Accepted papers to appear in an upcoming issue
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Stable RF frequency dissemination by a simple hybrid frequencies modulation scheme
- received 06/11/2014; accepted 07/31/2014; posted 07/31/2014; Doc. ID 213854
- [full text: PDF (597) KB)]
- Abstract: In this paper, we propose a novel fiber-based stable radio frequency transfer system by a hybrid frequencies modulation scheme. Creatively, two radio frequency signals are combined and simultaneously transferred by only one laser diode. One frequency component is used to detect the phase fluctuation and the other one is the derivative compensated signal providing a stable frequency for the remote end. Experimentally, a stable 200MHz signal is transferred over 100km optical fiber with the help of a 1GHz detecting signal and stability of 2×10−17 at 105 s is achieved. Three orders improvement of stability proves that the system is simple but effective as well.
- (060.2360) Fiber optics and optical communications : Fiber optics links and subsystems
- (060.2630) Fiber optics and optical communications : Frequency modulation
- (120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
Low Noise mid-IR Upconversion Detector for Improved IR-DFWM Gas Sensing
- received 06/10/2014; accepted 07/30/2014; posted 07/31/2014; Doc. ID 212856
- [full text: PDF (483) KB)]
- Abstract: We compare a nonlinear upconversion detector with a conventional cryogenic InSb detector for the detection of coherent infrared light and show near shot-noise limited performance in the upconversion system, while the InSb detector is limited to 500 times lower signal-to-noise-ratio (SNR) despite having about 10 times more IR photons available. The two detectors are compared for the detection of a coherent degenerate four-wave mixing (DFWM) signal in the mid-infrared and this is applied to measure trace-level acetylene in a gas flow at atmospheric pressure by probing its fundamental ro-vibrational transitions. Beside lower noise the upconversion system provides image information of the signal, thus adding new functionality compared to standard point detection methods. We show how the upconversion detector system is implemented as a simple replacement of the cryogenic detector.
- (040.0040) Detectors : Detectors
- (040.3060) Detectors : Infrared
- (110.3080) Imaging systems : Infrared imaging
- (190.7220) Nonlinear optics : Upconversion
- (300.6290) Spectroscopy : Spectroscopy, four-wave mixing
Simple Model for the Nonlinear Optical Response of Gases in the Transparency Region
- received 06/11/2014; accepted 07/30/2014; posted 07/30/2014; Doc. ID 213951
- [full text: PDF (416) KB)]
- Abstract: We present a simple model for the nonlinear optical response of atomic gases for pulses with center wavelengths in the transparency region and peak fields for which ionization is not prevalent. By comparing with simulations based on the Schrödinger equation for a hydrogen atom we demonstrate that the model accurately captures the dispersion of the nonlinear polarization as well as non-instantaneous effects for a variety of photon energies and also a two-color pulse. Our approach should be of utility in simulating near- and mid-infrared pulse propagation in dielectric media for which extreme nonlinear effects can arise.
- (190.0190) Nonlinear optics : Nonlinear optics
- (190.2620) Nonlinear optics : Harmonic generation and mixing
- (190.7110) Nonlinear optics : Ultrafast nonlinear optics
Basic limit for the efficiency of coherence-limited solar power conversion
- received 06/30/2014; accepted 07/30/2014; posted 07/30/2014; Doc. ID 215024
- [full text: PDF (424) KB)]
- Abstract: A basic upper bound for the efficiency of solar power conversion (generally, from any blackbody source) is derived, generalizing the eponymous Landsberg limit to arbitrary solar and sky view factors (e.g., arbitrary optical concentration and/or angular confinement), and to coherence-limited devices such as rectifying aperture antennas for which illustrative results are presented
- (030.1640) Coherence and statistical optics : Coherence
- (030.5620) Coherence and statistical optics : Radiative transfer
- (350.6050) Other areas of optics : Solar energy
A 128×128 long-wavelength/mid-wavelength two-color HgCdTe infrared focal plane array detector with ultra-low spectral crosstalk
- received 06/18/2014; accepted 07/29/2014; posted 07/30/2014; Doc. ID 214198
- [full text: PDF (793) KB)]
- Abstract: High temporal and spatial coherent simultaneous long-wavelength/mid-wavelength (LW/MW) two-color focal plane array (FPA) infrared detection is the cutting-edge technique for third-generation infrared remote sensing. In this letter, HgCdTe LW/MW two-color infrared detectors were designed and fabricated. The top long-wavelength and bottom mid-wavelength infrared planar photodiodes were processed by selective B+-implantation after etching the long-wavelength epilayer into a curvature and exposing the mid-wavelength layers for the implantation of the n region of the MW photodiode by a micro-mesa array technique. A 128×128 MW/LW HgCdTe infrared FPA detector is fabricated photo-lithographically by simultaneous non-planar B+-implantation of the LW and MW photodiodes, passivation and metallization of the side walls, mesa isolation, and flip-chip hybridization with read-out integrated circuit. The inner mechanisms for suppressing the crosstalk and improving photoresponse have been carried out by combining experimental work with numerical simulations.
