Development of advanced seed laser modules for lidar and spectroscopy applications

Abstract

We report on recent progress made in the development of highly compact, single mode, distributed feedback laser (DFB) seed laser modules with integrated drive electronics for lidar and spectroscopy applications from space based platforms. One of the intended application of this technology is in the NASA's Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. NASA Langley Research Center (LaRC) is working on a prototype laser based spectroscopy system for simultaneous measurement of CO 2 and O 2 for planned Active Sensing of CO 2 Emissions over Nights, Days, and Seasons (ASCENDS) mission application. For this purpose, 1571 nm spectral band for CO 2 sensing and 1262 nm spectral band for oxygen sensing have been selected. In this paper, we discuss recent progress made in the development of single mode, compact and stable, seed laser technologies for CO 2 and O 2 transmitters with focus on linewidth and noise measurements. The 1571 nm and 1262 nm DFB laser modules with integrated drive electronics have advanced current and temperature drivers built into them. A combination of temperature and current tuning allows coarse and fine adjustment of the diode wavelengths. The current tuning was demonstrated at a rate of ~0.7 pm/mV over a working range of ~1 V for a total of 0.7 nm. Also, temperature tuning at a rate of ~2 pm/mV over a working range of ~1 V for a total wavelength range of ~2 nm was demonstrated. The current tuning was performed at a rate of up to 200 kHz allowing rapid adjustment and dithering of the laser frequency. Furthermore, the best performance of laser linewidth observed was ~11 kHz with frequency stability <10 MHz over 1 hour period. The microcooler arrangement embedded inside these modules has provided significant reduction in power consumption. The electronics has been designed, prototyped and tested using space-qualified components within a hermetically sealed package of volume less than 2" x 2" x 0.5".

Diode lasers: From laboratory to industry

“…Troupak et al [123] discussed the experiences of using diode pump technology in space LIDAR missions and space-flight missions by NASA in the book on semiconductor laser diode technology. While Prasad et al [124] accounted the developmental progress made in DFB seed laser modules for LIDAR and their suitability for NASA′s future laser based missions. So diode lasers are emerging as a promising candidate for future space mission devices.…”