室温高能宽带可调谐Fe:ZnSe中红外激光技术研究

The mid-IR laser sources operating in the 3−5μm wavelength region are in great demand for a variety of applications including molecular spectroscopy, medical diagnostics, environmental monitoring, remote sensing, infrared countermeasures. There is a lack of robust solid-state mid-IR laser sources with broadly tunable output in this waveband.. Fe:ZnSe crystal offers a unique blend of physical (high thermal conductivity, low saturation intensity), spectroscopic characteristics(ultrabroad gain bandwidth, high absorption coefficient) that make it the gain media of choice for cost effective tunable lasing in the mid-IR region. Problem with this active material arises from the fact that the upper laser level lifetime of Fe2+ ions in ZnSe sharply shortens with elevated temperature. Mid-IR 5T2→5E transition in Fe:ZnSe crystal features multi-phonon quenching at room temperature. To achieve satisfactory efficiencies at room temperature, it is necessary to excite the crystal by short pulses, the energy of Fe:ZnSe laser in this case was only 6mJ, limited by the low energies of Q-switched solid-state lasers used for pumping. The major problem with the output energy scaling-up is in the development of high energy short pulse pump laser source and fabrication technology for large aperture, good optical quality Fe:ZnSe gain elements. . In this project, we will fabricate good optical quality Fe:ZnSe gain elements prepared by post-growth thermal diffusion technology. The characteristics of a Fe:ZnSe laser in a scheme with two sides small angle pumping by a nonchain electric-discharge pulsed HF laser at room temperature will be studied. The aim of the project is obtaining a room temperature Fe:ZnSe laser with output energy E>100mJ, continuously tunable over the whole spectral range of 3.8-4.3μm wavelength region. Room temperature high energy, widely tunable Fe:ZnSe laser has the potential for successful applications in remote sensing, infrared countermeasures.

3-5微米中红外激光在分子光谱学、医疗、环保和光电对抗等领域中有重要应用，目前急需可靠的高能、宽带调谐中红外激光源。Fe:ZnSe晶体具有优良的物理特性（高热导、低饱和）和光谱特性（高吸收系数和宽增益光谱）,是实现高能、宽带调谐中红外激光输出最有前途的材料。由于Fe2+离子的上能级寿命随温度升高迅速下降，Fe:ZnSe晶体在室温时存在强烈的多声子淬灭效应，室温条件下这类激光器只能通过窄脉冲光源泵浦才能形成高效振荡。受调Q固体激光泵源能量的限制，目前室温条件下调Q固体激光泵浦的Fe:ZnSe激光最高输出能量仅为6mJ。本项目拟通过高温热扩散法制备高光学质量的Fe:ZnSe晶体，以新型非链式高能窄脉冲HF激光器作为泵浦源，采用小角度双向对称泵浦方案，在室温条件下实现脉冲能量大于100mJ的Fe:ZnSe中红外激光宽光谱可调谐输出。这种新型中红外激光在光电对抗和遥感探测领域具有广阔的应用前景。

3-5微米中红外激光在分子光谱学、医疗、环保和光电对抗等领域中有重要应用，目前急需可靠的高能、宽带调谐中红外激光源。Fe:ZnSe晶体具有优良的物理特性（高热导、低饱和）和光谱特性（高吸收系数和宽增益光谱），是实现高能、宽带调谐中红外激光输出最有前途的材料。本项目通过高温热扩散法制备出高光学质量的Fe:ZnSe晶体，以新型非链式高能窄脉冲HF激光器作为泵浦源，采用小角度双向对称泵浦方案，在室温条件下实现了脉冲能量215mJ的Fe:ZnSe中红外激光输出。这种新型中红外激光在光电对抗和遥感探测领域具有广阔的应用前景。