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APPLICATIONS-CENTERED RESEARCH IN OPTICS

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March


Image-based Displacement and Rotation Detection using Scale Invariant Features for 6 Degree of Freedom ICF Target Positioning

  • chen fengdong, Liu guodong, Zhiwei Lu, bin feng, yong xiang, and Liu Bingguo
  • received 11/27/2014; accepted 03/23/2015; posted 03/24/2015; Doc. ID 225420
  • [full text: PDF (1181) KB)]
  • Abstract: A precise online ending supervision for target positioning is required in ICF experiments. Conventional visual measuring methods mainly rely on edge information which may sensitive to illumination and target attitude and often need judgment of human being. This paper presents a 6-degree of freedom ICF target displacement and rotation detection method using scale invariant feature transform (SIFT) algorithm. SIFT algorithm can extract and describe image key-points, which are localized to sub-pixel accuracy and can perform reliable matching between different views of an object. For testing the accuracy offline, the displacement is driven by an electromotor on a calibrated optical grating-vision measuring platform. When the platform moving along its x axis, the images of each step are captured with corresponding grating sensor values recorded. Offline experimental results prove that the different values between image SIFT points and grating sensor are less than 1μm (1/10 pixel). In online condition, a 6-degree of freedom precise parallel robot subsystem is used as ending driver, and a target alignment sensor(TAS) is used to capture four orthogonal images of the target. The feedback information is got by SIFT features. Thinking to the excellent matching ability and 1/10 sub-pixel localization accuracy of the SITF features, the proposed method can online detect the displacement and rotation of target accurately and reliably. The experimental results demonstrate the effectiveness of the proposed method.

Keywords (OCIS):

  • (110.0110) Imaging systems : Imaging systems
  • (330.4150) Vision, color, and visual optics : Motion detection
  • (150.1488) Machine vision : Calibration
  • (100.4999) Image processing : Pattern recognition, target tracking

Characterization of a broadband polarization rotator for silicon-based cross-slot waveguides

  • Jinbiao Xiao, Jiayuan Wang, and Xiaohan Sun
  • received 01/22/2015; accepted 03/23/2015; posted 03/23/2015; Doc. ID 232639
  • [full text: PDF (1004) KB)]
  • Abstract: A silicon-based polarization rotator (PR) for cross-slot waveguides is proposed and characterized. The rotation region of the PR is formed by removing one of the silicon wires from a cross-slot waveguide, leading to a strong hybridness of the lowest eigenmodes. As a result, the TE (TM) polarization can be rotated efficiently to the TM (TE) polarization at a length of 18.9 μm. The results show that the extinction ratio (ER) (insertion loss) is 31.6 (0.37) dB for TE-to-TM mode and 31.9 (0.37) dB for TM-to-TE mode. Moreover, a wide bandwidth of ~230 nm for both polarizations is obtained for keeping the ER over 20 dB. In addition, fabrication tolerances to the structural parameters are investigated, and field evolution along the propagation distance is also demonstrated.

Keywords (OCIS):

  • (130.2790) Integrated optics : Guided waves
  • (130.3120) Integrated optics : Integrated optics devices
  • (230.7380) Optical devices : Waveguides, channeled
  • (130.5440) Integrated optics : Polarization-selective devices

Spectral and total effective emissivity of a non-isothermal blackbody cavity formed by two coaxial tubes

  • Guohui Mei, Jiu Zhang, Xu Wang, Shumao Zhao, and Zhi Xie
  • received 11/24/2014; accepted 03/23/2015; posted 03/23/2015; Doc. ID 228378
  • [full text: PDF (3938) KB)]
  • Abstract: A blackbody cavity is developed for continuously measuring the temperature of molten steel, which consists of a cylindrical outer tube with a flat bottom, a coaxial inner tube and an aperture diaphragm. The ray-tracing approach based on the Monte Carlo method was applied to calculate the effective emissivity for the non-isothermal cavity with the diffuse wall. The influence of the wall temperature distribution on the spectral and total effective emissivity was studied for various cavity geometrical parameters. For a practical blackbody cavity of the temperature sensor used in the tundish, the effective emissivity was calculated and verified, our results will be helpful to optimize the novel sensor design and use it better for measuring the temperature of molten steel.

