In this article we explore novel applications of the Bayesian methods to areas such as holography and image processing and sensor fusion.

In recent years, there have been intense efforts in the study of the physical principles and applications of the scanning near-field optical microscope. Extensive theoretical analyses, numerical simulations, and experimental investigations have been conducted. The results demonstrate that image resolution and contrast depends not only on the aperture size of the probe and the reflection/transmission of the sample, but also on other parameters and experimental conditions. In this paper, the influences of the operating mode, probe-sample interaction, polarization of light, and detector orientation are discussed. Furthermore, the progress on the use of linear systems transfer function for the characterization of image resolution is reviewed. Finally, future directions in research and development are discussed.

We present scanning near-field optical microscopy as an optical instrument characterized by a transfer function. This approach gives some theoretical guidelines for the design of near-field optical measurement systems. We emphasize that it is important to distinguish between the resolution for the optical field and the resolution for the object. In addition, we discuss the evanescent-to- propagating conversion capability of different probe tips.

A new optical configuration for a near field scanning optical polarized microscope with an illumination mode is reported. It uses two circularly polarized laser beams with different frequencies which are generated by an axial Zeeman laser. A laser beam is incident on an optical fiber and is launched form the apex of a sharpened fiber probe in order to illuminate the sample. The scattered light on the surface of the sample is collected with an objective lens and goes through the optical elements of the quarter wave plate and the linear polarizer. The light from polarization devices is converted to an electric signal with a photomultiplier and fed into a lock-in amplifier. The quarature components and intensity signal are acquired to computer, and the retardation and the azimuth angle of the birefringence are then calculated via computer. The measurement characteristic of the developed system and image of birefringence material are shown.

The coherent superposition of optical waves or optical interference is an integral part of the image formation in near-field optics and can be used to increase the lateral resolution. Cavity effects increase the resolution furthermore and shadow formation avoids aperture limitations in reflection-collection nearfield optics. The application range of optical scanning probe microscopy is extended by taking advantage of optical interference and standing waves by preserving at the same time spectroscopic imaging ability, the main advantage of optical scanning probe techniques.

A new method is proposed to enhance the resolution of the image detected by scanning near-field optical microscope based on spatial filtering technique.

A Fourier analysis on the imaging process in PSTM has been presented. Analytical expressions for scalar/vector angular spectrum transfer function were derived. As the numerical result shown, the ASTF of a PSTM consists of two distinct components, the propagating component and evanescent component. For evanescent component, their amplitudes decrease dramatically while the phases remain constant as tip-sample distanced increases, which were found responsible for the degrading of the sharpness, contrast and intensity of the image. For propagating component, their phases increase linearly with d while the amplitudes keep constant, which causes distortion and bring blurring to the image. Compared with scalar-ASTF a vector-ASTF spreads out much wider and decreases an order faster as tip aperture diameter decreases. Based on ASTF the influences of such parameters as tip-sample distance, tip aperture diameter and the incident angle of illuminating laser beam on PSTM image has been discussed.

This paper attempts to answer the question of 'how to explain the image of photon scanning tunneling microscope (PSTM)'. To explain the image of PSTM, the essential difficulty is the false image information within the complex image of the topographical image and refractive index image of sample. In this paper, we have derived the PSTM imaging formula and introduced the eliminating false image information method and image separating method, and discussed the key to super-resolution of near-field optical microscopy. Numerical simulation and experiments with the method of perturbation diffraction combined with (pi) - symmetric lighting eliminating false image information are provided.

This article addresses the development and progress in the rapidly growing area of optical pattern recognition. In optical pattern recognition there are two basic approaches; namely, matched filtering and associative memories. The first employs optical correlators and the later uses neural networks. This paper reviews various types of optical correlators and neural networks as applied to real-time optical pattern recognition for which some of the recent advances are included.

Super resolution has been an active field during the last fifty years. Previous works have shown that the super resolution effect is an SW adaptation process which adapts the SW acceptance chart of the signal to the one of the system. This new point of view is based on handling the Wigner chart of the input signal as well as the Wigner chart of the signal which can be accepted by the system, by taking into account the number of degrees of freedom of the signal and the system and then studying the distribution of the degrees of freedom in the Wigner chart. In this paper we draw the distinction between geometrical super resolution and diffraction limited resolution. In addition we introduce the term system's and signal's geometrical SW and show that the SW adaptation approach previously demonstrated is valuable only to binary sensing devices. In practical cases, the dynamic range of the detector is also a factor that determines the number of degrees of freedom and thus it should also be taken into account in the adaptation process. As a result, for 1D objects instead of adapting 2D chart as was done in previous SW adaptation process. Several examples demonstrate the SW adaptation process for obtaining the desired super resolution effect.

