Near Field Optics

We present a near field optical study of a plasmonic gap waveguide vertically integrated on silicon.
The experimental study is based on a near field scanning optical microscope configured in
perturbation mode. This operation mode is described and modeled to give a physical insight into
the measured signal. A high spatial resolution allows for the characteristics of the plasmonic gap
modes, such as near field distributions, effective indices, direction of propagation, and coupling
between perpendicularly polarized modes, to be imaged and analyzed with accuracy. This
experimental work is supported by numerical simulations based on finite element optical mode
solvers and by the application of the strongly coupled-mode theory to the device.

We identify an observer frame error which influenced physics at a critical time. Refraction due to relative media motion was considered from the incorrect inertial frame for Stellar Aberration by Lodge (1893) after Michelson's null result, giving a light path 'dragged' from the refractive plane normal by the incident medium.[1]  But in the frame of the new medium (Earth) the light path refracts back towards the normal. Jones's (1970) spinning glass disk experiment inherited that wrong observer frame.[2] We find that using correct rotating observer frames is consistent with Special Relativity (SR) and that the error erroneously falsified the Stokes/Fresnel frame 'drag' theory supported by Michelsons finding, producing incorrect assumptions and paradox. We extend Young's experiment and consider the Huygens-Fresnel Principle,[3] wave/particle coupling, extinction, and shocks, finding quantum vacuum field implications. SR's postulates are confirmed but important domain limits emerge at Maxwell's near/far field transition zone.  A quantum mechanism giving mutually exclusive hierarchical inertial systems derives SR. We find extra predictive powers, symmetries and the ability to resolve perceived paradox and anomalies. New perspectives on Stokes, Raman and beyond arise from a local reality model using Einstein's 1952 view that 'space' is actually;  "infinitely many spaces in relative motion."

— This paper is a baseline document to review the latest technologies, algorithms and available hardware that can be used to build and automate a library system using Radio Frequency Identification technology as the infrastructure, allowing the librarian to track and manage real-life objects. The purpose is to review the current research that have been accomplished around this area in order to produce the best possible design, and implementation of a robust solution with maximum efficiency to automate a library system. The article first provides an overview of the radio frequency identification technology, its history, radio frequency principle, and how distance and frequency can affect the signal coverage distance. Then radio frequency identification structure and types are explained, after that the paper evaluates the latest researches in the radio frequency identification infrastructure and middleware. Finally the issue of radio signal collision is discussed, and corresponding anti-collision algorithms are briefly explained. Keywords— Active Passive RFID, Far Field, Near Field, RFID in libraries.

Many emerging light-emitting diode (LED) applications require short-distance illumination. For that, we derive an exact formula of the illumination profile produced by Lambertian LEDs, in which all parameters are fundamental constants. Moreover, we propose a general, simple, but accurate mathematical model of the irradiance pattern, valid for Lambertian and non-Lambertian LEDs at short distances. This model provides the irradiance profile as a function of both the LED-target distance and the coordinates of every point on the irradiated surface. The model is formulated in terms of simple sigmoid functions, in which LED size and light flux are fundamental parameters. The accuracy of the irradiance pattern model is tested both with theory and with experimental measurements.

The effect that femtosecond laser filamentation has on the refractive index of Nd:YAG ceramics, and which leads to the formation of waveguide lasers, has been studied by micro-spectroscopy imaging, beam propagation experiments and calculations. From the analysis of the Nd3+ luminescence and Raman images, two main types of laser induced modifications have been found to contribute to the refractive-index change: (i) a lattice defect contribution localized along the self-focusing volume of the laser pulses, in which lattice damage causes a refractive-index decrease, and (ii) a lattice strain-field contribution around and inside the filaments, in which the pressure-driven variation of the inter-atomic distances causes refractive-index variations. Scanning near-field optical-transmission and end-coupling experiments, in combination with beam propagation calculations, have been used to quantitatively determine the corresponding contribution of each effect to the refractive-index field of double-filament waveguides. Results indicate that the strain-field induced refractive-index increment is the main mechanism leading to waveguiding, whereas the damage-induced refractive-index reduction at filaments leads to a stronger mode confinement.

This paper presents the pioneer use of our unique Sub-micron Scanning System (SSS) for point spread function (PSF) and crosstalk (CTK) measurements of focal plane CMOS Active Pixel Sensor (APS) arrays. The system enables the combination of near-field optical and atomic force ...

We propose an illumination mode near-field optical microscope operated under an optical feedback for imaging biological specimens in their natural environment. For feedback control, rapidly varying evanescent signal has been generated over the sample surface. It has been found that evanescent signal can be profitably used as a control signal by utilizing its sample feature dependent discrimination sensitivity. Neurons have been successfully observed both in air and in liquid with a resolution well beyond the diffraction limit.

In near-field optics, measurement of vertical variations of the near field is of great interest for characterizing the efficiency of resonances such as surface plasmon polaritons. The use of the signal obtained through the lock-in amplifier using a feedback on the vertical vibration of the probe is shown to enable the reconstruction of the near field without the use of the slower technique of approach curves. Therefore, a tomography of the near field is directly available.

In near-field optics, measurement of vertical variations of the near field is of great interest for characterizing the efficiency of resonances such as surface plasmon polaritons. The use of the signal obtained through the lock-in amplifier using a feedback on the vertical vibration of the probe is shown to enable the reconstruction of the near field without the use of the slower technique of approach curves. Therefore, a tomography of the near field is directly available.