Keywords (OCIS):

  • (120.5630) Instrumentation, measurement, and metrology : Radiometry
  • (120.6780) Instrumentation, measurement, and metrology : Temperature
  • (130.6010) Integrated optics : Sensors
  • (230.6080) Optical devices : Sources

Automatic Estimation of Noise Parameters in Fourier-Domain OCT Cross-Sectional Images using Statistical Information

  • Patrick Steiner, Jens Kowal, Boris Považay, Christoph Meier, and Raphael Sznitman
  • received 02/05/2015; accepted 03/22/2015; posted 03/23/2015; Doc. ID 233953
  • [full text: PDF (1806) KB)]
  • Abstract: We present an application and sample independent method for the automatic discrimination of noise and signal in optical coherence tomography Bscans. The proposed algorithm models the observed noise probabilistically and allows for a dynamic determination of image noise parameters and the choice of appropriate image rendering parameters. This overcomes the observer variability and the need for a priori information about the content of sample images, both of which are challenging to estimate systematically with current systems. As such, our approach has the advantage of automatically determining crucial parameters for evaluating rendered image quality in a systematic and task independent way. We tested our algorithm on data from four different biological and non-biological samples (index finger, lemon slices, scotch tape and and detector cards), acquired with three different experimental spectral domain OCT measurement systems including a swept source OCT. Results are compared to parameters determined manually by four experienced OCT users. Overall, our algorithm works reliably regardless of which system and sample are used and estimates noise parameters in all cases within the confidence interval of those found by observers.

Keywords (OCIS):

  • (030.4280) Coherence and statistical optics : Noise in imaging systems
  • (100.2960) Image processing : Image analysis
  • (110.4500) Imaging systems : Optical coherence tomography

Sub-MHz frequency stabilization of a diode laser by digital laser current modulation

  • Le Luo, Jiaming Li, Ji Liu, Leonardo deMelo, Zixin Wang, and Tianshu Lai
  • received 01/28/2015; accepted 03/22/2015; posted 03/26/2015; Doc. ID 233220
  • [full text: PDF (424) KB)]
  • Abstract: Digital laser current modulation (DLCM) is a convenient laser stabilization scheme whose major advantages are simplicity and inexpensiveness to implement. However, there is a tradeoff between the signal-to-noise ratio (SNR) of the error signal and the laser linewidth due to the direct laser frequency modulation. In this paper, we demonstrated that DLCM can reduce the full width at half maximum (FWHM) linewidth of a tunable diode laser down to 500 kHz using the modulation transfer spectrum of D₂ line of a ⁶Li atomic vapor. For this purpose, a theoretical model is provided to analyze the DLCM-based modulation transfer spectrum. From the analysis, we experimentally explored the modulation effect on the DLCM spectrum to minimize the laser linewidth. Our result shows the optimized DLCM can stabilize a diode laser into sub-MHz regime without requiring acousto-optic (AOM) and electro-optic modulators (EOM).

Keywords (OCIS):

  • (020.3690) Atomic and molecular physics : Line shapes and shifts
  • (140.2020) Lasers and laser optics : Diode lasers
  • (300.6210) Spectroscopy : Spectroscopy, atomic
  • (300.6260) Spectroscopy : Spectroscopy, diode lasers
  • (300.6290) Spectroscopy : Spectroscopy, four-wave mixing
  • (140.3425) Lasers and laser optics : Laser stabilization

Increasing the stability of the estimation of phase wavefront aberration distribution function through nonlinear adaptive filtering

  • kambiz rahbar, Karim Faez, and Ebrahim Attaran-Kakhki
  • received 11/19/2014; accepted 03/22/2015; posted 03/23/2015; Doc. ID 227163
  • [full text: PDF (366) KB)]
  • Abstract: Small amounts of aberration can strongly influence optical systems' performance. Thus reducing the noise in the process of estimating the aberration distribution function is of prime importance. This article provides a solution for nonlinear adaptive filtering of wavelet coefficients with the aim of increasing the stability of the estimation process of phase aberration distribution function. It should be noted that the estimation process is based on the wavelet profilometry. The basic idea in this technique is based on the assumption that noise spectrum is widely distributed with small amounts. Thus, using nonlinear filtering may increase the stability of the extraction process of aberration function's parameters. Considering the importance of determining the true threshold, based on the correlation of third order cumulats, a new utility function is defined. Using this function, it is expected that the threshold would adapt itself to its optimum value. Simulation results confirmed the accuracy and efficiency of the proposed solution.

