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Hollow-core waveguides consisting of a glass capillary tube with an internal reflective coating are capable of delivering pulse energies of tens of millijoules with improved focusability compared to step index fibers of similar core diameter. We demonstrate the capability of these fibers to deliver high-power Q-switched pulses at the fundamental (1064 nm), second (532 nm), and third (355 nm) harmonics of a Nd:YAG laser, both in terms of peak power and beam quality delivered. In terms of peak power delivery, the primary limitation is the occurrence of bend-induced optical damage to the reflective coating. The damage mechanism and the influential factors are analyzed, in particular, the dependence upon the number of guided modes, core diameter, coating thicknesses, and input polarization alignment. OCIS codes: 060.2270, 060.2310, 060.2400.

A scanning beam interferometer installed on the Frascati tokamak upgrade (FTU) experiment is presented. The scanning beam scheme combined with the small dimensions of the beams produces a system with very high spatial resolution: more than 30 adjacent (nonoverlapping) chords sample most of the plasma cross section. A good time resolution is achieved by the use of a proper scanning device, with a scanning frequency [greater than or equal to] 8 kHz. Very fast events are measured by three additional fixed lines of sight providing a time resolution [greater than or equal to] 100 kHz. The instrument is a two-color medium-infrared-compensated-type interferometer; two wavelengths (colors) are used to measure both the density and the mechanical vibrations of optical components. A C[Q.sub.2] laser ([lambda] = 10.6 [micro]m) is the main light source, and a CO laser ([lambda] = 5.4 [micro]m) is the compensation one. The optical scheme is a double pass Mach-Zehnder type. All the retroreflector mirrors are mounted directly on the FTU mechanical structure thanks to the compensation system that allows for large vibration amplitudes of optical components. Heterodyne detection at 30 and 40 MHz is obtained by frequency shifting the reference beams with two acousto-optic modulators (Bragg cells). Many features are implemented to achieve high measurement accuracy and reliability. A real-time system computes the integral density measured on one of the fixed lines of sight and provides an analog signal for density feedback control. The interferometer was used to measure density profiles both in medium-density discharges ([n.sub.e] [approximately equal to] [10.sup.20] [m.sup.-3]) and in high-density pellet injected discharges ([n.sub.e] [approximately equal to] 7-8 x [10.sup.20] [m.sup.-3]). The measurement error is [approximately equal to] 2 x [10.sup.18] [m.sup.-2] under optimal conditions but can be higher in some cases, mainly because of the large tilt of the retroreflector mirrors. OCIS codes: 120.3180, 130.6750.

A novel, double-beam common-path laser interferometer is developed to measure the longitudinal ([d.sub.33]) piezoelectric coefficient thin films and the results are compared with the values obtained by Berlincourt and laser scanning vibrometer methods. The results have shown that, for thin-film samples, the [d.sub.33]f values obtained from the Berlincourt method are larger than those obtained from the interferometer and vibrometer methods.

A secure holographic memory system is proposed by use of an encoded reference beam. The reference beam is encrypted by a fiber-optic faceplate, which serves as a phase mask. There are seven keys in the system including the position and direction of the fiber bundle and the direction of the incident beam. The experiment shows that the total key length is larger than 1.8 x [10.sup.19]. The method can be used directly in a shift-multiplexing system with high selectivity. OCIS codes: 210.0210, 210.2860, 070.4560, 190.5330.

The effect of the polarization state on electro-optic coupling is studied by using the wave coupling theory of the linear electro-optic effect. The numerical results show that the polarization state obviously influences the electro-optic coupling. The conditions for realizing perfect coupling are emphasized. As an application of perfect coupling, a novel polarization rotator, which can rotate the polarization of a light beam with an arbitrary angle but keep the output intensity unchanged, is presented. OCIS codes: 190.0190, 230.2090.

We report the development and initial implementation of what we believe to be a new rapid-spatial-scan millimeter-wave interferometer for plasma density measurements. The fast scan is effected by electronic frequency sweeping of a wideband (180-280 GHz) backward-wave oscillator whose output is focused onto a fixed blazed diffraction grating. The system, which augments the rotating-grating scanned multiview H-1 heliac interferometer, can sweep the plasma cross section in a period of less than 1 ms with a beam diameter in the plasma of 20 mm and phase noise of the order of 0.01 rad. OCIS codes: 120.3180, 350.5400.

