Accepted papers to appear in an upcoming issue
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Wavelet-based depth-of-field extension, accurate autofocusing and particle pairing for digital inline particle holography
- received 08/02/2013; accepted 11/27/2013; posted 12/03/2013; Doc. ID 194697
- [full text: PDF (5003) KB)]
- Abstract: Depth-of-field extension and accurate 3D position location are two important issues in digital holography for particle characterization and motion tracking. We propose a method of locating the axial positions of both opaque and transparent objects in the reconstructed 3D field in the wavelet domain. The spatial-frequency property of the reconstructed image is analyzed from the viewpoint of the point spread function of the digital in-line holography. The reconstructed image is decomposed into high and low frequency subimages. By using the variance of the image gradient in the subimages as focus metrics, the depth-of-field of the synthesis image can be extended with all the particles focalized, and the focal plane of the object can be accurately determined. The method is validated by both simulated and experimental holograms of transparent spherical water droplets and the opaque nonspherical coal particles. The extended focus image is applied to the particle pairing in digital holographic particle tracking velocimetry (DHPTV) to obtain the 3D vector field.
- (090.2880) Holography : Holographic interferometry
- (100.6890) Image processing : Three-dimensional image processing
- (120.7250) Instrumentation, measurement, and metrology : Velocimetry
- (090.1995) Holography : Digital holography
Two-mode Mode Multiplexer/Demultiplexer in Polymer Planar Waveguide
- received 08/23/2013; accepted 11/26/2013; posted 11/27/2013; Doc. ID 196312
- [full text: PDF (597) KB)]
- Abstract: We proposed a two-mode multiplexer/demultiplexer device using unbalanced Mach Zehnder Interferometer with Y junctions. The proposed device had simulated extinction ratio greater than 30 dB for both mux and demux operations with an excess loss of 0.17 dB. The device was fabricated using polymer materials and characterized via a tunable laser source over the wavelength 1545 – 1555 nm. The experimental performance of the device was closely agreed with the theoretical prediction. The proposed device is easy to fabricate and will have applications in future multimode transmission systems for further extending fiber transmission capacity.
- (060.4230) Fiber optics and optical communications : Multiplexing
- (130.3120) Integrated optics : Integrated optics devices
- (130.5460) Integrated optics : Polymer waveguides
Tuning the Lateral Leakage Loss of TM-like modes in Shallow-etched Waveguides using Liquid Crystals
- received 09/30/2013; accepted 11/26/2013; posted 11/27/2013; Doc. ID 198633
- [full text: PDF (687) KB)]
- Abstract: We examine the tuning effect a liquid crystal cladding has on the lateral leakage loss of TM-like modes in shallow-etched waveguides. For such waveguides with an air cladding, the guided TM-like mode and the unguided cladding TE-like mode can only be phase matched at precisely one angle. We find that for an anisotropic cladding such as a liquid crystal, this phase matching is now possible for a range of angles. Each of these angles corresponds to a given orientation of the molecules in the liquid crystal cladding. We show that the waveguide width at which the minimum in leakage loss occurs can be changed by varying the orientation of the liquid crystal cladding. We find different tuning regimes, identify a suitable tuning range and discuss the feasibility of tunable leakage loss experiments.
- (130.3120) Integrated optics : Integrated optics devices
- (230.2090) Optical devices : Electro-optical devices
- (230.7390) Optical devices : Waveguides, planar
- (130.4815) Integrated optics : Optical switching devices
Study on optimal strategy for fabrication of large aperture aspheric surface
- received 10/04/2013; accepted 11/26/2013; posted 11/27/2013; Doc. ID 197128
- [full text: PDF (745) KB)]
- Abstract: Aspheric surface is widely used because of its desirable characteristics. It can obtain nearly perfect imaging quality with less optical elements, and reduce the size and mass of optical system. Various machine systems have been developed based on modern deterministic polishing technologies for large aperture aspheric surfaces. Several factors affect the final precision of large aperture aspheric surface, such as the velocity limit of the machine, and path designed, among others. Excess velocity, which will be truncated by the computer numerical control system automatically, may cause the dwell time to deviate from the desired location. When a path designed on a two-dimensional surface map with equidistant pitch is projected onto an aspheric surface, the pitch changes as a result of the varied curvature of the aspheric surface. It may affect the removal map and cause some ripple errors. A multi-region distribution strategy, which includes velocity checking, is proposed in this study to avoid exceeding the velocity limits. The strategy can be used to modify local error and edge effect. A three-dimensional spiral path generation method is also presented using an iterative method to ensure the uniformity in the space length of the adjacent circle of the spiral path. This process can reduce the ripple error caused by the overlapping of tool paths. A polishing experiment was conducted, and the results prove the validity of the strategies.
