Our paper deals with advanced approaches exploiting electron-beam lithography origination technologies in order to produce the so-called DOVIDs offering new visual features, though based on subwavelength origination. Synthesized security elements are recorded with a resolution reaching even 2,500.000 dpi and are specially developed for the security measures of the most important state valuable documents. We shall mention some principal features, where the ultra-precise recording of diffractive elements is requested.

A new fabrication process for the patterning of organic semiconductors at the nanoscale has been developed using low temperature thermal nanoimprint lithography and the details of this process are discussed. Novel planar nanotransistors have been fabricated and characterized from poly(3-hexylthiophene) (P3HT) and we demonstrate the feasibility of using such devices as highly sensitive chemical sensors.

In this article, the fabrication of poly(3-hexylthiophene) self-switching diodes (SSDs) is described. The unique design of the SSD enables it to be fabricated from a single layer of semiconductor material with a single lithographic step using nanoimprint lithography combined with argon milling. The resultant device morphology showed good uniformity and the SSDs exhibited pronounced current rectification and wide working voltage range.

Our paper deals with the recent advances in synthetically written optical security devices (DOVIDs) and holograms. The synthesized holographic security elements are recorded with a resolution reaching 500.000 dpi and are specially developed for the "layman-level" security of the most important state valuables and documents, like banknotes and identity cards. We especially pay an attention to such holographic features being impossible to originate through conventional optical holography of matrix based devices.

Our paper deals with the survey of currently exploited electron-beam technologies to produce several protective optical elements. The computer-synthesized security elements are recorded with a resolution reaching 500.000 dpi and are specially developed for the security of the most important state valuables and documents. We shall mention some principal features, where the ultra-precise recording of diffractive elements is exploited.

Invented in late 1940s, holography has played a very important role in many technical applications. While the 60s and 70s belonged to, say, a classical period of the holography and diffractive optics (optical elements, lenses, beam splitters), the last two decades have shown an enormous expansion of various mainly synthetically designed and created holographic elements. Ever since its invention, holograms have also attracted our attention, because of their true three-dimension perception of a depicted object and related optical features. These phenomena caused, the holograms have become very well and easily publicly recognized, but still very difficult to falsify. Holography based optically variable microstructures and related advanced anti-counterfeit measures are thus ones of the leading features in security elements used for the protection against falsification of valuables, documents (banknotes, visa, passports, ID cards, tax stamps, etc.), serving for the protection of interests and many others. Our talk deals with the survey of currently exploited technologies to produce several protective optical elements. A special attention will be paid to the synthetically developed special optical elements by means of the unique technology - the electron beam lithography, what is one of the world's most advanced technologies used for the protection against falsification. The computer-synthesized security elements are recorded with an incredible resolution of up to 500.000 dpi and are specially developed for the security of the most important state valuables and documents. Finally, we shall discuss some technological possibilities for its future development.

We theoretically and experimentally study the polarization properties and the spatial and wavelength dependence of side scattered radiation from a fibre Bragg grating (FBG). Antenna theory is used to model the radiation pattern from the FBG. Recently, it was reported by other authors that side scattered light from a fibre Bragg grating exhibits a remarkable anisotropy in its azimuthal distribution, proposed to be due to an inhomogeneous transverse grating profile. We show that the angular distribution of the scattered light depends on the actual phase-matching angle thus the observation angle - and if any, on the grating tilt. Hence, inhomogeneities in the cross-section of the fibre grating are not necessarily responsible for the anisotropic light distribution as was reported. It is shown that the scattered light pattern from any grating (even a uniform un-tilted one) possesses a non-uniform intensity distribution. The spatial distribution of the scattered light is then treated as the Fraunhofer diffraction pattern. In an analogy to dipole radiation, the presented model explicitly shows that the scattered light is located in specifically defined regions of a cone depending on the principal parameters of the FBG. The technique has interesting implications for several optical fibre Bragg grating devices.

In our recent published works we reported that the propagation length dependence of the conversion efficiency of the Cerenkov second harmonic generation (CSHG) in planar waveguides with a nonlinear substrate follows quite strict rules depending on an actual waveguide geometry together with the wavelength of the pump radiation. Namely, simple integral expressions show that the propagation length exponent may vary continuously from zero to a quadratic dependence. In this contribution, we generally analyze the propagation length dependence of CSHG for some specific arrangements. We also study, for the first time, the effect of pump depletion together with the influence of the pump wavelength and the effective refractive index. It is shown that the length dependence can thus be described by several categories, where the conversion efficiency is - with respect to the propagation length - linearly proportional and quadratic, but also the length exponent may continuously vary from 1 to 2 (for the classical phase-matching), including the so-called Cerenkov peak region, where the length exponent is equal to 3/2.

We present the state of the art for commercial design and simulation software in the 'front end' of photonic circuit design. One recent advance is to extend the flexibility of the software by using more than one numerical technique on the same optical circuit. There are a number of popular and proven techniques for analysis of photonic devices. Examples of these techniques include the Beam Propagation Method (BPM), the Coupled Mode Theory (CMT), and the Finite Difference Time Domain (FDTD) method. For larger photonic circuits, it may not be practical to analyze the whole circuit by any one of these methods alone, but often some smaller part of the circuit lends itself to at least one of these standard techniques. Later the whole problem can be analyzed on a unified platform. This kind of approach can enable analysis for cases that would otherwise be cumbersome, or even impossible. We demonstrate solutions for more complex structures ranging from the sub-component layout, through the entire device characterization, to the mask layout and its editing. We also present recent advances in the above well established techniques. This includes the analysis of nano-particles, metals, and non-linear materials by FDTD, photonic crystal design and analysis, and improved models for high concentration Er/Yb co-doped glass waveguide amplifiers.

Analytical expressions for Cerenkov second-harmonic-generation in planar waveguiding structures are derived, based on evaluation of the conversion in the Fourier domain, assuming no depletion of the fundamental guided beam. The derivation is much shorter than that in existing methods and allows for a relatively simple interpretation of the main features.

Abnormal reflecting mirror (ARM) structures, consisting of a corrugated optical waveguiding structure, can serve as a wavelength-selective end mirror in a laser cavity. The ARM structure shows, for each wavelength in a certain region, 100% reflection at a certain angle of incidence. In the vicinity of this angle the waveguide is resonantly excited, leading to strong enhancement of the optical field in the layer structure, which is interesting for efficient second-harmonic generation (SHG). In this paper, experimental results of a first prototype, exhibiting Čerenkov SHG, are reported.

Abnormal reflecting mirror (ARM) structures, consisting of a corrugated optical waveguide structure, can serve as a narrow band reflection filter in which strong field enhancement may occur by excitation of the guided mode. The latter is quite interest for SHG. We report experimental results of a first prototype, which exhibits CSHG in the ARM structure.