Tetravalent Chromium (Cr 4+) as Laser-Active Ion for TunableSolid-State Lasers

在我们计划开发的研究项目中， 一系列新型可调谐固体激光材料 基于四价铬（Cr 4+）作为激光活性 离子在各种低场介电晶体基质中， 研究它们的光谱和激光特性。 这些 新型可调谐固态激光器有望 在技术上重要的近红外操作 光谱范围在1 - 2 μ m之间。常规 掺铬激光器是基于Cr 3+作为活性 离子。 不同的光谱和激光特性 新的四价铬掺杂激光晶体将被 为了更好地了解 在这些可调谐的固态 激光 一种具有合适的 四面体位点，其中Cr 4+离子可以取代 四价阳离子将被选择和生长， 光谱和激光研究。 最 有前途的晶体主体是各种氧化物晶体 晶体中含有SiO 4或GeO 4四面体 晶格 吸收光谱的测量， 激发光谱，荧光光谱，和 荧光寿命随温度的变化 和波长进行光学识别 活性中心 增益和激发态吸收将 测量以确定可能的损失机制 在四价铬掺杂晶体中。 不同 将研究激光器操作模式。 的 预期激光（1-2 μ m）和成形（500- 1000 nm） 二次谐波产生的波长是 对于光学中许多可能的应用是重要的 通信，相干激光雷达，夜视 技术，遥感，测距，计数器 测量，红外半导体诊断，和 医疗应用。

In the proposed research program we plan to develop a series of new tunable solid-state laser materials based on tetravalent chromium (Cr4+) as laser-active ion in various low field dielectric crystal hosts and study their spectroscopic and laser properties. These novel tunable solid state lasers are expected to operate in the technologically important near infrared spectral region between 1 - 2 um. Conventional chromium-doped lasers are based on Cr3+ as an active ion. The spectroscopic and lasing properties of the various new tetravalent chromium-doped laser crystals will be investigated in order to obtain better understanding of lasing mechanisms in these tunable solid-state lasers. One host crystal candidate with suitable tetrahedral sites where Cr4+ ion may substitute for a tetravalent cation will be selected and grown for spectroscopic and laser studies each year. Most promising crystal hosts are various oxide crystals containing the SiO4 or GeO4 tetrahedra in its crystal lattice. Measurements of the absorption spectra, excitation spectra, fluorescence spectra, and fluorescence lifetime as a function of temperature and wavelength will be performed to identify optically active centers. Gain and excited state absorption will be measured to determine possible loss mechanisms in tetravalent chromium-doped crystals. Different modes of laser operation will be investigated. The expected lasing (1-2 um) and forming (500-1000nm) wavelengths by second harmonic generation are important for many possible applications in optical communication, coherent laser radar, night vision technology, remote sensing, range finding, counter measure, infrared semiconductor diagnosis, and medical applications.