- (220.4610) Optical design and fabrication : Optical fabrication
- (220.5450) Optical design and fabrication : Polishing
- (240.5450) Optics at surfaces : Polishing
High-speed scanning stroboscopic fringe patterns projection technology for 3D shape precision measurement
- received 09/25/2013; accepted 11/26/2013; posted 11/27/2013; Doc. ID 198090
- [full text: PDF (2364) KB)]
- Abstract: A high-speed scanning stroboscopic fringe patterns projection system is designed. A high-speed rotating polygon mirror and a line-structured laser cooperate to produce stable and unambiguous stroboscopic fringe patterns. The system combines the rapidity of the grating projection with the high accuracy of the line-structured laser light source. The fringe patterns have fast frame rate, great density, high precision, and high brightness, with conveniences and accuracy in adjusting brightness, frequency, line width, and amount of phase shift. The characteristics and the stability of this system are verified by experiments. Experiment results show that the finest line width can reach 40 um and that the minimum fringe cycle is 80 um. Circuit modulation makes the light source system flexibly adjustable, easy to real-time control and convenient to project various fringe patterns. Combined with different light intensity adjustment algorithms and 3D computation models, the 3D topography with high accuracy can be obtained for objects measured under different environments or objects with different sizes, morphologies, and optical properties. The proposed system shows a broad application prospect for fast 3D shape precision measurements, particularly in the industrial field of 3D online detection for precision devices.
- (110.6880) Imaging systems : Three-dimensional image acquisition
- (120.6650) Instrumentation, measurement, and metrology : Surface measurements, figure
- (110.2650) Imaging systems : Fringe analysis
Wave-front analysis applied in the flat stitching of large-aperture photon sieves
- received 09/23/2013; accepted 11/26/2013; posted 11/27/2013; Doc. ID 198121
- [full text: PDF (1272) KB)]
- Abstract: Large aperture can be easily achieved by employing photon sieves fabricated on the stitching membrane which are suitable for packaging and folding. We do research to find out the image quality degradation caused by stitching. Simulation has been done to investigate the behavior of the stitching wave front. 10×10 pieces have been concerned as a model, and its wave-front error has been evaluated using the wave-front method discussed in this work. Besides, we find that the errors in outer zones are more remarkable than the inner ones of the same photon sieve. Testing and alignment directions based on this method are also mentioned in this work.
- (050.1970) Diffraction and gratings : Diffractive optics
- (110.3000) Imaging systems : Image quality assessment
- (110.4100) Imaging systems : Modulation transfer function
- (220.1140) Optical design and fabrication : Alignment
Plasmon focusing in short gold sphere nanochains for surface enhanced Raman scattering
- received 09/06/2013; accepted 11/26/2013; posted 11/26/2013; Doc. ID 197287
- [full text: PDF (2341) KB)]
- Abstract: Power-flow focusing in metal nanostructures is attracting a growing attention to design efficient and tunable substrates for surface enhanced Raman spectroscopy (SERS), and to propose a more reliable alternative to random surfaces for single-molecule sensing. In this report, finite-difference time-domain simulations were used to explore the near-field amplification features of short chains of gold (Au) nanospheres. Five-sphere chains were shown to induce stronger field enhancements than dimers or infinite chains due to a more efficient trapping and focusing of the incident energy. In addition, interaction with a suitably tuned SiO2/Au double-layer substrate was demonstrated to largely widen the resonance’s bandwidth, meeting another practical need for SERS.
- (240.6680) Optics at surfaces : Surface plasmons
- (290.5850) Scattering : Scattering, particles
- (350.4990) Other areas of optics : Particles
- (050.4865) Diffraction and gratings : Optical vortices
- (250.5403) Optoelectronics : Plasmonics
- (240.6695) Optics at surfaces : Surface-enhanced Raman scattering
Probing Limits on Spatial Resolution Using Nonlinear Optical Effects and Nonclassical Light
- received 03/26/2013; accepted 11/25/2013; posted 11/26/2013; Doc. ID 187528
- [full text: PDF (781) KB)]
- Abstract: Using a simple optical set up to detect and characterize transmission gratings, we demonstrate that going beyond the diffraction limit is not possible using linear interaction of nonclassical illumination with the target grating. Nonlinear optical interactions with the target grating, or with the optical medium around it, however, do allow improvement in resolution.
