This PDF file contains the front matter associated with SPIE Proceedings Volume 6793, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Nonlinear effects in optical fibers impose different limitations on the communications link, and an understanding of such effects is almost a prerequisite for actual lightwave-system designers. On the other hand, they offer a variety of possibilities for all-optical signal processing, amplification and regeneration. The nonlinear effects are enhanced dramatically and new phenomena are observed in the so called photonic crystal fibers. In this paper we review the effects - both detrimental and potentially beneficial - of optical nonlinearities in conventional and in photonic crystal fibers.

The author has proposed a method, the Levitation Mass Method (LMM). In the LMM, the inertial force of a mass levitated using a pneumatic linear bearing is used as the reference force applied to the objects under test, such as force transducers, materials or structures. The inertial force of the levitated mass is measured using an optical interferometer. In this paper, the previous achievement, the recent achievements, and the future prospects on the methods of generating and measuring the static and dynamic micro-Newton level forces based on the LMM are discussed.

In this work the capacitance of AlGaN/GaN heterostructure in presence of InN quantum dots has been studied. This calculation has been done for different InN quantum Dot size, energy dispersion and in different temperatures. The presence of InN quantum dot will cause a negative differential capacitance which can evidence the position of quantum dots in the structures. Our calculation results show this negative differential capacitance is much higher at low temperature and for quantum dots with low energy and higher size dispersion.

We propose a new digital method for tracking position of particles from in-line holograms by using single wavelet coefficient. By computing a wavelet transform of the 1-D intensity profile of a hologram, resultant wavelet coefficients provide space-varying frequency information of an interference pattern. Our study finds that a dilation which is given by the maximum value of the real wavelet coefficient appeared at the center position of the interference pattern is determined by a recording distance and a wavelength of a coherent illuminating light. Therefore, this dilation can be used for extracting the recording distance of particles from the holograms. A feasibility of this method is experimentally verified by analyzing holograms of a line object.

This paper presents a second harmonic generation scheme using a nonlinear optic crystal and a multimode Fabry-Perot blue laser diode that has potential to generate widely tunable coherent deep ultraviolet at approximately 225 nm. Using the Fabry-Perot multimode laser diode with the sum-frequency technique, a high second harmonic power is hardly observed due to low conversion efficiency. In this paper, an approximately 1 μW second harmonic ultraviolet power at around 225 nm ultraviolet wavelength and approximately 6 nm ultraviolet wavelength tunability can be obtained using a multi mode blue LD chip, a nonlinear optic crystal, and an external high-Q-cavity setup.

The propagation characteristics of a random-metal dielectric film acting as a propagating far-field light/optical near-field converter were investigated. A finite-difference time-domain method was used for the analysis of the characteristics, because of the complicated structure of the film formed with fused silica balls and silver paste. The propagating efficiency of the optical intensity was estimated, and two efficiency-determining factors were clarified; the optical coupling efficiency determined by the silica ball size, and the absorption determined by the silver layer between the silica balls.

An analytical expression is proposed for evaluating the performances of reflection-spectrum envelope for sampled gratings. The accuracy of the expression has been verified by the simulated reflectivity spectrum by use of transfer matrix method. A new technique of multiple reflection-spectrum envelope concatenation is introduced to demonstrate a 23-channel grating with uniform characteristics in all channels. The proposed technology can densify sampled grating both in spectral channel number and in spatially physical corrugation.

Fiber couplers are widely used in telecommunication and industry as a passive splitting power device. The effective power coupling and transmitting from one fiber to another is mainly determined by both coupling length and coupling coefficient. Coupling length can be calculated directly but for coupling coefficient it depends upon the refractive index and separation fiber axis. After fusion processes of two SMF-28e^(R) couplers, the refractive index is unknown due to change in the radius of fiber (r_cladd<40μm and r_core<1.5μm). Coupling coefficient range is obtained from a distribution of coupling ratio and compared with the empirical formula which also enables to calculate refractive index. In this experiment, coupling coefficient in the range of 0.6-0.9/mm is calculated as a function of separation fiber axis and refractive index of core and cladding. The result shows a good correlation between experimental results and theoretical calculation.

An extrinsic fiber Fabry-Perot interferometric sensor is reported for use in vibrometric applications. The sensor operates on the principle of a "virtual" dual-cavity generated within the sensing arm due to the introduction of a birefringent element into the optical path of the sensing cavity. The resulting two sets of "phase-shifted" interference signals produced allowed non-ambiguous directional detection as well as improved resolution in displacement measurements. Experimental displacement data obtained using the fiber interferometer were found to be in good agreement with the reference sensor employed. The potential for overcoming polarization-induced signal fading is also qualitatively illustrated.

