From an industry perspective, the past decade has been a whirlwind of innovation in automotive light detection and ranging (LiDAR). Numerous laser technologies and system solutions have been fiercely competing for market share. However, recent trends suggest a growing convergence on vertical-cavity surface-emitting laser (VCSEL) and antireflective VCSEL (AR-VCSEL) based solutions. This commentary, rooted in the practical realities of the industry, examines the historical trajectory of industrial laser technology for commercial automotive LiDAR. It specifically focuses on the recent applications of VCSEL/AR-VCSEL technologies and their future prospects. Liang et al. present an industrial perspective on the evolving landscape of laser technology used in advanced LiDAR systems. The authors discuss recent trends, practical considerations within the industry, current challenges, and potential solutions, explicitly focusing on VCSEL/AR-VCSEL-based technologies and their strong potential for commercial LiDAR applications.

A distributed Bragg reflector (DBR) is a key building block in the formation of semiconductor microcavities and vertical cavity surface emitting lasers (VCSELs). The success in epitaxial GaAs DBR mirrors paved the way for the ubiquitous deployment of III-V VCSELs in communication and mobile applications. However, a similar development of GaN-based blue VCSELs has been hindered by challenges in preparing DBRs that are mass producible. In this article, we provide a review of the history and current status of forming DBRs for GaN VCSELs. In general, the preparation of DBRs requires an optimization of epitaxy/fabrication processes, together with trading off parameters in optical, electrical, and thermal properties. The effort of epitaxial DBRs commenced in the 1990s and has evolved from using AlGaN, AlN, to using lattice-matched AlInN with GaN for DBRs. In parallel, dielectric DBRs have been studied since 2000 and have gone through a few design variations including epitaxial lateral overgrowth (ELO) and vertical external cavity surface emitting lasers (VECSEL). A recent trend is the use of selective etching to incorporate airgap or nanoporous GaN as low-index media in an epitaxial GaN DBR structure. The nanoporous GaN DBR represents an offshoot from the traditional epitaxial approach and may provide the needed flexibility in forming manufacturable GaN VCSELs. The trade-offs and limitations of each approach are also presented.

Multijunction vertical-cavity surface-emitting lasers (VCSELs) have gained popularity in automotive LiDARs, yet achieving a divergence of less than 16° (D86) is difficult for conventional extended cavity designs due to multiple-longitudinal-mode lasing. Our innovation, the antireflective vertical-cavity surface-emitting laser (AR-VCSEL), addresses this challenge by introducing an antireflective light reservoir, where the electric field intensity is substantially higher than the gain region. This reduces the required cavity length for minimal divergence, preserving the single-longitudinal-mode lasing. A 6-junction AR-VCSEL array showcases a halved divergence and tripled brightness compared to its conventional counterpart. Various multijunction AR-VCSEL array designs achieve a divergence range of 8° to 16° (D86). Notably, a 7 μm AR-VCSEL emitter achieves 28.4 mW in single transverse mode lasing. AR-VCSEL stands out among semiconductor lasers, offering a well-balanced power density and brightness, making it a cost-effective solution for long-distance LiDARs. The antireflective cavity concept may inspire diverse applications in photonic devices beyond LiDARs.