The recording of the volume speckle field from an object at different planes combined with the wave propagation equation allows the reconstruction of the wavefront phase and amplitude without requiring a reference wave. The main advantage of this single-beam multiple-intensity reconstruction (SBMIR) technique is the simple experimental setup because no reference wave is required as in the case of holography. The phase retrieval technique is applied to the investigation of diffusely transmitting and reflecting objects. The effects of different parameters on the quality of reconstructions are investigated by simulation and experiment. Significant enhancements of the reconstructions are observed when the number of intensity measurements is 15 or more and the sequential measurement distance is 0.5 mm or larger. Performing two iterations during the reconstruction process using the calculated phase also leads to better reconstruction. The results from computer simulations confirm the experiments. Analysis of transverse and longitudinal intensity distributions of a volume speckle field for the SBMIR technique is presented. Enhancing the resolution method by shifting the camera a distance of a half-pixel in the lateral direction improves the sampling of speckle patterns and leads to better quality reconstructions. This allows the possibility of recording wave fields from larger test objects. OCIS codes: 100.5070, 100.3010, 030.6140, 030.1640, 050.1960, 090.0090.

Fresnel-type diffractive optical elements (DOEs) for general beam shaping of monochromatic, spatially incoherent light are demonstrated. Direct and indirect methods, i.e., adding a lens' phase to the designed Fraunhofer-type DOEs, are used for the design. The indirect method can reduce the calculation time by approximately half without loss of design accuracy. Two different design examples are shown. For one design the direct method gives a maximum sidelobe intensity of 5.0% of the maximum intensity in the signal window. For the second design the indirect method gives 23.0% of this value. The generated patterns can maintain their basic shapes over a long distance. The elements have been fabricated by directly using gray-scale commercial slides as masks. Experimental results are in close agreement with numerical predictions.

Thin birefringent prisms placed near an image plane introduce sinusoidal fringes onto a 2D polarized scene making possible a snapshot imaging polarimeter, which encodes polarization information into the modulation of the fringes. This approach was introduced by Oka and Kaneko [Opt. Express 11, 1510 (2003)], who analyzed the instrument through the Mueller calculus. We show that the plane-wave assumption adopted in the Mueller theory can introduce unnecessary error in a polarimeter design. To directly take prism effects such as beam splitting and deviating into accounts we introduce a geometric imaging model, which allows for a versatile simulation of the birefringent prisms and provides a means for optimization. A calcite visible system is investigated as an example, which essentially shows how each design parameter affects the overall image quality and how to modify the polarimeter design to optimize overall performance. The approach is applicable to any prismatic imaging polarimeter with different prism materials and different working wavelengths.

We have investigated a process based on the dip method to fabricate a polymeric vertical microlens (PVM). After the primary dip step, the PVM is formed by hanging the liquid SU-8 on a wall in virtue of the strong adhesive force and liquid cohesion. The microlens is then baked and exposed in ultraviolet light to further cross-link the negative photoresist SU-8 to enhance thermal stability and reliability. According to the experimental results, the radius of curvature of the fabricated vertical microlens varies from 120.8 to 34.2 [micro]m, which relates to the dip depth or the thickness of the dipped pool. To characterize the PVM, an edge-emitting laser diode ([lambda] = 1.31 [micro]m) is then bonded onto the optical bench and a detector is utilized to observe the beam divergence with and without the lens insertion. Compared with an angle of 40.8[degrees] without the microlens, the beam passing through a suitable PVM shows a vertical far-field angle of 3.32[degrees]. Furthermore, the lens efficiency, approximately 83.4%, is also specified by the measurements. OCIS codes: 130.1750, 220.3630.

We present a shaper scheme that fully controls the spectral phase, amplitude, and polarization of femtosecond laser pulses. In particular, it enables independent manipulation over the major axis orientation and the axis ratio of the polarization ellipse. This is accomplished by integrating a 4f-shaper setup in both arms of a Mach-Zehnder interferometer and rotating the polarization by 90[degrees] in one of the arms before overlaying the beams. The generated pulses are resolved in a simple and intuitive detection scheme. OCIS codes: 320.5540, 320.7080, 190.7110.

