Optical spectral analysis with micro particle array

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The aim of this project is the development of a new method for the optical analysis of light with the help of spherical microparticles. Due to their high degree of symmetry, such particles show a very good resonance behavior. The corresponding resonance spectra are characteristic for each single micro-resonator. Light of an unknown source to be analyzed is used to excite an array of spherical particles with different sizes. The spectrum can be approximated with the intensity distribution over the particles together with their resonance spectra. The evaluation can be traced back to a linear system of equations. The solution of this mathematical problem plays a central role by the determination of the unknown spectrum and is therefore an important part within the whole project. The quality of the spectral reconstruction depends on a variety of parameters, e.g. the number of particles, size and size distribution. Also, the kind of light source plays an important role. The requirements on the microparticle array for a narrow bandwidth laser differ from those of a broadband light source. The performance of the method will be tested first on a narrow bandwidth laser diode. Based on preliminary works, spectral resolutions in the sub-picometer range can be expected. The applicability for broadband sources can be shown by appropriate light emitting diodes.At first, it seems that the determination of an unknown spectrum is limited to the range of calibration. One aim of this project is to investigate the possibility of an extrapolation outside the range of calibration with help of wave-optical simulations, which will be verified if applicable.