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Optics Letters

Takahiro Tanaka, Masahiro Kato, Norio Saito, Shigeki Owada, Kensuke Tono, Makina Yabashi, Tetsuya Ishikawa
A reliable diagnostic device for free-electron lasers (FELs) is essential for both users and the evaluation of FEL sources and beamline optics. Here, we propose a compact bolometric radiometer (CBR) that can operate at room temperature. The CBR is mainly designed for FELs in the wavelength range from the extreme-ultraviolet (EUV) to x-rays; moreover, we confirmed that the proposed device can also be applied to synchrotron radiation. As an application of the CBR, we evaluated an FEL beamline transmission by means of bolometric technique in the EUV range for the first time, to the best of our knowledge...
November 15, 2017: Optics Letters
Daryl Preece, Halina Rubinsztein-Dunlop
We develop a basis for three-dimensional rotation of arbitrary light fields created by computer generated holograms. By adding an extra phase function into the kinoform, any light field or holographic image can be tilted in the focal plane with minimized distortion. We present two different approaches to rotate an arbitrary hologram: the Scheimpflug method and a novel coordinate transformation method. Experimental results are presented to demonstrate the validity of both proposed methods.
November 15, 2017: Optics Letters
Yung-Jr Hung, Ya-Ching Liang, Chia-Wei Huang, Jyun-Fu Shih, Shih Hu, Tzu-Hsiang Yen, Chia-Wei Kao, Chun-Hu Chen
Graphene oxide (GO) ultrathin film can be wafer-scale deposited by spin coating, can be patterned by laser interference lithography and oxygen plasma etching, can be thinned atomically (0.26 nm/min) and oxidized by ozone treatment, and is a relatively transparent and low-refractive-index material compared to pristine graphene. All those unique properties prompt us to realize a low-loss (∼5  dB/cm), high-extinction-ratio (19 dB), and narrowband (0.425 nm) GO/silicon hybrid waveguide Bragg reflector by transferring 7-nm-thick GO gratings (n=1...
November 15, 2017: Optics Letters
Andrey B Matsko, Lute Maleki
We show theoretically that dynamic behavior of light confined in the modes of a nonlinear optical ring cavity characterized by resonant Rayleigh scattering can be described using the Bose-Hubbard model. Nonlinear interaction between clockwise and counterclockwise optical modes results in instability and intermode hopping occurring at a rate defined by the frequency separation of the Rayleigh doublet harmonics. Hopping may lead to an instability and breathing behavior of a Kerr frequency comb observed in the cavity...
November 15, 2017: Optics Letters
Matthieu Dubreuil, Sylvain Rivet, Yann Le Grand
A new high-speed second-harmonic generation (SHG) polarimetric method is reported. It is based on the spectral analysis of the SHG radiation emitted by a nonlinear medium excited with circularly polarized femtosecond laser pulses. The setup uses only passive components for polarization encoding and a fast spectrometer for spectral analysis. The method is validated on a z-cut quartz plate, then on a collagen-rich biological tissue with a view to single image polarization-resolved SHG microscopy.
November 15, 2017: Optics Letters
Suruj S Deka, Si Hui Pan, Qing Gu, Yeshaiahu Fainman, Abdelkrim El Amili
To achieve high packing density in on-chip photonic integrated circuits, subwavelength scale nanolasers that can operate without crosstalk are essential components. Metallo-dielectric nanolasers are especially suited for this type of dense integration due to their lower Joule loss and nanoscale dimensions. Although coupling between optical cavities when placed in proximity to one another has been widely reported, whether the phenomenon is induced for metal-clad cavities has not been investigated thus far. We demonstrate coupling between two metallo-dielectric nanolasers by reducing the separation between the two cavities...
November 15, 2017: Optics Letters
Qitian Ru, Zachary E Loparo, XiaoSheng Zhang, Sean Crystal, Subith Vasu, Peter G Schunemann, Konstantin L Vodopyanov
We report an octave-wide mid-IR spectrum (2.3-4.8 μm) obtained from a subharmonic optical parametric oscillator (OPO) based on a newly developed nonlinear crystal, orientation-patterned gallium phosphide (OP-GaP), which was synchronously pumped by a femtosecond 1560 nm fiber laser. We proved that the octave-wide output is in the form of a single frequency comb. The observed f-to-2f frequency beats, originating directly from the OPO, can be used for self-referencing and phase locking of the pump laser comb with no need for supercontinuum generation...
November 15, 2017: Optics Letters
Bowen Bai, Lu Liu, Zhiping Zhou
A polarization beam splitter-rotator based on asymmetric directional coupling is proposed. An ultrashort cross-polarization coupling length of 7.7 μm is achieved by manipulating the optical field distribution via the plasmonic effect, which is the shortest one reported so far, to the best of our knowledge. At the wavelength of 1.55 μm, the extinction ratios are as high as 50.9 dB and 28.2 dB for fundamental transverse magnetic (TM0) and transverse electric (TE0) polarizations, respectively, and the corresponding insertion losses are 1...
November 15, 2017: Optics Letters
Avishay Shamir, Aviran Halstuch, Yonatan Sivan, Amiel A Ishaaya
We demonstrate, for the first time to our knowledge, fast all-optical switching in standard silica fibers, based on a transient Bragg grating. The grating is implemented in the fiber using an immunization photo-pretreatment process, followed by side illumination with femtosecond laser pulses through a suitable phase mask. Each pulse is nonlinearly absorbed, creating a thermal grating that is washed out by thermal diffusion. Reflections measured from such gratings are characterized by a very fast rise time, nanoseconds duration, and a high extinction ratio...