A double-lens extended fractional Fourier transform (EFRT) is proposed. In the double-lens setup, arbitrary-order EFRTs including real orders and complex orders can be carried out. To verify that the single-lens EFRT and the double-lens EFRT are equivalent, numerical simulations and optical experiments for the real-order EFRT and the complex-order EFRT are performed. Their results indicate that the double-lens EFRT is consistent with the single-lens EFRT. Thus the double-lens setup can be regarded as another basic optical configuration. Compared with the single-lens EFRT, the double-lens EFRT has some advantages. OCIS codes: 070.2580, 070.2590.

We utilize a modified interferometric exposure model, enhanced with the Beer-Lambert law, to study how some process parameters influence the structural dimensions within the whole exposure area. An experimental apparatus is built to verify the accuracy of this model. The simulation results indicate that when the incident angle is larger than 15[degrees], the effect of the beam deformation cannot be neglected. One cannot readily obtain periodic structures with the same dimensions during static exposure because of the Gaussian distribution of the light intensity. The theoretical results match the experimental ones quite well. The variation of Dill's parameter A has a greater influence on the transmittance and the linewidth when A is decreasing. If a poor contrast fringe is exposed in the photoresist, it will not only cause a greater nonuniformity of the structural dimensions but also a decreased aspect ratio in the structure after the development process. OCIS codes: 260.3160, 220.4000.

A new approach for designing diffractive optical corrective elements with zooming capability to convert nonlinear sinusoidal scanning into linear scanning is proposed. Such a device will be useful for linearizing the angular scan of a resonant mirror scanner. The design methodology is to create a graded index of a refraction device as the reference design with its index of refraction parameters based on beam retardation through propagation in an inhomogeneous medium. The diffractive element is designed by utilizing a binarizing algorithm of the accumulated phase from transmission through the refractive element. In contrast to a prior approach, which was introduced based on the beam propagation through inhomogeneous media, the new approach takes beam diameters into consideration. This makes both the refractive element and its associated diffractive element more robust against beam fanning. OCIS codes: 050.0050, 050.1380, 220.0220, 050.1970.

The degradation of image quality caused by aberrations of projection optics in lithographic tools is a serious problem in optical lithography. We propose what we believe to be a novel technique for measuring aberrations of projection optics based on two-beam interference theory. By utilizing the partial coherent imaging theory, a novel model that accurately characterizes the relative image displacement of a fine grating pattern to a large pattern induced by aberrations is derived. Both even and odd aberrations are extracted independently from the relative image displacements of the printed patterns by two-beam interference imaging of the zeroth and positive first orders. The simulation results show that by using this technique we can measure the aberrations present in the lithographic tool with higher accuracy. OCIS codes: 110.3000, 110.5220, 120.3940, 220.4840.

A broadband antenna for GSM1800-UMTS base stations with multiple switchable beams in azimuth is presented in this paper. The multiple beams are obtained by means of a broadband Butler matrix. The radiating element is broadband and consists of two stacked patches. The elevation pattern is shaped with null filling and upper lobe reduction that has been achieved by means of a broadband corporate feed network implemented in microstrip technology. Photographs and measurements of the manufactured prototypes are presented confirming that the design of all of the elements is correct. Index Terms--Broadband antennas, multibeam antennas, planar arrays.

The accuracy of a phase-retrieval procedure for microwave beams was analyzed and verified using an 84-GHz quasi-optical beam transmitted by a corrugated waveguide. The output intensity and phase profiles of the beam were directly measured with a microwave receiver. The beam intensity was also measured at several planes and the data were used with a phase-retrieval algorithm to yield an independent estimate of the phase. Moment and matching coefficient methods were used to analyze the retrieved profiles. In the higher order moment analysis, the intensity profiles, which were calculated from the retrieved phase profiles, coincided well with the measured profiles in terms of the beam size, asymmetric property (skewness), and flatness/peakedness (kurtosis) over the entire profile. Analysis indicated that the mode content of the beam obtained by phase retrieval matched that of the direct measurement with a matching coefficient of 0.97 using both the intensity and phase profiles. Index Terms--Electron cyclotron heating (ECH), Gaussian beam, gyrotron, phase measurement, phase retrieval, quasioptical mirror.

An experimental and theoretical investigation of laser beam shaping using a simple binary diffractive optic is presented. Beam tailoring has been characterized by the experimental determination of two relevant parameters: beam propagation factor M2 and the beam-shaping longitudinal range, which represents the propagating distance for which the tailored beam remains nearly unchanged.