Previous papers have demonstrated the ability of the time multiplexing or the direction multiplexing approaches for obtaining 2D super resolution effects. In this paper different and easier for experimental demonstration techniques are presented and analyzed.

In the last decade an enormous effort was made in semiconductor industry to reduce the structure dimensions of modern electronic devices towards the 100 nm limit. This development is accompanied by the demand for novel analytical tools in device failure analysis providing both high lateral and high time resolution capability. Scanning force microscopy (SFM) was already proven to be a very promising candidate if only the topography of the sample is concerned. To investigate simultaneously other properties, e.g. electrical, thermal, or optical surface properties with almost the same resolution novel sensor concepts have to be introduced. In this paper we focus on the some aspects of the development and fabrication of integrated cantilever probes for scanning probe microscopy (SPM). We demonstrated that a variety of different materials, e.g. silicon, gallium arsenide, diamond, metal layers etc., are available for this purpose. Furthermore several concepts for SPM probes are described which exploit the unique properties of the above mentioned substrate materials. Probe concepts rely on, e.g. a coplanar waveguide integrated onto a cantilever for both high frequency scanning electrical force microscopy and ultrafast scanning tunneling microscopy, an electrical conductive and superhard diamond tip for nano spreading resistance profiling, a miniaturized Schottky diode tip for scanning thermal microscopy, and an aperture tip for scanning near-field optical microscopy.

We have successfully fabricated an extremely high throughput probe for near-field optics introducing a triple-tapered structure to reduce the loss in a tapered core, to focus the light, and to excite effectively the HE₁₁ mode. A focused ion beam and selective chemical etching were used for fabrication. Over 100 times increase in the throughput of the triple-tapered probe with the aperture diameter D < 100 nm was realized in comparison with the conventional single-tapered probe. Furthermore, due to the third taper with a small cone angle, the localized optical near-field on the triple-tapered probe with D equals 60 nm has been confirmed.

Microfabricated aperture probes for SNOM applications revealed polarization properties which seem to depend on the aperture geometry which is well defined due to the fabrication process. A finite integration approach was used to theoretically calculate the optical transmission characteristics of these probes. In particular the influence of the aperture aspect ratio and the metal film thickness on the transmission and the polarization properties is studied in detail. A modified tip geometry is proposed to improve both, the light confinement at the tip apex and the polarization properties of the aperture probe.

A scanning near-field optical microscope (SNOM) has been used to measures directly the evanescent field distribution surrounding an optical fiber taper. The SNOM interaction with the fiber taper is explain for the first time using a wave optics approach. Result of evanescent field measurements with varying wavelengths and surrounding refractive index media are presented. Experimental results are compared with theoretical data produced by the Finite Difference Beam Propagation Method.

For the passive fiber probe, the dependence of the probes' transmission efficiencies on the parameters such as fiber probe shape, taper length, tip diameter and incident wavelength are analyzed with the coupled local-mode theory. It shows that the transmission efficiency of a parabolic fiber probe is about an order of magnitude higher than that of the conical fiber probe. With the increase of the incident wavelength, the transmission efficiency of fiber probes decrease. The images of phase grating by conical fiber probe and by parabolic fiber probe are compared. The Nd:YVO₄ frequency-doubling laser with a miniature structure is used as light source in the experiment of SNOM, which provides higher transmission efficiency and make it fascinating in some SNOM's applications. As for active fiber probe, the ASE fiber probe is proposed. It has a wide spectrum of 6nm and may greatly reduce the coherent noise in SNOM image. It may improve the output photon flux several times higher than that of passive fiber probe. Meanwhile, the guide-wave reflection properties in fiber taper are investigated.

The principles of operation of the solid immersion lens (SIL) are described. Two types of SIL, the hemisphere and super-sphere, and their tolerances, are discussed. Several application of the SIL to microscopy, lithography, and optical storage are reviewed, along with a description of the theoretical considerations for determining the spot size, the effect of the air gap, and the effect of multiple- layer structures on the ellipticity of the spot.

