A novel architecture of converged radio-over-fiber (RoF) and wavelength division multiplexed passive optical network (WDM-PON) system, namely RoF-WDM-PON, is demonstrated. 20-GHz 1-Gb/s radio frequency (RF) signals and 1-Gb/s baseband (BB) signals are simultaneously generated and transmitted using optical carrier suppression (OCS) modulation techniques. The proposed scheme is compatible with the conventional RoF and PON system. 25-km single-mode fiber (SMF) transmission is successfully achieved.

We propose a novel technique to increase the confidentiality of an optical code division multiple access (OCDMA) system. A virtual user technique is analyzed and implemented to make an OCDMA system secure. Using this technique, an eavesdropper will never find an isolated authorized user's signal. When authorized users and virtual users transmit data synchronously and asynchronously, network security increases by 25% and 37.5%, respectively.

We propose a stable multi-longitudinal Brillouin/semiconductor fiber laser (BSFL) as the upstream source in a bidirectional single-fiber wavelength-division multiplexing-passive optical network (WDM-PON). The downstream wavelength serves as the pump of the BSFL. Brillouin-frequency-shifted (~10.8 GHz) upstream carrier is generated to suppress the Rayleigh backscattering and back re°ection-induced crosstalk. The stable multi-longitudinal operation of the BSFL, attributed to the four-wave mixing (FWM) effect in the semiconductor optical amplifier (SOA) reduces the difficulty of generating a stable single-longitudinal fiber laser-based upstream carrier. Bidirectional symmetric transmission at 10 Gb/s over a 12.5-km single mode fiber with less than 2-dB power penalty is demonstrated.

The improved range Doppler algorithm is proposed to abate the trade-off between resolutions and depth of focus in spectral domain optical coherence tomography. By considering the finite beam width and the shape of the wavefronts produced by the Gaussian beam, a physical diffraction model is presented to simulate the light propagation process in the sample. The two-dimensional processing of the spectrum data is decomposed into two one-dimensional processings of Stolt transform and matched filter. Experimental results show that image reconstruction can be achieved. The transverse and axial resolutions are both improved significantly, especially in the out-of-focus range, and the resolutions are almost equivalent throughout the entire region of interest.

An injection-locked Ti:sapphire laser is developed, with injection locking achieved using the Pound-Drever-Hall technique. By measuring the dependence of output power on the pump power with various Ti:sapphire laser parameters, we experimentally studied the influences of the ring cavity length, the focal length of the pump-laser mode-matching lens, and the output–coupler transmission on the threshold and slope efficiency. The dependence of the output power on the master laser power is also investigated. The present study provides a guideline for developing a Ti:sapphire laser with high slope efficiency and low threshold.

Nd3+ strengthens the Er3+:2.7-\mu m emission 104 times in fluorophosphate glass; in addition, it can also decrease its upconversion effects and the 1.5-\mu m emission accordingly. Cross-relaxation process is the principal transition mechanism in this codoping system. Compared with Er3+ singly doped glass, J-O parameters along with the Arad, \beta, \tau_R values of Er3+ change markedly in Er3+:Nd3+ codoped glass because Nd3+ greatly influences the local environment around Er3+. Results also show that Nd3+ has a good 4I13/2 lifetime quenching effect as well as thermal load reduction ability for Er3+:2.7-\mu m emission.

High power second harmonic generation (SHG) in MgO-doped LiNbO3 waveguides is investigated using a three-dimensional (3D) coupled thermo-optical model. Simulations performed for a 1 111.6-nm fundamental laser show the influence of the absorptions and the thermally induced dephasing on the conversion efficiencies of the different waveguides. The onset of the thermally induced dephasing effect for each waveguide is also indicated. As a result of high light intensity in the waveguide, nonlinear absorptions are identified as the possible main factors in efficiency losses in specific cases.

Based on double optical pumping channels, we experimentally study the competition between two coexistent six-wave mixing (SWM) processes falling into two electromagnetically induced transparency windows by scanning the frequency of the probe field in two similar five-level atomic systems of 85Rb. By blocking one optical pumping channel unrelated to the four-wave mixing (FWM) process, one SWM process, together with the FWM process, generated by a conjugated small-angle static grating could be observed in the spectrum. Moreover, the other SWM process obtained by blocking the first SWM channel is also observed together with the FWM process in a lower N-type four-level subsystem. These experimental results agree well with theoretical predictions.

Multi-reference configuration interaction is used to produce potential energy curves (PECs) for the excited B1\Pi state of KH molecule. To investigate the correlation effect of core-valence electrons, five schemes are employed which include the different correlated electrons and different active spaces. The PECs are fitted into analytical potential energy functions (APEFs). The spectroscopic parameters, ro-vibrational levels, and transition frequencies are determined based on the APEFs and compared with available experimental and theoretical data. The molecular properties for B1| obtained in this letter, which are better than those available in literature, can be reproduced with calculations using the suitable correlated electrons and active space of orbitals.

