Multiple Polarization Switching In Mutually Coupled 1550nm-VCSELs

Vertical cavity surface emitting lasers (VCSELs) possess lots of advantages such as low threshold current, small divergence angle, single longitudinal mode outputs, easy to integrate into two-dimensional arrays and so on, and then they have a broad application prospect in optical communications, optical storage and optical switch etc. The polarization switching (PS) property of VCSELs has attracted a lot of attention in recent years. Reported investigations on multiple PS are mostly generated by current while there is little research on PS produced by other parameters. The injecting parameters of mutually-coupled system and free-running frequencies of two VCSELs have been important issues from investigation of PS for they are key points to affect the running states and can be controlled easily.Based on the spin-flip model, the characteristics of multiple polarization switching (PS) in mutually-coupled vertical-cavity surface emitting lasers (VCSELs) are investigated via by continuously changing some important parameters. The simulated results show that multiple PS can be generated through continuously varying the mutually-coupled strength, the oscillated frequency of one VCSEL or the oscillated frequencies of both two VCSELs. The intervals of PS brought by the continuous change of injection rate are equality and we discussed the relation of the max injection rate that can bring PS and delay time. PS can be observed by varying the frequency of a VCSEL continuously when frequency of another VCSEL remains unchanged. Furthermore, the PS of laser with lower frequency is sparse. The PS came from the frequency changes of two VCSELs arises periodically. For above phenomena, longer delay times lead more intensive PS and sharper rising or falling edge of PS.