Description: Freedom Photonics is developing a high power (>5 W), efficient (>20% wall-plug), 1650 nm laser/amplifier source for remote and in situ sensing of methane gas based on space-qualified packaging of photonic integrated circuits (PICs). In this tipping point project, Freedom will combine previously demonstrated 1650nm seed laser PICs developed under NASA SBIR efforts with a novel high power 1650 nm semiconductor optical amplifier (SOA) and develop a ruggedized package for low size, weight, and power lidar systems. Key technology developments will be: 1) ruggedized, space-qualified packaging of high-power SOAs; and 2) development of a 1650 nm high-power SOA based on Freedom's proprietary tapered amplifier structure previously demonstrated at 1550 nm. Freedom is currently developing space-qualified packaging of PICs under multiple NASA projects including SBIRs and instrument development funding, and in this Task that effort is extended to include the high-power, free-space coupled SOAs. The novel SOA tapered amplifier structure and semiconductor base can be tuned to a wide range of wavelengths (760 – 2100 nm) but design modifications must be made for optimal performance. Previous work by Freedom to develop a 1550 nm SOA for commercial lidar and telecom applications will thereby be the base for a 1650 nm design targeting typical methane absorption wavelengths used by NASA's differential absorption lidar systems. The resulting system is envisioned to be incorporated in NASA lidar systems with different scales and applications including drone-mounted sensors for local monitoring, airborne instruments for high-resolution regional mapping, low Earth orbit lidars for global monitoring, and rover-mounted lidars for planetary science.

Benefits: There are multiple benefits to this approach, both in terms of size, weight, and power (SWaP) reduction as well as the architecture modularity. Current lidar systems are bulky, with significant portions of the size coming from both the seed laser and high power amplifier/laser sections. Ongoing work between NASA and Freedom has pursued PIC-based seed lasers at various wavelengths to significantly reduce the seed laser SWaP, while the high power section has typically been irreplaceable by PICs due to the high power requirements. Freedom's development of high-power SOAs enables the bigger, much less power efficient (~1-4%) free-space or fiber-coupled laser amplifier to be replaced in some applications such as integrated path measurements. This Task will develop a suitable SOA for methane detecting lidars in this class, with an architecture that can be ported to many other wavelengths to target nearly any species of interest. By modifying the laser and SOA wavelengths, essentially the same lidar system can be used with minimal redesign for key species in Earth Science such as water vapor and carbon dioxide. The low SWaP of the resulting system additionally opens up opportunities and applications traditional differential absorption lidars are too large for, including drone- and rover-mounted systems.