A new setup of interferometers is proposed in which the set of specific optical markers--optical vortices-could be generated. The classical Mach-Zender two-beam interferometer has been modernized using the Wollaston prism. In this setup, the optical vortices could be obtained for a wide range of both beam parameters. The numerical analysis and experiments confirm our theoretical predictions. OCIS codes: 120.0120, 120.3180, 260.3160, 260.5430.

A method of creating rugate interference filters that have flat-topped reflectance across an extended spectral region is presented. The method applies known relations from the classical coupled wave theory to develop a set of equations that gives the spatial frequency distribution of rugate cycles to achieve constant reflectance across a given spectral region. Two examples of the application of this method are discussed: a highly reflective coating for eye protection against harmful laser radiation incident from normal to 45[degrees], and a spectral beam splitter for efficient solar power conversion. OCIS codes: 120.2440, 230.1360, 230.4170, 240.0310, 310.1620.

We report a new self-interferometric technique for visualizing phase patterns that are encoded onto a phase-only liquid-crystal display (LCD). In our approach, the LCD generates both the desired object beam as well as the reference beam. Normally the phase patterns are encoded with a phase depth of 2[pi] radians, and all of the incident energy is diffracted into the first-order beam. However, by reducing this phase depth, we can generate an additional zero-order diffracted beam, which acts as the reference beam. We work at distances such that these two patterns spatially interfere, producing an interference pattern that displays the encoded phase pattern. This approach was used recently to display the phase vortices of helical Ince-Gaussian beams. Here we show additional experimental results and analyze the process. OCIS codes: 050.1950, 070.4560, 120.5050, 120.5060, 230.3720, 230.6120.

We report, what is to our knowledge, the first experimental realization of partially coherent bottle beams. It is shown that partially coherent bottle beams can be achieved by the focusing of partially coherent light with an axicon-lens system. The influence of the spatial coherence of the incident partially coherent light and other parameters, such as the radius of the limiting aperture of the axicon and the distance between the axicon and the lens, on the size of the bottle beams is investigated. We find that the longer the spatial coherence length, the larger the size of the resultant bottle beams. This dependence of the size of the bottle beams on the spatial coherence of the incident light provides a facile approach for generating adjustable partially coherent bottle beams. This kind of partially coherent bottle beam may have applications in atom optics, such as in atom trapping and atom guiding, etc. OCIS codes: 030.1640, 140.3300.

The theoretical model presented in part 1 of this work is employed to simulate and fit experimental probe beam deflection (PBD) data of Fe[(CN).sub.6.sup.3-]/Fe[(CN).sub.6.sup.4-] and [Fe.sup.3+]/ [Fe.sup.2+] couples. Current and beam deviation dependency on time at constant potential (chronoamperometry and chronodeflectometry) is analyzed via a new treatment based on the migration and diffusion properties of all the species involved. The diffusion coefficients of electroactive species are obtained by fitting chronoamperometric curves. Those coefficients are then employed to simulate the respective chronodeflectometric profiles. The experimental data and the theoretical function are fitted by the minimum squares Simplex algorithm. The effect of working with systems in which both electroactive species are charged is discussed in detail. Specifically, the possibility of quantitative analysis of nonspecific techniques data is analyzed when a relative high concentration of supporting electrolyte is used. Such analysis widens the scope of techniques as PBD since in many cases the effect of supporting electrolyte species could be negligible as compared to the response of electroactive species. The variation of the refraction index with the concentration gradient of each soluble species is also discussed.

A scheme is presented to perform longitudinal and transverse spatial phase coding of continuous-wave optical beams. This phase coding scheme has an information storage capacity which scales with the power of the read-out optical beam, and can be extended to implement a multiplex array detector.

On the basis of our previous work on the extension of the geometrical-optics approximation to Gaussian beam scattering by a spherical particle, we present a further extension of the method to the scattering of a transparent or absorbing spheroidal particle with the same symmetric axis as the incident beam. As was done for the spherical particle, the phase shifts of the emerging rays due to focal lines, optical path, and total reflection are carefully considered. The angular position of the geometric rainbow of primary order is theoretically predicted. Compared with our results, the MSbius prediction of the rainbow angle has a discrepancy of less than 0.5[degrees] for a spheroidal droplet of aspect radio K within 0.95 and 1.05 and less than 2[degrees] for K within 0.89 and 1.11. The flux ratio index F, which qualitatively indicates the effect of a surface wave, is also studied and found to be dependent on the size, refractive index, and surface curvature of the particle. OCIS codes: 140.0140, 290.4020, 290.5850, 200.0200.