A full wave approach is developed to analyze the scattered electromagnetic fields due to fluctuations in the surface height and/or electromagnetic medium parameters such as the complex electric permittivity, conductivity, and magnetic permeability. Since the scales of the medium fluctuations considered could be significantly smaller or larger than the electromagnetic wavelengths, the familiar perturbation and physical/geometrical optics techniques based on the Kirckhoff approximations of the fields on the boundaries cannot be used nor is it possible to investigate sub- wavelength structures based on far-field measurements.

From the moment of its creation scanning near-field optical microscope (SNOM) has been attracting significant attention in the way of its application to superlocal optical action on objects. In fact, near-field radiator is a unique light source with dimensions smaller than the radiation wavelength. Using of such source in micro- and nanoelectronics, biology and other fields of science and technology extends potentialities of existing technologies. However, there are some principle physical and technical limitations of effective localization oflight action. Near-field radiator has to provide high power of the output radiation and its action has to be localized within as small region as possible. The highest transmission, that near-field probes have at the present time, is about iO — lOs. This means that with 10 mW input power coupled into the fiber probe and 50nm output aperture light power density at probe exit is about 41O- 4 lO W/cm2. Further increasing ofthe input power results in heating and destruction of the probe. This effect restricts efficiency of near-field action on surface. Localization of the near-field action on surface has, in turn, principle limitation related to the relaxation mechanism of absorbed light energy. Below these physical mechanisms that limit efficiency of near-field action are considered in details and possible ways of the efficiency increasing are discussed.

The advance of nanotechnologies in electronics and optics has offered possibilities of applying methods of near-field optics. Optical memory is the area where these methods can be successfully employed. It is now possible to make memory elements with the bit size as small as a few tens of nanometers (which corresponds to the storage density of 1011 bit/cm). Nanoelectronics methods and synthesized hologram techniques can also be used for this purpose. With such small bit size data reading becomes rather a problem. Based on the wave optics principles, the wavelength of the reading laser should be of the order of bit size. Though the wavelengths of diode lasers now approach 400 nm (there are already blue diode lasers with ?.=4O4 mu), wavelengths shorter than 390 nm are hardly possible in the near future. It means that the bit size is always smaller than the wavelength of diode lasers. To overcome this difficulty, we should apply the superresolution approach, which is realized in near-field optics. Another important field of application of near-field optics is scanning optical microscopy, especially noncontact microscopy of subnanometer resolution. The development of such microscopes may be important not only for making optical data storage systems but also for investigating biological structures. In this regard, the analysis of possible approaches to near-field calculations of electromagnetic field assumes great significance. It should be noted that the near-field theory is well elaborated and found practical use The mathematics of the theory based on Huygens's principle and Kirchhoff's formula is successfully used for studying different diffraction phenomena. However, though applicable in a number of approximations, this mathematics does not work in the near-field calculations (especially when R is of the order of 2). This brings up the questions: how can the field be determined in this case, can we apply Kirchhoff's formula and Huygens's construction, or should we employ Maxwell equations and solve a boundary problem for each particular case. There are other, more subtle, questions (especially when R is ofthe order of)t) involving coherence and interference effects, wave formation, etc. We start the analysis with the approximations that are used in the deduction of Kirchhoff's formula, then proceed with rigorous mathematical treatment of Huygens's construction, and conclude with the consideration of field properties near the light source when R<'(A..

A recently derived radiative transfer equation with three Lorentzian kernels of delay is applied to an albedo problem on a scalar wave field quasi-monochromatic pulse diffuse reflection from a semi-infinite random medium consisting of resonant point-like scatterers. The albedo problem is solved exactly in terms of the Chandrasekhar consisting of resonant point-like scatterers. The albedo problem is solved exactly in terms of the Chandrasekhar H-function, extended analytically into the single scattering complex albedo (lambda) -plane. Simple analytical asymptotics for the non- stationary scattering function is obtained in the limit related to large values of the time variable. The exact analytic solution for the time-evolution of a diffusely reflected short pulse is used to analyze an accuracy of the non-stationary scattering function calculated in the diffusion approximation. It is shown that the diffusion asymptotics describes the exact solution with a relative error not exceeding one percent only at larger values of dimensionless wave propagation time t equals t/t_o > 200 where t_o stands for a mean free time of wave radiation between scattering events defined in terms of the wave phase in a random medium consisting of point-like scatterers tuned to the Mie resonance. Besides, the accuracy of the diffusion asymptotics falls off providing that wave scattering approaches the resonance conditions.

