Polarization-independent bidirectional 4×4 optical switch in free space

Optical switches play an important role in all optical communication networks and multiprocessor computer systems. The 2×2 and 4×4 optical switches are the basic units of large-scale switch matrices. Using a conventional polarization control method, the optical switch system and structure is optimized, and a novel optical switch is proposed, which has the advantages of relatively low crosstalk and insertion loss, compact and simple construction, higher performance and cost effectiveness. First, a novel 2×2 optical switch is proposed using phase spatial light modulator (PSLM), polarizing beam splitter (PBS) and mirror. This configuration uses fewer optical components, is compact in structure, efficient in performance, and insensitive to polarization of the signal beam. Second, a new optical experimental module of 4×4 optical switch is presented by cascading a 2×2 optical switch. The routing method of polarization-independent bidirectional 4×4 optical switch is investigated. Finally, the operational characteristics of the polarization-independent bidirectional 2×2 and 4×2 optical switches are discussed in detail.