A fast method for inverse determination of optical parameters from two measured signals

• Xin-Hua Hu, Jun Lu, Yuanming Feng, Xun Chen, Xiaohui Liang, Jue Ding, and Yong Du
• received 03/15/2013; accepted 05/20/2013; posted 05/20/2013; Doc. ID 187100
• [full text: PDF (1722) KB)]
• Abstract: Solving inverse problems requires multiple iterations of forward calculation of the measured signals. We present a fast method combining the GPU accelerated Monte Carlo simulations of individual photons and a new perturbation scheme. The latter allows rapid calculations of the diffuse reflectance and transmittance signals from a turbid sample of absorption coefficient µa, scattering coefficient µs and anisotropy factor g based on the principle of correlated sampling. To demonstrate its strong utility, we have applied the new method for determining the optical parameters of a diluted intralipid sample with satisfactory results.

Keywords (OCIS):

• (290.4210) Scattering : Multiple scattering
• (290.5820) Scattering : Scattering measurements

2.79 μm high peak power LGS electro-optically Q-switched Cr,Er:YSGG laser

• Li Wang, Jintao Wang, Jingwei Yang, Xianyou Wu, Dunlu Sun, Shaotang Yin, Haihe Jiang, Jiyang Wang, and Changqing Xu
• received 01/31/2013; accepted 05/20/2013; posted 05/21/2013; Doc. ID 184620
• [full text: PDF (499) KB)]
• Abstract: A flash lamp pumped Cr,Er:YSGG laser utilizing a self-grown LGS (La3Ga5SiO14) crystal as an electro-optic Q-switch is proposed and demonstrated for the first time. It is proved that LGS crystal with relatively high damage threshold can be used as the electro-optic Q-switch at 2.79 μm, and 216 mJ pulse energy with 14.36 ns pulse width is achieved. Its corresponding peak power of pulse can reach 15 MW which is at least 10 times higher than that of the LN Q-switched laser system.

Keywords (OCIS):

• (140.0140) Lasers and laser optics : Lasers and laser optics
• (140.3070) Lasers and laser optics : Infrared and far-infrared lasers
• (140.3540) Lasers and laser optics : Lasers, Q-switched
• (140.3580) Lasers and laser optics : Lasers, solid-state

Modal characterization of fiber-to-fiber coupling processes

• Daniel Flamm, Christian Schulze, Kai-Chung Hou, Philipp Gelszinnis, Siegmund Schroeter, and Michael Duparré
• received 03/15/2013; accepted 05/19/2013; posted 05/20/2013; Doc. ID 186804
• [full text: PDF (957) KB)]
• Abstract: We present a detailed experimental investigation of a fiber-to-fiber coupling process by characterizing the modecontent at the output of the system. In our experiment a single mode fiber is transversally scanned with respectto a multi-mode fiber revealing position dependent higher order mode excitation. The outlined measurementsystem can be used for automated optimization of fundamental mode content and beam quality. Additionally,our approach characterizes the modal transmission properties of the multi-mode waveguide in its present stateand is hence of high relevance for the conception of transport fibers and fiber laser systems.

Keywords (OCIS):

• (030.4070) Coherence and statistical optics : Modes
• (060.2270) Fiber optics and optical communications : Fiber characterization
• (060.2310) Fiber optics and optical communications : Fiber optics
• (090.1995) Holography : Digital holography

A path length modulation technique for scatter noise immunity in squeezing measurements

• Andrew Wade, Sheon Chua, Michael Stefszky, Daniel Shaddock, and David McClelland
• received 04/19/2013; accepted 05/19/2013; posted 05/21/2013; Doc. ID 189118
• [full text: PDF (645) KB)]
• Abstract: We present a technique for frequency shifting scattering induced noise on squeezed light beams, providing immunity from scattered light whilst preserving the squeezed states. Using a 500 Hz pre- and post-squeezing apparatus path length modulation, we show up to a 20 dB reduction in scattering induced noise whilst recovering squeezing measurement below the shot noise level. Such a technique offers immunity to spurious scattering sources without the need for optically lossy isolation optics.