Keywords (OCIS):

  • (080.1010) Geometric optics : Aberrations (global)
  • (100.2650) Image processing : Fringe analysis
  • (100.7410) Image processing : Wavelets
  • (150.0155) Machine vision : Machine vision optics

Square wave encoded fringe patterns for high accuracy depth sensing

  • Fu Li, Guangming Shi, Lili Yang, Ruodai Li, Zhe Gao, and Xuemei Xie
  • received 01/14/2015; accepted 03/21/2015; posted 03/23/2015; Doc. ID 232557
  • [full text: PDF (3374) KB)]
  • Abstract: Depth sensing with multiple fringe patterns has high precision. However, depth acquisition for discontinuous surfaces needs accurate and reliable absolute phase in this method. In this paper, a square wave encoded in three sinusoidal fringe patterns for depth sensing is proposed. The periods of the square wave and the sinusoidal wave are coprime. Because of the specific pattern design strategy, Gabor filter is used to get the wrapped phase and coprime theorem is utilized to determine the absolute phase of the encoded sinusoidal wave reliably. Quantitative analyses and practical experiments have been presented to verify the performance of the proposed method. The precision of our method is close to that of the classic three-step phase shifting method, besides depth in the discontinuous surfaces can be measured correctly. By adopting high-resolution projector and camera, our proposed method can acquire a denser and more precise depth map than Kinect and ToF camera.

Keywords (OCIS):

  • (150.5670) Machine vision : Range finding
  • (150.6910) Machine vision : Three-dimensional sensing

Pump hysteresis and bi-stability of dissipative solitons in all-normal-dispersion fiber lasers

  • Xuliang Fan, Siming Wang, Yong Wang, Deyuan SHEN, Dingyuan Tang, and L.M. Zhao
  • received 01/23/2015; accepted 03/21/2015; posted 03/23/2015; Doc. ID 232916
  • [full text: PDF (1273) KB)]
  • Abstract: We report the results of numerical simulations on pump hysteresis and bi-stability of a dissipative soliton fiber laser. The fiber laser is made of normal dispersion fibers and passively mode-locked by using the nonlinear polarization rotation technique. The dependence of the final steady state on the initial light field is investigated. Bi-stability between the single-pulse state and the double-pulse state in the mode-locking regime is demonstrated. Different initial conditions could lead to different attractors even with a same point in the parameter space.

Keywords (OCIS):

  • (060.4370) Fiber optics and optical communications : Nonlinear optics, fibers
  • (060.5530) Fiber optics and optical communications : Pulse propagation and temporal solitons
  • (140.3510) Lasers and laser optics : Lasers, fiber
  • (190.1450) Nonlinear optics : Bistability
  • (190.5530) Nonlinear optics : Pulse propagation and temporal solitons

Design of optical power delivery network based on power limitation of standard single-mode fiber at a wavelength of 1550 nm

