Advanced matrix laser lithography for fabrication of photonic micro-structures

Direct laser beam writing techniques represent an interesting alternative to focused electron and ion beam writing approaches for the fabrication of photonic micro-structures. Although the resolution of laser beam writers is strongly limited by the Rayleigh diffraction limit, it is not always necessary to create features significantly smaller than the recording wavelength. In such cases, a laser exposure can be used, with all its advantages. In this paper a direct laser writing technique is presented one; which significantly improves the performance of commonly used direct laser writers by introducing an exposure of a large area within a single step. The elementary exposed area can contain a general micro-structure without any special requirements. In contrast to writing techniques based on a single spot focus, the writing beam can have the shape of a general aperiodic structure and exposes an area of about 10^-2 square millimetre. This complicated exposure field is created using a demagnified projection of the exposed structure from a two-dimensional computer-driven spatial light modulator. The main advantages of the method compares to the single point exposure are a significantly improved exposure speed, a perfect alignment of features within a single exposed area, and the possibility of tuning the exposing field very precisely using continuous modulation of the signal on the spatial light modulator. The in-house-developed device is presented together with several realized samples

Measurement of fluid motion and temperature changes in the real model of the heat exchanger using pLIF

The aim of this project is a qualitative and quantitative experimental description of a development of the fluid flow inside the real model of a stratification tank of the heat exchanger. The experimental research deals with the Particle Image Velocimetry method and Planar Laser Induced Fluorescence Method. The results of this project provide the worthy information about the fluid behaviour, boundary condition and risen fluid flow inside the tank model. This final outcome is necessary for the verification and validity of the analysis models and simulations

High Frequency Modulation Method for Measuring of Birefringence

A method of optical birefringence measurement is presented. It uses an el ectro-optic modulator for the high frequency modulation of polarization of the laser beam. The developed optical apparatus exhibits high sensitivity. It is able to measure very small birefringence of samples down to 10-3 rad. The accuracy and sensitivity of the method was checked by measurement of calibrated Sol eil – Babi net compensator. Method can be also used for online and accurate measurement of an optical components birefringence. This application was developed with the aim to measure Cotton-Mouton effect in air and nitrogen

Multiple wavelength generation using a compacted hybrid Raman / Bi-EDF amplifier

A multiple wavelength laser source is generated by a Brillouin seed signal and a compacted hybrid Raman / bismuth-based erbium doped fiber amplifier (Bi-EDFA) in a linear cavity. The gain media of the Raman/Bi-EDFA is only a 2.15 m Bi-EDF pumped bi-directionally by two laser diodes (LDs). In comparison to all of the conventional multiple wavelength sources generated via using the same Bi-EDF and LDs, the proposed multiple wavelength source has much more number of lines due to using Raman and EDF amplification