Passive mode locking with face-to-face VCSELs

We present the potential for two Vertical-cavity surface emitting lasers (VCSELs) facing each other to be configured for optimal fundamental mode-locking over a wide range of parameters. The study is performed theoretically and numerically using time-delay-differential equation model to show that the proposed dual-laser configuration can function as a typical gain-absorber system. Additionally, a variety of nonlinear dynamics chaotic dynamics is shown. Fundamental mode-locking is observed when the current is applied to one chip while the second chip remains unbiased. The reported setup may be used as an alternative to the popularly used conventional SESAM mode-locked VECSEL to generate high-quality mode-locked pulses.