- (040.1880) Detectors : Detection
- (040.3060) Detectors : Infrared
- (040.5160) Detectors : Photodetectors
- (110.3080) Imaging systems : Infrared imaging
Lock-in spectroscopy employing a high-speed camera and a micro-scanner for volumetric investigations of unsteady flows
- received 06/12/2014; accepted 07/29/2014; posted 07/30/2014; Doc. ID 213936
- [full text: PDF (2210) KB)]
- Abstract: Spectroscopic methods are established tools for non-intrusive measurements of flow velocity. However, those methods are either restricted by measuring pointwise or with low measurement rates of several Hertz. In order to investigate fast unsteady effects e.g. of sprays, volumetric (3d) measurement techniques with kHz rate are required. For this purpose, a spectroscopic technique is realized with a power amplified, frequency modulated laser and a Mfps high-speed camera allowing continuous, fast planar measurements of the velocity. Volumetric data is finally obtained by also employing an oscillating micro-electro-mechanical systems (MEMS) scanner for slewing the laser light sheet in depth. As result, volumetric velocity measurements are obtained for 256x128x25 voxels with a repetition rate of 1 kHz, which allows to investigate unsteady effects of sprays such as transients and local velocity oscillations. The respective measurement capabilities are demonstrated by experiments. Hence, a significant progress regarding the data rate was achieved in spectroscopy by using the Mfps high-speed camera, which enables new application fields such as the analysis of fast unsteady phenomena.
- (110.6880) Imaging systems : Three-dimensional image acquisition
- (120.6200) Instrumentation, measurement, and metrology : Spectrometers and spectroscopic instrumentation
- (280.7250) Remote sensing and sensors : Velocimetry
- (140.3518) Lasers and laser optics : Lasers, frequency modulated
Localized surface modes in parity-time-symmetric potentials
- received 06/25/2014; accepted 07/29/2014; posted 07/30/2014; Doc. ID 214785
- [full text: PDF (314) KB)]
- Abstract: We investigate light beam propagation along the interface between linear and nonlinear media with parity-time symmetry. A novel class of two-dimensional localized surface modes are found analytically and numerically. If the potential is parity-time-invariant along the direction parallel to the interface between the two media, stable localized surface modes can exist. Otherwise, if the potential is parity-time-invariant along the direction perpendicular to the interface between the two media, there is no stable localized surface modes.
- (190.3270) Nonlinear optics : Kerr effect
- (190.6135) Nonlinear optics : Spatial solitons
53 W average power few-cycle fiber laser system generating soft X-rays up to the water window
- received 06/09/2014; accepted 07/29/2014; posted 07/30/2014; Doc. ID 213634
- [full text: PDF (485) KB)]
- Abstract: We report on a few-cycle laser system delivering sub-8 fs pulses with 353 µJ pulse energy and 25 GW of peak power at up to 150 kHz repetition rate. The corresponding average output power is as high as 53 W, which represents the highest average power obtained from any few-cycle laser architecture so far. The combination of both high average and high peak power provides unique opportunities for applications. We demonstrate high harmonic generation up to the water window and record-high photon flux in the soft X-ray spectral region. This table-top source of high-photon flux soft X-rays will for example enable coherent diffractive imaging with sub-10 nm resolution in the near future.
