All ETDs from UAB

Authors

Nosoung Myoung

Advisory Committee Chair

Sergey B Mirov

Advisory Committee Members

Vladimir V Fedorov

Mary Ellen Zvanut

Sergey Vyazovkin

Patrick Kung

Document Type

Dissertation

Date of Award

2011

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

The dissertation is focused on thermo-diffusion doping of Fe2+:ZnSe, Fe2+:ZnS, Fe2+:Co2+:ZnSe, and Fe2+:Co2+:ZnS polycrystals and their laser-spectroscopic characterization. Most materials absorb infrared (IR) light at specific patterns of frequencies directly related to their structure. IR spectra can therefore be used to identify and quantify the constituents of an unknown material, making detection of chemicals by their absorption of IR light an important analytical tool. For instance, Mid-infrared lasers (ë = 3 to 5µm) are widely used for an environmental monitoring, remote sensing of atmosphere and defense-related applications. Tunable middle infrared lasers are essential for highly sensitive detection of organic molecules because the strongest vibrational absorption lines of many molecules lie within middle infrared spectral range. Emerging Fe2+:ZnSe lasers have potential to operate at room temperature over 3-6µm spectral range. The major problem of Fe:ZnSe (ZnS) gain materials is in a lack of cost effective technology of high quality Fe:ZnSe (ZnS) crystals fabrication. We are making a new approach for the fabrication of gain and passive Fe2+:II-VI semiconductor materials with a pre-assigned concentration of Fe2+ ions by thermal diffusion from the metal films deposited by a precisely controlled thermal evaporation. This method potentially enables a uniform distribution of iron ions over the crystal volume and offers a good flexibility in optimization of iron concentration. Developed Fe:ZnSe crystals were characterized spectroscopically as a function of temperature, Fe concentration and thermal diffusion parameters. 3µm pumped gain-switched lasers based on optimal Fe:ZnSe crystals were developed and characterized. We also studied the effect of co-doping Fe:ZnSe (or Fe:ZnS) crystals with Co. Kinetics of luminescence of Fe ions were measured as a function of Co concentration to evaluate the efficiency of energy transfer from Co to Fe ions.

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