2-GHz clock quantum key distribution over 260 km of standard telecom fiber

• Shuang Wang, Wei Chen, Jun-Fu Guo, Zhen-Qiang Yin, Hong-Wei Li, Zheng Zhou, Guang-Can Guo, and Zheng-Fu Han
• received 11/21/2011; accepted 02/02/2012; posted 02/02/2012; Doc. ID 158617
• [full text: PDF (1397) KB)]
• Abstract: We report a demonstration of quantum key distribution (QKD) over a standard telecom fiber exceeding 50 dB in loss and 250 km in length. The differential phase shift QKD protocol was chosen and implemented with 2 gigahertz system clock rate. By careful optimization of the 1-bit delayed Faraday-Michelson interferometer and the use of super-conducting single photon detector (SSPD), we achieved a quantum bit error rate below 2.00\% when the fiber length was no more than 205 km, and of 3.45\% for the 260 km length fiber with 52.9 dB loss. We also improved the quantum efficiency of SSPD to obtain high key rate for 50 km length.

Keywords (OCIS):

• (270.0270) Quantum optics : Quantum optics
• (270.5565) Quantum optics : Quantum communications

Singly-resonant optical parametric oscillator based in adhesive-free-bonded periodically-inverted KTiOPO4 plates: oscillation at four wavelengths and terahertz generation

• Pu Zhao, Srinivasa Ragam, Yujie Ding, Ioulia Zotova, Xiaodong Mu, Huai-Chuan Lee, Stephanie Meissner, and Helmuth Meissner
• received 12/12/2011; accepted 02/02/2012; posted 02/02/2012; Doc. ID 159872
• [full text: PDF (406) KB)]
• Abstract: We implemented a singly-resonant optical parametric oscillator based in adhesive-free-bonded periodically-inverted KTiOPO4 plates. It has major advantages such as walk-off compensation and oscillation at four wavelengths. The threshold of the oscillation was measured to be 8 MW/cm2, which is about a factor of 4 lower than that based in two separate KTiOPO4 crystals. By frequency-mixing the dual-wavelength output in GaP stacks, we generated the terahertz radiation at 2.54 THz. The tuning range of the terahertz output was demonstrated to be 2.19-2.77 THz.

Keywords (OCIS):

• (190.2620) Nonlinear optics : Harmonic generation and mixing
• (190.4400) Nonlinear optics : Nonlinear optics, materials

Plasma Assisted Coherent Backscattering for Standoff Spectroscopy

• Luqi Yuan, Konstantin Dorfman, Alexey Zheltikov, and Marlan Scully
• received 11/09/2011; accepted 02/01/2012; posted 02/01/2012; Doc. ID 157863
• [full text: PDF (464) KB)]
• Abstract: We show that an intense coherent backward signal can be generated through a Raman-type four-wave mixing process using forward propagating fields only. Phase matching for this process is achieved through a plasma modulation of the refractive index. Applications to standoff spectroscopy are discussed.

Keywords (OCIS):

• (190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
• (270.1670) Quantum optics : Coherent optical effects

Source location from fluorescence lifetime in disordered media

• Natalia IRISHINA, Miguel MOSCOSO, and Remi Carminati
• received 12/05/2011; accepted 02/01/2012; posted 02/01/2012; Doc. ID 159150
• [full text: PDF (280) KB)]
• Abstract: We show that the inverse source location problem can be solved in a scattering medium using the fluorescence lifetime and realistic {\it a priori} information. The intrinsic ill-posedness of the problem is reduced when the level of scattering increases. This works is a proof of principle demonstrating the high potential of quantitative lifetime imaging in complex media.

Keywords (OCIS):

• (260.2510) Physical optics : Fluorescence
• (290.3200) Scattering : Inverse scattering

Sub-wavelength Imaging Enhancement through a 3-Dimensional Plasmon Lens with Rough Surface

• Shaowu Huang, Haogang Wang, Kung-Hau Ding, and Leung Tsang
• received 12/09/2011; accepted 02/01/2012; posted 02/01/2012; Doc. ID 159689
• [full text: PDF (645) KB)]
• Abstract: In this paper we investigate the sub-wavelength imaging of a 3-dimensional (3-D) plasmon super-lens based on the full vector wave simulations of optical wave propagation and transmission. The transmission fields, time-average Poynting’s vectors, and transfer functions of dipole sources are calculated. Comparisons are made between the results of lenses with flat and periodic/random rough surfaces. We also study the problem of practical imaging system geometry using laser as an illumination source. Results show that the lens with periodic or random roughness can provide improved focus of the transmission fields and the Poynting’s flux. We also show that near field interference effects are reduced as a result of roughness. Examples illustrate that the sub-wavelength imaging is enhanced by roughness in the plasmon super-lens.