Keywords (OCIS):

• (000.2190) General : Experimental physics
• (270.0270) Quantum optics : Quantum optics
• (270.6570) Quantum optics : Squeezed states
• (290.0290) Scattering : Scattering
• (290.1350) Scattering : Backscattering
• (290.5880) Scattering : Scattering, rough surfaces

Superweak amplification of beam shifts at pseudo-Brewster angles

• Joerg Goette and Mark Dennis
• received 03/20/2013; accepted 05/18/2013; posted 05/21/2013; Doc. ID 187503
• [full text: PDF (715) KB)]
• Abstract: The magnitudes of beam shifts (Goos-Hänchen and Imbert-Fedorov, spatial and angular) are greatly enhanced when a reflected light beam in postselected by an analyzer, by analogy with superweak measurements in quantum theory.We introduce the related idea of a pseudo-Brewster angle, where no light is transmitted for a fixed incident angle, and initial and final polarizations.We derive a formula for the angular and spatial shifts close to Brewster and pseudo-Brewster angles, whose maximum size is limited by higher-order terms from the reflection coefficients occurring in the Artmann shift formula.

Keywords (OCIS):

• (120.5700) Instrumentation, measurement, and metrology : Reflection
• (260.5430) Physical optics : Polarization
• (260.6970) Physical optics : Total internal reflection
• (240.3695) Optics at surfaces : Linear and nonlinear light scattering from surfaces

Optical bistability in a high-Q racetrack-resonator based on small SU-8 ridge waveguides

• Daoxin Dai, Yaocheng Shi, Li Jin, Xin Fu, and Bo Yang
• received 04/02/2013; accepted 05/18/2013; posted 05/20/2013; Doc. ID 187977
• [full text: PDF (1042) KB)]
• Abstract: A racetrack resonator with a high Q-value (~34700) is demonstrated experimentally based on small SU-8 optical ridge waveguides, which are fabricated with an improved etchless process to be low-loss. Optical bistability is observed in the present racetrack-resonator even with a low input optical power, which is attributed to the significant thermal nonlinear optical effect due to the high Q-value and the large negative thermo-optical coefficient of SU-8. Theoretical modeling for the optical bistability is also given and it agrees well with the experimental result.

Keywords (OCIS):

• (130.3120) Integrated optics : Integrated optics devices
• (130.4310) Integrated optics : Nonlinear
• (230.1150) Optical devices : All-optical devices
• (230.4555) Optical devices : Coupled resonators
• (130.7408) Integrated optics : Wavelength filtering devices
• (130.5460) Integrated optics : Polymer waveguides

Tunneling of electromagnetic energy in multiple connected leads usingϵ-Near-Zero Materials

• Abdelwaheb OURIR, Agnes Maurel, and Vincent Pagneux
• received 03/20/2013; accepted 05/17/2013; posted 05/20/2013; Doc. ID 187095
• [full text: PDF (496) KB)]
• Abstract: A realization of a reectionless power splitter is proposed by use of a metamaterial junction. To design thejunction, the electromagnetic wave transmission in multiple connected leads is investigated theoretically andnumerically. A closed analytical form is derived for the scattering matrix of any geometry of the interconnectedleads. We show that the use of a junction made of ϵ-near-zero material (ENZ) allows to produce perfecttransmission. This can be achieved by reducing the area of the ENZ junction (squeezing eect) and by tuningthe widths of the output leads with respect to the input lead. It is also shown that the same eect is obtainedwithout squeezed junction by using a Match Impedance Zero Index Material (MIZIM junction).

Keywords (OCIS):

• (230.1360) Optical devices : Beam splitters
• (240.7040) Optics at surfaces : Tunneling
• (160.3918) Materials : Metamaterials

Quantum Frequency Conversion in Nonlinear Microcavities

• Yuping Huang, Vesselin Velev, and Prem Kumar
• received 02/20/2013; accepted 05/17/2013; posted 05/20/2013; Doc. ID 185606
• [full text: PDF (491) KB)]
• Abstract: We study nonlinear microresonantors as potential implements for quantum frequency conversion of narrow-band optical signals. Using silicon-nitride microdisks as a concrete example, we show that high-conversion performance can be achieved with relatively low pump power. Being chip integratable, such devices hold promise for use in large-scale quantum applications, including atomic-memory based quantum repeaters.