An investigation had an objective of measuring the impact of phase- and amplitude-aberrations resulting from propagation through an inhomogeneous tissue on the beamwidth associated with, the fundamental (1f), the nonlinearity generated second harmonic (2f) and the linearly propagated, effective apodization signal at the same (2f) frequency. The characteristics of the different pattern associated with the linear-propagation effective apodization transmit case bonded well with the detailed spatial characteristics of the nonlinearly generated second harmonic field.

Parabolic cylindrical reflectors (PCRs) can have a large field of view, for example a 15 m reflector can access an area of 1[degrees] by 120[degrees] at 1.4 GHz. It is seen that the radiation pattern is asymmetric. This causes problems in situations where the radiation pattern rotates with time, such as radio astronomy. The rotation of the radiation pattern limits the field of view. In this paper a normalized signal to noise ratio is calculated for a full observation and this is then used to determine the field of view. The greatest variation occurs where the radiation pattern of a single feed element is used. The variation is reduced by RF beamforming. If the radiation pattern has an aspect ratio of 2.5:1 the observed field of view is approximately constant and has a value that is three times larger than that of an equivalent parabolic dish. Index Terms--Earth rotational synthesis, field of view, sensitivity, parabolic cylindrical reflector (PCR).

A new method to record an image through a thick dynamic phase distorting medium by using a photorefractive LiNb[O.sub.3] crystal is demonstrated. The method uses only one beam of light, the object light. By making use of the photorefractive fanning effect, gratings are formed in the LiNb[O.sub.3] crystal through the interference between the object light and its own fanning light. Because the time scale of the distorting fluctuation is much shorter than the writing time of the LiNb[O.sub.3] crystal, the fluctuated light does not induce any fanning. Therefore only the static portion of the image is recorded in the crystal, and the intensity distribution of the image can then be reconstructed at any later time. OCIS codes: 090.1000, 030.7060, 100.3010, 190.5330, 190.5940, 290.7050.

Prisms and slabs made of high-refractive-index materials such as ZnSe, Ge, and Si can be designed as broadband, 50%--50%, beam splitters (BSs) for obliquely incident s-polarized light in the near- and mid-IR. The beam-splitting face of the prism or slab is uncoated, while the exit face is antireflection coated. The split beams travel in orthogonal directions when light is incident at the Brewster angle. A novel design is also described that uses Brewster-angle reflection at the Si[O.sub.2]-Si interface to achieve a 50%-50% s-polarization BS over the 1.2-3.5 [micro]m spectral range. Such s-polarization BSs are particularly suited for interferometry and holography. OCIS codes: 230.1360, 260.5430, 260.3160, 160.4330.

We evaluate the eigenfields of an unstable Bessel--Gauss resonator (UBGR) by use of the transfer-matrix method in which the transverse profiles and their corresponding losses of the UBGR are considered as the eigenvectors and eigenvalues of a transfer matrix so that the dominant mode fields and their losses of the UBGR can be readily extracted in terms of the matrix eigenvalue algorithm. Moreover, based on the eigenfields across two mirrors that resulted from the transfer-matrix method, we simulate the field distributions in the cavity and the propagation of output beams by means of the angular spectrum method. The computation results show that the UBGR easily produces a fundamental Bessel--Gauss mode of good quality, and the output beams retain the original Bessel--Gauss distribution during propagation. OCIS codes: 140.3300, 140.3410, 140.4780.

Near-forward scattering of an optically trapped 5-[micro]m-radius polystyrene latex sphere by the trapping beam was examined both theoretically and experimentally. Since the trapping beam is tightly focused, the beam fields superpose and interfere with the scattered fields in the forward hemisphere. The observed light intensity consists of a series of concentric bright and dark fringes centered about the forward-scattering direction. Both the number of fringes and their contrast depend on the position of the trapping beam focal waist with respect to the sphere. The fringes are caused by diffraction that is due to the truncation of the tail of the trapping beam as the beam is transmitted through the sphere. OCIS codes: 140.7010, 290.4020.

