Space Optical Communications Using Laser Beams

This invention provides a new method for optical data transmissions from satellites using laser arrays for laser beam pointing. The system is simple, static, compact, and provides accurate pointing, acquisition, and tracking (PAT). It combines a lens system and a vertical-cavity surface-emitting laser VCSEL)/Photodetector Array, both mature technologies, in a novel way for PAT. It can improve the PAT system's size, weight, and power (SWaP) in comparison to current systems. Preliminary analysis indicates that this system is applicable to transmissions between satellites in low-Earth orbit (LEO) and ground terminals. Computer simulations using this design have been made for the application of this innovation to a CubeSat in LEO. The computer simulations included modeling the laser source and diffraction effects due to wave optics. The pointing used a diffraction limited lens system and a VCSEL array. These capabilities make it possible to model laser beam propagation over long space communication distances. Laser beam pointing is very challenging for LEO, including science missions. Current architectures use dynamical systems, (i.e., moving parts, e.g., fast-steering mirrors (FSM), and/or gimbals) to turn the laser to point to the ground terminal, and some use vibration isolation platforms as well. This static system has the potential to replace the current dynamic systems and vibration isolation platforms, dependent on studies for the particular application. For these electro-optical systems, reaction times to pointing changes and vibrations are on the nanosecond time scale, much faster than those for mechanical systems. For LEO terminals, slew rates are not a concern with this new system. NASA has developed a new laser beam pointing technology for use in space optical communications. With further development, possible applications include communications from the Earth to spacecraft in Earth orbit and in deep space, such as at the moon and Mars. A possible application is to the Artemis Program for CubeSats in low-Lunar Orbit (LLO). Current architectures use dynamical systems, (i.e., moving parts, e.g., fast-steering mirrors (FSM), and/or gimbals,) to turn the laser to point to the ground terminal and possibly use vibration isolation platforms (VIP). This patented technology from NASA Ames uses a combined lens system and a vertical-cavity surface-emitting laser (VCSEL)/Photodetector Array. This static system has the potential to replace the current dynamic systems and VIP, dependent on studies for the particular application. Laser beam pointing is very challenging for low-Earth Orbit (LEO), including science missions. Computer simulations using this design have been made for an application to a CubeSat in LEO.