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Chinese Optics Letters 第12卷 第1期

Author Affiliations
Abstract
Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
A modified extended-ptychographical-iterative-engine (ePIE) algorithm is proposed to overcome the disadvantages of ePIE technique and reduce the influence of stage hysteresis or backlash error. The exit wave of a rotatable “screen” illuminated by plane wave is used as the illumination on the specimen, and the complex transmission functions of the rotatable object and specimen can be simultaneously reconstructed. Compared with the standard x-y scanning PIE algorithm, the proposed algorithm can completely avoid the influence of stage hysteresis (or backlash error). The proposed algorithm also has higher convergence speed and better accuracy than the standard PIE algorithm.
050.1970 Diffractive optics 100.5070 Phase retrieval 070.0070 Fourier optics and signal processing 110.3010 Image reconstruction techniques 
Chinese Optics Letters
2014, 12(1): 010501
Author Affiliations
Abstract
In holographic encryption, double random-phase encoding in the Fresnel domain (DRPEiFD) is a prevalent encryption method because it is lensless and secure. However, noises bring adverse effects during decryption. In this letter, we introduce quick-response (QR) coding during encryption to resist noises. We transform the original information into a QR code and then encrypt the code as a hologram through DRPEiFD. To retrieve the input, we decrypt the hologram in the opposite manner to the encryption and subsequently obtain a QR code with noises. By scanning this code with proper applications in smartphones, we can obtain a noise-free retrieval. Numerical experiments and images scanned by a smartphone are shown to validate our proposed method.
060.4785 Optical security and encryption 070.4560 Data processing by optical means 090.1760 Computer holography 100.4998 Pattern recognition, optical security and encryption 
Chinese Optics Letters
2014, 12(1): 010601
Author Affiliations
Abstract
An optical fiber sensor for ultrathin layer sensing based on short-range surface plasmon polariton (SRSPP) is proposed, and the sensing characteristics are theoretically analyzed. Simulation results indicate that even for a detecting layer much thinner than the vacuum wavelength, a resolution as high as 3.7\times 10-6 RIU can be obtained. Moreover, an average thickness-detection sensitivity of 6.2 dB/nm is obtained, which enables the sensor to detect the thickness variation of the ultrathin layer up to tens of nanometers. The sensitive region of thickness could be adjusted by tuning the structure parameters.
060.2370 Fiber optics sensors 250.5403 Plasmonics 280.1415 Biological sensing and sensors 
Chinese Optics Letters
2014, 12(1): 010602
Author Affiliations
Abstract
The dispersion compensation properties of dual-concentric core photonic crystal fibers are theoretically investigated in this letter. The effects of geometric structure on the dispersion properties of dual-concentric core photonic crystal fibers are carefully studied by finite element method. The first layer of holes around the core area is enlarged in a new manner with the near-core point fixed. Considering the tradeoff among several parameters, results show that the dispersion compensation wavelength and strength can be tuned to desired values by constructing an appropriate design of the geometric structure of photonic crystal fibers.
060.5295 Photonic crystal fibers 230.2035 Dispersion compensation devices 
Chinese Optics Letters
2014, 12(1): 010603
Author Affiliations
Abstract
A quasi-cyclic low-density parity check (QC-LDPC) code is constructed by an improved stability of the shortest cycle algorithm for 160-Gb/s non-return zero differential quadrature phase shift keying (NRZ-DQPSK) optical transmission system with the fiber-based optical parametric amplifier (FOPA). The QC-LDPC code with stability of the shortest cycle reduces the bit error ratio (BER) to 10-14 and restrains the error floor effectively.
060.4510 Optical communications 220.4830 Systems design 190.4223 Nonlinear wave mixing 
Chinese Optics Letters
2014, 12(1): 010604
Author Affiliations
Abstract
We report a 3.75-Gb/s visible light communication (VLC) system thatusessingle-carrier frequency-domain equalization (SC-FDE) based on a single red–green–blue (RGB) light-emitting diode (LED), with the measured bit error rates (BERs) under a pre-forward-error-correction threshold of 3.8 \times 10-3. The fundamental characteristics of an RGB-LED-based VLC system are measured. We also compare SC-FDE with OFDM in terms of peak-to-average power ratio and BER performance, which shows that SC-FDE outperforms the OFDM modulation scheme.