- (190.1900) Nonlinear optics : Diagnostic applications of nonlinear optics
- (270.5290) Quantum optics : Photon statistics
- (180.4315) Microscopy : Nonlinear microscopy
Design of macro-filter-lens with simultaneous chromatic and geometric aberration correction
- received 10/03/2013; accepted 11/25/2013; posted 11/27/2013; Doc. ID 198587
- [full text: PDF (1353) KB)]
- Abstract: A macro-filter-lens design that can correct for the chromatic aberration and geometric aberration simultaneously while providing long focal length is presented. The filter is easy to fabricate since it involves two spherical surfaces and a planar surface. Chromatic aberration correction is achieved by making all the rays travel the same optical distance inside the filter element (negative meniscus). Geometric aberration is corrected by the lens element (plano-convex) which makes the output rays parallel to the optic axis. This macro-lens filter design does not need additional macro lens and provides an inexpensive and optically good (aberration compensated) solution for macro imaging of objects not placed close to the camera.
- (080.3620) Geometric optics : Lens system design
- (120.2440) Instrumentation, measurement, and metrology : Filters
- (120.3620) Instrumentation, measurement, and metrology : Lens system design
- (220.1000) Optical design and fabrication : Aberration compensation
- (350.2450) Other areas of optics : Filters, absorption
CW and passively Q-switched Nd:YAG laser with a multi-segmented crystal diode-pumped at 885 nm
- received 09/19/2013; accepted 11/25/2013; posted 11/26/2013; Doc. ID 197636
- [full text: PDF (1296) KB)]
- Abstract: Mitigation of thermal effects in a 1064 nm Nd:YAG laser is demonstrated through the combination of a multi-segmented crystal rod and upper laser level pumping by diode at 885 nm towards optimizing the generated beam profile. Continuous wave (cw) and passively Q-switched operation is demonstrated obtaining 7.5 W and 2 mJ at 100 Hz, respectively with excellent beam quality. Comparison with a conventional uniform Nd:YAG rod reveals improvements of up to 64% in optical conversion efficiency and 67 % in output power for retaining the beam quality. Thermal lensing measurements validate the improved thermal management in the multi-segmented crystal in conjunction with M-square values better than 1.3.
- (140.3480) Lasers and laser optics : Lasers, diode-pumped
- (140.3530) Lasers and laser optics : Lasers, neodymium
- (140.3540) Lasers and laser optics : Lasers, Q-switched
- (140.3580) Lasers and laser optics : Lasers, solid-state
- (140.6810) Lasers and laser optics : Thermal effects
Turning Film for Widening the Viewing Angle of a Blue Phase Liquid Crystal Display
- received 10/22/2013; accepted 11/25/2013; posted 11/27/2013; Doc. ID 199937
- [full text: PDF (1443) KB)]
- Abstract: We report a new turning film structure for widening the viewing angle of a vertical-field-switching (VFS) blue phase liquid crystal display, which employs a directional backlight. The turning film consists of periodic prismatic structure; each period has three prisms with different base angles so that the output light can be spread to a larger angle. Simulation results show that a full width half maximum (FWHM) of ± 80° in horizontal direction and ± 45° in vertical direction can be achieved.
- (120.2040) Instrumentation, measurement, and metrology : Displays
- (160.3710) Materials : Liquid crystals
- (110.2945) Imaging systems : Illumination design
(OIC) Controllable photonic mirror fabricated by atomic layer deposition on the nanosphere template
- received 09/04/2013; accepted 11/25/2013; posted 11/27/2013; Doc. ID 196933
- [full text: PDF (2986) KB)]
- Abstract: In this study, a controllable photonic mirror was fabricated using the atomic layer deposition (ALD) coating technique on a polystyrene (PS) nanosphere template. PS nanospheres were self-assembled on an Al/glass substrate to form the bottom electrode. A 20-nm ALD Al2O3 film was then coated onto the surface of the reduced PS nanosphere structure. The PS nanospheres were removed in air at 350oC to form hollow Al2O3 nanospheres. Then a 30-nm indium tin oxide film was sputtered on the hollow nanosphere structure to form the top electrode. The results show that the incorporation of the photonic mirror could control the reflectance to a value of 0.3% per 0.1V of bias voltage.
