the fluorescence intensity linearly increases in proportion to Biotin-4-Fluorescin (B4F) concentration and a 10 pg/mL appears to be the lowest detectable concentration for B4F after incubation time of 5 minutes.

A novel fiber-optic distribution monitoring system using birefringent optical circuit synthesis (BOCS) method to monitor the external influences on the fiber is demonstrated. The detection mechanism is based on the synthesis of the transfer function of sensing fiber by using the measurement values of Stokes parameters of transmission light with a optical frequency scanning. The sensing fiber is modeled as one with the birefringence distribution characteristic and is divided into a series of birefringent lattice segments. The mode coupling angle at each birefringent segment is taken as the sensing parameter and its variation distribution as the perturbation distribution along the fiber length can be derived from two profiles of mode coupling angle obtained from the BOCS. The operation principles of the proposed system is described and several experimental results are demonstrated. At last, the discussions on the experimental results and the limitations of the proposed detection method are presented.

Distributed feedback (DFB) fiber lasers have their unique properties useful for sensing applications. This paper presents a high performance distributed feedback (DFB) fiber laser sensor array system. Four key techniques have been adopted to set up the system, including DFB fiber laser design and fabrication, interferometric wavelength shift demodulation, digital phase generated carrier (PGC) technique and dense wavelength division multiplexing (DWDM). Experimental results confirm that a high dynamic strain resolution of 305 fε/√Hz (@ 1 kHz) has been achieved by the proposed sensor array system. And the multiplexing of eight channel DFB fiber laser sensor array has been demonstrated. The proposed DFB fiber laser sensor array system is suitable for ultra-weak signal detection, and has potential applications in the field of petroleum seismic explorations, earthquake prediction, and security.

A novel underwater fiber laser geophone is presented. Theoretical and experimental analyses are carried out to test the performance of the geophone, which shows a sensitivity of more than 30 pm/g and a flat frequency response in the range of 5 Hz~200 Hz are achieved.ati

A novel liquid-level sensor was proposed and studied by using a specialty double-cladding fiber (DCF). The sensor operates according to a light wavelength modulation method which results from the variation of the surrounding refractive index (RI). As the surrounding RI changes, the effective refractive index of cladding mode of DCF increases or decreases and the phase-matching condition changes, so does shift the resonance wavelength. In our experiments, the DCF sensor was exposed to different liquids with certified RI, and liquid levels were varied. Experimental results showed that the shift of the transmission spectra linearly depended on the fraction change of DCF immersed into the liquid. The liquid level sensitivities are 451.8 pm/mm and 1030.44 pm/mm for the different liquid with RI of 1.3514 and of 1.4286, respectively. The sensor has the advantages of large linear response range, as well as high sensitivity and simple structure et al.

A highly integrated sensor based on the hybrid coupler, which is comprised of the short range surface plasmon polariton (SRSPP) and dielectric waveguides, is proposed for ultra-thin layer detection. The dependence of the coupling efficiency between SRSPP and dielectric waveguide mode on the refractive index change of detecting layer is analyzed theoretically. For a detecting layer thinner than 1/10 wavelength, the refractive index resolution can be high up to 5.5×10^-6 RIU with large sensing range as 5×10^-2 RIU and rather short sensing length as tens of microns.

SPR biosensor with OLED and nano-grating for HBV LAMP product detection is reported. Directional emissions by grating-coupler match the resonant condition of SP modes. Concentration changes result in color shift at specific angle. Real time detection of virus load down to 5 copies/25 ul can be achieved in 30 minutes. Surface plasmon Resonant (SPR) biosensor has been used for quantitative measurement of molecular interactions for its advantages of high sensitivity, label-free and real-time detection. In this paper, we report recent efforts on further enhancement of SPR biosensors by the heterogeneous integration of organic electroluminescence light source and nano-grating structure for the feasibility study on the fast and high sensitivity detection of HBV isothermal amplification products, Mg₂P₂O₇. We demonstrated the surface plasmon coupled through hybrid nano-grating structure has highly directional emissions corresponding to the resonant condition of surface plasmon modes on the Au/air interface and controllable plasmonics band-gap by pitch modulation. SPGCE resulted in color change from yellowish green to orange at a certain viewing angle, when contacting glucose with concentration increasing from 10 to 40%.