060.0060 Fiber optics and optical communications 060.4080 Modulation 060.2605 Free-space optical communication 
Chinese Optics Letters
2014, 12(1): 010605
Author Affiliations
Abstract
We propose an integral imaging system that uses three lens arrays, including two convex lens arrays and a concave lens array. Compared with the conventional integral imaging system, the proposed system can remarkably enhance the viewing angle. The maximum viewing angle can be enlarged to 48o, which is 4.8 times wider than that of the conventional system. The principle of the proposed system is elucidated, and the experimental results are presented in this letter.
110.6880 Three-dimensional image acquisition 080.2740 Geometric optical design 120.4640 Optical instruments 
Chinese Optics Letters
2014, 12(1): 011101
Author Affiliations
Abstract
We demonstrate a series of experiments on imaging through both stationary aberrating media and moving aberrating media by computational ghost imaging (CGI). An incoherent LED light source is used instead of the common pseudothermal light source (laser light passing through a rotating ground glass). A digital micromirror device is used as a simple spatial light modulator to perform CGI. Moreover, a digital filtering method is introduced to improve imaging quality through moving aberrating media. This imaging modality may have potential applications in medicine and astronomy.
110.0113 Imaging through turbid media 110.1758 Computational imaging 
Chinese Optics Letters
2014, 12(1): 011102
Author Affiliations
Abstract
Graphene saturable absorber (SA) is used as the passive Q-switcher of a 0.9-\mu m solid-state laser. When the laser medium is a Nd:La0.11Y0.89VO4 crystal, the initial transmittance of the graphene SA is 78%; at an absorbed pump power of 7.62 W, the maximum average output power, largest pulse energy, and minimum pulse width are 0.62 W, 2.58 μJ, and 84 ns, respectively. This study shows that graphene is a promising and cost-saving SA for 0.9-\mu m pulse generation.
140.3380 Laser materials 140.3530 Lasers, neodymium 140.3540 Lasers, Q-switched 
Chinese Optics Letters
2014, 12(1): 011401
Author Affiliations
Abstract
1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
A mathematical model of the mirror misalignment of a four-equal-sided nonplanar ring cavity is established in this letter. The variations in the optical axis are discussed through an augmented 6 × 6 ray matrix formulation. Numerical analysis shows that the self-consistence of the optical axis can always be obtained because of the thermal effects in any case of mirror misalignment. For a fabricated design, optical axis variations always appear. The influence of thermal effects (i.e., pump power) on optical axis variations are studied. The tilt of the optical axis remains constant, whereas its decentration varies with pump power. Further analysis shows that the actual closing point of the optical axis moves close to the ideal point as the pump power increases. The theoretical analysis proposed is proven and validated by the experimental results.
140.3410 Laser resonators 140.3560 Lasers, ring 140.3570 Lasers, single-mode 
Chinese Optics Letters
2014, 12(1): 011402
Author Affiliations
Abstract
Optical tweezers with a low numerical aperture microscope objective is used to manipulate the microspheres at the water-air interface. In this letter, we determine the optimal optical trap for the lateral manipulation of microspheres at a water-air interface. The experimental results show that the trapping force is influenced by the expansion of the trapping beam at the back aperture of the objective. The optimal filling ratio of 0.65 is suggested for lateral optical manipulation at the water-air interface. The lateral trapping forces at the water-air interface are theoretically investigated with the ray-optics model. The numerical results show that the lateral trapping forces can be changed by shrinking the diameter of the trapping laser beam. The numerical results are in accordance with the experimental results.