Crystal ordering of colloidal self-assembled photonic crystals fabricated by vertical drawing deposition technique has been improved following application of acoustic noise vibrations. The scanning electron microscopy has confirmed the improvement in the crystal order on the surface (111) plane and has demonstrated that thin opal films crystallized under acoustic agitation consist of similarly oriented crystallites, the characteristic transverse dimension of which is larger compared to that of sample grown without acoustic field. Three-dimensional lattice arrangement of the opal crystal has been examined by means of laser diffraction and optical transmission spectroscopy. Novel approach towards optical characterisation of the opal crystallinity has been suggested.

The formation of In_0.53Ga_0.47As/InP single quantum well with narrow well width grown by Organometallic Vapor Phase Epitaxy is verified by photoluminescence spectroscopy. PL spectra exhibit the e(1)-hh(1) transition in the well. PL measurement was conducted at various temperatures from 15K to 200K in order to investigate the important temperature-dependent parameters of this structure. Important parameters such as activation energies responsible for the photoluminescence quenching and broadening mechanisms are achieved. Because of small thermal activation energy of 15.1 meV in the narrow well, carriers can escape from the well to the barrier states. The dependence of PL width on temperature revealed that Inhomogeneous mechanism is the dominant mechanism for the broadening of PL peak and homogeneous mechanism is responsible at high temperature due to electron-phonon interaction.

The research objective was to study 1) the situation and readiness of the Thai education for the integration of nanotechnology and 2) to propose the plans, the strategies and guidelines for educational reform to adapt nanotechnology to the system. The data collection was done by 4 methods: 1) documentary study, 2) observation, 3) informal interviews, and 4) group discussion. The findings revealed that: 1. William Wresch's Theory (1997) was used in this research to study of the situation and readiness of the Thai education for the integration of nanotechnology. 1) Getting connected to nanotechnology by search engine websites, libraries, magazines, books, and discussions with experts. 2) Curriculum integration: nanotechnology should be integrated in many branches of engineering, such as industrial, computer, civil, chemical, electrical, mechanical, etc. 3) Resources for educators: nanotechnology knowledge should be spread in academic circles by publications and the Internet websites. 4) Training and professional resources for teachers: Teachers should be trained by experts in nanotechnology and researchers from the National Nanotechnology Center. This will help trainees get correct knowledge, comprehension, and awareness in order to apply to their professions and businesses in the future. 2. As for the plans, the strategies, and guidelines for educational reform to adapt nanotechnology to the present system, I analyzed the world nanotechnology situation that might have an effect on Thai society. The study is based on the National Plan to Develop Nanotechnology. The goal of this plan is to develop nanotechnology to be the national strategy within 10 years (2004-2013) and have it integrated into the Thai system. There are 4 parts in this plan: 1) nanomaterials, 2) nanoelectronics, 3) nanobiotechnology, and 4) human resources development. Data for human resource development should be worked with the present technology and use the country's resources to produce many products of nanotechnology, such as 1) handicrafts, decorations, and gifts, 2) agricultural products and food, 3) beverages, such as alcoholic and non- alcoholic drinks, and 5) textiles.

Quality-factors of waveguide coupled microsphere resonators of 30 μm diameter are measured. A Teflon buffer layer is deposited on the waveguide to separate the microsphere from the waveguide and the effect of this separation on the measured quality-factor is discussed. The whispering-gallery mode propagation along the cavity of the microsphere as well as the optical path lengths of the modes are determined; the experimental and theoretical data are compared and discussed. A five-fold increase of the Q-factor was obtained by increasing the sphere-waveguide separation.

The power density characteristics of a Q-switched neodymium doped double-clad fiber laser are presented. a steady state numerical model is developed to simulate this fiber laser. First, the mathematical model governing the dynamic behavior of the fiber laser is developed and then the equations are solved by the finite difference method. The results of the numerical simulation are used to determine the characteristics of the device such as the power density in cavity and out put power per input pump power.