- (160.4236) Materials : Nanomaterials
- (310.6845) Thin films : Thin film devices and applications
- (130.3990) Integrated optics : Micro-optical devices
(OIC) Ion beam sputtering of Fluoride thin films for 193 nm applications
- received 09/04/2013; accepted 11/24/2013; posted 12/03/2013; Doc. ID 196747
- [full text: PDF (872) KB)]
- Abstract: Ion beam sputtering of AlF₃, LaF₃, and GdF₃ as single layers, AR coatings and HR coatings for 193nm is presented. The low temperature of the process allows for both CaF₂ and fused silica substrates to be used with the same optical results.
- (310.1860) Thin films : Deposition and fabrication
- (310.6860) Thin films : Thin films, optical properties
Interference method for ultra-precision measurement and compensation of laser beam angular deflection
- received 10/11/2013; accepted 11/24/2013; posted 11/26/2013; Doc. ID 199303
- [full text: PDF (965) KB)]
- Abstract: A new interferometric method for ultra-precise measurement of laser beam angular deflection is proposed. Also angular tilt of measuring device in relation to the beam axis can be measured. The method is based on interference fringe period analysis in the selected plane of measurement. The theoretical basis and experimental verification of the method are presented. It is shown that by using the proposed technique it is possible to measure the laser beam angular deflection or instability with ultra-high resolution reaching single nanoradians. The proposed method allows the measurement and further compensation of laser beam deflections in a very compact design.
- (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
- (120.3940) Instrumentation, measurement, and metrology : Metrology
- (120.4640) Instrumentation, measurement, and metrology : Optical instruments
- (140.3295) Lasers and laser optics : Laser beam characterization
Island analysis of low activity dynamic speckles
- received 08/30/2013; accepted 11/24/2013; posted 11/26/2013; Doc. ID 196734
- [full text: PDF (702) KB)]
- Abstract: In this work we present a method to evaluate activity in low dynamic speckle patterns. It consists in binarizing the speckle image and studying the resulting speckle grain regions, here called islands, as they experiment displacements and deformations. Numerical simulations and controlled experiments were used to analyze the variations of the island features with the aim of finding a correlation with the activity of the speckle pattern. From the obtained results, it was possible to conclude that thedeveloped method can be useful for the analysis of low activity speckle patterns with the advantagesofrequiring only pairs of frames, thus permitting the assessment of non stationary processes.If the phenomenon is stationary, so that stacks of frames registers are representative of it, then dilute activity images can also be constructed.
- (030.6140) Coherence and statistical optics : Speckle
- (120.6150) Instrumentation, measurement, and metrology : Speckle imaging
- (120.6165) Instrumentation, measurement, and metrology : Speckle interferometry, metrology
Highly sensitive compact refractive index sensor based on phase-shifted sidewall Bragg gratings in slot waveguide
- received 09/30/2013; accepted 11/23/2013; posted 11/26/2013; Doc. ID 198495
- [full text: PDF (522) KB)]
- Abstract: The geometrical and physical parameters of phase-shifted sidewall Bragg gratings in silicon slot waveguide are optimized to possess performance characteristics desirable for integrated optical sensors. By tailoring the spectral response of such phase-shifted sidewall gratings, highly sensitive compact refractive index sensors detecting the resonance wavelength shift or the variation of light intensity are designed with the transfer matrix method. Both refractive index sensors have a minimum detection limit on the order of 10¯⁶, a linear response and a compact structure dimension as small as 11.7 µm offerring the capabilities for sensor array and lab-on-a-chip integration. The resonance-shift sensor has a much wider detection range of 1.32 RIU than the intensity-measurement sensor. The performance parameters are compared with other refractive index sensors including Mach-Zehnder interferometers, ring resonators, surface gratings, and phase-shifted gratings in silicon nanowire.