Keywords (OCIS):

• (100.6640) Image processing : Superresolution
• (110.0110) Imaging systems : Imaging systems
• (240.6680) Optics at surfaces : Surface plasmons
• (290.5880) Scattering : Scattering, rough surfaces
• (110.4235) Imaging systems : Nanolithography
• (050.6624) Diffraction and gratings : Subwavelength structures

Infrared cylindrical cloak in nanosphere dispersed liquid crystal metamaterial

• Grzegorz Pawlik, Karol Tarnowski, Wiktor Walasik, Antoni Mitus, and Iam Khoo
• received 07/08/2011; accepted 01/31/2012; posted 01/31/2012; Doc. ID 150729
• [full text: PDF (645) KB)]
• Abstract: We present a design of an infrared cylindrical cloak using nanosphere dispersed nematic liquid crystal (NLC) metamaterial following the approach of Shalaev et al. [1]. Cloaking conditions require spatial distribution of liquid crystal birefringence with constant extraordinary index of refraction and radially dependent ordinary index of refraction. An approximate analytical formula for the later is derived. Finite Element (FE) simulations confirm the cloaking effect. Owing to the tunable birefringence of the liquid crystal component, such cloaking material offers the interesting possibilities of real--time control of invisibility. The possibility of experimental realization is briefly discussed.

Keywords (OCIS):

• (230.3720) Optical devices : Liquid-crystal devices
• (160.3918) Materials : Metamaterials
• (230.3205) Optical devices : Invisibility cloaks

Diode-pumped CW eye-safe Nd:YAG laser at 1415 nm laser

• Heechul Lee, Sung Ug Byeon, and Alexei Lukashev
• received 11/08/2011; accepted 01/31/2012; posted 01/31/2012; Doc. ID 157710
• [full text: PDF (367) KB)]
• Abstract: The output performance of the 1415 nm emission in Nd:YAG in a plane-concave cavity under traditional pumping into 4F5/2 level (808 nm) and directly in-band pumping into 4F3/2 level (885 nm) was described. An end-pumped Nd:YAG yielded maximum continuous wave output power of 6.3 W and 4.2 W at 885 nm and 808 nm laser diode (LD) pumping, respectively. To the best of our knowledge this is the first demonstration of such a laser system.

Keywords (OCIS):

• (140.3480) Lasers and laser optics : Lasers, diode-pumped
• (140.3530) Lasers and laser optics : Lasers, neodymium

Laser-filamentation-induced Snowfall in a cloud chamber

• Jingjing Ju, Jiansheng Liu, Cheng Wang, Haiyi Sun, Wentao Wang, Xiaochun Ge, Chuang Li, Seeleang Chin, Ruxin Li, and Zhizhan Xu
• received 11/10/2011; accepted 01/31/2012; posted 01/31/2012; Doc. ID 157795
• [full text: PDF (431) KB)]
• Abstract: Using 1-kHz, 9 mJ femtosecond laser pulses, we demonstrate laser-filamentation-induced spectacular snowfall in a cloud chamber. An intense updraft of warm moist air is generated owing to the continuous heating by the high-repetition filamentation. As it encounters the cold air above, water condensation and snowfall spread unevenly across the whole cloud chamber via convection and cyclone-like action on a macroscopic scale. This indicates that high-repetition filamentation plays a significant role in macroscopic laser-induced water condensation and snowfall.

Keywords (OCIS):

• (000.6850) General : Thermodynamics
• (010.3920) Atmospheric and oceanic optics : Meteorology
• (140.3450) Lasers and laser optics : Laser-induced chemistry
• (010.1615) Atmospheric and oceanic optics : Clouds

Realizable planar gradient-index solar lenses

• Panagiotis Kotsidas, Vijay Modi, and Jeffrey Gordon
• received 12/19/2011; accepted 01/31/2012; posted 01/31/2012; Doc. ID 160233
• [full text: PDF (1761) KB)]
• Abstract: The design and simulation of single-element planar hemispherical gradient-index solar lenses that can accommodate the constraints of realistic materials and fabrication techniques are presented.