Keywords (OCIS):

• (190.7220) Nonlinear optics : Upconversion
• (270.0270) Quantum optics : Quantum optics
• (140.3945) Lasers and laser optics : Microcavities

High-speed secure key distribution over an optical network based on computational correlation imaging

• Ling-An Wu, Shen Li, Xu-Ri Yao, Wen-Kai Yu, and Guang-Jie Zhai
• received 03/12/2013; accepted 05/17/2013; posted 05/20/2013; Doc. ID 186668
• [full text: PDF (456) KB)]
• Abstract: We present a protocol for an optical key distribution network based on computational correlation imaging, and demonstrate its security. With current technology, the key distribution rate could reach hundreds of Mbit/s with suitable choice of parameters. The setup is simple and inexpensive, and may be employed in real networks where high-speed long-distance secure communication is required.

Keywords (OCIS):

Parametric four-wave mixing using a single cs laser

• Erik Brekke and Laura Alderson
• received 05/07/2013; accepted 05/17/2013; posted 05/21/2013; Doc. ID 189762
• [full text: PDF (502) KB)]
• Abstract: Four-wave mixing can be used to generate coherent output beams, with frequencies difficult to acquire in commercial lasers. Here a single narrow ECDL locked to the two photon 5s-5d transition in rubidium is combined with a tapered amplifier system to produce a high power cw beam at 778 nm and used to generate coherent light at 420 nm through parametric four-wave mixing. This process is analyzed in terms of the intensity and frequency of the incoming beam as well as the atomic density of the sample. The efficiency of the process is currently limited when on resonance due to the absorption of the 420 nm beam, and modifications should allow a significant increase in output power.

Keywords (OCIS):

• (190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
• (190.4410) Nonlinear optics : Nonlinear optics, parametric processes
• (190.7220) Nonlinear optics : Upconversion

Pulse-to-pulse alignment technique based on synthetic-wavelength interferometry of optical frequency combs for distance measurement

• Guanhao Wu, Mayumi Takahashi, Hajime Inaba, and Kaoru Minoshima
• received 05/16/2013; accepted 05/17/2013; posted 05/20/2013; Doc. ID 190707
• [full text: PDF (430) KB)]
• Abstract: A synthetic-wavelength interferometry of optical frequency combs is proposed for the pulse-to-pulse alignment in absolute distance measurement. The synthetic wavelength derived from the virtual second harmonic and the real second harmonic is used to bridge the interference intensity peak finding method and the heterodyne interferometric phase measurement, so that the pulse-to-pulse alignment can be linked directly to single-wavelength heterodyne interferometry. The experimental results demonstrate that the distance measured by peak finding method with micrometer accuracy can be improved to nanometer level by applying the method proposed.

Keywords (OCIS):

• (120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
• (120.3180) Instrumentation, measurement, and metrology : Interferometry
• (120.3930) Instrumentation, measurement, and metrology : Metrological instrumentation
• (320.7100) Ultrafast optics : Ultrafast measurements
• (320.7120) Ultrafast optics : Ultrafast phenomena

Backward optical parametric efficiency in quasi phase matched GaN waveguide presenting stitching faults

• Carlos Montes, Pierre Aschieri, and Marc Micheli
• received 03/20/2013; accepted 05/16/2013; posted 05/16/2013; Doc. ID 187504
• [full text: PDF (389) KB)]
• Abstract: We model a backward mirrorless optical parametric oscillator in afragmented GaN waveguide consisting in a sequence of submicronic periodically poled elements separated by uniformly polarized connection sections representing stitching errors. We find that the generated coherent phase of the backscattered wave locks the phases of the forward propagating waves in such a way that the dynamics is nonintuitivelly as much efficient as for a uniform quasi phase matched waveguide. The best coherence transfer to the backward wave, obtained for perfect group velocity matching of the forward propagating waves, requires a nanoscale poled periodicity which is achieved in GaN through epitaxy.

Keywords (OCIS):

• (190.4410) Nonlinear optics : Nonlinear optics, parametric processes
• (190.4970) Nonlinear optics : Parametric oscillators and amplifiers

Efficient second harmonic generation from mid-infrared to near-infrared regions in silicon-organic hybrid plasmonic waveguides with small fabrication-error sensitivity and large bandwidth

• Eric Cassan, Zhang Jihua, and Xinliang ZHANG
• received 03/14/2013; accepted 05/16/2013; posted 05/17/2013; Doc. ID 187071
• [full text: PDF (1179) KB)]
• Abstract: We theoretically investigate the quadratic nonlinear property of a silicon-organic hybrid plasmonic waveguide with a thin polymer layer deposited on top of a silicon slab and covered by a metal cap. Due to the hybridization property of the waveguide modes, efficient phase-matched second harmonic generation (SHG) from mid-infrared (λ~3.1 μm) to near-infrared wavelength (λ~1.55 μm) is achieved with small fabrication-error sensitivity (225 nm ≤ tolerated waveguide width ≤ 378 nm) and large bandwidth (Δλ = 100 nm). The SHG yield is as large as 8.8% for a pumping power of 100 mW.