- (140.3510) Lasers and laser optics : Lasers, fiber
- (340.7480) X-ray optics : X-rays, soft x-rays, extreme ultraviolet (EUV)
Photonic microwave signal mixing technique using phase-coherent orthogonal optical carriers for radio-over-fiber application
- received 05/19/2014; accepted 07/29/2014; posted 07/31/2014; Doc. ID 212431
- [full text: PDF (5055) KB)]
- Abstract: An optical-assisted microwave mixing technique based on orthogonal and phase-coherent optical carriers is proposed and demonstrated. The high-quality binary phase shift keying, amplitude shift keying, and on-off keying microwave modulation at 20 GHz implemented in optical domain have been tested. Ultra-high bandwidth response of the proposed mixing device is also analyzed and compared. The phase-stability of the photonic microwave signal in the radio-over-fiber system is improved by the proposed signal mixing technique.
- (060.4080) Fiber optics and optical communications : Modulation
- (230.0250) Optical devices : Optoelectronics
- (350.4010) Other areas of optics : Microwaves
- (060.5625) Fiber optics and optical communications : Radio frequency photonics
Sub-diffraction-limited radius measurements of micro-cylinders using conventional bright-field optical microscopy
- received 06/23/2014; accepted 07/29/2014; posted 07/31/2014; Doc. ID 214478
- [full text: PDF (966) KB)]
- Abstract: A technique for measuring the radius of dielectric micro-cylinders with sub-diffraction-limited precision is presented. Diffraction fringes arising from the dielectric cylinder are measured using conventional bright-field optical microscopy, and compared with theory to deduce the radii. The technique has been demonstrated measuring the radii of the major-ampullate silks from Plebs eburnus spiders. Precision better than 50 nm is demonstrated, using a standard optical microscope with a numerical aperture of 0.6 for the objective. Accuracy was verified using scanning electron-microscopy. This technique will facilitate rapid, precise measurement of dielectric micro-cylinder radii, enabling a new optical-microscopy based measurement approach for these challenging micro-optics.
- (050.1940) Diffraction and gratings : Diffraction
- (120.3940) Instrumentation, measurement, and metrology : Metrology
- (230.3990) Optical devices : Micro-optical devices
- (290.3200) Scattering : Inverse scattering
- (160.1435) Materials : Biomaterials
Observation of the Uller--Zenneck wave
- received 07/01/2014; accepted 07/29/2014; posted 07/31/2014; Doc. ID 215016
- [full text: PDF (2309) KB)]
- Abstract: The Uller--Zenneck wave has been theoretically predicted to exist at the planar interface of two homogeneous dielectric materials of which only one must be dissipative. Experimental confirmation of this century-old prediction was obtained experimentally by exciting the Uller--Zenneck wave as a Floquet harmonic of non-zero order at the periodically corrugated interface of air and crystalline silicon in the 400--to--900-nm spectral regime. Application for intra-chip optical interconnects at $\sim$850 nm appears promising.
- (130.2790) Integrated optics : Guided waves
- (240.0240) Optics at surfaces : Optics at surfaces
- (240.6690) Optics at surfaces : Surface waves
Quantitative, three-dimensional imaging of aluminum drop combustion in solid propellant plumes via digital in-line holography
- received 06/10/2014; accepted 07/28/2014; posted 07/30/2014; Doc. ID 213671
- [full text: PDF (1606) KB)]
- Abstract: Burning aluminized propellants eject reacting molten aluminum drops with a broad size distribution. Prior to this work, in situ measurement of the drop size statistics and other quantitative flow properties was complicated by the narrow depth-of-focus of microscopic videography. Here, digital in-line holography (DIH) is demonstrated for quantitative volumetric imaging of the propellant plume. For the first time, in-focus features, including burning surfaces, drop morphologies, and reaction zones, are automatically measured through an optical depth spanning many mm.
