VCSEL with intra-cavity circular Bragg gratings for single-mode operation

In this paper, we present the design and fabrication of a single-mode Vertical-Cavity Surface-Emitting Laser (VCSEL) incorporating circular Bragg gratings (CBGs). By periodically etching the surface of a half-cavity VCSEL surface into concentric rings, first-order Bragg gratings are formed in the lateral direction, providing an additional mechanism of optical confinement at the Bragg wavelength. To enable lasing, dielectric DBRs are evaporated on the top. We fabricated the device with a large oxidized aperture size of 11 μm. Experimental results demonstrate the impact of the CBG structure on mode selection and power convergence, with the proposed VCSEL achieving continuous single-mode operation and an output power exceeding 3.7 mW. Dynamic responses show that our device is highly promising for high-speed applications, particularly for transmission distances of up to 10 km.