Keywords (OCIS):

• (230.4320) Optical devices : Nonlinear optical devices
• (250.5403) Optoelectronics : Plasmonics
• (230.7405) Optical devices : Wavelength conversion devices
• (250.4390) Optoelectronics : Nonlinear optics, integrated optics

Diffractive digital lensless holographic microscopy with fine spectral tuning

• Omel Mendoza-Yero, Enrique Tajahuerce, Jesús Lancis, and Jorge Garcia-Sucerquia
• received 04/26/2013; accepted 05/15/2013; posted 05/20/2013; Doc. ID 189619
• [full text: PDF (2636) KB)]
• Abstract: We experimentally demonstrate an all-diffractive optical set-up for digital lensless holographic microscopy with easy wavelength lines selection and micrometric resolution. In the proposed system, an ultrashort laser pulse is focused with a diffractive lens onto a pinhole of diameter close to its central wavelength to achieve a highly spatially coherent illumination cone as well as a spectral line with narrow width. To scan the complete spectrum of the light source the diffractive lens is displaced with respect to the pinhole plane. The proposed microscopy setup allows us to spectrally separate contributions from different sections of a sample, which may be attractive for several applications in life sciences.

Keywords (OCIS):

• (050.1940) Diffraction and gratings : Diffraction
• (110.0180) Imaging systems : Microscopy
• (090.1995) Holography : Digital holography

Photon-Number-Resolved Detection of Photon-Subtracted Thermal Light

• Jingyun Fan, Yanhua Zhai, Francisco Becerra, Boris Glebov, Jianming Wen, Adriana Lita, Brice Calkins, Thomas Gerrits, Sae Woo Nam, and Alan Migdall
• received 02/22/2013; accepted 05/15/2013; posted 05/21/2013; Doc. ID 185827
• [full text: PDF (888) KB)]
• Abstract: We examine the photon statistics of photonsubtracted thermal light using photonnumberresolved detection. We demonstrate experimentally that the photonnumber distribution transforms from a BoseEinstein distribution to a Poisson distribution as the number of subtracted photons increases. We also show that second and higherorder photon correlation functions can be directly determined from the photonnumberresolved detection measurements of a single optical beam.

Keywords (OCIS):

• (270.5290) Quantum optics : Photon statistics
• (270.5570) Quantum optics : Quantum detectors

Scattering imaging method in transmission x-ray microscopy

• Jian Chen, Kun Gao, Xin Ge, Zhili Wang, Kai Zhang, Youli Hong, Zhiyun Pan, Zhao Wu, Peiping Zhu, Wenbing Yun, and Ziyu Wu
• received 12/11/2012; accepted 05/15/2013; posted 05/15/2013; Doc. ID 176481
• [full text: PDF (1375) KB)]
• Abstract: We present a new x-ray microscopy technique based on structured illumination in a microscope that characterizes the size of the sub-resolution-limit features. The technique is effective for characterizing fine structures substantially beyond the Rayleigh resolution of the microscope. We carried out optical experiments to demonstrate the basic principle of this new microscopy technique. Experimental results show good agreement with theoretical predictions. This technique should find a wide range of important imaging applications with feature size down to nanometer scale, such as bones, oil and gas reservoir rocks, advanced composites and functional nano-devices and materials.

Keywords (OCIS):

• (340.7440) X-ray optics : X-ray imaging
• (340.7460) X-ray optics : X-ray microscopy
• (110.2945) Imaging systems : Illumination design

112-Gb/s data at 37.5-GHz mm-wave frequency delivery over 80-km fiber and 2-m wireless link by H- and V-polarization multiplexing

