We propose a novel new architecture for a quantum communications laser transmitter that is designed for free-space polarization encoded quantum key distribution (QKD) between a spacecraft and a ground based system. The transmitter will operate at 775 nm, a wavelength that has previously been analyzed to be optimize free-space QKD due to the combined influence of atmosphere transition and detection efficiency by Si:APD detectors.
The proposed laser system is the key enabling component for the development of advanced quantum communications for NASA applications. Secure encrypted communications for NASA missions requires the frequent distribution of keys between the spacecraft and the ground. The proposed quantum communications laser transmitter is the key building block of a QKD system based on polarization state modulation. Quantum key distribution (QKD) using polarization modulation with decoy states has increasing interest in the commercial marketplace as a method to enable secure encrypted data transfer. There are already three start up companies addressing this area at 1550 nm for fiber optic system. The proposed quantum communications laser will open new markets for free space QKD as well as continue to develop the planar waveguide hybrid integration technology that can be applied to many different applications that require the development of advanced optical components.