ER-Doped Laser Transmitter for a 1.6µm-CO2 Differential Absorption LIDAR: - Er-doped laser crystals (Subproject A) - Fiber lased pumped, high-power, pulsed, single-frequency Er-doped laser transmitter for 1.6 µm-CO2DIAL (Subproject B)

子项目A：这个子项目的目标是实现半导体激光泵浦的固体激光器，它直接工作在二氧化碳所需的1600 nm(1572 nm、1579 nm、1603 nm或1609 nm)附近的激光雷达波长。这样，就可以实现简单而高效的激光系统，并进一步研究其在激光雷达应用中的可扩展性。在激光波长、活性离子掺杂浓度和光学质量方面，将生长出适用于拟议的二氧化碳激光雷达应用的高效新激光晶体，并对其进行优化。晶体将根据它们的激光参数和激光性能进行充分的表征。尤其是掺Er石榴石混合晶体和掺Er倍半氧化物是解决激光雷达波长和实现高效、紧凑和可靠的二极管泵浦高功率激光光源的最有兴趣的候选材料。波长接近1.6微米的另一个有趣的候选晶体是掺Er的钒酸盐。这些晶体在感兴趣的区域显示出高横截面、高增益和多功能性的激光波长。本项目中实现的最合适的掺Er晶体将用于IPM(Erbium激光发射机)相关子项目B的高功率运转。子项目B：为新的CO2差分吸收激光雷达(DIAL)系统开发一种基于掺Er激光晶体的高功率脉冲单频激光发射机。将在子项目A中生长和表征高质量的激光晶体。激光将由一种独特的激光光源泵浦，即两个最近上市的连续40瓦平均功率Erb光纤激光器单元。通过在1530 nm处进行带内泵浦，可以预期Er激光发射器具有非凡的效率，因此激光器将以非常小的量子缺陷运行。一个特殊的环形谐振腔与Er激光器的小热透镜相结合，将确保平均功率大于10W，重复频率约1 kHz，并具有高稳定性和可靠性。通过在环形腔内注入频率稳定的单频半导体激光器，实现了单频、纯光谱运转，频率稳定度为10 MHz。Dial测量所需的高重复性在线/离线频率切换将通过两个注入播种器和一个光纤开关来完成。这将证明，该系统满足所有的要求，准确的，距离分辨的二氧化碳-DlAL测量。

Subproject A:The goal of this subproject is to achieve diode laser pumped solid-state lasers which directly operate at the required lidar wavelengths near 1600 nm (1572 nm, 1579 nm, 1603 nm or 1609 nm) for C02. This way, simple and efficient laser systems can be realized and further investigated with respect to their scalability for lidar applications. Efficient new laser crystals for the proposed C02 lidar applications will be grown and optimized with respect to laser wavelength, active ion doping concentration, and optical quality. The crystals will be fully characterized with respect to their laser parameters and laser performance. Especially, Er-doped mixed garnet crystals and Er-doped sesquioxides are particularly most interesting candidates to address the lidar wavelengths and to achieve the goal of efficient, compact, and reliable diode pumped high power laser sources. Further interesting crystal candidates for wavelengths near 1.6 µm are Er-doped vanadates. These crystals exhibit high cross sections, high gain, and a versatility of laser wavelengths in the regions of interest. The most suitable Er-doped crystals realized in this project will be used for high power operation by the related subproject B of IPM ( Erbium laser transmitter ).Subproject B:A high-power, pulsed, single-frequency laser transmitter based on an Er-doped laser crystal shall be developed for a new CO2 differential absorption lidar (DIAL) system. Laser crystals with excellent quality will be grown and characterized within Subproject A. The laser will be pumped by a unique laser source, two cw 40-W average-power Erbium fiber laser units, which recently became commercially available. An extraordinary efficiency of the Er-laser transmitter can be expected by in-band pumping at about 1530 nm so that the laser will operate with a very small quantum defect. A special ring resonator in combination with the small thermal lensing of the Er-laser will ensure operation with an average power of more than 10 W at a repetition rate of about 1kHz as well as with high stability and reliability. By injection-seeding of frequency-stabilized, single-frequency diode lasers in the ring cavity, single-frequency and spectrally pure operation of the Erlaser will be achieved with a frequency stability of 10 MHz. Highly reproducible online/offline frequency switching required for DIAL measurements will be accomplished by two injection-seeders in combination with a fiber switch. It will be demonstrated that this system fulfills all requirements for accurate, range-resolved CO2-DlAL measurements.