November 15, 2017: Optics Letters
Michael Maria, Ivan Bravo Gonzalo, Thomas Feuchter, Mark Denninger, Peter M Moselund, Lasse Leick, Ole Bang, Adrian Podoleanu
In this Letter, we investigate the possibility of using a commercially available Q-switch-pumped supercontinuum (QS-SC) source, operating in the kilohertz regime, for ultra-high resolution optical coherence tomography (UHR-OCT) in the 1300 nm region. The QS-SC source proves to be more intrinsically stable from pulse to pulse than a mode-locked-based SC (ML-SC) source while, at the same time, is less expensive. However, its pumping rate is lower than that used in ML-SC sources. Therefore, we investigate here specific conditions to make such a source usable for OCT...
November 15, 2017: Optics Letters
Razvigor Ossikovski, Oriol Arteaga, Sang Hyuk Yoo, Enric Garcia-Caurel, Kurt Hingerl
We demonstrate experimentally the validity of the partial spatial coherence formalism in Mueller polarimetry and show that, in a finite spatial resolution experiment, the measured response is obtained through convolving the theoretical one with the instrument function. The reported results are of primary importance for Mueller imaging systems.
November 15, 2017: Optics Letters
Wei Liang, Anatoliy Savchenkov, Vladimir Ilchenko, Robert Griffith, Edwin De Cuir, Steven Kim, Andrey Matsko, Lute Maleki
We report on an accurate measurement of the frequency splitting of an optical rotating ring microcavity made out of calcium fluoride. By measuring the frequencies of the clockwise and counter-clockwise coherent Raman emissions confined in the cavity modes, we show that the frequency splitting is inversely proportional to the refractive index of the cavity host material. The measurement has an accuracy of 1% and unambiguously confirms the classical theoretical prediction based on special theory of relativity...
November 15, 2017: Optics Letters
Yun-Han Lee, Tao Zhan, Shin-Tson Wu
We report an electro-optic image shifter to enhance the resolution of display devices with a Pancharatnam-Berry phase deflector (PBD). The switching time of our PBD is less than 1 ms. Through synchronizing and computational factorization, we are able to double the display resolution for reducing the screen door effect. Such a thin and lightweight PBD image shifter can be easily integrated into wearable display devices. Its potential application for virtual reality and augmented reality is emphasized.
November 15, 2017: Optics Letters
Dmitry V Petrov, Alexey R Zaripov, Nikita A Toropov
The Letter demonstrates a possibility to enhance the Raman scattering of a gaseous medium due to an enhanced electromagnetic field caused by the excitation of propagating surface plasmon polaritons (PSPPs) on a silver holographic grating. Efficiency of collinear and noncollinear schemes of PSPP excitation on a metal-gaseous medium interface was studied. When using a collinear scheme, we registered an eightfold enhancement of the Raman scattering of atmospheric nitrogen and oxygen, where the average gain near the PSPP-active surface was ∼4×10(3)...
November 15, 2017: Optics Letters
Sina Saravi, Alexander N Poddubny, Thomas Pertsch, Frank Setzpfandt, Andrey A Sukhorukov
We propose the concept of atom-mediated spontaneous parametric down-conversion, in which photon-pair generation can take place only in the presence of a single two-level emitter, relying on the bandgap evanescent modes of a nonlinear periodic waveguide. Using a guided signal mode, an evanescent idler mode, and an atom-like emitter with the idler's transition frequency embedded in the structure, we find a heralded excitation mechanism, in which the detection of a signal photon outside the structure heralds the excitation of the embedded emitter...
November 15, 2017: Optics Letters
Nickolai Zhavoronkov, Mikhail Ivanov
Attosecond (1  as=10(-18)  s) pulses produced through high harmonic generation (HHG) are a basis for studies of electron dynamics during light-matter interaction on an electron's natural time scale. Extensively exploited HHG technology has, however, a few unsolved problems, where producing of circularly polarized or chiral attosecond pulses belongs to them. We have demonstrated experimentally a way to control the ellipticity of attosecond pulse trains produced via HHG in two-color, bi-circular laser fields...
November 15, 2017: Optics Letters
Yi Zhou, Rui Chen, Yungui Ma
We propose an off-axis meta-lens-based optical wavelength demultiplexer. The performance of the device initially proposed with four output channels (1527-1596 nm, channel spacing 23 nm) composed of an optical fiber array is analyzed by both scalar diffraction theory and ray tracing method. The results show that the fiber energy coupling efficiency of the demultiplexer could be larger than 89% and the channel bandwidth is about 9 nm. Influences of the two key parameters, focal length f and off-axis angle α, are also investigated...
November 15, 2017: Optics Letters
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
Yunhe Zhao, Yunqi Liu, Chenyi Zhang, Liang Zhang, Guangjun Zheng, Chengbo Mou, Jianxiang Wen, Tingyun Wang
We investigated an all-fiber mode converter based on long-period fiber gratings (LPFGs) written in the few-mode fiber. Mode conversion between the fundamental core mode and different higher-order core modes (LP11, LP21, and LP02 modes) can be realized via a single LPFG with an efficiency of 99% at the resonance wavelength. Moreover, optimized mode conversion between the LP01 and LP21 modes can be realized by cascading two LPFGs with different grating pitches. The maximum conversion efficiency is estimated to be ∼99...
November 15, 2017: Optics Letters
Jie Liu, Chaoran Huang, Chester Shu
In our previous work [Opt. Lett.42, 3852 (2017)OPLEDP0146-959210.1364/OL.42.003852], there is an error in Fig. 1. That error is addressed here.
November 15, 2017: Optics Letters
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