Fluorescence lifetime imaging microscopy (FLIM) has been demonstrated as advantageous at discriminating between free and protein-bound forms of the NADH coenzyme, providing not only with the lifetimes of the both states (shorter τ₁ and longer τ₂), but also with the relative concentrations of both (fractions a₁ and a₂ correspondingly). Given the role of NADH in cellular energetics, NADH FLIM has been applied for the noninvasive characterization of metabolic changes in a range of pathologies. However, for the discrimination of pathological states, a proper characterization of NADH fluorescence lifetime dynamics at physiological conditions has to be conducted. We have applied FLIM NADH for the characterization of metabolic changes during cell culture growth. Our results demonstrate that during the exponential growth stage there's a well expressed trends of gradual decrease of the free/bound ratio, as measured from the center from the cell colonies. At the same time the cells at the edges of a colony exhibit higher values of the ratio. Several possible reasons for the phenomena observed are discussed.

We propose a simple highly nonlinear photonic crystal fiber in optical coherence tomography window. Based on the finite difference method, different properties of highly nonlinear photonic crystal fibers are calculated. It is demonstrated that the nonlinear coefficients more than 64 and 55 [Wkm]^-1 at 1.06 μm and 1.31 μm, respectively, with flattened chromatic dispersion of 0 ± 3.7 ps/(nm.km) and low confinement losses less than 10^-9 dB/m, simultaneously. It is also shown that small chromatic dispersion value and nearly zero dispersion slop provide the possibility of efficient supercontinuum generation in the optical coherence tomography window using a few ps pulses.

We report on the thickness resolution of a localized surface plasmon microscope in the observation of lipid bilayers. We calculated plots of the effective refractive index as a function of bilayer thickness. On the basis of measured effective refractive indices, we theoretically determined the resolution to be less than 1 nm.

In the field of biomedical optics, many approaches need to process tremendous data set using complicated algorithms, which cause heavy computation and limit their applications in the real-time conditions, such as clinical diagnoses and therapy. In this paper, we present and review several successful applications using GPU (graphic processing unit) to accelerate the processing of biomedical optics data including image processing, Monte Carlo simulation, image reconstruction and statistics analysis. It is shown that GPU are proved to obtain significant performance improvement in contrast with the traditional used methods based on CPU calculation.

We report coherent anti-Stokes Raman scattering (CARS) microscopy with radially polarized (RP) excitation for facilitating longitudinally oriented molecules detection. Our finite-difference time-domain (FDTD) simulation results show that the maximum near-field RP-CARS radiation from the two longitudinally orientated nanoparticles is around 1.3 times higher than that from transversely orientated nanoparticles. Our further CARS experiments show that RP-CARS radiation from molecules oriented along the longitudinal direction is approximately 3-fold stronger than that using linearly polarized CARS technique, and the lateral resolution of RP-CARS imaging can be improved by about 10% compared to the linearly polarized CARS imaging.

In this paper, we propose and investigate a technique to deduce hemoglobin oxygen saturation (SO₂) variation image using Spectroscopic Optical Coherence Tomography (OCT). The technique is based on Morlet wavelet transformation and make use of the different absorption properties of hemoglobin (Hb) and oxyhemoglobin (HbO₂) around 800 nm. In order to test the technique, we combined three superluminescent light emitting diodes (SLED) together in a Fourier Domain Common Path OCT (FD-CP-OCT) set-up. The result using chicken embryo in vivo shows that we are able to obtain highly localized oxygen saturation variation.

The paper reports 3D in vivo endoscopic imaging enabled by integrating rapid-scanning MEMS mirrors into an optical coherence tomography (OCT) imaging probe. OCT provides high-resolution cross-sectional information suitable for in vivo noninvasive early cancer diagnosis. However, conventional OCT systems are bulky and slow, and thus are difficult to apply to internal organs where most cancers are originated. Microelectromechanical systems (MEMS) technology offers the advantages of small size and fast speed and can be used to miniaturize optical imaging probes. The MEMS mirrors have large aperture size (1 mm × 1 mm), large scan range (> ±25°) and low drive voltage (< 10 V). A 5.8mm-diameter FEB-protected MEMS-OCT has been built and 3D OCT images of live mice have been successfully acquired with a resolution of ~10μm and a frame rate of 2.5 frames per second.