140.7010 Laser trapping 170.4520 Optical confinement and manipulation 080.5692 Ray trajectories in inhomogeneous media 
Chinese Optics Letters
2014, 12(1): 011403
Author Affiliations
Abstract
K3Gd(PO4)2:Tb3+ phosphors are synthesized by the solid reaction method, and the phases and luminescence properties of the obtained phosphors are well characterized. The emission spectra of K3Gd(PO4)2:Tb3+ exhibit the typical emissions of Tb3+. Concentration quenching of Tb3+ is not observed in K3Gd(PO4)2:Tb3+, likely because the shortest average distance of Tb3+–Tb3+ in K3Gd(PO4)2:Tb3+ is adequately long such that energy transfer between Tb3+–Tb3+ ions cannot take place effectively. This result indicates that K3Tb(PO4)2 phosphors have potential application in near ultraviolet (n-UV)-convertible phosphors for white light-emitting diodes.
160.0160 Materials 230.0230 Optical devices 300.0300 Spectroscopy 
Chinese Optics Letters
2014, 12(1): 011601
Author Affiliations
Abstract
Presently, energy conservation and carbon dioxide emission reduction have become increasingly important because of global warming. Using solar energy, which is considered as one of the most important renewable energy sources, does not only decrease the consumption of fossil fuels, but also slows down the pace of global warming. For indoor illumination, our team has developed a technique called "Natural Light Illumination." Instead of using solar cells, our system directly guides sunlight into the interior of a structure. However, the efficiency of the light-collecting module is still low. To address this problem, we propose a new light-collecting module based on a prism array structure with high efficiency. We use optical simulation tools to design and simulate the efficiency of the module, which is found to be 57%. This value is higher than that of the original concentrator (i.e., 11%).
220.2740 Geometric optical design 220.1770 Concentrators 220.1770 Concentrators 
Chinese Optics Letters
2014, 12(1): 012201
Author Affiliations
Abstract
College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
The backscattering characteristics of optical microfiber (OM) are experimentally studied by controlling heating temperature and cooling method during the OM fabrication process. OM samples with various reflectances from 0.1% to 1% are achieved. An OM with waist length of 5 mm, waist diameter of 1 \mu m, and approximately 0.5% reflectance is used as the end reflector of a fiber Fabry-Perol (F-P) interferometer. A piezoelectric ceramic transducer (PZT) fiber phase modulator is used to test the sensing performance of the fiber F-P interferometer. Experimental results verify that the OM with low reflectance can be used as a reflector in the F-P interferometer.
230.0230 Optical devices 230.4000 Microstructure fabrication 060.2370 Fiber optics sensors 
Chinese Optics Letters
2014, 12(1): 012301
Author Affiliations
Abstract
High-performance blue organic light-emitting diodes (OLEDs) are developed. A concept of using multiple-emissive layer (EML) configuration is adopted. In this letter, bis(2-methyl-8-quinolinolate)-4-(phenylphenolato)Al (BAlq) and 9,10-di(naphtha-2-yl)anthracene (ADN), which serve n- and p-type EMLs, respectively, are used to evaluate and demonstrate the multi-EML concept for blue OLEDs. The thickness effect of individual EMLs and the number of EMLs, e.g., triple and quadruple EML components, on the power efficiency of blue OLEDs are systematically investigated. To illustrate the point, the total thickness of the emissive region in different blue OLEDs are kept contact at 30 nm for comparison. The power efficiency of blue OLEDs with a quadruple EML structure of BAlq/ADN/BAlq/ADN is about 40% higher than that of blue OLEDs having a single EML unit. The Commission Internationale deL'eclairage color coordinates of multi-EML OLEDs have values that represent the average of blue emissions from individual EMLs of BAlq and ADN.
230.0230 Optical devices 230.3670 Light-emitting diodes 230.0250 Optoelectronics 160.4890 Organic materials 130.5990 Semiconductors 
Chinese Optics Letters
2014, 12(1): 012302
Author Affiliations
Abstract
The widespread use and application of in-plane switching liquid crystal displays (IPS-LCDs) is limited by their slow response. In this letter, a fast-response IPS-LCD with a protrusion structure is proposed. The gray-to-gray response time of the IPS-LCD is reduced by 20% to 30%. The difference in cell gap induced by the protrusion accounts for the faster response. Moreover, the viewing angle and gamma shift of the proposed IPS-LCD are simulated and found to be better than that of conventional IPS-LCDs.
