FAQ – Judd-Ofelt analysis
These FAQs provide a foundational understanding of Judd-Ofelt analysis and address common queries encountered by researchers in this field.
LOMS.cz online tool was optimise for primary use in Chrome and Safari (with partial GUI utility problems) web browsers, however partial trouble issues may occur as follows:
1) Download template/reference files (Safari): Safari does not support downloading files from this application with proper filename. File content is not affected. Please append .csv extension to the downloaded template file name and .zip extension to the downloaded reference file name or use another browser.
2) Sign up process (Safari): During the sign up process, the "I agree to the privacy policy" check button may appear out of the defined blue box. This issue was observed only for some version of Safari browser.
3) Combinatorial JO analysis for more than 10 inserted absorption bands may take up to several minutes. Chrome (or other browser) memory then may reach its limits. In such cases, please use another browser or update your browser settings. In case of Chrome, run a [chrome.exe --js-flags="--max_old_space_size=4096"] protocol for example.
Judd-Ofelt (J-O) analysis is used to determine the intensity parameters (Ωλ, where λ = 2, 4, 6) of rare-earth ions in various host materials. These parameters provide insights into the local environment around the ions and are essential for calculating theoretical radiative transition probabilities, branching ratios, and radiative lifetimes of excited states in doped optical materials.
The main parameters obtained from Judd-Ofelt analysis are the intensity parameters Ω₂, Ω₄, and Ω₆. These parameters describe the strength of the electric-dipole transitions and are related to the asymmetry of the local environment of the rare-earth ions.
Judd-Ofelt analysis involves the following steps:
1. Measure the absorption spectrum of the doped optical material.
2. Identify the transitions from the ground state to various excited states.
3. Fit the measured oscillator strengths of these transitions to the theoretical expressions derived by Judd and Ofelt.
4. Extract the intensity parameters (Ω₂, Ω₄, Ω₆) by minimizing the difference between the experimental and theoretical oscillator strengths.
Detailed step-by-step guide can be find here.
1. Measure the absorption spectrum of the doped optical material.
2. Identify the transitions from the ground state to various excited states.
3. Fit the measured oscillator strengths of these transitions to the theoretical expressions derived by Judd and Ofelt.
4. Extract the intensity parameters (Ω₂, Ω₄, Ω₆) by minimizing the difference between the experimental and theoretical oscillator strengths.
Detailed step-by-step guide can be find here.
Judd-Ofelt parameters are used to:
1. Calculate theoretical radiative transition probabilities and lifetimes of excited states.
2. Predict branching ratios for different transitions.
3. Understand the local symmetry and bonding environment around the rare-earth ions.
4. Design and optimize optical devices such as lasers, amplifiers, and phosphors based on rare-earth-doped materials.
1. Calculate theoretical radiative transition probabilities and lifetimes of excited states.
2. Predict branching ratios for different transitions.
3. Understand the local symmetry and bonding environment around the rare-earth ions.
4. Design and optimize optical devices such as lasers, amplifiers, and phosphors based on rare-earth-doped materials.
The host material significantly influences the Judd-Ofelt parameters. Different hosts provide varying degrees of asymmetry and local field effects, which alter the values of Ω₂, Ω₄, and Ω₆. For instance, a more asymmetric environment typically leads to higher Ω₂ values. The host material's composition, structure, and phonon energy also play crucial roles in determining these parameters.
Including multiple transitions ensures a more accurate determination of the Judd-Ofelt parameters. It allows for a better fit between experimental and theoretical oscillator strengths and reduces the uncertainty in the calculated parameters. This comprehensive approach provides a more reliable characterization of the rare-earth ion environment. Note, that the use of minimum number of transitions (four) may not be sufficient to calculate all three JO parameters. See the Combinatorial Judd-Ofelt analysis section for further discussion.
Common challenges include:
1. Accurate measurement of absorption spectra, especially for weak transitions.
2. Correct identification of transitions and their assignments.
3. Dealing with overlapping absorption peaks and/or absorption peaks affected by the position of absorption edge of the host material.
4. Ensuring a good fit between experimental and theoretical data, which may require high-quality samples and precise experimental conditions.
1. Accurate measurement of absorption spectra, especially for weak transitions.
2. Correct identification of transitions and their assignments.
3. Dealing with overlapping absorption peaks and/or absorption peaks affected by the position of absorption edge of the host material.
4. Ensuring a good fit between experimental and theoretical data, which may require high-quality samples and precise experimental conditions.