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András Gellért Barta, Csaba Sumánszki, Péter Reismann
INTRODUCTION: Patients with phenylketonuria have lower bone mineral density compared to healthy people, however, the ethiology of these alterations is not clear. Hungarian data were missing in this topic. AIM: The main aim of our study was to survey the correlation between metabolic control and change of bone mineral density in early treated Hungarian adult patients with phenylketonuria. METHOD: In this monocentric study bone mineral density of 59 adult PKU patients have been repeatedly measured in a 4-year interval using dual-energy X-ray absorptiometry...
November 2017: Orvosi Hetilap
Yuechuan Lin, Wei Jin, Fan Yang, Yanzhen Tan, Hoi Lut Ho
We report performance optimization of hollow-core photonic bandgap fiber (HC-PBF) photothermal (PT) gas sensors. The PT phase modulation efficiency of a C2H2 filled HC-PBF (HC-1550-02) is found independent of the pump modulation frequency for up to ∼330  kHz, but starts to drop quickly to 10% of the maximum value at a couple of megahertz. With a 1.1 m long HC-PBF gas cell with angle-cleaved single-mode fiber/HC-PBF joints to reduce reflection and a modified 3×3 Sagnac interferometer with balanced detection for phase demodulation, a noise equivalent concentration of ∼67  ppbC2H2 is achieved with a 1 s time constant, and it goes down to ∼18  ppb with 145 s integration time...
November 15, 2017: Optics Letters
Yun Wang, Timothy Lee, Francesco De Lucia, Muhammad I M Abdul Khudus, Pier J A Sazio, Martynas Beresna, Gilberto Brambilla
We simulate and experimentally demonstrate deep ultraviolet generation from a 1550 nm laser source in a fully fiberized system by cascading second- and third-harmonic generation using a periodically poled silica fiber and an optical sub-micron diameter fiber. Harmonic generation is achieved by harnessing intermodal phase matching in optical microfibers and a permanent χ((2)) induced via thermal poling. As a result, efficient nonlinear processes can be observed, despite the low third-order nonlinear susceptibility of silica glass...
November 15, 2017: Optics Letters
Peng Bai, Y H Zhang, W Z Shen
High performance single photon detector at the wavelength of 1550 nm has drawn wide attention and achieved vast improvement due to its significant application in quantum information, quantum key distribution, as well as cosmology. A novel infrared up-conversion single photon detector (USPD) at 1550 nm was proposed to work in free-running regime based on the InGaAs/ InP photodetector (PD)- GaAs/AlGaAs LED up-converter and Si single photon avalanche diode (SPAD). In contrast to conventional In0.53Ga0.47As SPAD, the USPD can suppress dark count rate and afterpulsing efficiently without sacrificing the photon detection efficiency (PDE)...
November 10, 2017: Scientific Reports
Samuel H Clasen, Carmen M O Müller, Alexandre L Parize, Alfredo T N Pires
Cassava starch was grafted with three different esters by the etherification reaction and its modification was characterized by (1)H NMR, FTIR, DSC, SEM, XDR, contact angle and SLS. The samples grafted with diethyl maleate, dipropyl maleate, and dibutyl maleate showed DS values of 2.3, 1.0 and 2.0, respectively, determined from (1)H NMR analysis and confirmed by FTIR analysis, with the appearance of bands at 1721, 1550 and 1126cm(-1). The FTIR, XRD, SEM and DSC results indicated a change in the intra and intermolecular hydrogen interactions in the grafted starch when compared to native starch...
January 15, 2018: Carbohydrate Polymers
Maria Kyriakidou, Jane Anastassopoulou, Aristeidis Tsakiris, Maria Koui, Theophile Theophanides
BACKGROUND/AIM: Mid-infrared spectroscopy (4000-500 cm(-1)) was used to analyze the spectral changes and differences of the characteristic absorption bands of the skin components due to cancer development for early clinical diagnosis. MATERIALS AND METHODS: Human biopsies from basal cell carcinoma, malignant melanoma, and nevus were used, while normal skin tissue served as a control. RESULTS: The high quality of Fourier-transform infrared (FT-IR) spectra showed that upon cancer development the intensity of the absorption band at approximately 3062 cm(-1) was increased, indicating that most of the proteins had the configuration of amide B and the β-sheet protein structure predominated...
November 2017: In Vivo
O Eyal, A Willinger, S Banyoudeh, F Schanbel, V Sichkovskyi, V Mikhelashvili, J P Reithmaier, G Eisenstein
We report on high quality InAs/InP quantum dot optical amplifiers for the 1550 nm wavelength range operating over a wide temperature range of 25 to 100 °C. A temperature dependent shift of the peak gain wavelength at a rate of 0.78 nm/K is observed. Consequently, two possible modes of operation are performed for a systematic device characterization over the entire temperature range. In the first mode, the signal wavelength is tuned to always match the peak gain wavelength while in the second mode, the signal wavelength is kept constant as the gain spectrum shifts with the temperature...
