Pulse generation, spectroscopy and transitions dynamics of Er~(3+) ions in YAG host

摘要

In Er: YAG, Er:YSGG and Er:YLF lasers the most important are the three lowest energy levels of Er~(3+) ion. Transitions between these levels decide about wavelength of generated laser radiation. In Er: YAG laser these levels are: ~4I_(15/2) (energy: 280 cm~(-1)), ~4I_(13/2) (6710 cm~(-1)), ~4I_(11/2) (10330 cm~(-1)) [1]. Er:YAG has many absorption lines mainly in visual and near infrared wavelength spectrum. This laser may generate optical radiation at two wavelengths: 1,6 μm and 2,94μm. For the first one EnYAG works as a three level quantum system and the for the second one it works as a four level quantum system. In this case the top laser level is ~4I_(11/2) and the down laser level is ~4I_(13/2) Both the wavelength generated and the work mode may be selected by dopant concentration. In lasers such as Er:YAG an analysis of transitions between levels during optical radiation absorption and generation the Boltzman distribution of energy levels occupation and thermalization effects must be taken into consideration [2]. Authors have developed computer software, which allows analysing transitions dynamics, laser output power/energy and rod's temperature increase (during pulse generation) which depends on: 1. pump properties, 2. initial temperature, 3. dopant concentration Analysis may be carried on for monopulse generation as well as for pulse generation. This software allows simplifying EnYAG laser application designing.