An introduction to the merging field of nano-photonics is given, with emphasis on device realizations and applications. Due to the small size and high efficiency of these devices, nano-photonics has the potential for high- density integration, leading to VLSI photonics. We discuss our work in recent year on the microdisk laser, micro-ring photonic wire lasers, and microring resonators. These are among some of the smallest lasers and modulators ever fabricated. The physics of the modification of spontaneous emission rates with low-dimensional photonic structures is discussed briefly. The nanofabrications of these devices are described. A model of the microcavity resonator is then presented, which provides useful design rules as well as insights into alternative coupling structures that significantly increase the coupling length.

We propose a set of novel optical limiters by sandwiching index-matched nonlinear liquid between a glass plate and a relief grating. Strong light beams can change the index of the liquid to induce index mismatch and reactivate grating to diffract, reflect or evanesce most of the output light away to protect eyes or sensor. In this paper, different gratings for the use of optical limiting including diffraction gratings, total-reflection gratings and sub- wavelength gratings are analyzed and compared.

We have performed Raman spectroscopy using a near-field scanning optical microscope. The small sample volume coupled with the light-starved nature of the Raman effect makes nano-Raman studies difficult. We present results showing near-field effects in an investigation of Rb-doped KTP. These effects include a change in selection rules due to the presence of a z-polarization component in the near-field, a surface-enhancement effect in near-field Raman data, a reduced Rayleigh tail, and simultaneous topography with the near-field probe. An image taken within a Raman feature demonstrates that nano-Raman imaging is indeed possible if the near-field instrument has considerable long-term stability.

The progress of near-field optics research and its application in some Chinese universities and institutions is overviewed. The research activities on the instrumentation aspect of scanning near-field optical microscope, novel sample-tip regulation mechanism, fiber-tip preparations, high resolution imaging and near-field spectroscopy in confined mesoscopic systems, light emission new materials and devices, theoretical development of near-field light- matter interactions, new observations of physical phenomena in the near-field region, optical nanostructuring, are summarized. The current research projects and future prospective of the possible application of SNOM and near- field fluorescence imaging to biology, such as the in vitro cell nuclear assembly and apoptosis as well as gene recognition and DNA sequencing, and opto-electro devices are discussed.

InGaAs single quantum dot photoluminescence spectra and images are investigated by using a low-temperature near- field optical microscope. By modifying the commonly used near-field apertured prove, a high spatial resolution and high detection efficiency are achieved simultaneously. Local collection of the emission signal through a 500 nm aperture contributes to the single-dot imaging with a (lambda) /6 resolution, which is a significant improvement over the convention spatially resolved spectroscopy. Tailoring the tapered structure of the near-field probe enables us to obtain the emission spectra of single dots in the weak excitation region, where the carrier injection rate is approximately 10⁷ excitons/s per dot. By employing such a technique, we examine the evolution of single-dot emission spectra with excitation intensity. In addition to the ground-state emission, excited-state and biexciton emissions are observed for higher excitation intensities. By a precise investigations of the excitation power dependences of individual dots, 2D identification of their emission origins is obtained for the first time.

The light emitting properties of GaN blue light diode has been characterized by near-field optical microscopy, near- field spectroscopy and conventional spectroscopy. Since the mechanism of the light mission from this material with high defect density is not yet fully understand, it is necessary to study the optical properties in conjunction with the nano-scale structure. The conventional spectroscopic methods are limited by the diffraction barrier, hence the information of the correlation of light emission and defects is not sufficient. By using near-field spectroscopy and near-field optical microscopy, we have studied the electro- emission spectrum of GaN blue diode, which is fabricated on sapphire substrate using low-pressure MOCVD epitaxy technique in our lab. The results how that the near-field spectroscopy can provide spatially resolved local spectrum of the samples surfaces with sub-wavelength resolution and hence provide a new technique to study the mechanism of light emission at nanometer scale. The dependence of light emission intensities vs. injection currents in the near- field spectra reveals the donor levels of the energy bands in GaN blue diode.

Microcavity shows the growing importance of the intensity enhancement, inhibition nd spectral narrowing of spontaneous emission. The advantages of microcavity lasers are the very low threshold and small size. We have fabricated InGaP microdisks with radius of about 5 micrometers . The photoluminescence of our InGaP microdisks in far-field and near-field observation are compared. A strong enhancement of the photoluminescence intensity in the microdisks with respect to that of the un-patterned sample of the same epitaxial wafer is obtained. Far-field fluorescence imaging shows a bright red emission of fluorescence around the circumference of the microdisk. Simultaneous acquisition of near-field image and topography gives the correlation of the sample surface and light distribution. The optical disk mode pattern in our InGaP microdisks can be interpreted as whispering-gallery mode and the mixture of other modes.