Keywords (OCIS):

• (110.2760) Imaging systems : Gradient-index lenses
• (350.6050) Other areas of optics : Solar energy
• (220.1080) Optical design and fabrication : Active or adaptive optics

Perfect blazing with Echelle gratings in TE and TM polarization

• Bernd Kleemann
• received 11/28/2011; accepted 01/31/2012; posted 02/01/2012; Doc. ID 157207
• [full text: PDF (312) KB)]
• Abstract: Perfect blazing with echelle gratings in a high order Littrow mount exists not only with TM polarization as it can perhaps be assumed, but also with TE and TM polarizations simultaneously. This finding contradicts with a heuristic explanation as why perfect blazing is not possible simultaneously in TE and TM polarizations given in (E. G. Loewen and E. Popov, Diffraction Gratings and Applications, New York: Marcel Dekker (1997)). As a matter of fact, in the ideal case of infinite conductivity, light is diffracted in the Littrow order with 100% efficiency for both polarization states. For metal gratings a small loss occurs. Three conditions are necessary for perfect blazing: (1) the apex angle must be very close to 90°, (2) a specific Littrow order has to be used, and (3) the blaze angle has to be 4° to 6° larger than the Littrow angle. The last property is particularly intriguing since typically the difference between the two angles is smaller than 1.0°.

Keywords (OCIS):

• (050.0050) Diffraction and gratings : Diffraction and gratings
• (050.1950) Diffraction and gratings : Diffraction gratings
• (050.1960) Diffraction and gratings : Diffraction theory

Dynamic Brillouin gratings permanently sustained by chaotic lasers

• Marco Santagiustina and Leonora Ursini
• received 08/10/2011; accepted 01/31/2012; posted 02/01/2012; Doc. ID 152587
• [full text: PDF (398) KB)]
• Abstract: A method to induce permanent and localized dynamic Brillouin gratings in optical fibers is introduced.The thumbtack correlation of chaotic laser signals is exploited. A numerical analysis of two possible experimental setups is performed, demonstrating the possibility to obtain a permanent grating in a polarization maintaining fiber.

Keywords (OCIS):

• (060.2370) Fiber optics and optical communications : Fiber optics sensors
• (060.4370) Fiber optics and optical communications : Nonlinear optics, fibers
• (290.5900) Scattering : Scattering, stimulated Brillouin

An aperiodic interferometer for six degrees of freedom position measurement

• David Burt, Phillip Dobson, Kevin Docherty, Christopher Jones, Richard Leach, Stephen Thoms, John Weaver, and Yuan Zhang
• received 01/09/2012; accepted 01/30/2012; posted 01/31/2012; Doc. ID 159512
• [full text: PDF (519) KB)]
• Abstract: We present a new class of interferometer system which is capable of simultaneous measurement of absolute position and rotation in all six degrees of freedom (DOF) with nanometre precision. This novel capability is due to the employment of a system of interference fringes that is not periodic. One of the key strengths offered by this new approach is that the absolute position of the system can be determined with a single measurement, rather than by counting fringes during displacement from a known location. The availability of a simultaneous measurement of all six DOF eliminates many problems associated with conventional interferometry.

Keywords (OCIS):

• (120.3180) Instrumentation, measurement, and metrology : Interferometry
• (120.3930) Instrumentation, measurement, and metrology : Metrological instrumentation

Single-shot time-frequency imaging spectroscopy using an echelon mirror

• Hiroyuki Sakaibara, Yuki Ikegaya, Ikufumi Katayama, and Jun Takeda
• received 12/19/2011; accepted 01/30/2012; posted 02/01/2012; Doc. ID 160127
• [full text: PDF (967) KB)]
• Abstract: We demonstrate single-shot time-frequency imaging spectroscopy with an echelon mirror, for measuring ultrashort laser pulses as well as ultrafast responses of materials using the same optical setup. The echelon mirror produces a spatially encoded time delay for the probe pulse, thereby both the probe and pump pulses are focused on samples with small spot size. Using the optical Kerr gate apparatus, we successfully mapped the time-frequency images of ultrashort laser pulses, and subsequently evaluated the chirp characteristics with the phase-retrieval procedure on a single-shot basis. By simply replacing the Kerr medium with samples, we could also visualize the phonon-polariton oscillations in ferroelectric LiNbO3.

