Theoretical Investigation of State Bistability Between Pure- and Mixed-Mode States in a 1550-nm VCSEL Under Parallel Optical Injection

Based on the spin-flip model, state bistability (SB) between pureand mixed-mode states in a 1550-nm vertical-cavity surface-emitting laser under parallel optical injection is theoretically investigated. The simulated results show that two types of SB can be observed when the injection light frequency (v_inj) is smaller than the dominant mode frequency of the free-running laser (ve). For type-I SB, which occurs through fixing vinj and scanning injection power (Pinj) along different routes, there exist two hysteresis loops in which the laser operates at pureor mixed-mode state, depending on the variation route of Pinj, and the hysteresis loop width increases sharply for increasing IΔνI (Δv = v_inj - v_e) with relatively strong Pinj whereas the loop width increases slowly for relatively weak P_inj, in agreement with our recent experimental report. Furthermore, type-II SB is also investigated through fixing P_inj and scanning v_inj along different routes. There also exist two hysteresis loops in which the laser may operate at a pureor mixed-mode state. With an increase of Pinj, the hysteresis loop width located at lower IΔνI increases sharply and then decreases after reaching a maximum. However, for the hysteresis loop located at higher IΔνI, the loop width gradually increases with the increase of P_inj.