- (120.1740) Instrumentation, measurement, and metrology : Combustion diagnostics
- (090.1995) Holography : Digital holography
- (050.6875) Diffraction and gratings : Three-dimensional fabrication
Generation of high-order Laguerre-Gaussian modes by means of Spiral Phase Plates
- received 06/20/2014; accepted 07/28/2014; posted 07/28/2014; Doc. ID 214502
- [full text: PDF (881) KB)]
- Abstract: Spiral phase plates for the generation of Laguerre-Gaussian beam with non-null radial index were designed and fabricated by electron beam lithography on polymethylmethacrylate over glass substrates. The optical response of these phase optical elements was theoretically considered and experimentally measured and the purity of the experimental beams was investigated in terms of Laguerre-Gaussian modes contributions. The far-field intensity pattern was compared with theoretical models and numerical simulations, whereas interferometric analyses confirmed the expected phase features of the generated beams. The high quality of the output beams confirm the applicability of these phase plates for the generation of high-order Laguerre-Gaussian beams.
- (050.1970) Diffraction and gratings : Diffractive optics
- (050.4865) Diffraction and gratings : Optical vortices
- (110.6895) Imaging systems : Three-dimensional lithography
Self-Q-switched waveguide laser based on femtosecond laser inscribed Nd:Cr:YVO4 crystal
- received 06/16/2014; accepted 07/28/2014; posted 07/30/2014; Doc. ID 214105
- [full text: PDF (954) KB)]
- Abstract: We report on the self-Q-switched laser operation of a monolithic Nd:Cr:YVO4 channel waveguide cavity. Femtosecond laser inscription was used to fabricate a buried channel waveguide in the substrate. The Nd:Cr:YVO4 crystal works as both the gain medium and the saturable-absorber, which enables the realization of a self-Q-switched waveguide laser pumped at 808 nm and emitting at 1064 nm. The compact waveguide cavity achieved maximum output powers up to 57 mW, corresponding to a single-pulse energy of 22.8 nJ, at 2.3 MHz repetition rate with a pulse duration of 85 ns.
- (130.3120) Integrated optics : Integrated optics devices
- (140.3540) Lasers and laser optics : Lasers, Q-switched
- (230.7380) Optical devices : Waveguides, channeled
Tailoring of the free spectral range and geometrical cavity dispersion of a microsphere by a coating layer
- received 06/25/2014; accepted 07/28/2014; posted 07/30/2014; Doc. ID 214698
- [full text: PDF (2237) KB)]
- Abstract: Modal dispersion of a whispering gallery mode (WGM) resonators is a very important parameter for use in all non-linear optics application. In order to tailor the WGM modal dispersion of a microsphere we have coated a silica microsphere with a high refractive index coating in order to study its effect on the WGM modal dispersion. We used Er3+ ions as a probe for modal dispersion assessment. We found that, by varying the coating thickness, the geometrical cavity dispersion can be used to shift overall modal dispersion in a very wide range in both the normal and anomalous dispersion regime.
- (140.4780) Lasers and laser optics : Optical resonators
- (160.5690) Materials : Rare-earth-doped materials
Strong polarization mode coupling in microresonators
- received 05/20/2014; accepted 07/28/2014; posted 07/28/2014; Doc. ID 212505
- [full text: PDF (720) KB)]
- Abstract: We observe strong modal coupling between the TE₀₀ and TM₀₀ modes in Si₃N₄ ring resonators revealed by avoided crossings of the corresponding resonances. Such couplings result in significant shifts of the resonance frequencies over a wide range around the crossing points. This leads to an effective dispersion that is one order of magnitude larger than the intrinsic dispersion and creates broad windows of anomalous dispersion. We also observe the changes to frequency comb spectra generated in Si₃N₄ microresonators due polarization mode and higher-order mode crossings and suggest approaches to avoid these effects. Alternatively, such polarization mode-crossings can be used as a novel tool for dispersion engineering in microresonators.