Quantitative phase microscopy by digital holography provides direct access to the phase profile of a transparent subject with high precision. This is useful for observing phenomena that modulate phase, but are otherwise difficult or impossible to detect. In this letter, a carefully constructed digital holographic apparatus is used to measure optically induced thermal lensing with an optical path difference precision of less than 1 nm. Furthermore, by taking advantage of the radial symmetry of a thermal lens, such data are processed to determine the absorption coefficient of transparent media with precisions as low as 1 \times 10^{-5} cm^{-1} using low power (30 mW) continuous wave (CW) excitation.

An on-axis phase-shifting reflective point-diffraction microscopic interferometer for quantitative phase microscopy based on Michelson architecture is proposed. A cube beamsplitter splits the object wave spectrum into two copies within two arms. Reference wave is rebuilt in one arm by low-pass filtering on the object wave frequency spectrum with a pinhole-mask mirror, and interferes with the object wave from the other arm. Polarization phase-shifting is performed and phase imaging on microscale specimens is implemented. The experimental results demonstrate that the proposed scheme has the advantage of long-term stability due to its quasi common-path geometry with full use of laser energy.

In this letter, the method of direct object-image relationship in normal-view disk-type multiplex holography is adopted for theoretical analysis. The corresponding parameters in hologram fabrication and reconstruction process for both virtual-image and real-image generation are also introduced through numerical simulation and experimental results.

We outline the use of digital holographic tomography to determine the three-dimensional (3D) shapes of falling and static objects, such as lenslets and water droplets. Reconstruction of digitally recorded inline holograms is performed using multiplicative and Radon transform techniques to reveal the exact 3D shapes of the objects.

Past research has demonstrated that digital Fresnel holograms can be binarized in a non-iterative manner by downsampling the source image with a grid lattice prior to the hologram generation process. The reconstructed image of a hologram that is binarized with this approach is superior in quality compared with that obtained with direct thresholding, half-toning, and error diffusion. Despite the success, the downsampling mechanism results in a prominent texture of regularly spaced voids in the shaded regions. To alleviate this problem, an enhanced non-iterative method for the generation of binary Fresnel holograms is presented. Our method is based on a multi-direction line-sampling formed by a combined grid and cross lattice, which is capable of preserving a more solid texture in the shaded regions and enhancing the visual quality of the reconstructed image. Computer simulations and optical reconstructions are shown to demonstrate the effectiveness of our proposed technique.

We investigate the computer-generated hologram with full parallax and which can be reconstructed with white light. The object of the hologram is processed from three-dimensional computer graphics polygon data and has shaded surface for hidden surface removal. The optically reconstructed image from the printed hologram is evaluated.

The results of experiments on the synthesis of the off-axis quantized kinoforms of binary objects with the use of the weighting iterative Fourier transform (WIFT) algorithm are presented. Kinoforms are registered with a liquid-crystal spatial light modulator (SLM). A simple procedure to introduce the carrier frequency into the structure of an axial kinoform is proposed. An image reconstructed by an off-axis kinoform is free from the noises with the zero and close frequencies caused by the imperfection of both the phase mode of operation of the SLM and the effects of quantization of the registered phase. Data on the diffraction efficiency are also given.

We present a lensless projection of color images based on computer-generated Fourier holograms. Amplitude and phase modulation of three primary-colored laser beams is performed by a matched pair of spatial light modulators. The main advantage of the complex light modulation is the lack of iterative phase retrieval techniques. The advantage is the lack of speckles in the projected images. Experimental results are given and compared with the outcome of classical phase-only modulation.

We introduce a phase-only hologram generation method based on an integral imaging, and propose an enhancement method in representable depth interval. The computational integral imaging reconstruction method is modified based on optical °ow to obtain depth-slice images for the focused objects only. A phase-only hologram for multiple plane images is generated using the iterative Fresnel transform algorithm. In addition, a division method in hologram plane is proposed for enhancement in the representable minimum depth interval.

A multi-plane adaptive-additive algorithm is developed for optimizing computer-generated holograms for the reconstruction of traps in three-dimensional (3D) spaces. This algorithm overcomes the converging stagnation problem of the traditional multi-plane Gerchberg{Saxton algorithm and improves the diffraction efficiency of the holograms effectively. The optimized holograms are applied in a holographic optical tweezers (HOT) platform. Additionally, a computer program is developed and integrated into the HOT platform for the purpose of achieving the interactive control of traps. Experiments demonstrate that the manipulation of micro-particles into the 3D structure with optimized holograms can be carried out effectively on the HOT platform.