  • Kyouzou Tujikawa, Lin Ma, Nobutomo Hanzawa, and Fumihiko Yamamoto
  • received 01/22/2015; accepted 03/20/2015; posted 03/23/2015; Doc. ID 232922
  • [full text: PDF (750) KB)]
  • Abstract: We investigated the optical power delivery (OPD) limit of standard single-mode fibers (SMF) at a wavelength of 1550 nm. We demonstrate that the intrinsic limits on OPD of SMF are the fiber transmission loss and the nonlinear effect of stimulated Raman scattering (SRS). These limits cannot be overcome without choosing a different operation wavelength. We employed a C-band amplified spontaneous emission (ASE) source pumped by a high power erbium-doped fiber-optical amplifier (EDFA) as a broadband light source. As a result, the nonlinear effect caused by stimulated Brillouin scattering (SBS) was successfully suppressed. By using this technique, we succeeded in delivering 3.5 W of optical power over a 5 km-long SMF. In addition, we demonstrated that the SRS becomes the main power-limiting factor when the delivery distance exceeds 5 km. We also used commercially available photovoltaic cells to convert optical power into electric power, and we confirmed a conversion efficiency of 17.4%. Consequently, about 500 mW of electric power can be delivered by using a 5 km-long SMF. We can construct an OPD system that can deliver electric power of the order of several hundreds of mW over a distance of more than five kilometers through SMF. Our results will be useful with a view to realizing long-range OPD systems such as an application of sensing network.

Keywords (OCIS):

  • (060.2270) Fiber optics and optical communications : Fiber characterization
  • (060.2430) Fiber optics and optical communications : Fibers, single-mode

Reconstruction of purely absorbing, absorbing and phase-shifting, and strong phase-shifting objects from their single-shot in-line holograms

  • Tatiana Latychevskaia and Hans-Werner Fink
  • received 02/03/2015; accepted 03/20/2015; posted 03/23/2015; Doc. ID 233663
  • [full text: PDF (3731) KB)]
  • Abstract: We address the problem of reconstructing phase-shifting objects from their single shot in-line holograms. We show that a phase-shifting object cannot be reliably recovered from its in-line hologram by conventional reconstruction routines but that an iterative reconstruction should be applied. We demonstrate examples of simulated in-line holograms of objects with the following properties: purely absorbing, both absorbing and phase shifting, and strong phase-shifting. We investigate the effects of noise and interference resolution in holograms on the reconstruction results and discuss details of an optimal iterative procedure to quantitatively recover the correct absorbing and phase-shifting properties of the object. We also review previously published reconstructions of experimental holograms and summarize the optimal parameters for retrieval of phase-shifting objects from their in-line holograms.

Keywords (OCIS):

  • (090.0090) Holography : Holography
  • (100.3010) Image processing : Image reconstruction techniques
  • (100.3190) Image processing : Inverse problems
  • (100.5070) Image processing : Phase retrieval
  • (090.1995) Holography : Digital holography

Control of transverse mode spectrum of Novosibirsk Free Electron Laser radiation

  • Andrey Kaveev, Andrey Agafonov, Yulia Choporova, Boris Knyazev, Grigory Kropotov, Vladimir Pavelyev, Konstantin Tukmakov, and Boris Volodkin
  • received 01/19/2015; accepted 03/20/2015; posted 03/20/2015; Doc. ID 232750
  • [full text: PDF (1279) KB)]
  • Abstract: This paper presents experimental results on the formation of given laser modes from an illuminating Gaussian beam of the terahertz Novosibirsk Free Electron Laser (NovoFEL) at a wavelength of 141 micrometer. Binary silicon diffractive optical elements were applied. The experimental results obtained are in good agreement with the results of computer simulation.

Keywords (OCIS):

  • (050.1380) Diffraction and gratings : Binary optics
  • (050.1970) Diffraction and gratings : Diffractive optics
  • (140.2600) Lasers and laser optics : Free-electron lasers (FELs)
  • (040.2235) Detectors : Far infrared or terahertz

Electric field induced band-bending on GaN: in-situ effects of electron beam irradiation on time-dependent cathodoluminescence

