To build a free-space inter-satellite optical communication systems, the line of sight of their optics must be aligned during the entire period of communications. In order to meet this requirement, satellites use the attitude informations for rough pointing, and a tracking system for fine pointing to other satellites. One important aspect in inter-satellite optical communications is to obtain maximum link performance using minimum power. This aim can be achieved with very small transmitter beam divergence angle. The disadvantage of too narrow divergence angle is that the transmitter beam may sometimes miss the receiver satellite due to the pointing vibrations.
In this study, an algorithm to maximize the link of inter-satellite optical communication systems using the adaptive beam divergence angle with data rate adaptation is proposed. This adaptation makes it possible to maintain communication link without link failure when the systems meet some large unknown vibration conditions. Also it can operate a communication link with high data rate when the systems are under the stabilized conditions.