In this paper the characteristics of grating structure in magnetic field measurements based on differential group delay of fiber gratings are analyzed. Theoretical simulations are realized using the coupled-mode theory and transfer matrix method. The effects of grating parameters of uniform Bragg grating on measurement range and sensitivity are analyzed. The impacts of chirped, phase-shifted and apodized gratings on DGD peak values are also monitored. FBG transmitted spectrums and DGD spectrums are recorded by means of an optical vector analyzer (OVA). Both the simulations and experiments demonstrate that the phase-shifted gratings can obviously improve the sensitivity.

The portable three-dimensional vision coordinate measuring system, which consists of a light pen, a CCD camera and a laptop computer, can be widely applied in most coordinate measuring fields especially on the industrial spots. On the light pen there are at least three point-shaped light sources (LEDs) acting as the measured control characteristic points and a touch trigger probe with a spherical stylus which is used to contact the point to be measured. The most important character of this system is that three light sources and the probe stylus are aligned in one line with known positions. In building and studying this measuring system, how to construct the system's mathematical model is the most key problem called Perspective of Three-Collinear-points Problem, which is a particular case of Perspective of Three-points Problem (P3P). On the basis of P3P and spatial analytical geometry theory, the system's mathematical model is established. What's more, it is verified that Perspective of Three-Collinear-points Problem has a unique solution. And the analytical equations of the measured point's coordinates are derived by using the system's mathematical model and the restrict condition that three light sources and the probe stylus are aligned in one line. Finally, the effectiveness of the mathematical model is confirmed by experiments.

In this paper, a new method is proposed to fabricate an optical fiber extrinsic Fabry-Perot interferometer (EFPI) as an ultrasonic sensor. An acoustic emission detecting system is constructed based on multiple EFPI sensors and demodulation circuit. Ultrasound detection experiments were done from both traditional piezoelectric transducer (PZT) and high voltage discharge. In the experiments, strong ultrasound signals were detected in both cases. The signal attenuation related to the distance and the angle between the acoustic emission source and the FP sensor are obtained. The results indicate that the receiving angle of the FP sensor is nearly 90° and the maximum detection distance in the air is more than 200cm. Furthermore, four sensors are used to locate the position of the ultrasound source produced by high voltage discharge.

A novel FBG sensing head geometry with half corroded by hydrofluoric acid and half kept intact for strain-temperature discrimination has been proposed. Utilizing different diameters of two halves of the gratings, different strain sensitivities are achieved (≈50% difference) while temperature sensitivities remain the same. The maximum experimental errors obtained were within ±5.49 με and ±1.6 °C, respectively. The design has not only realized the simultaneous measurement of temperature and strain, but also obtained the temperature insensitive measurement.

An analysis, based on mode coupled equation, is presented of polarization effects in the Sagnac interferometer sensor for distributed detection. The Sagnac distributed disturbance location sensor with polarization controller is established. With a modified demodulation method, experiment results show the system's sensitivity can be improved effectively.

A novel accelerometer based on a strain-chirped optical fiber Bragg grating (FBG) is proposed. The FBG is glued in a slanted direction onto the lateral side of a right-angled triangle cantilever beam with a mass bonded on its free end. Vertical acceleration applied to the cantilever beam leads to a uniform bending along the beam length. As a result, the FBG is chirped and its reflection bandwidth changes linearly with the applied acceleration. A high sensitivity of 0.679 nm/g has been achieved in the experiment. The experimental results of the sensor are compared with the results of a conventional accelerometer for the dynamic measurements. This sensor is temperature insensitive, owning to the temperature-independence nature of reflection bandwidth of the FBG.

A two-dimensional (2-D) inclinometer based on three optical fiber Bragg gratings (FBGs) is proposed and demonstrated. Preliminary experiments show that a high measurement sensitivity of 192 pm/° and resolution of 0.005° can be achieved and this sensor is proved to be insensitive to temperature.