This paper presents some analysis for the matching between the elliptical mode field of 1550nm high power laser diode with the circular mode field of the single mode fiber in order to obtain high coupling efficiency with relaxed misalignment tolerances. Three coupling schemes namely Butt, single ball lens and double ball lenses coupling schemes have been employed in pigtailing the butterfly laser diode module using laser welding technique with dual beams from Nd:YAG laser welding system for the attachment of coupling components. The process of fiber attachment to laser diode and welding of various coupling components, such as lens holders, fiber ferrule and welding clips have been performed in what is so called active alignment process, where the system continues measuring the coupled power during the process of coupling and welding of coupling components in their holder to each other and to the main substrate. It has been found that double ball lenses coupling scheme is efficient and more effective for mode matching of highly elliptical (large divergence ratio) laser diode mode field with the circular mode field of a single mode fiber, whereas for small divergence ratios the single ball lens is adequate.

When Raman scattering is excited from the evanescent light field created by illuminating the apex of a sharp metallic nano-tip, it achieves new aspects with strong enhancement of scattering efficiencies and super resolving capabilities. The primary mechanism of tip-sample interaction is electromagnetic, which is based on the excitation of localized surface plasmon polaritons. However, when the tip is close enough to the sample, typically at molecular distances, the chemical interactions between the tip and the sample become important. Strong temporal fluctuations of Raman scattering, including fluctuations of peak frequencies and peak intensities, together with extraordinary enhancement of several peaks, were observed. These temporal fluctuations, which are typical signature of single molecule detection, were attributed to the changes of molecular orientations of the sample molecules in the upper layer of the nanocluster, which got chemically adsorbed at the tip molecules.

Transparent conducting thin films of zinc oxides and aluminum doped zinc oxide (AZO) were prepared by the spray pyrolysis technique using an aqueous solution of dehydrate zinc acetate (CH₃COOH. 2H₂O, pure- Merck A. R. grade) and hex hydrate aluminum chloride (AlCl₃ .6H₂O) on the micro glass slides. The prepared thin films are found to be highly adherent to the substrate and possess uniform conduction. The optical and electrical properties of the film were investigated in terms of different Al concentration in the starting solution and different substrate temperature. Four probe method in Van der pauw configuration was used for electrical resistivity measurements. The resistivity of Al doped film is observed to vary with doping concentration. The lowest resistivity is observed in the film doping with 2 at % [Al/Zn]. The Hall coefficient measurements show that both ZnO and AZO show the n-type conduction. The carrier concentration was observed to be highest at 2 at% of Al doping. The optical measurements of all the samples with aluminum concentrations was found to be >85 % showing the film to be highly transparent in nature. With increase in Al concentration, the optical band gap was observed increase from 3.27 eV to 3.41 eV.

Transparent titanium oxide thin film was deposited by DC reactive magnetron sputtering method onto glass slides and silicon wafer substrates. The film was characterized by AFM, XRD and spectrophotometer for film's thickness, crystallographic structure and transmission spectrum respectively. The film's thickness was, from AFM, found to be about 296 nm. XRD measurement shows that the film is crystallized in rutile phase. Absorption coefficient and the thickness of the films were calculated from interference of transmittance spectra. Optical constants such as refractive index (n) and extinction coefficient (k) were determined as a function of wavelength over the wavelength range from 400 to 800 nm using envelope methods.

We fabricated an FePt/MgO tunneling junction (Fe₅₅Pt₄₅) with out-of-plane magnetization on a GaAs-based light-emitting-diode structure. The technique of spin-polarized electroluminescence (EL) was used to study the electrical spin injection from FePt into GaAs at room temperature. Under the magnetic field of 1 T the spin polarization of the injected electrons was at least 6.0%. The zero-magnetic-field spin polarization, which indicates the spin injection without magnetic field, was at least 3.3%.

The ground state transition energy as various temperatures of a single quantum well structure has been calculated. The numerical technique called shooting method was developed to get eigen values and eigen functions. Passler's model and Aspnes's equation are adopted to calculate the energy gap (E_g) of Al_0.3Ga_0.7As and GaAs respectively. Our calculation has been tested by comparing the results to PL experimental data of Al_0.3Ga_0.7As / GaAs single quantum well. Good agreement has been found in the low temperature range (less than 40 K) and fair result has been obtained in the range of temperature higher than 40 K.

In this paper, we design the ring resonator filters such as moving average (MA), autoregressive (AR) and autoregressive moving average (ARMA) filters. These filters are designed as add/drop filter, channel selection and dispersion compensator. The transfer functions of optical filters are derived using Z-transforms.