- (050.2770) Diffraction and gratings : Gratings
- (050.5080) Diffraction and gratings : Phase shift
- (130.3120) Integrated optics : Integrated optics devices
- (130.6010) Integrated optics : Sensors
- (230.7370) Optical devices : Waveguides
Orthogonal reference pattern multiplexing for collinear holographic data storage
- received 10/04/2013; accepted 11/23/2013; posted 11/27/2013; Doc. ID 198869
- [full text: PDF (3537) KB)]
- Abstract: An orthogonal reference pattern multiplexing (ORPM) method for collinear holographic data storage (CHDS) is investigated to increase the data storage density and realize parallel optical image superimposition. Holograms are multiplexed in the same volume of the recording medium with multiple orthogonal reference patterns (RPs). The physical principle of this method is analyzed based on scalar diffraction theory. The orthogonal condition of the RPs is derived in order to suppress the inter-page crosstalk. The parameters of the radial-line reference pattern have significant influence on the signal to noise ratio (SNR) of the reconstructed data page. They are optimized to reduce the intra-page crosstalk. With a random binary phase mask (RBPM) located closely before the spatial light modulator, SNR of the reconstructed data page is three times of the SNR without RBPM. Three data pages are multiplexed in the same volume of the medium using ORPM method. The reconstructed data pages for the CHDS system show the effectiveness of the RBPM in suppressing the intra-page and inter-page crosstalk.
- (070.0070) Fourier optics and signal processing : Fourier optics and signal processing
- (090.4220) Holography : Multiplex holography
- (120.5060) Instrumentation, measurement, and metrology : Phase modulation
- (210.2860) Optical data storage : Holographic and volume memories
Generation of bidirectional stretched-pulses in a nanotube-mode-locked fiber laser
- received 09/27/2013; accepted 11/22/2013; posted 12/02/2013; Doc. ID 198466
- [full text: PDF (507) KB)]
- Abstract: The bidirectional stretched-pulses in a nanotube-based erbium-doped fiber laser are observed experimentally for the first time to our best knowledge. The proposed fiber laser generates two stable pulse trains in opposite directions with different central wavelengths, pulse widths, and repetition rates. In addition, the bidirectional operation with the same central wavelengths is also demonstrated by changing the polarization controller and pump power. Experimental results suggest that the cavity asymmetries together with the fiber birefringence play key roles in the formation of these unique features.
- (060.5530) Fiber optics and optical communications : Pulse propagation and temporal solitons
- (140.3510) Lasers and laser optics : Lasers, fiber
- (140.3600) Lasers and laser optics : Lasers, tunable
Compact in-line optical notch filter based on an asymmetric microfiber coupler
- received 09/12/2013; accepted 11/22/2013; posted 11/26/2013; Doc. ID 197477
- [full text: PDF (2966) KB)]
- Abstract: Novel compact in-line fiber filters with narrow rejection bandwidths are proposed and experimentally demonstrated based on asymmetric microfiber couplers. It is composed of silica and bismuth-oxide-glass microfibers and less than 500-μm long. Single transmission dips in a wavelength range of up to 300 nm are obtained and the transmission extinction ratio is over 30 dB. Additionally, -20dB bandwidth of 0.88 nm is achieved. This narrow bandwidth of the transmission notch is benefitted from the huge refractive-index difference between the two microfibers. These experimental results agree well with the theoretical predictions. With the advantages of simple structure, being fiberized and small footprint, this device can be attractive elements in micro/nanophotonics, optical sensing, optical signal processing and optical fiber communications.
- (060.2340) Fiber optics and optical communications : Fiber optics components
- (230.2285) Optical devices : Fiber devices and optical amplifiers
- (130.7408) Integrated optics : Wavelength filtering devices
(OIC) Spatially-resolved surface topography retrieved from far-field intensity scattering measurements
- received 09/11/2013; accepted 11/22/2013; posted 12/05/2013; Doc. ID 197435
- [full text: PDF (2125) KB)]
- Abstract: A far field set-up based on the fast and simultaneous recording of 1 million intensity ARS patterns allows both to reconstruct surface topography, and to cancel local defects in this topography. A spectral analysis is performed on measured data and allow to extract roughness and slopes mapping of a surface taking into account the spectral bandpass.
- (120.6660) Instrumentation, measurement, and metrology : Surface measurements, roughness
- (290.3200) Scattering : Inverse scattering
- (290.5820) Scattering : Scattering measurements
- (290.5880) Scattering : Scattering, rough surfaces