  Oriented to the point-to-multipoint free space optical communication (FSO)
scenarios, this paper analyzes the micro-mirror array and phased array-type
optical intelligent reflecting surface (OIRS) in terms of control mode, power
efficiency, and beam splitting. We build the physical models of the two types
of OIRSs. Based on the models, the closed form solution of OIRSs' output power
density distribution and power efficiency, along with their control algorithms
have been derived. Then we propose the algorithms of beam splitting and
multi-beam power allocation for two types of OIRSs. The channel fading in FSO
system and the comparison of two types of OIRSs in actual systems are discussed
according to the analytical results. Experiments and simulations are both
presented to verify the feasibility of models and algorithms.