The intensity-dependent nonlinear refraction in a non- resonant five-level molecular systems is studied in detail using rate equations, including saturable refraction, reverse saturable refraction, and the transition between these two effects.

We describe guiding of neutral atoms through a hollow optical fiber with a micron-sized hollow core. Two-step photoionization experiment shows the frequency dispersion properties of the dipole interaction between an atom and an optical near field. These characteristics are advantageous to species- and state-selective manipulation of atoms. Then we discus a new scheme of atom deposition by means of the guiding technique, including a numerical simulation. We also present two methods for controlling atomic motion using a sharped optical fiber with a nanometric optical n ear field, i.e., atom deflection and atom trap. Deflection angle and trap potential are estimated based on a near-field intensity distribution derived from a Yukawa-type screened potential. The manipulation techniques are useful for precise control of atoms with a spatial accuracy beyond diffraction limit, which will lead to atomic-scale crystal growth.

We proposed and demonstrated a novel silicon planar apertured probe array as a near-field optical head for optical memory. In comparison with the conventional fiber probe, the apertured probe array has durability, higher read-out data transmission rate and it allows us to overcome difficulty of precise mechanical tracking of the single fiber probe because it can be used for reading data as a surface information. The probe array was fabricated by utilizing wet etching technique of a silicon wafer. Inverted pyramids were formed on the silicon plate, and apertures were fabricated at the tops of the inverted pyramids. An aperture with a size less than 100nm was realized. By scanning the probe array we obtained resolved images of the lines in corrugation which was made on a metal thin film. The observed line width was 250 nm. Furthermore, we put spherical lens inside the inverted pyramids to focus the propagating light at the apertures automatically. The near- field intensity at an aperture was 16 times larger than that without a spherical lens.

We have observed near-field optical images of phase change marks and evaluated the readout signals including the optical near-field. Samples were composed of multilayered structures on glass substrates. Crystalline marks were recorded by a focused laser beam with an optical microscope in the as-deposited amorphous films. In readout, the optical and the topographical images of the recorded marks were evaluated at the same time by a collection mode near-field scanning optical microscope (NSOM). The surface profiles showed less than 1 nm dips around the marks. Therefore it means that the NSOM image of phase change marks depends on the refractive index change. The evaluated signal modulation of the optical image showed a sinusoidal curve to the top SiN layer thickness, and the maximum modulation was 60 percent.

We report a fiber optical nanometer range position sensor based on reciprocal interferometry, a concept of import in interferometric fiber-optic gyroscopes. The configuration resembles a modified Michelson interferometer with only one of the two arms used. The principle of operation is the interference between the reflected light wave from the fiber end and that from a reflective object. As both the reference and the sensing light waves shares the expected interference behavior, which agrees well with its mathematical simulation. A position sensing resolution of about 20 nm, which is limited by the choice of available components, has been demonstrated. The systems immunity to the influence of temperature change has also been verified.

In this paper, we obtain 2D fractal as a cyclic process which define different fine structures using a functional from that can represent circle and square as limit cases. The self similarity for these cases is introduced intensity patterns in the Franhoufer region are shown for different configurations.

In this paper, some considerations about the scalar and vectorial theory related with the interaction fractal object and electromagnetic wave are shown. Different combination is in the density function, that permits us to obtain the Cantor function, can be used for this objectives.

In order to produce microelectromechanical systems on base of gallium arsenide it is necessary to develop novel etching techniques. The conventional dip etching is not suitable to fabricate such systems reliably and with sufficiently small thickness variations. To overcome this problem we used a modified spray etching technique. A comparison between both methods is given.

A new approach to the investigation of probes for scanning near-field optical microscopes and recognition of parameters of arbitrary secondary light sources in nanometric scale is suggested. A new numerical technique of analytical continuation of the Fourier spectrum with the object restoration procedure based on Zernike polynomials iterative extrapolation is presented.

A new proposal for near-field data storage and the basic experiment under a high speed disk rotation are described. Using the thermally nonlinear property of an Antimony thin film and an intermediate layer of SiN with a thickness of 20 nm, less than 100 nm sized marks were recorded and retrieved in an optical phase change film beyond the diffraction limit, with a wavelength of 680nm and a lens NA of 0.6.