October 30, 2017: Optics Express
Ramin Djabery, Mohammad Naser-Moghaddasi, Alireza Andalib
In this paper, a polarization modulator is proposed, based on surface plasmons in a 1550 nm window. Following the generalized Snell's law, the meta-surface for converting an incident propagating wave to a surface wave is carefully designed with nearly 84% efficiency. Moreover, the coupling ratio for TE and TM polarization of the incident wave is calculated. Furthermore, the LiNbO3 structure is used as a polarizer. Finally, the calculations are verified by employing the rigorous numerical finite-difference time-domain simulation method, and the results are found to be in excellent agreement...
November 1, 2017: Applied Optics
Fengqiang Li, Joshua Yablon, Andreas Velten, Mohit Gupta, Oliver Cossairt
Lasers and laser diodes are widely used as illumination sources for optical imaging techniques. Time-of-flight (ToF) cameras with laser diodes and range imaging based on optical interferometry systems using lasers are among these techniques, with various applications in fields such as metrology and machine vision. ToF cameras can have imaging ranges of several meters, but offer only centimeter-level depth resolution. On the other hand, range imaging based on optical interferometry has depth resolution on the micrometer and even nanometer scale, but offers very limited (sub-millimeter) imaging ranges...
November 1, 2017: Applied Optics
E Rajendra Reddy, S Thabitha Rani, M Manjula, L Vinay Kumar, T Ajay Mohan, E Radhika
BACKGROUND: Detection and evaluation of dental caries is of epidemiological importance. Its early detection is important to commence appropriate treatment planning. Cavitated, noncavitated, and initial lesions of dental caries can be detected by various indices. OBJECTIVES: The objective of the study was to assess the caries experience in schoolchildren using decayed-missing-filled teeth (DMFT)/decayed-extracted-filled teeth (deft), International Caries Detection and Assessment System-II (ICDAS-II), and Caries Assessment Spectrum and Treatment (CAST) systems...
September 2017: Indian Journal of Dental Research: Official Publication of Indian Society for Dental Research
Elisa F Carneiro, Felipe Calliari, Gustavo C Amaral, Guilherme P Temporão
We theoretically propose and experimentally validate a practical random bit generation method based on the detections of a coherent state in the few-photon regime by a gated single-photon threshold detector, operating at the telecom wavelength of 1550 nanometers. By fine tuning the mean number of photons per pulse of a laser beam directed to the single-photon detector, a 50-50 chance of detection or no-detection is reached; under this condition, detections inside the gate window are treated as "1"s, while "0"s are associated with the absence of detections...
August 20, 2017: Applied Optics
Animesh Bala, Kanan Roy Chowdhury, Md Borhan Mia, Mohammad Faisal
A triangular lattice dispersion compensating photonic crystal fiber is presented in this paper. The fiber produces high birefringence and operates at fundamental mode only. The full vector finite element method with a perfectly matched absorbing layer boundary condition is applied to investigate the guiding properties of the proposed fiber. The designed fiber demonstrates that it is possible to obtain a very large negative dispersion of -9486.1  ps/(nm·km) at 1550 nm wavelength with a negative dispersion more than -7000  ps/(nm·km) over the entire C-band (1530-1565 nm), which is suitable for broadband dispersion compensation...
September 1, 2017: Applied Optics
Donghai Niu, Shiqi Sun, Qiang Xu, Minghui Jiang, Xibin Wang, Zhiyong Li, Changming Chen, Yuanda Wu, Daming Zhang
In this paper, the power-consumption characteristics of a polymeric thermo-optic (TO) switch consisting of a silica under-cladding on silicon substrate, a polymer core surrounded with polymer upper-cladding, and aluminum heating electrodes with different widths were investigated. Norland optical adhesive 73 with a larger TO coefficient was selected as the core layer, which could reduce the power consumption effectively. The silica under-cladding, with large thermal conductivity, could shorten the response time...
July 20, 2017: Applied Optics
Mehdi Hassani Keleshtery, Hassan Kaatuzian, Ali Mir, Ashkan Zandi
We demonstrate the analogue of electromagnetically induced transparency (EIT) in a metal-dielectric-metal (MDM) plasmonic waveguide. Plasmonic induced transparency is a method similar to EIT. In this paper, a plasmonic MDM waveguide is proposed by using an ellipse shaped side-coupled ring resonator and simulated by finite difference time domain. Plasmonics as a new field of chip-scale technology is an interesting substrate, which is used to propose and numerically investigate a novel MDM structure. The aforementioned framework is a 2×2 plasmonic ring resonator, employing gold as a metal and polymethyl methacrylate as a dielectric...