In February 2005 a joint atmospheric propagation experiment was conducted between the Australian Defence Science and Technology Organisation and the University of Central Florida. A Gaussian beam was propagated along a horizontal 1500 m path near the ground. Scintillation was measured simultaneously at three receivers of diameters 1, 5, and 13 mm. Scintillation theory combined with a numerical scheme was used to infer the structure constant [C.sup.2.sub.n], the inner scale [l.sub.0], and the outer scale [L.sub.0] from the optical measurements. At the same time, [C.sup.2.sub.n] measurements were taken by a commercial scintillometer, set up parallel to the optical path. The [C.sup.2.sub.n] values from the inferred scheme and the commercial scintillometer predict the same behavior, but the inferred scheme consistently gives slightly smaller [C.sup.2.sub.n] values. OCIS codes: 010.1290, 010.1300, 290.5930.

The potassium dihydrogen phosphate (KDP) crystals present in the final optics assembly at the National Ignition Facility (NIF) are used for conversion of an infrared laser light beam into an ultraviolet beam. The conversion is highest for a certain incident angle, the alignment of which is determined from the position of the backreflection beam, which exhibits a distinct characteristic shape. When a phase-plate device is introduced before the final assembly to increase the uniformity of the beam, the backreflection pattern changes drastically. The algorithm that is best for tracking the special-shaped beam is no longer suitable for tracking the phase-modified beam. We discuss our detection schemes for both situations. In particular, we demonstrate how the algorithm senses the modified beam by using a newly proposed criterion of correlation peak pedestal area and executes an alternate algorithm in real time without operator intervention. This new algorithm continuously tracks the beam pattern to guarantee reliable and repeatable sensing. Results from simulation and real-world implementation of the algorithm at the NIF facility are presented. OCIS codes: 000.5490, 70.5010, 100.5010, 100.5090, 120.1880, 190.2620.

The analysis of a slitless volume holographic spectrometer is presented in detail. The spectrometer is based on a spherical beam volume hologram followed by a Fourier-transforming lens and a CCD. It is shown that the spectrometer is not sensitive to the incident angle of the input beam for the practical range of applications. A holographic spectrometer based on the conventional implementation is also analyzed, and the results are used to compare the performance of the proposed method with the conventional one. The experimental results are consistent with the theoretical study. It is also shown that the slitless volume holographic spectrometer lumps three elements (the entrance slit, the collimator, and the diffractive element) of the conventional spectrometer into one spherical beam volume hologram. Based on the unique features of the slitless volume holographic spectrometer, we believe it is a good candidate for portable spectroscopy for environmental and biological applications. OCIS codes: 090.7330, 300.6190, 070.2590.

A simple model for the path of a light beam through an optical coating is the path of a ray predicted by Snell's law. By determining the exit point of a beam for various types of coating, one finds that the simple model is a good approximation in the case of antireflection coatings, but not for coatings of other designs. An approximate method for determining the correct path of a beam through the coating is derived and the path is illustrated using a Gaussian incident beam and tracing the position of the peak field of the beam as it traverses the coating.

We consider block transmission over the incoherent channel, whereby several symbols either launched consecutively in time, or in parallel over several diversity paths, are equally affected by common isotropic phase and additively corrupted by circularly Gaussian additive noise. Our novel approach toward transmission over such a vector incoherent channel (VIC) model is based on coherency matrix and generalized Stokes parameters (GSP) descriptions of optimal detection inspired by classical optical polarization theory, but further extended to the dual context of generic electrical, as well as optical, communication. The four classical real-valued parameters introduced into optics by Stokes in 1853 to characterize the state of polarization of an optical beam, extended to [D.sup.2] GSP, underlie our new alternative novel description of maximum a posteriori/maximum-likelihood (MAP/ML) optimal detection over the VIC channel. The modulation formats of polarization-shift keying (POLSK), differential phase-shift keying, and amplitude-shift keying, as well as recent and novel combinations thereof, will all be seen to be equivalent to a new conceptual form of modulation called GSP-shift keying. Several forms of the optimal MAP/MI. receiver for vector multienergy transmission are developed, generalizing the classical scalar incoherent receiver and the known POLSK receivers. Index Terms--Generalized Stokes parameters (GSP), incoherent channel, noncoherent transmission, optimal detection, polarization-shift keying (POLSK), state of polarization (SOP), Stokes parameters.

