Options for cost and performance improvements and integrated emitter design in GaN based electro-optical devices

While InGaN based lasers in the blue and green wavelength range have developed into well-established light sources over the last two decades, there is of course a constant drive to raise performance, lower price and enable new device designs. This publication discusses options for laser designs involving etched planes and facets that can drastically reduce production costs and at the same time offer opportunities for new device concepts. It also presents our newest results on high-power lasers in the blue wavelength range. First, InGaN lasers produced with etched facets are compared to state-of-the-art edge emitters. Tilt-angles and on-wafer mirror layer roughness are identified as the main contributors to the existing performance gap, mainly manifesting itself in a ~10 mA threshold current difference for devices with 400 µm resonator length. Following this, the application of the technology of smooth m-plane etching for the fabrication of nano-fins is demonstrated and an application example of a laser with etched facets in a photonic integrated circuit (PIC) is shown. In the second part of the paper, we describe the main improvements that our blue high-power InGaN chips experienced through epi and chip design optimization. Power conversion efficiencies (PCE) of 50% and above have been reached and a multi-die-package comprising several blue power lasers is demonstrated.