Keywords (OCIS):

• (300.6500) Spectroscopy : Spectroscopy, time-resolved
• (320.1590) Ultrafast optics : Chirping
• (320.7100) Ultrafast optics : Ultrafast measurements
• (320.7150) Ultrafast optics : Ultrafast spectroscopy

Hybrid light-emitting devices based on phosphorescent platinum(II) complex sensitized CdSe/ZnS QDs

• Gang Cheng, Wei Lu, Yong Chen, and Chi-Ming Che
• received 12/26/2011; accepted 01/30/2012; posted 02/01/2012; Doc. ID 160516
• [full text: PDF (678) KB)]
• Abstract: We report on hybrid light-emitting devices based on the emission of phosphorescent sensitized colloidal CdSe/ZnS quantum dots (QDs). Emission lifetime measurements demonstrated that the energy transfer (ET) from square-planar platinum(II) complex [4-CF3-(N^C^N)PtCCC6H4-4'-F](N^CH^N=1,5-bis(2'-pyridyl)benzene) (Pt-2) to QDs is more efficient than that from octahedral iridium(III) complex bis[(4,6-difluorophenyl)pyridinato-N,C2]-(picolinato)iridium (FIrpic). This different ET efficiency might be attributed to the different spatial structures between Pt-2 and FIrpic. Pure red emission with Commission Internationale De L´Eclairage coordinates of (0.66, 0.33) and maximum external quantum efficiency of 2.08% and white emission with power efficiency of 3.15 lm/W were realized at different concentrations of Pt-2 and QDs, respectively.

Keywords (OCIS):

• (230.3670) Optical devices : Light-emitting diodes
• (260.2160) Physical optics : Energy transfer
• (330.1690) Vision, color, and visual optics : Color
• (160.4236) Materials : Nanomaterials

Redistributing energy flow in the focal field of an azimuthally polarized beam with rotationally symmetric sector-shaped obstacles

• Xiangyang Jiao, Sheng Liu, Qian Wang, Xuetao Gan, Peng Li, and Jianlin Zhao
• received 11/11/2011; accepted 01/29/2012; posted 02/01/2012; Doc. ID 158102
• [full text: PDF (1364) KB)]
• Abstract: The redistribution of transversal energy flow in the focal field is represented by obstructing an azimuthally polarized beam with odd fold symmetric sector-shaped obstacles. Several energy flow rings which can finally transport the absorptive particles into fixed locations are formed in the focal plane. Furthermore, the local polarization state of the focal field is also modified by use of the rotationally symmetric obstacles. This kind of energy flow may have wide applications in optical trapping and manipulation.

Keywords (OCIS):

• (050.1960) Diffraction and gratings : Diffraction theory
• (260.5430) Physical optics : Polarization
• (350.4855) Other areas of optics : Optical tweezers or optical manipulation

Robust laser frequency stabilization by serrodyne modulation

• Ralf Kohlhaas, Thomas Vanderbruggen, Simon Bernon, Andrea Bertoldi, Arnaud Landragin, and Philippe BOUYER
• received 01/19/2012; accepted 01/29/2012; posted 01/30/2012; Doc. ID 161503
• [full text: PDF (312) KB)]
• Abstract: We report the relative frequency stabilization of a distributed feedback erbium-doped fiber laser on an optical cavity by serrodyne frequency shifting. A correction bandwidth of 2.3 MHz and a dynamic range of 220 MHz are achieved, which leads to a strong robustness against large disturbances up to high frequencies. We demonstrate that serrodyne frequency shifting reaches a higher correction bandwidth and lower relative frequency noise level compared to a standard acousto-optical modulator based scheme. Our results allow to consider promising applications in the absolute frequency stabilization of lasers on optical cavities.