  • Eva Campo, Milan Pophristic, Laurel Hopkins, and Ian Ferguson
  • received 01/13/2015; accepted 03/20/2015; posted 03/20/2015; Doc. ID 231586
  • [full text: PDF (1576) KB)]
  • Abstract: Electron beam bombardment of GaN has been monitored by secondary electron (SE), cathodoluminescence (CL) imaging, simultaneous in-situ CL, and specimen current (SC) measurements. Under extreme irradiation conditions, system perturbations, as seen by SE and time-dependent CL, are attributed to internal charge dynamics, extending beyond the scanned areas. Under moderate irradiation conditions, the size of affected regions correlates with nominal scanned regions. Time-dependent CL at the near band edge (NBE) revealed complex interplay with SC, which was modeled through band-bending at the Au/GaN interface. The system has shown distinctive internal electric field dynamics upon sample handling; affecting both time-dependent CL spectra and SC, as well as producing contrast reversal in SE imaging, to which humidity adsorption could be contributing. The band-bending model presented here can account for both moderate irradiation and humidity effects through variations of depletion widths and Schottky barrier heights. Our findings are consistent with current models where e-beam activated VGa promote decreased NBE intensities and CN promote DL emissions. © 2014 Optical Society of America

Keywords (OCIS):

  • (160.2540) Materials : Fluorescent and luminescent materials
  • (160.6000) Materials : Semiconductor materials
  • (250.1500) Optoelectronics : Cathodoluminescence

Electromagnetically induced transparency in all-dielectric metamaterial-waveguide system

  • Pei Ding, Jinna He, Junqiao Wang, FAN chunzhen, and Erjun Liang
  • received 01/06/2015; accepted 03/19/2015; posted 03/20/2015; Doc. ID 231708
  • [full text: PDF (1887) KB)]
  • Abstract: We demonstrate theoretically an analogue of electromagnetically induced transparency (EIT) at visible frequencies in an all-dielectric metamaterial-waveguide (ADMW) system that consists of a two-dimensional silicon nanopillar array on top of a dielectric slab waveguide. By varying the lattice period of the array, we show that the transmission feature of the hybridized ADMW system can be efficiently engineered due to the period-dependent guided modes. For ADMW systems with different lattice period, the EIT-like transparency windows are confirmed from either the two detuned guided modes or the Fano-type interference between the guided modes and the magnetic dipole mode in silicon nanopillars. We have also demonstrated the significant E-field enhancement in the waveguide and the remarkable slow-light effect associated with the EIT-like transmission. Compared with the hybrid waveguide-plasmon (HWP) system including metal-resonator array, the silicon-based ADMW system enables to produce high quality factor (Q-factor) resonances with low absorption losses, thereby having promising applications in low-loss slow light devices, bio/chemical sensing, enhancing emission rate, and optical modulation.

Keywords (OCIS):

  • (240.6680) Optics at surfaces : Surface plasmons
  • (260.5740) Physical optics : Resonance
  • (160.3918) Materials : Metamaterials
  • (350.4238) Other areas of optics : Nanophotonics and photonic crystals

Study on compact polarization beam splitters based on directional coupling in Bragg reflection waveguides

  • Bing Chen, Chunliang Liu, and Guizhong Liu
  • received 01/05/2015; accepted 03/19/2015; posted 03/20/2015; Doc. ID 231879
  • [full text: PDF (1949) KB)]
  • Abstract: Directional coupling in dual-channel Bragg reflection waveguides are investigated through both plane-wave expansion and finite-difference time-domain methods. A polarization beam splitter based on directional coupling in Bragg reflection waveguides is proposed, and its transmission characteristics are investigated by using finitedifferent time-domain method. Calculated results indicate that for the polarization beam splitter with the coupling length of 59.76μm, TM0 and TE0 modes at a wavelength of 1.55μm can be spatially separated, and the corresponding transmittances are 91.72% and 97.97%, respectively. The compact polarization beam splitter is expected to be applied to highly density photonic integrated circuits.

Keywords (OCIS):

  • (130.2790) Integrated optics : Guided waves
  • (130.3120) Integrated optics : Integrated optics devices
  • (130.5296) Integrated optics : Photonic crystal waveguides
  • (130.5440) Integrated optics : Polarization-selective devices

Wavelength-Dependent Spatial Correction and Spectral Calibration of a Liquid Crystal Tunable Filter Imaging System