A method for remotely detecting liquid chemical contamination on terrestrial surfaces is presented. Concurrent to irradiation by an absorbing near-infrared beam, the subject soil medium liberates radiance called thermal luminescence (TL) comprising middle-infrared energies ([v.sub.mir]) that is scanned interferometrically in beam duration [tau]. Cyclic states of absorption and emission by the contaminant surrogate are rendered from a sequential differential-spectrum measurement [[delta]S([v.sub.mir], [tau])] of the scanned TL. Detection of chemical warfare agent simulant wetting soil is performed in this manner, for example, through pattern recognition of its unique, thermally dynamic, molecular vibration resonance bands on display in the [delta]S([v.sub.mir], [tau]) metric. OCIS codes: 300.0300, 120.3180, 120.5630, 120.6200, 120.6810.

The scattering process induced in blood by a collimated laser beam is theoretically investigated. An individual red blood cell (RBC) has a scattering phase function strongly peaked in the forward direction. For far-field experiments, the small scattering volumes can be considered as 'macroscopic particles' characterized by an effective scattering phase function. Using the single-cell phase function as 'input data' the angular distribution of light scattered at small angles by the whole scattering volume, containing RBCs in suspension, is calculated analytically. The angular dispersion of the light scattered by blood can be approximately described by the same formula used to characterize the light scattered by a single cell but with an effective, hematocrit-dependent anisotropy parameter. OCIS codes: 290.0290, 290.4210, 290.5850.

A simple analytic model is derived for describing the attenuation of a shock wave in a Plexiglas plate. At the same time, experimental measurements are presented with a well-designed optical-fiber sensor based on detection-beam deflection. The amplitude of the shock-wave pressure is measured experimentally and calculated numerically for analytic expressions at different distances from the region of the surface breakdown by the radiation of a single-pulse Nd:YAG laser. Good agreement between the experimental and the calculated values of the shock-wave pressure is established. OCIS codes: 060.0060, 230.0230.

A study of lateral, vertical, and combined spot-size converters is presented that employs full-vectorial numerical techniques such as modal solution and beam propagation based on the finite-element method. Spot-size expansion, coupling efficiency to an optical fiber, the mode-beating phenomenon, and transmission losses are demonstrated for all three spot-size-converter designs. Optimization of the device fabrication parameters is also reported. A significant improvement in the coupling efficiency and reduction of the device length are achieved when the length and the width are changed simultaneously. OCIS codes: 060.2310, 130.1750, 130.3120, 230.7020.

By measuring the excitation efficiency of an optical waveguide on a diffraction grating one can accurately register the changes in the incidence angle of the exciting light beam. This phenomenon was applied to detect ultrasmall deflections of silicon dioxide cantilevers of submicrometer thickness that were fabricated with corrugation on top to act as diffraction grating couplers. The power of light coupled into the cantilevers was monitored with a conventional photodetector and modulated using mechanical vibration of the cantilever, thus changing the spatial orientation of the coupler with respect to the incident light beam. The technique can be considered as an alternative to the methods known for detection of cantilever deflection. OCIS codes: 050.2770, 310.2790, 230.4000, 310.6860.

We have developed a 756 nm, 3 W single-frequency cw Ti:sapphire laser by using the technique of injection locking. A cw Ti:sapphire laser in a ring-type configuration was forced to lase unidirectionally by use of an optical diode to prevent a high-power backward laser from disturbing the injection laser. A master laser was amplified by a broad-area laser diode and coupled into a single-mode fiber to generate a 50 mW injection laser with a Gaussian beam profile, which was enough to lock the Ti:sapphire laser at full power of 3 W. Such a high-power single-frequency Ti:sapphire laser enables a watt-level blue or near-ultraviolet single-frequency laser to be generated by frequency doubling.

For the azimuthally varying complex-argument Laguerre-Gauss beams, the Fourier integral representation is used to obtain the time-averaged power and the transport equation for the mean-squared beam width. From the coefficients in the transport equation, two propagation parameters are derived and compared with the previous treatments. 2005 Optical Society of America OCIS codes: 260.1960, 350.5500, 070.2590.

