Laser Components USA, Inc.

LiDAR technology has gained significant importance in various fields, including autonomous vehicles, environmental monitoring, and remote sensing. 905nm pulsed laser diodes are an essen2al component of a LiDAR system, which performance relies heavily on the laser power level and the characteris2cs of its emi4ed light beam. While the fabrica2on of high-power pulsed laser diodes is already mature, reliably combining a high-power level and a concentra2on of the laser beam (>90%) within a limited emi8ng width is an ongoing challenge. Another major concern is the development of facet coa2ngs capable of withstanding the high-power density generated by these lasers. Facet degrada2on due to the excessive op2cal power leads to a reduced laser efficiency and a risk of increased failure rates. In this work, we tackle the above-men2oned challenges. To do so, we have devised novel op2cal waveguide designs of triple junc2on lasers with op2mised mode profiles and an effec2ve confinement structure. This enables lasers to reach a power density that is five (5) 2mes higher than the standard one and to confine most of the beam energy within an emi8ng width less than 60 μm. These designs enable efficient power extrac2on and minimise power losses, thereby enhancing the overall laser performance. Furthermore, our research explores innova2ve approaches to facet coa2ngs that enhance the facet reliability and minimise power-induced degrada2on. This results in highly reliable high-power density lasers, as demonstrated by thousands of hours of life test data. Through this research, we have achieved significant advancements in op2cal waveguide design and fabrica2on for high-power laser diodes in LiDAR applica2ons. Experimental results clearly demonstrate improved power efficiency, reliable facet coa2ngs, and effec2ve energy confinement within the desired emi8ng width.

The dry etch process is a common fabrication method used in III-V semiconductor industries and applied to optoelectronic devices. This technique is more efficient, repeatable, and scalable when evolving from small to larger wafer diameters. On the other hand, optical design of waveguide geometry in GaAs-based broad area lasers is of paramount importance to improve the performance and the reliability of high-power pulsed lasers (PLDs). Therefore, particular attention must be given to the design and fabrication of waveguide shapes. Three parameters of the waveguide shape are of interest: the etch depth the sidewall angle and the sidewall roughness. In this paper, we propose a process methodology for dry etch patterning of trenches in GaAs which gives very good sidewall slope control with very low roughness. Several experiments have been carried out using design of experiment (DOE) to fix the parameters involved in a conventional inductively coupled plasma (ICP) etcher and utilizing a common photoresist as a mask. By controlling input parameters for the ICP etcher, such as ICP power, RF power, coil power and gas mixture ratio, we have demonstrated that a targeted angle with very low sidewall roughness (<200 nm) is possible, while the trenching depth achieved is greater than 17 μm. A full electro-optical characterization, as well as reliability tests, have been performed on high power lasers processed using such an etch process. We have compared the performance of lasers made by both dry and wet (the legacy process used in our production) etching and we conclude that the dry process is highly reliable. Results are reported in this paper which cover a wide range of performances, from the characterization of microfabrication to electro-optical tests.