May 20, 2017: Applied Optics
Michael C Brupbacher, Dajie Zhang, William M Buchta, Marc B Airola, David M Brown, Michael E Thomas, James B Spicer
This study presents results for the high-temperature (up to 1550 K) optical properties of polycrystalline Cr-doped α-alumina materials. Diffuse reflectance spectra in the wavelength range of 510-840 nm are presented as a function of temperature to illustrate changes to the optical behavior of these materials including a previously unreported thermally activated splitting of the U-band absorption (A24→T24) in octahedrally coordinated Cr(3+). Measurements were made using a unique laser-based approach for high-temperature solid-state spectroscopy, involving front-side supercontinuum laser illumination and back-side CO2 laser heating...
September 20, 2017: Applied Optics
S Bhardwaj, K Mittholiya, A Bhatnagar, R Bernard, J A Dharmadhikari, D Mathur, A K Dharmadhikari
We describe two types of waveguides (type I and depressed cladding) inscribed in lithium niobate using a variable repetition rate (200 kHz-25 MHz), 270 fs duration fiber laser. The type I modification-based waveguides have propagation losses in the range from 1.2 to 10 dB/cm at 1550 nm, depending on experimental parameters. These waveguides are not permanent; they deteriorate over time. Such deterioration of waveguides can be slowed down from 30 days to 100 days by pre-annealing the samples and by writing at a 720 kHz laser repetition rate...
July 10, 2017: Applied Optics
Wanwan Liu, Yifu Chen, Xin Hu, Long Wen, Lin Jin, Qiang Su, Qin Chen
Non-metallic plasmonic materials have recently attracted research interest due to their adjustable plasmonic material properties and the potential low loss, which is important to plasmonic waveguides with ultrahigh mode confinement. In this paper, we analyzed the mode properties of four types of plasmonic waveguides based on noble metals, aluminum-zinc-oxide (AZO), and TiN, where the propagation length and mode size are chosen to compare the figures of merit. It is found that AZO has the smallest imaginary part of permittivity in the near-infrared region, while AZO waveguides have propagation lengths comparable to those of Cu waveguides but shorter than those of Au and Ag waveguides...
June 1, 2017: Applied Optics
Konstantin Gorbachenya, Viktor Kisel, Anatoly Yasukevich, Pavel Loiko, Xavier Mateos, Viktor Maltsev, Nikolai Leonyuk, Magdalena Aguiló, Francesc Díaz, Uwe Griebner, Valentin Petrov, Nikolai Kuleshov
A single-layer graphene saturable absorber is employed for passive Q-switching of an Er, Yb:GdAl3(BO3)4 (Er,Yb:GdAB) compact laser, representing the first Er-doped oxoborate laser Q-switched by graphene. This laser is based on a c-cut 1.8 at. % Er(3+), 15 at. % Yb(3+):GdAB crystal diode-pumped at 0.976 μm. It generates a maximum average output power of 360 mW at 1.55 μm with a slope efficiency of 23% (with respect to the incident power). Stable ∼1  μJ/130  ns pulses are achieved at a repetition rate of 400 kHz...
June 1, 2017: Applied Optics
Xiaobo Hu, Juanjuan Xue, Jiao Tian, Guoen Weng, Shaoqiang Chen
The effect of the Cu/Ga ratio on properties of deep-level defects in CuGaSe2 thin films were studied, using photocapacitance methods with two-wavelength excitation. The transient photocapacitance method, using a monochromatic probe light, determined two kinds of defects located at 0.8 eV and 1.5 eV above the valence band, respectively, the positions of which kept almost constant regardless of Cu/Ga ratio. In addition to the probe light, laser light with a wavelength of 1550 nm corresponding to 0.8 eV was then used to study the saturation effect of the deep-level defect at 0...
May 10, 2017: Applied Optics
Chia-Ti Wu, Chia-Chih Huang, Yeun-Chung Lee
In this paper, we propose a novel wavelength demultiplexer based on metal-insulator-metal plasmonic waveguides with a nanoscale ring resonator. Its transmission characteristics are numerically studied using finite element method (FEM) simulations, and the eigenwavelengths of the ring resonator are theoretically calculated. For the proposed structure, we found that the ratio of the orders of resonant transmittance peaks for two different high-order modes of the ring resonator is close to the ratio of the two communication wavelengths 1310 and 1550 nm...
May 10, 2017: Applied Optics
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