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Optics Express

Tobias Fobbe, Sergej Markmann, Felix Fobbe, Negar Hekmat, Hanond Nong, Shovon Pal, Patrick Balzerwoski, Janne Savolainen, Martina Havenith, Andreas D Wieck, Nathan Jukam
Dispersion control is a key objective in the field of photonics and spectroscopy, since it enhances non-linear effects by both enabling phase matching and offering slow light generation. In addition, it is essential for frequency comb generation, which requires a phase-lock mechanism that is provided by broadband compensation of group velocity dispersion (GVD). At optical frequencies, there are several well-established concepts for dispersion control such as prism or grating pairs. However, terahertz dispersion control is still a challenge, thus hindering further progress in the field of terahertz science and technology...
September 19, 2016: Optics Express
H F Martins, K Shi, B C Thomsen, S Martin-Lopez, M Gonzalez-Herraez, S J Savory
A major cause of faults in optical communication links is related to unintentional third party intrusions (normally related to civil/agricultural works) causing fiber breaks or cable damage. These intrusions could be anticipated and avoided by monitoring the dynamic strain recorded along the cable. In this work, a novel technique is proposed to implement real-time distributed strain sensing in parallel with an operating optical communication channel. The technique relies on monitoring the Rayleigh backscattered light from optical communication data transmitted using standard modulation formats...
September 19, 2016: Optics Express
Joachim Krauth, Tobias Steinle, Bowen Liu, Moritz Floess, Heiko Linnenbank, Andy Steinmann, Harald Giessen
We introduce a broadly tunable robust source for fingerprint (170 - 1620 cm<sup>-1</sup>) Raman spectroscopy. A cw thulium-doped fiber laser seeds an optical parametric amplifier, which is pumped by a 7-W, 450-fs Yb:KGW bulk mode-locked oscillator with 41 MHz repetition rate. The output radiation is frequency doubled in a MgO:PPLN crystal and generates 0.7 - 1.3-ps-long narrowband pump pulses that are tunable between 885 and 1015 nm with >80 mW average power. The Stokes beam is delivered by a part of the oscillator output, which is sent through an etalon to create pulses with 1...
September 19, 2016: Optics Express
Jokhakar Jignesh, Bill Corcoran, Chen Zhu, Arthur Lowery
Simultaneous polarization and phase noise tracking and compensation is proposed based on an unscented Kalman filter (UKF). We experimentally demonstrate the tracking under noise-loading and after 800-km single-mode fiber transmission with 20-Gbaud QPSK and 16-QAM signals. These experiments show that the proposed UKF outperforms both conventional blind tracing algorithms and a previously proposed extended Kalman filter, at the cost of higher complexity. Additionally, we propose and test modified Kalman filter algorithms to reduce computational complexity...
September 19, 2016: Optics Express
W J Yu, H Sun, L Gao
We propose a mechanism to actively tune optical bistable behavior with the external magnetic field in nonlinear coated nanospheres with a magneto-optical (MO) shell and nonlinear metallic core. We show that such nanostructures can exhibit typical bistable phenomena near surface plasmon resonant wavelengths, which can be modified through the external magnetic fields B. We demonstrate numerically that the optical bistability exists only when the volume fraction η of the metallic core is larger than a critical one η<sub>c</sub>...
September 19, 2016: Optics Express
Kirilas Michailovas, Andrius Baltuska, Audrius Pugzlys, Valerijus Smilgevicius, Andrejus Michailovas, Audrius Zaukevicius, Rokas Danilevicius, Saulius Frankinas, Nerijus Rusteika
We report on the developed front-end/pump system for optical parametric chirped pulse amplifiers. The system is based on a dual output fiber oscillator/power amplifier which seeds and assures all-optical synchronization of femtosecond Yb and picosecond Nd laser amplifiers operating at a central wavelength of 1030 nm and 1064 nm, respectively. At the central wavelength of 1030 nm, the fiber oscillator generates partially stretched 4 ps pulses with the spectrum supporting a <120 fs pulse duration and pulse energy of 0...
September 19, 2016: Optics Express
Benjamin Kambs, Jan Kettler, Matthias Bock, Jonas Nils Becker, Carsten Arend, Andreas Lenhard, Simone Luca Portalupi, Michael Jetter, Peter Michler, Christoph Becher
We present experimental results on quantum frequency down-conversion of indistinguishable single photons emitted by an InAs/GaAs quantum dot at 904 nm to the telecom C-band at 1557 nm. Hong-Ou-Mandel (HOM) interference measurements are shown prior to and after the down-conversion step. We perform Monte-Carlo simulations of the HOM experiments taking into account the time delays of the different interferometers used and the signal-to-background ratio and further estimate the impact of spectral diffusion on the degree of indistinguishability...