Spherical aberration arising- from deviations of the thickness of an optical disc substrate from a nominal value can be compensated to a great extent by illuminating the scanning objective lens with a slightly convergent or divergent beam. The optimum conjugate change and the amount and type of residual aberration are calculated analytically for an objective lens that satisfies Abbe's sine condition. The aberration sensitivity is decreased by a factor of 25 for numerical aperture values of approximately 0.85, and the residual aberrations consist mainly of the first higher-order Zernike spherical aberration term [A.sub.60]. The Wasserman-Wolf-Vaskas method is used to design biaspheric objective lenses that satisfy a ray condition that interpolates between the Abbe and the Herschel conditions. Requirements for coma by field use allow for only small deviations from the Abbe condition, making the analytical theory a good approximation for any objective lens used in practice. 2005 Optical Society of America OCIS codes: 080.1010, 210.4590.

In classical physics a beam of light propagates in a perfectly straight line and this means that we can measure small displacements with unlimited accuracy. However, this is not correct for real laser beams when we take the quantum properties of light into account. Spatial measurements will be limited by quantum noise, similar to the limitations for optical communication and sensing. Here we derive the spatial quantum noise limit and show how to measure it. Next we demonstrate that we can use specially prepared light with quantum correlations, so-called squeezed light, to improve spatial measurements to below this quantum limit. In this way we prepare a beam which goes in a straighter line than the output of any conventional laser.

A beam-shaping technique is presented for asymmetrical laser beams with different beam waists and divergences in both vertical and horizontal directions. We utilize a pair of two-dimensional micrograting arrays to equalize the beam parameter products of an asymmetrical beam in orthogonal directions by deflecting the appointed parts of the beam on the longer side of the beam and by recombining the parts on the shorter side. When combined with divergent transformation by means of collimating optical components, the beam-shaping system can produce a symmetrical beam in orthogonal directions with optimized beam waists and divergences. A beam-equalization system is designed and demonstrated for a typical asymmetrical beam of a laser diode bar. In the experiment an emission beam with dimensions of 1 [micro]m x 10 mm and half-divergences of 148 mrad x 576 mrad in the far field is transformed into an almost-square distribution with dimensions of ~12 mm x 12 mm and half-divergences of ~2 mrad x 2 mrad, which confirm the effectiveness of the proposed technique. OCIS codes: 140.0140, 140.3300, 140.2010.

We theoretically demonstrate beam shaping through adaptive feedback in an acousto-optic device with electrical feedback by using experimentally determined parameters. Cases of positive feedback and negative feedback from undiffracted and diffracted orders are investigated. In addition, we demonstrate the dependence of the final value of the induced grating strength in the acousto-optic cell on the feedback parameters. OCIS codes: 070.1060, 170.6110.

The cyclic error of a homodyne interferometer is caused mainly by phase mixing due to the imperfection of polarizing optical components such as polarizing beam splitters. In Appl. Opt. 43, 2443 (2004), we concentrated on the relationship between these imperfect optical characteristics and the cyclic error and found the preamplifier-gains condition for removing the cyclic error. Here we demonstrate the cyclic error correction method experimentally and show that the method can be applied in real time. We obtained 0.04-nm cyclic errors, with a standard deviation above 5 [micro]m. OCIS codes: 000.2170, 120.3180, 120.3930.

On the basis of the truncated second-order moments method in the cylindrical coordinate systems and the expansion of the hard-edged aperture function into a finite sum of complex Gaussian functions, an approximate method used to calculate the generalized beam propagation factor ([M.sup.2] factor) is proposed. The approximate analytical expressions of the generalized [M.sup.2] factor for rotationally symmetric hard-edged diffracted flattened Gaussian beams defined by Gori [Opt. Commun. 107, 335 (1994)] and Li [Opt. Lett. 27, 1007 (2002)] are derived, respectively; we show that it depends on the beam order N and the beam truncation parameter 5. Some typical numerical examples are given to illustrate its applications that we compare by using the obtained analytical method and the numerical integration method. OCIS codes: 110.1220, 050.1940, 350.5500.

Mini-Pole in-vacuo superconducting undulators, a vertical-winding racetrack coil structure, a horizontal-winding racetrack coil structure and a staggered array structure, are examined for use in the x-ray source in a 1.5 GeV or a medium-energy 3 GeV storage ring.