PFI-TT: Reliable High-Power Circular-Beam Semiconductor Lasers

这个创新技术转化伙伴关系（PFI-TT）项目的更广泛的影响/商业潜力是展示了一种新型可靠的、高光束质量的半导体激光器，能够产生圆形的、几乎理想的输出激光束，其功率范围是目前现有技术在不使用外部系统的情况下无法达到的。以更低的成本提供更高质量、近乎完美的激光束，有望实现对社会有益的新应用：更快的数据网络、创新的医疗保健解决方案、增强的自动驾驶汽车安全性和改进的消费产品。这将通过消除包含额外光束退化的外部光学元件来实现。这些进步源于更容易操作和聚焦的光束产生更强烈的激光聚焦光斑。所采用的新处理方法也将为增加未来光子集成电路的密度带来重大的额外承诺，这对于支持社会对互联网和数据中心应用快速增长的需求至关重要。提出的项目特别解决了大多数边缘发射二极管激光器长期存在的限制-它们固有的不对称，高椭圆，因此在10-500 mW范围内输出光束像散（难以聚焦）。像垂直腔面发射激光器（VCSEL）这样的设备可以发射圆形输出光束，但最大输出功率限制在~5-10毫瓦。提出的创新使用一种新颖的方法来制造边缘发射激光器，采用通过有源电子-空穴复合区域的深度蚀刻，然后采用特殊的湿热氧化工艺来改善蚀刻损伤，同时平滑和钝化蚀刻侧壁。利用这种高折射率对比度设计，单模圆形输出激光器的功率是商用单模vcsel的80倍。该项目的重点是对具有表面钝化涂层的封装激光器进行寿命测试，并展示其成功商业化所需的长寿命、连续运行（例如5000-10000小时）的能力。利用时间分辨光致发光技术评估和优化氧化物-半导体界面特性；将对包括像散在内的光束质量进行表征，并对预期的高速射频调制性能进行评估。替代方法包括量子点活性区域材料和原子层沉积电介质也将被探索。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The broader impact/commercial potential of this Partnerships for Innovation - Technology Translation (PFI-TT) project is the demonstration of a new class of reliable, high-beam-quality semiconductor lasers capable of producing a circular, nearly ideal output laser beam operating in a power range which is currently inaccessible by existing technologies without the use of external systems. Providing a higher quality, near perfect laser beam at much lower cost promises to enable new applications beneficial to society: faster data networks, innovative healthcare solutions, enhanced autonomous vehicle safety, and improved consumer products. This will be achieved by eliminating external optical components which incorporate additional beam degradation. These advances result from the more-easily manipulatable and focusable beam producing a more intense, laser focused spot. The new processing methods employed will also have significant additional promise for increasing the density of future photonic integrated circuits, critical for supporting society’s rapidly growing needs for internet and data center applications.The proposed project specifically addresses a long-standing limitation of most edge-emitting diode lasers – their inherently asymmetric, highly elliptical, and thus astigmatic (hard to focus) output beams in 10-500 mW range. Devices like vertical cavity surface emitting laser (VCSEL) can emit a circular output beam, but are limited to maximum output powers of ~5-10 mW. The proposed innovation uses a novel method to fabricate edge-emitting lasers, employing a deep etch through the active electron-hole recombination region followed by a special wet thermal oxidation process to ameliorate etch damage while smoothing and passivating the etched sidewall. With this high-index-contrast design, single-mode circular output lasers with powers 80 times greater than that of commercial single-mode VCSELs have been achieved. The focus of this project is to lifetest packaged lasers with facet passivation coatings and demonstrate their capability for long-life, continuous operation (e.g., 5000-10000 hours) as required for successful commercialization. The oxide-semiconductor interface properties will be assessed and optimized using time-resolved photoluminescence; beam quality including astigmatism will be characterized, and the expected high-speed RF modulation performance evaluated. Alternative approaches including quantum-dot active region material and atomic layer deposition dielectrics will also be explored.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.