September 19, 2016: Optics Express
Jing Gao, Hui Wu
We present a multi-function electronic-photonic integrated circuit (EPIC) design which exploits a new operation mode of a Mach-Zehnder modulator (MZM). Different from the conventional design, the two arms of the modulator are driven by time-shifted signals of tunable amplitude. We study its operation in the linear and quadratic regions where the MZM is biased at π/2 and π initial phase difference, respectively. In the linear region, the modulator sums the waveforms of the driving signals in the two arms, which can be used to add pre-emphasis function to the modulator, and hence it obviates an electrical pre-emphasis driver...
September 19, 2016: Optics Express
Peng Shao, Sebastien Besner, Jitao Zhang, Giuliano Scarcelli, Seok-Hyun Yun
Brillouin imaging of turbid biological tissues requires an effective rejection of the background noise due to elastic scattering of probe laser light. We have developed a narrowband spectral notch filter based on a pair of a free-space Fabry-Perot etalon and a mirror. The etalon filter in a 4-pass configuration is able to suppress elastically-scattered laser light with a high extinction ratio of > 40 dB and transmit inelastically-scattered light in a frequency shift range of 2-14 GHz with only 2 dB insertion loss...
September 19, 2016: Optics Express
Yin Huang, Changjun Min, Georgios Veronis
We introduce broadband waveguide absorbers with near unity absorption. More specifically, we propose a compact non-parity-time-symmetric perfect absorber unit cell, consisting of two metal-dielectric-metal (MDM) stub resonators with unbalanced gain and loss side-coupled to a MDM waveguide, based on unidirectional reflectionlessness at exceptional points. With proper design, light can transport through the perfect absorber unit cell with reflection close to zero in a broad wavelength range. By cascading multiple unit cell structures, the overall absorption spectra are essentially the superposition of the absorption spectra of the individual perfect absorber unit cells, and absorption of ~ 100% is supported in a wide range of frequencies...
September 19, 2016: Optics Express
B Wang, C Cojocaru, W Krolikowski, Y Sheng, J Trull
We present a novel single-shot cross-correlation technique based on the analysis of the transversally emitted second harmonic generation in crystals with random distribution and size of anti-parallel nonlinear domains. We implement it to the measurement of ultrashort laser pulses with unknown temporal duration and shape. We optimize the error of the pulse measurement by controlling the incident angle and beam width. As novelty and unlike the other well-known cross correlation schemes, this technique can be implemented for the temporal characterization of pulses over a very wide dynamic range (30 fs-1ps) and wavelengths (800-2200 nm), using the same crystal and without critical angular or temperature alignment...
September 19, 2016: Optics Express
Andreas Karsaklian Dal Bosco, Yasuhiro Akizawa, Kazutaka Kanno, Atsushi Uchida, Takahisa Harayama, Kazuyuki Yoshimura
We experimentally investigate an intermittent route to chaos in a photonic integrated circuit consisting of a semiconductor laser with time-delayed optical feedback from a short external cavity. The transition from a period-doubling dynamics to a fully-developed chaos reveals a stage intermittently exhibiting these two dynamics. We unveil the bifurcation mechanism underlying this route to chaos by using the Lang-Kobayashi model and demonstrate that the process is based on a phenomenon of attractor expansion initiated by a particular distribution of the local Lyapunov exponents...
September 19, 2016: Optics Express
T L Huang, C L Sung, H P Cheng, C Y Cho, H C Liang, K W Su, K F Huang, Y F Chen
A dual-wavelength self-mode-locked monolithic Nd:YAG laser at 1061 and 1064 nm is realized at cryogenic temperatures. At an incident pump power of 5.5 W, the total output power can reach 2.5 W and the mode-locked pulse width is 29 ps at a pulse repetition rate of 7.75 GHz. The synchronization of the dual-wavelength emissions leads to a beat frequency of 670 GHz in the individual mode-locked pulse. It is further discovered that the laser output consists of two orthogonally polarized components with a central frequency difference of 127 MHz...