Keywords (OCIS):

• (000.2170) General : Equipment and techniques
• (140.4780) Lasers and laser optics : Optical resonators
• (230.2090) Optical devices : Electro-optical devices
• (140.3425) Lasers and laser optics : Laser stabilization

n-ZnO/LaAlO3/p-Si heterojunction for visible-blind UV detection

• D. S. Tsai, C. F. Kang, H. H. Wang, C. A. Lin, J. J. Ke, Y. H. Chu, and Jr-Hau He
• received 11/16/2011; accepted 01/29/2012; posted 01/30/2012; Doc. ID 158336
• [full text: PDF (753) KB)]
• Abstract: A visible-blind ultraviolet (UV) photodetector (PD) using a double heterojunction of n-ZnO/LaAlO3 (LAO)/p-Si was demonstrated. Inserted LAO layers exhibit electrical insulating properties and serve as blocking layers for photoexcited elections from p-Si to n-ZnO, leading to a high rectification ratio (~103 at ±2 V) and a visible-blind UV detectivity of the n-ZnO/LAO/p-Si PDs due to the high potential barrier between LAO and p-Si layers (~2.0 V). These results support the n-ZnO/LAO/p-Si PDs for the use in the visible-blind UV PDs in a visible-light environment.

Keywords (OCIS):

• (040.5160) Detectors : Photodetectors
• (040.7190) Detectors : Ultraviolet
• (160.1890) Materials : Detector materials

Realizable differential matrices for depolarizing media

• Thomas Germer
• received 10/10/2011; accepted 01/28/2012; posted 02/01/2012; Doc. ID 156124
• [full text: PDF (242) KB)]
• Abstract: The evolution of a Stokes vector through depolarizing media is considered. A general form for the differential matrix is derived that is appropriate in the presence of depolarization, and is parameterized in a manner that ensures that it yields, upon integration, a valid Mueller matrix for any choice of parameters with some limited constraints. The form expands the more limited form for a non-depolarizing matrix given by Azzam [J.Opt. Soc. Am. 68, 1756–1767 (1978)] and which was extended recently by others to include depolarization. A decomposition for a Mueller matrix is proposed, based upon the parameters for the differential matrix, which when integrated over unit length, would yield the same Mueller matrix.

Keywords (OCIS):

• (120.2130) Instrumentation, measurement, and metrology : Ellipsometry and polarimetry
• (230.5440) Optical devices : Polarization-selective devices
• (260.5430) Physical optics : Polarization

Ultrafast three-dimensional submicron-resolution readout of coherent optical-phonon oscillations with shaped unamplified laser pulses at 20 MHz

• Alexander Lanin, Andrei Fedotov, and Aleksei Zheltikov
• received 10/27/2011; accepted 01/28/2012; posted 01/30/2012; Doc. ID 157236
• [full text: PDF (691) KB)]
• Abstract: An ultrafast three-dimensional readout of coherent optical-phonon oscillations from a diamond film is demonstrated using temporally and spectrally shaped ultrashort laser pulses, delivered by a compact, oscillator-only laser system. This system integrates a long-cavity ytterbium-fiber-laser-pumped 30-fs Cr: forsterite oscillator with a photonic-crystal-fiber soliton frequency shifter and a periodically poled lithium niobate spectrum compressor, providing coherent Raman excitation and time-delayed interrogation of optical phonons in diamond at a 20-MHz repetition rate with a submicron spatial resolution.

Keywords (OCIS):

• (190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
• (190.5650) Nonlinear optics : Raman effect

High-speed addition/subtraction/complement/doubling of quaternary numbers using optical nonlinearities and DQPSK signals

• Jian Wang, Scott Nuccio, Jeng-Yuan Yang, Xiaoxia Wu, Antonella Bogoni, and Alan Willner
• received 11/30/2011; accepted 01/27/2012; posted 01/30/2012; Doc. ID 159138
• [full text: PDF (516) KB)]
• Abstract: We propose a simple approach to implementing multiple arithmetic functions of quaternary numbers using optical nonlinearities and differential quadrature phase-shift keying (DQPSK) signals. By adopting 100-Gbit/s DQPSK signals (A, B) and exploiting non-degenerate four-wave mixing (FWM) for addition/subtraction and degenerate FWM for complement in a single highly nonlinear fiber (HNLF), we demonstrate 50-Gbaud/s simultaneous quaternary addition (A+B), dual-directional subtraction (A-B, B-A), and complement (-A, -B). Power penalties less than 4 dB (addition), 3 dB (dual-directional subtraction), and 2 dB (complement) are observed at a bit-error rate (BER) of 10-9.

Keywords (OCIS):

• (190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
• (200.3760) Optics in computing : Logic-based optical processing