We propose a design of a tunable band-pass filtering device using an optical micro ring resonator. Such a device can be used to generate the required filtering signals in the optical communication transmission line. In principle, the chaotic signals are generated by a Kerr effects nonlinear type via a micro ring resonator. The input power can be used to control the specific filtering signals. The required information can be retrieved from the chaotic signals by using the specific filter, i.e. the specified users. The ring parameters used with the ring radii are ranged between 10-20 μm and n₂ = 2.2 x 10^-15 m²/W. The simulation results obtained have shown the potential of using such a proposed device as tunable band-pass or band-stop filters, which can be used to form the information security.

An investigation of the optical thickness of the aerosol surrounded in the Suvranabhumi airport area using the local constructed sun-photometer is reported. The measurement data obtained are presented comparing to the ones obtained by the standard sun-photometer, where the measurement error of 5 % is obtained. The measurement was implemented within a three months period, starting from November 1th, 2006. The optical thickness obtained of 0.45 is noted, which is described in term of air quality as transparent view. Such effects may be introduced by the airplane fuel waste, infrastructure constructions and industrial estates. Further, the effects of the climate changes and global warming around the investigated area, and wireless communication link degradation are discussed.

In this paper, we present an experimental investigation of all-optical switch using a symmetric Mach-Zehnder interferometer (MZI) combined with double fiber ring resonators. Here, we replace the ordinary-fiber ring resonator on one arm of MZI by a 980 nm-laser pumped erbium-doped fiber (EDF) ring resonator to form an EDFA. When adjusting the EDF pump power up we note increasing in switching power. Experimental results indicate that using MZI with double EDF ring, switching power is lowered significantly to nanowatt level in comparison with that of MZI with a single EDF ring of milliwatt level.

A new scheme of the entangled photon states re-generation the dynamic simulation of light traveling in nonlinear fiber optic ring resonator incorporating an erbium-doped fiber (EDF) has been investigated. We have shown that the weak entangled photon states can be recovered after circulating in the amplified fiber optic medium. The output entangled photon states can be re-generated by adjusting the polarization controller of the amplified photons, where the re-generated entangled states can be controlled and performed. The ring-cavity lifetime is much longer than the Kerr-effect response time of the fiber ring. The results obtained have shown that this system can be used to achieve the recovered polarization entangled states with the obtained high gain. The amplifying noise has also been detected and seen on the spectrum output. This is affected to the entangled photon visibility, which is discussed.

This paper proposes a system of signal security using the optic series waveguide micro ring resonator, where the chaotic noise generation and cancellation can be performed. The required communication signals can be multiplexed with the generated chaotic noise in a micro ring resonator before transmission. The required information can be recovered via optic series waveguide micro ring resonator by a specific user at the output port of the waveguide micro-ring resonator. Simulation results obtained have shown the potential of applications which is closed to the practical applications, especially, The required information can be retrieved by the specified users. The ring parameters used with the ring radii are ranged between 10-20 μm, κ₁ = κ₂ = 0.0225 and n₂ = 2.2 × 10^-15 m²/W. The simulation results obtained have shown the potential of using such a proposed device for tunable band-pass and band-stop filters, which can be used for the information security in the system by the optic series waveguide micro ring resonator.

We propose the results of optical Kerr effects in fiber grating for the measurement resolution. When the high power laser is launched into fiber grating, optical Kerr effects are induced in grating region then the effective refractive index is changed depending on the input power. The results that are given by the mathematical simulation, have shown the relation between the reflectivity and Bragg wavelength. All results can be used to analyze and improve the resolution of measurement system for fiber grating sensors and its applications.

This paper presents a new concept of quantum-chaotic encoding of light traveling in a fiber optic ring resonator. The Kerr nonlinear effects type of light in a fiber optic ring resonator is induced, and the four-wave mixing of the propagating waves at resonance occurred. The output signals can generate the double security which one is the quantum bits i.e. code, and the other is the chaotic signal/code. The proposed system has shown the potential of using for communication security, where the double security via the quantum-chaotic encoding can be performed.

In this work, we present a review of recent works on photorefractive effect in Pb-based relaxor ferroelectric material. The review is based on the well known Kukhtarev's model [1] and recent experimental photorefractive two beam coupling works by He et al [2] and Abe et. al. [3,4]. We also suggest the generation of higher orders and other applications such as optical correlation, phase conjugation, which may be worked well with a Pb-Based relaxor ferroelectric materials. From this work, we have seen the bright future of the research in photorefractive effect using the Pb-based relaxor ferroelectric materials.