• Xinying Li, Jianjun Yu, Junwen Zhang, Ze Dong, and Nan Chi
• received 03/08/2013; accepted 05/15/2013; posted 05/16/2013; Doc. ID 186666
• [full text: PDF (1532) KB)]
• Abstract: We experimentally demonstrated the 2×56-Gb/s two-channel polarization-division-multiplexing quadrature-phase-shift-keying (PDM-QPSK) signal delivery over 80-km single-mode fiber-28 (SMF-28) and 2-m Q-band (36-46GHz) wireless link, adopting antenna horizontal- (H-) and vertical-polarization (V-polarization) multiplexing. At the wireless receiver, the classic constant-modulus-algorithm (CMA) equalization based on digital signal processing (DSP) can realize polarization de-multiplexing and remove the crosstalk at the same antenna polarization. For 2-m wireless delivery, the bit-error ratio (BER) of each channel after 80-km SMF-28 transmission can be under 3.8×10-3, while the BER without fiber transmission under 1×10-5. The signal baud rate and performance requirements for optical and wireless devices can be reduced by adopting antenna polarization multiplexing, but meanwhile double antennas and devices are required. The adoption of antenna polarization multiplexing can also increase wireless transmission capacity at the cost of stricter requirements for V-polarization. The isolation is only about 19dB when the V-polarization deviation approaches to 100, which will affect the wireless delivery for high-speed (>50Gb/s) signal.

Keywords (OCIS):

• (060.0060) Fiber optics and optical communications : Fiber optics and optical communications
• (060.5625) Fiber optics and optical communications : Radio frequency photonics

Characterizing weld pool surfaces from polarization state of thermal emissions

• Nicolas CONIGLIO, Alexandre Mathieu, Olivier Aubreton, and Christophe Stolz
• received 04/11/2013; accepted 05/14/2013; posted 05/15/2013; Doc. ID 188724
• [full text: PDF (726) KB)]
• Abstract: In the present work, a vision-based remote sensing methodology is proposed to measure the topography of weld pool surfaces from one single view. Thermal radiations emitted by the hot liquid metal at a wavelength within the arc plasma blind spectral window are acquired by a wavefront division polarimetric system. The refractive index of the liquid metal and the topography of the weld pool surface are inferred from the polarimetric state of the thermal radiations.

Keywords (OCIS):

• (150.6910) Machine vision : Three-dimensional sensing
• (160.3900) Materials : Metals
• (110.5405) Imaging systems : Polarimetric imaging

Optical feedback stabilized laser tuned by single-sideband modulation

• KASSI Samir, Johannes Burkart, and Daniele Romanini
• received 03/28/2013; accepted 05/14/2013; posted 05/14/2013; Doc. ID 187904
• [full text: PDF (1309) KB)]
• Abstract: We report on a sub-kHz linewidth distributed feedback diode laser, optical feedback locked to an ultrastable V-shaped cavity with drift rates below 20 Hz/s. This source is tunable over 1 THz by selecting a cavity mode and using an innovative single-sideband modulation scheme which allows for frequency shifting over up to 40 GHz with mHz accuracy. This robust setup achieves high performance without advanced vibration isolation and will be a powerful tool for metrological applications, in particular a redetermination of the Boltzmann constant by molecular spectroscopy.

Keywords (OCIS):

• (120.3930) Instrumentation, measurement, and metrology : Metrological instrumentation
• (140.3490) Lasers and laser optics : Lasers, distributed-feedback
• (140.4780) Lasers and laser optics : Optical resonators
• (140.3425) Lasers and laser optics : Laser stabilization
• (130.4110) Integrated optics : Modulators

Integral three-dimensional image capture equipment with closely positioned lens array and image sensor

• Jun Arai, Takayuki Yamashita, Masato Miura, Hitoshi Hiura, Naoto Okaichi, Fumio Okano, and Ryohei Funatsu
• received 03/28/2013; accepted 05/13/2013; posted 05/15/2013; Doc. ID 187878
• [full text: PDF (572) KB)]
• Abstract: We have developed a compact integral three-dimensional (3D) imaging equipment that positions the lens array and image sensor in close proximity to each other. In the conventional scheme, a camera lens is used to project the elemental images generated by the lens array onto the image sensor. In contrast, the imaging equipment presented here combines the lens array and image sensor into one unit and makes no use of a camera lens. This scheme eliminates the resolution deterioration and distortion caused by the use of a camera lens and improves, in principle, the quality of the reconstructed 3D image. We captured objects with this imaging equipment and displayed the reconstructed 3D images using display equipment consisting of a liquid crystal panel and a lens array. The reconstructed 3D images were found to have appropriate motion parallax.

Keywords (OCIS):

• (110.0110) Imaging systems : Imaging systems
• (110.6880) Imaging systems : Three-dimensional image acquisition
• (120.2040) Instrumentation, measurement, and metrology : Displays