Lighrwieght Multi-function Optical Ground Station

We are proposing to demonstrate a small aperture, lightweight, portable, and eyesafe lasecom system that is capable of supporting ground to LEO lasercom links.  The proposed system receives light directly into single mode fiber (SMF), without the need for adaptive optics (A0). Because it is SMF coupled it can support coherent detection modems, with bandwidth of up to 400 Gbps on a single wavelength. Allowing direct high-bandwidth optical uplinks and downlinks from the ground to LEO networks such as SpaceBACN. In addition to Ground to Space (G2S), This lightweight system can support Ground to Aircraft (G2A) and terrestrial Point to Point (P2P) missions. The optics are based on our commercial lightweight point to point system, which is capable of single frequency bi-directional data transmission at 400 Gbps using SMF coupling without adaptive optics. The proposed system would be a scaled-up version of our P2P system to enable G2S communication. It would be a bi-static configuration with separate 15 cm transmit (Tx) and receive (Rx) apertures. While the Tx aperture is similar to other proposed G2S systems, the Rx aperture is smaller than the 50 cm to 70 cm generally used for G2S applications.  There are two reasons for this.   First, large apertures are a good solution for direct-detection systems, such as those that support SDA 2.0/3.0. But, they are not good for coherent detection systems, such as those that support SpaceBACN. Large apertures require Adaptive Optics (AO) to make use of the full aperture.  However, AO does not function well in the moderate to strong turbulence conditions experienced in most daytime operations.    Second, large apertures require large gimbals, precluding man-portable system designs. In addition, larger apertures are not generally needed for GTA and P2P applications. To account for the lower optical gain of the 15 cm Rx aperture, the system uses a high-gain preamplifier.  This is only possible when coupling the system directly into SMF.  Link budget calculations show that using a preamp with a sensitivity of -40 dBm, downlink from a 2.5 W satellite terminal has sufficient link margin. even at 20 degrees from the horizon.  Our design is eyesafe in all modes of operations; G2S, G2A, and P2P. It is also virtually unjammable due to the use of coherent detection. During the base period, we propose to build and demonstrate this lightweight, eyesafe , SMF-coupled system. We do not plan to test against satellites, but instead will field test it at long- range using a surrogate space terminal, under turbulence conditions representative of an actual space link. In the option period we are proposing to add a quantum receiver to enable secure communications and precision timing, based on Quantum 2.0 technology. For this option, X-Lumin will work Xairos, the inventor of a novel quantum time transfer (QTT) system that provides accurate (picosecond-level), resilient (resistant to jamming) and secure (unspoofable) time distribution.