The dynamic model of semiconductor fiber ring laser (SFRL) is improved by employing the distributed birefringence model of the fiber. A matrix is introduced to the laser model which is made up of a stochastic sequence with Rayleigh distribution. The framing structure characteristic of chaos waveform and the similarity of adjacent frames are observed with this improved model. It is the fiber birefringence that contributes to the framing structure of output chaos waveforms and the adjacent-frame similarity. The disturbance changed the birefringence Rayleigh distributed and then changed the Jones matrix of the fiber ring. Namely, the initial state of the chaotic system is changed. Duo to the sensitivity of a chaotic system to its initial conditions, the change brings variety in the output waveform. Therefore the adjacent-frame similarity decreases when a disturbance acts on the fiber. The disturbance in different position leads to different decrement in the degree of similarity of adjacent frames. So the validity of the cross-correlation method for detecting and locating a disturbance is confirmed by the simulation again.

We have demonstrated a coherent OTDR based on log-detector. The effect of laser linewidth and electrical filter bandwidth on coherent OTDR performance is theoretically analyzed and experimentally investigated.

In dermis, collagen and elastin are important structural proteins of extracellular maxtrix. The matrix-disorder is associated with various physiologic processes, such as localized scleroderma, anetoderma, photoaging. In this work, we demonstrate the capability of nonlinear optical microscopy in imaging structural proteins in normal and pathological human dermis.

A novel refractometric sensor based on nanofiber is presented. It is used to measure the refractive indices of glucose solutions of different concentrations. The sensor has a high sensitivity and can detect an index variation of ~10^-6. In addition, by solving Maxwell equations and numerical calculations, phase shift of nanofiber caused by index change of ambient medium is obtained. Experimental results show that the measured values are in close agreement with the theoretical values. The stability of the sensor can be applied to many fields, such as biological, chemical and pharmaceutical and process control applications.

Plasmons on the surface of large metalized holes containing analyte are excited by the fundamental mode of a microstructured fiber. Phase matching between Plasmon and core modes is facilitated by the perforation of fiber core. A comparison of Au and Ag metalized layer is illustrated. There are some differences between gold and silver layer in SPR excitation ability, strength, and sensitivity.

A new liquid refractive index sensor using double-sided polishing long-period fiber gratings (DSP-LPFG) is presented. The influence of residual cladding thickness on the sensitivity of measuring liquid refractive index is investigated. The proposed sensor response to external liquid refractive indices varying in the range of n=1.330 - 1.375 has been carried out by measuring the transmission wavelength changes. Experimental results show that well-controlled polishing parameters can significantly increase the sensitivity. The sensitivity of -143.396 nm/RIU can be obtained in this study.

The relation of beat frequency, sweep rate, optical frequency modulation excursion and length of fiber under test (FUT) based on tunable semiconductor laser is studied. Experimental results show that the frequency of beat signal will increase when the length of the FUT, optical frequency modulation excursion or sweep rate increases.

A recognition method based on the gait characteristic for walking intrusion signal is presented. The gait characteristic of a normal walker in the nature state is an average gait period of 1.2s, in which a step period is about 0.6s and a foot touchdown time is about 0.2s. When a person walks fast or runs, the step period is reduced to about 0.4s and the foot touchdown time still keeps about 0.2s. It is included in the vibration signal caused by a walking intruder inevitably. So the detection system output signal caused by a human intrusion is intermittent and periodical. If a sensing system output waveform has a period of 0.3-0.75s and a duration time of 0.15-0.25s, the disturbance source can be adjudged as a human intrusion, not as an animal or other random one. The effectiveness of the proposed method is verified by the experimental results with an in-line Sagnac interferometer fiber fence system and a φ-OTDR intrusion detection system, respectively.

We studied the electrical performance of ambipolar organic transistors based on an F₁₆CuPc/α6T pn heterojunction illuminated by a light from a white LED. As the illumination intensity is increased up to ca. 3000 Lux, the hole mobility decreases to about 1/3 while the electron mobility is only slightly increased. Photogeneration carriers (electrons) enhances n-channel operating characteristics, which results a decrease in gate voltage applied to the second active layer (or the increase in gate voltage applied in the depletion layer or the first layer), which suppresses p-channel operating characteristics although the photogeneration carriers (holes) also enhances p-channel operating characteristics. This result implies that the photoinduced charge transfer in the F₁₆CuPc/α6T pn heterojunction devices is mainly dominated by the acceptor semiconductor (F₁₆CuPc). The drain current is significantly increased (n-channel) or decreased (p-channel) by a light, which is used as an additional control parameter making the device interesting for sensor applications.