Inter-satellite laser communication system

Laser communication links in space are attractive alternatives to present-day microwave links. This paper firstly makes an overview of an optical inter-satellite communication terminal. This terminal contains several modules such as transmit assembly, receive assembly, diplexers, mirrors assembly, acquisition and tracking sensor optics, etc. Out of these modules present in the terminal, we proposed the optical antenna design and development of-collimation lenses system. And also carried out partial prototyping and evaluating of sensitive acquisition tracking sensor (ATS) module featuring a receiving collimator fiber assembly. ATS system is overviewed using proposed two level system controls. The lower level controls the gimbals of the optical head of the electro-optical transceiver. The higher level is a fast closed loop that simultaneously controls the beam width and direction. Initial pointing acquisition assumes exchange of position related information between the satellites to establish the initial line of sight (LOS). After initial acquisition a cooperative extremum-seeking algorithm is used for the fast higher level closed loop control This compact and light weight terminal achieves single wavelength data transmission at 2.5 Gbps.