Lasing and Macroscopic Coherence of Hybridized Modes in Coupled 2D Waveguide-VCSEL Resonators

Hybrid resonators in vertical and lateral direction are introduced by depositing a full vertical cavity surface emitting laser (VCSEL) stack on top of a periodically structured substrate. As a result, waveguided (WG) modes in the cavity plane are scattered into the vertical direction and exhibit linear dispersion curves in addition to the original parabolic cavity mode. A large in‐plane coherence length even below threshold enables a coherent interaction of both resonators, as observed in a pronounced anticrossing and hybridization of waveguided and VCSEL modes in the far field spectrum. Resulting from this coupling, both original VCSEL modes as well as hybrid WG‐VCSEL modes show stimulated emission. Here, hybrid modes exhibit a macroscopically increased spatial extension of the coherent laser mode, proven by both spatially resolved spectra as well as sharp modes in k‐space. The coherent coupling of two conceptually very different devices with perpendicular propagation directions facilitates a multitude of new applications. Microlasers are typically realized utilizing either highly reflective mirrors or total internal reflection of selected modes in an optical waveguide. Such waveguided modes are coherently coupled to the surface emission of a full vertical cavity surface emitting laser (VCSEL) stack via a high‐order periodic modulation of the cavity, leading to the observation of hybridized lasing modes with a macroscopically enhanced in‐plane coherence length.