  • Roy Berns, Brittany Cox, and Farhad Abed
  • received 12/09/2014; accepted 03/19/2015; posted 03/20/2015; Doc. ID 227160
  • [full text: PDF (4008) KB)]
  • Abstract: The centroid wavelength of liquid crystal tunable filters, by definition, changes with incident angle, resulting in an imaging system with spectral sensitivity that varies across the image plane. Previous to this research, this effect was considered negligible. Imaging uniform colored papers with high chroma revealed that the effect is appreciable. A regression-based method of modeling and correcting systematic spectrophotometric errors in conventional reflectance spectrophotometry was used to correct this wavelength dependent spatial non-uniformity in an LCTF imaging system. For six high chroma sheets of spatially uniform paper, the uniformity was reduced from and average and maximum 0.95 and 4.00 to 0.08 and 0.18 CIEDE2000. The same method was used to transfer the scale of spectral reflectance factor from a reference spectrophotometer to the imaging system such that its reported values matched the reference spectrophotometer with a constant bandwidth. For an independent color target, residual errors were 0.008 spectral reflectance factor RMS and 0.44 and 1.65 average and maximum CIEDE2000 (0.63 and 2.34 ∆E*ab).

Keywords (OCIS):

  • (230.3720) Optical devices : Liquid-crystal devices
  • (300.6550) Spectroscopy : Spectroscopy, visible
  • (110.4234) Imaging systems : Multispectral and hyperspectral imaging

Skew ray tracing in a step-index optical fiber using Geometric Algebra

  • Angeleene Ang, Quirino Sugon Jr., and daniel mcnamara
  • received 12/22/2014; accepted 03/19/2015; posted 03/20/2015; Doc. ID 231285
  • [full text: PDF (498) KB)]
  • Abstract: We used Geometric Algebra to compute the paths of skew rays in a cylindrical, step-index optical fiber. To do this, we used the vector addition form for the law of propagation, the exponential of an imaginary vector form for the law of refraction, and the juxtaposed vector product form for the law of reflection. In particular, the exponential forms of the vector rotations enables us to take advantage of the addition or subtraction of exponential arguments of two rotated vectors in the derivation of the ray tracing invariants in cylindrical and spherical coordinates. We showed that the light rays inside the optical fiber trace a polygonal helical path characterized by three invariants that relate successive reflections inside the fiber: the ray path distance, the difference in axial distances, and the difference in the azimuthal angles. We also rederived the known generalized formula for the numerical aperture for skew rays, which simplifies to the standard form for meridional rays.

Keywords (OCIS):

  • (060.2310) Fiber optics and optical communications : Fiber optics
  • (080.0080) Geometric optics : Geometric optics
  • (080.2720) Geometric optics : Mathematical methods (general)

Volumetric Aerial Three-Dimensional Display based on heterogeneous imaging and image plane scanning

  • Yuki Maeda, Daisuke Miyazaki, and Satoshi Maekawa
  • received 01/23/2015; accepted 03/19/2015; posted 03/23/2015; Doc. ID 232947
  • [full text: PDF (1299) KB)]
  • Abstract: A volumetric display system that creates a distortion-free three-dimensional (3D) image in midair using a novel imaging system is reported. A roof mirror array forms an aerial real image with an image deformation by retro-reflection. To construct an imaging system using two roof mirror arrays arranged parallel can reduce the image deformation. A cross-sectional image of a 3D object is formed by the proposed imaging system in midair and swept by a galvanometer mirror scanner to create a 3D volume image. An aerial 3D volume image formation without the image deformation was confirmed by an experimental volumetric display system.

Keywords (OCIS):

  • (100.6890) Image processing : Three-dimensional image processing
  • (110.0110) Imaging systems : Imaging systems
  • (120.2040) Instrumentation, measurement, and metrology : Displays
  • (120.4820) Instrumentation, measurement, and metrology : Optical systems

Using the PSM Model to analytically describe diffraction in the planar volume reflection grating with finite absorption

