We have designed some holographic gold gratings in 700-1100nm wavelength range for stretching and compressing
pulse in CPA technology. These gratings optimized by Gsolver software based on rigorous coupled-wave analysis
(RCWA) for TM polarized light in the 1st order (littrow mount) and have super Gaussian profiles. We also shown
dependency of diffraction efficiency (DE) to depth and duty cycle of super Gaussian gold gratings in 1064nm.
KEYWORDS: Carbon dioxide lasers, Temperature metrology, Thin film deposition, Diffusion, Thin films, High power lasers, YAG lasers, Gas lasers, Nanostructured thin films, Nanoparticles
In this paper, we report on designing a new raster-scanned CO2 laser heater for homogeneous heating of the disk-shaped substrates. This new design aims at concentrating the laser energy near the substrate peripheral edge, which mostly tends to remain cooler than the inner parts during the heating process. A comprehensive heat diffusion model has been developed to predict the temperature and its homogeneity on the substrate depositioning face. This new kind of laser heater can favorably be used in preparation of nanostructured thin films where the shape and size of the embedded nanoparticles depend on the maintained temperature during the depositioning time interval. This heater can also be used for CO2 laser conditioning of the prepared thin films to enhance their damage threshold for high power laser applications.
A few holographic silver gratings with maximum diffraction efficiency in the 700-1100nm wavelength range were designed. They can be attractive for stretching and compressing pulse in CPA (chirped pulse amplification) technique. KPP1206 photoresist was used to model the final pattern on photoresist thin film. This paper was devoted to consider super Gaussian gratings. Therefore, approximately identical exposure energy density intervals were used for optimizing grating profile. Accordingly, the Genetic Algorithm (GA) was employed by Grating Solver software to optimize groove spacing, groove depth and groove shape of the grating for TM polarized light in the 1st order (littrow mount).Also, Dependency of diffraction efficiency (DE) to depth and duty cycle of super Gaussian silver gratings in 1064nm was shown.
A few holographic metallic (gold and silver) gratings with maximum diffraction efficiency (DE) in the 700 to 1100 nm wavelength range were designed. These designed diffraction gratings can be attractive for stretching and compressing pulses in chirped pulse amplification (CPA) technology. They were optimized for transverse magnetic polarized light in the first order (littrow mount). KPP1206 photoresist was used to model the final pattern on photoresist thin film. To obtain super Gaussian profiles, approximately identical exposure energy density intervals were used for optimizing grating profile. The optimized gold and silver gratings were compared in terms of DE, bandwidth and incidence angle range. Dependence of DE on the depth and duty cycle of super Gaussian gold and silver gratings showed that the silver grating had higher DE than the gold grating in 1064 nm. Fabricated silver grating based on modeling results had good agreement with experimental results.
We report on designing a new raster-scanned CO2 laser heater for homogenous heating of the disk-shaped substrates during pulsed laser depositioning of materials. This new design aims at concentrating the laser energy near the substrate peripheral edge, which mostly tends to remain cooler than the inner parts during the heating process. A comprehensive heat diffusion model has been developed to predict the temperature and its homogeneity on the substrate depositioning face. Conduction and radiation heat transfer in three dimensions with temperature dependant material properties and a moving heat source are taken into account in this transient model. The model is validated by a simple stationary Gaussian laser heat source whose results are in good agreement with our measured values. Using this model, optimum conditions for the growth of garnets are calculated. Short heat-up times, some within minutes, are corroborated by calculations and measurements. An experimental procedure is designed to test the possibility of optical damage occurring in the substrate during this short temperature heat-up time.
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