Maturation Of A Single Frequency Eryag Laser For Water Vapor/Methane Dial Application

Fibertek is under contract with Nasa Langley for the development of a laser transmitter for water vapor differential absorption lidar (DIAL) measurements. Water vapor plays a central role in feedback mechanisms linking components and processes in the Earth's atmosphere. Studying atmospheric water vapor content is important for understanding global energy transport and climate change. The driving design parameter for the water vapor DIAL application is a narrow single frequency linewidth with wavelength tunability that is coincident with a water vapor absorption line. Fibertek has developed a frequency doubled seeded single frequency resonantly pumped ErYAG laser system that can probe water vapor lines in the 822-823nm band. As an added benefit, the laser fundamental wavelength at 1645nm allows for probing atmospheric methane, which also plays an important role in climate change research. The laser emits 3mJ at 1645nm and 3mJ at 822nm at 1kHz with beam quality on the order of M-2=1.6. Fibertek has packaged the ErYAG laser in an environmentally hardened housing for an airborne DIAL application. This paper will present current results of the ErYAG laser work, progress in increasing the output power, efficiency, and reliability of the laser to meet requirements for a follow-on space qualifiable laser and plans for environmental testing the system.