  • David Brotherton-Ratcliffe, Ardie Osanlou, and Peter Excell
  • received 01/28/2015; accepted 03/19/2015; posted 03/23/2015; Doc. ID 233411
  • [full text: PDF (1550) KB)]
  • Abstract: The PSM model of grating diffraction is extended to include a complex refractive index for the case of an unslanted reflection geometry at oblique incidence and for the σ-polarization. The well-known upper diffraction efficiency limit characteristic of reflective absorption gratings is shown to be a direct consequence of the PSM model. Analytical formulae for the diffraction efficiency of phase, absorption and mixed harmonic-index gratings are compared with numerical computations using a rigorous coupled wave description. A conventional truncated coupled-wave description, similar to Kogelnik’s approach, is also derived from the harmonic-index rigorous coupled wave equations by limiting the propagating modes to a signal and reference wave and by ignoring second order derivatives. At low to moderate average loss the PSM theory is observed to provide a somewhat better fit to the rigorous coupled wave calculations, and this is particularly evident for gratings which are dominated by phase modulation. As the average absorption coefficient is increased, all three models show the diffractive response sharpening around Bragg resonance and the characteristic sideband structure attenuating and then disappearing altogether, giving rise to a broader spectral behavior away from resonance. At high average loss, the truncated coupled wave model is observed to very marginally out-perform PSM. However, overall the PSM model is found to provide an exceedingly good description of the general mixed-phase-absorption unslanted reflection grating with finite average loss.

Keywords (OCIS):

  • (050.0050) Diffraction and gratings : Diffraction and gratings
  • (050.1940) Diffraction and gratings : Diffraction
  • (050.1960) Diffraction and gratings : Diffraction theory
  • (090.0090) Holography : Holography
  • (090.7330) Holography : Volume gratings
  • (260.1960) Physical optics : Diffraction theory

Tunable subwavelength terahertz plasmon induced transparency in the InSb slot waveguide side-coupled with two stub resonators

  • Liu Huaiqing, Guobin Ren, Yixiao Gao, Yudong Lian, Yang Qi, and Shuisheng Jian
  • received 01/23/2015; accepted 03/19/2015; posted 03/25/2015; Doc. ID 232565
  • [full text: PDF (1088) KB)]
  • Abstract: We numerically investigated the realization of electromagnetically induced transparency (EIT) at terahertz region in an InSb slot waveguide side-coupled with two stub resonators. The mechanism of the EIT phenomenon is theoretically analyzed and numerically studied by using coupled mode theory (CMT) and Finite Element Method (FEM), respectively, and the theoretical results are in good agreement with the simulation results. The simulation results reveal that the EIT-like response is strongly dependent on the coupling separation between the two stub resonators and we derived the best separation between the two stub resonators to get the most obvious EIT-like spectra. More importantly, the central wavelength of the EIT-like spectra can be actively controlled by tuning the temperature. This plasmonic waveguide system may have potential applications for ultracompact THz integrated circuits, such as thermo-tunable filter, THz switching, slow-light components, and THz sensitive sensor.

Keywords (OCIS):

  • (130.0130) Integrated optics : Integrated optics
  • (240.6680) Optics at surfaces : Surface plasmons
  • (040.2235) Detectors : Far infrared or terahertz
  • (250.5403) Optoelectronics : Plasmonics

Supercontinuum generation with high power-efficiency in a highly nonlinear fiber pumped by two-color pulses

  • Dong Wang, Li Huo, Li Min, Yue Wu, and Caiyun Lou
  • received 12/23/2014; accepted 03/18/2015; posted 03/20/2015; Doc. ID 231389
  • [full text: PDF (1205) KB)]
  • Abstract: A power-efficiency supercontinuum generation scheme based on a two-color pulses generator followed by a supercontinuum generation stage is proposed and demonstrated experimentally. After chirp compression and Mamyshev reshaping, pedestal-free two-color pulses are obtained. By two-color pulses pumping in a highly nonlinear fiber at the anomalous dispersion region, supercontinuum with a 20-dB width of 207 nm is achieved at a modest total pump power of 24 dBm, which covers the spectral range from 1456 to 1663 nm.

Keywords (OCIS):

  • (060.4370) Fiber optics and optical communications : Nonlinear optics, fibers
  • (060.5530) Fiber optics and optical communications : Pulse propagation and temporal solitons
  • (320.6629) Ultrafast optics : Supercontinuum generation

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