230.3720 Liquid-crystal devices 230.2090 Electro-optical devices 160.3710 Liquid crystals 
Chinese Optics Letters
2014, 12(1): 012303
Author Affiliations
Abstract
A new plasmonic nanolens that can be tuned by varying the circular structure into an elliptical annulus and the aspect ratio from 1 to 0.1 and 1 to 2, respectively, is proposed. Using the rigorous finite-difference and time-domain algorithm, we find that when the aspect ratio ranges from 1 to 0.1, a good linear relationship exists between the aspect ratio and focusing spot size at the full-width at half-maximum in the x- and y-directions, respectively. The corresponding calculated FWHM ranges from 96 × 126 (nm) to 15 \times 52 (nm) (Full Width at Half Maximum).
240.6680 Surface plasmons 310.6628 Subwavelength structures,nanostructures 000.4430 Numerical approximation and analysis 350.5730 Resolution 
Chinese Optics Letters
2014, 12(1): 012401
Author Affiliations
Abstract
Tunneling is studied in two main single-photon avalanche diode (SPAD) topologies, which are n-tub guard ring (NTGR) and p-tub guard ring (PTGR). Device simulation, I-V measurements, and dark count calculations and measurements demonstrate that tunneling is the main source of noise in NTGR, but it is less dominant in PTGR SPADs. All structures are characterized with respect to dark noise, photon detection probability, timing jitter, afterpulsing probability, and breakdown voltage. Noise performance is disturbed because of tunneling, whereas jitter performance is disturbed because of the short diffusion time of photo-generated minority carriers in NTGR SPADs. The maximum photon detection probability is enhanced because of an improvement in absorption thickness.
250.1345 Avalanche photodiodes (APDs) 250.5403 Plasmonics 
Chinese Optics Letters
2014, 12(1): 012501
Author Affiliations
Abstract
Small particle light scattering can produce light with polarization characteristics different from those of the incident beam. An analytical solution to the scattering by a spheroid with inclusion for an on-axis polarized Gaussian beam incidence is provided within the generalized Lorenz-Mie theory framework. The shapes of the inclusion can be spherical, confocal spheroid, or non-confocal spheroid. The Muller scattering matrix elements are computed for plane wave incidence or Gaussian light beam incidence. The effect of the size and shape of the inclusion or the coating on the polarized Gaussian light scattering characteristics by a spheroidal water coating aerosol particle are computed and analyzed.
290.1090 Aerosol and cloud effects 290.1350 Backscattering 290.5850 Scattering, particles 290.5855 Scattering, polarization 
Chinese Optics Letters
2014, 12(1): 012901
Author Affiliations
Abstract
Head-up displays (HUDs) enable a pilot to manage aircraft activities by facilitating simultaneous access to the flight instrument data and to the outside scene. However, HUDs can also distract a pilot. This study shows that HUD luminance non-uniformity may force inappropriate distribution of attention between the events shown on HUD symbology and the outside scene because of the resultant differential contrast in the display area. Results of statistical analysis demonstrate considerable effects of HUD image luminance and ambient luminance, as well as their interaction, on the detection of events displayed on an HUD and the outside scene.
330.0330 Vision, color, and visual optics 350.0350 Other areas of optics 110.0110 Imaging systems 
Chinese Optics Letters
2014, 12(1): 013301
Author Affiliations
Abstract
A four-channel multilayer Kirkpatrick-Baez (KB) microscope is developed for the 8-keV X-ray imaging of experiments on laser inertial confinement fusion (ICF). A periodic multilayer that works at 8 keV and with a grazing incidence angle of 1.0o is coated on reflective surfaces to achieve a spatial resolution higher than 5 \mu m and an effective solid angle higher than ~10-7 sr. A precise assembly is realized by a conical reference cone to couple with an X-ray framing camera. This study provides detailed information on an optical and multilayer design, assembly method, and experimental results with a Cu X-ray tube. The instrument provides a high-resolution and high-throughput X-ray image for backlit or self-emission imaging of laser plasma at Cu K\alpha line radiation in Shenguang series laser facilities.
340.7440 X-ray imaging 310.6845 Thin film devices and applications 
Chinese Optics Letters
2014, 12(1): 013401