Chaos synchronization is crucial for secure optical communication and key distribution. It refers to the state where two or more chaotic systems achieve consistent output under coupling or driving. In 1990, Louis M. Pecora and Thomas L. Carroll from the U.S. Navy Laboratory first achieved chaos synchronization in circuit systems (Pecora and Carroll 1990), which sparked a research boom in chaotic optical synchronization. This chapter will focus on several typical chaos synchronization methods involving semiconductor lasers and optoelectronic oscillators, including unidirectional injection synchronization, mutual injection synchronization, and common signal-induced synchronization.