September 19, 2016: Optics Express
Miha Čančula, Miha Ravnik, Igor Muševič, Slobodan Žumer
We demonstrate polarization-selective microlensing and waveguiding of laser beams by birefringent profiles in bulk nematic fluids using numerical modelling. Specifically, we show that radial escaped nematic director profiles with negative birefringence focus and guide light with radial polarization, whereas the opposite - azimuthal - polarization passes through unaffected. A converging lens is realized in a nematic with negative birefringence, and a diverging lens in a positive birefringence material. Tuning of such single-liquid lenses by an external low-frequency electric field and by adjusting the profile and intensity of the beam itself is demonstrated, combining external control with intrinsic self-adaptive focusing...
September 19, 2016: Optics Express
Jian Li, Jin Tao, Zan Hui Chen, Xu Guang Huang
We give the effective refractive index of graphene plasmonic waveguides with both linear and nonlinear effects based on the nonlinear cross-phase modulation, and address the effects of photo-induced refractive index change and absorption change. A non-resonant all-optical nonlinear graphene plasmonic switch with an ultra-compact size of 0.25 μm<sup>2</sup> is proposed and numerically analyzed based on the dynamics of the photo-induced absorption change. The results show that the all-optical graphene plasmonic switch can realize a broad bandwidth over 5 THz, a potentially very high switching speed and an extinction ratio of 18...
September 19, 2016: Optics Express
Haize Bao, Wansu Bao, Yang Wang, Ruike Chen, Chun Zhou, Musheng Jiang, Hongwei Li
The decoy-state high-dimensional quantum key distribution provides a practical secure way to share more private information with high photon-information efficiency. In this paper, based on detector-decoy method, we propose a detector-decoy high-dimensional quantum key distribution protocol. Employing threshold detectors and a variable attenuator, we can promise the security under Gsussian collective attacks with much simpler operations in practical implementation. By numerical evaluation, we show that without varying the source intensity, our protocol performs much better than one-decoy-state protocol and as well as the two-decoy-state protocol in the infinite-size regime...
September 19, 2016: Optics Express
Veerendra Kalyan Jagannadh, Mark D Mackenzie, Parama Pal, Ajoy K Kar, Sai Siva Gorthi
Three-dimensional cellular imaging techniques have become indispensable tools in biological research and medical diagnostics. Conventional 3D imaging approaches employ focal stack collection to image different planes of the cell. In this work, we present the design and fabrication of a slanted channel microfluidic chip for 3D fluorescence imaging of cells in flow. The approach employs slanted microfluidic channels fabricated in glass using ultrafast laser inscription. The slanted nature of the microfluidic channels ensures that samples come into and go out of focus, as they pass through the microscope imaging field of view...
September 19, 2016: Optics Express
Olga Rodenko, Henrik Fodgaard, Peter Tidemand-Lichtenberg, Paul Michael Petersen, Christian Pedersen
We report on the design, development and investigation of an optical system based on UV light emitting diode (LED) excitation at 340 nm for time-resolved fluorescence detection of immunoassays. The system was tested to measure cardiac marker Troponin I with a concentration of 200 ng/L in immunoassay. The signal-to-noise ratio was comparable to state-of-the-art Xenon flash lamp based unit with equal excitation energy and without overdriving the LED. We performed a comparative study of the flash lamp and the LED based system and discussed temporal, spatial, and spectral features of the LED excitation for time-resolved fluorimetry...
September 19, 2016: Optics Express
Ronny Förster, Kai Wicker, Walter Müller, Aurélie Jost, Rainer Heintzmann
The reconstruction process of structured illumination microscopy (SIM) creates substantial artefacts if the specimen has moved during the acquisition. This reduces the applicability of SIM for live cell imaging, because these artefacts cannot always be recognized as such in the final image. A movement is not necessarily visible in the raw data, due to the varying excitation patterns and the photon noise. We present a method to detect motion by extracting and comparing two independent 3D wide-field images out of the standard SIM raw data without needing additional images...
September 19, 2016: Optics Express
Sukmock Lee, Heejoo Choi, Dae Wook Kim
The use of the discrete Fourier transform has decreased since the introduction of the fast Fourier transform (fFT), which is a numerically efficient computing process. This paper presents the iterative local Fourier transform (ilFT), a set of new processing algorithms that iteratively apply the discrete Fourier transform within a local and optimal frequency domain. The new technique achieves 2<sup>10</sup> times higher frequency resolution than the fFT within a comparable computation time. The method's superb computing efficiency, high resolution, spectrum zoom-in capability, and overall performance are evaluated and compared to other advanced high-resolution Fourier transform techniques, such as the fFT combined with several fitting methods...
September 19, 2016: Optics Express
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