- (140.4780) Lasers and laser optics : Optical resonators
- (190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
- (190.4390) Nonlinear optics : Nonlinear optics, integrated optics
- (230.3990) Optical devices : Micro-optical devices
Iterative ghost imaging
- received 06/16/2014; accepted 07/28/2014; posted 07/28/2014; Doc. ID 214046
- [full text: PDF (450) KB)]
- Abstract: The recovered image in ghost imaging (GI) contains the error term when the number of measurements $M$ is limited. By iteratively calculating the high-order error term, the iterative ghost imaging (IGI) receives a better image than one in GI without increasing any complexity. We firstly propose an effective scheme of IGI by which a narrowed point spread function (PSF) and an exponentially enhanced signal to noise ratio (SNR) are realized. The exponentially increasing phenomenon of SNR is caused by the fact that the linear relationship between the SNR and $M$ in GI is replaced by the $M^k$ in IGI. Thus, a perfect recovery of the unknown object is demonstrated with $M$ slightly bigger than the number of speckles. Based on our theoretical framework from the angle of high-order correlation $R_k$, the two critical behaviors of the iterative coefficients $\alpha$ and the measurements $M$ are firstly found and well explained.
- (030.6140) Coherence and statistical optics : Speckle
- (100.0100) Image processing : Image processing
- (270.0270) Quantum optics : Quantum optics
Hybrid structured fiber-optic Fabry–Perot interferometer for simultaneous measurement of strain and temperature
- received 06/11/2014; accepted 07/27/2014; posted 07/30/2014; Doc. ID 213898
- [full text: PDF (956) KB)]
- Abstract: We fabricate and experimentally demonstrate a hybrid structured Fabry-Perot interferometer (FPI) in the middle of a fiber line for simultaneous measurement of axial strain and temperature. The FPI is composed of a silica-cavity cascaded to a spherical air-cavity, both of which are formed in a hollow annular core fiber (HACF). The fabrication process of the FPI only includes a fusion splice between a single mode fiber and a HACF and several electrical arc discharges at the HACF near the splice point. Experimental results show that the strain and temperature sensitivities of the air-cavity are about 5.2 pm/µε and 1.3 pm/C°, respectively, and those of the silica-cavity are 1.1 pm/µε and 13 pm/C°, respectively.
- (060.2370) Fiber optics and optical communications : Fiber optics sensors
- (120.2230) Instrumentation, measurement, and metrology : Fabry-Perot
- (120.3180) Instrumentation, measurement, and metrology : Interferometry
A beam configuration proposal to verify that scattering forces come from the orbital part of the Poynting vector.
- received 06/25/2014; accepted 07/26/2014; posted 07/28/2014; Doc. ID 214297
- [full text: PDF (2583) KB)]
- Abstract: In this work the optical forces on an electric dipole generated by a beam made up of two Hermite-Gaussian modes circularly polarized have been analyzed. When the intensity of the two modes is not the same, the mechanical action of the scattering force is totally different from the behavior of the Poynting vector. The dynamics of resonant metallic nanoparticles under this field have been calculated by means of Langevin molecular dynamics simulations. This configuration could be useful to experimentally verify how radiation pressure on a Rayleigh particle is due to the transfer of linear momentum coming solely from the orbital part of the Poynting vector.
- (290.5870) Scattering : Scattering, Rayleigh
- (350.4855) Other areas of optics : Optical tweezers or optical manipulation
301-nm wavelength tunable differentially driven all-polymer optical filter
- received 07/08/2014; accepted 07/26/2014; posted 07/30/2014; Doc. ID 216457
- [full text: PDF (767) KB)]
- Abstract: An optical filter based on all-polymer grating assisted directional coupler is demonstrated. The wavelength tuning is differentially driven. The heater-electrodes created on the sidewalls of the polymer ridge can either blue- or red-shift the central wavelength. A total tuning range of 301 nm is achieved experimentally. The maximal local temperature gradient introduced across the coupler region is only 55°C to 68°C. The filter is also insensitive to uniform ambient temperature change. Central wavelength jitter of ±3 nm is observed when the chip holder temperature cycles from 20°C to 80°C.
- (230.3120) Optical devices : Integrated optics devices
- (230.7408) Optical devices : Wavelength filtering devices
- (130.5460) Integrated optics : Polymer waveguides