Collaborative Research: Two-photon absorption engineering in laser diodes for ultrafast pulse generation

半导体激光器是市场上影响最大的光子技术之一，应用范围从通信到医学。然而，尽管进行了数十年的研究，但从短脉冲光中获得的功率仍然很低。这个问题是由物理限制造成的，该项目将通过将新兴材料合成与先进的光学物理相结合的跨学科努力来解决这个问题，以产生功率远远超过当前技术水平的短脉冲。这将使科学理解和实际性能都取得重大进展，并将产生从用于自动车辆导航的激光雷达到先进显微镜等应用的理想来源。该项目将通过课程将研究成果与教育相结合，并将其纳入作为科罗拉多大学博尔德大学电气工程理学硕士(在线硕士学位)的一部分推出的在线课程，从而进一步造福社会。更多的传播和参与将通过各种途径进行，包括本科生研究机会、多样性、公平和包容性研讨会系列、科罗拉多博尔德大学的ECEE Connects以及德克萨斯聋校的科学活动。像双光子吸收这样的非线性因素限制了高功率连续波和超短脉冲领域的半导体激光器，限制了可用的峰值功率、脉冲宽度和脉冲能量。对于脉冲源，色散补偿提供了一些改进；然而，紧凑程度较低的替代方案，如光纤和固态激光器，目前提供了非常优越的性能。该项目将结合晶体生长和光学激光脉冲整形技术的最新进展来解决这些问题，并显著提高半导体超快光源的性能。具体地说。高带隙半导体包层现在可以与更长波长的增益介质进行外延集成，以将双光子吸收减少数量级。当与新的脉冲整形机制和脉冲堆叠相结合时，预计该方法将在芯片规模的半导体平台上实现千瓦峰值功率和飞秒脉冲。该项目的影响力将通过一系列参与和外展活动以及本科生研究机会进一步增强。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Semiconductor lasers are one of the most impactful photonic technologies on the market, with applications ranging from communications to medicine. However, the amount of power that can be obtained from short pulses of light remains low, despite decades of research. The problem is due to physical constraints, which the project will address through an interdisciplinary effort combing emerging materials synthesis with advanced optical physics to create short pulses with power well beyond the current state of the art. This will enable significant advances in both scientific understanding and practical performance, and will yield sources ideal for applications ranging from laser radar for autonomous vehicle navigation to advanced microscopy. The project will further benefit society by integrating research results with education through courses, and into an online course that was launched as part of the University of Colorado Boulder's Master of Science in Electrical Engineering (an online Master's degree). Additional dissemination and engagement will occur through avenues ranging from undergraduate research opportunities, a diversity, equity, and inclusion seminar series, ECEE Connects at the University of Colorado Boulder, as well as science events at the Texas School for the Deaf.Nonlinearities like two-photon absorption limit semiconductor lasers in both the high power CW and ultrashort pulse arenas, constraining the available peak powers, pulse widths, and pulse energies. For pulsed sources, dispersion compensation provides some improvement; however, less-compact alternatives, such as fiber and solid-state lasers currently offer vastly superior performance. This project will combine recent advances in crystal growth and optical laser pulse shaping techniques to solve these issues and dramatically advance the performance of semiconductor ultrafast sources. Specifically. high-bandgap semiconductor cladding layers can now be epitaxially integrated with longer-wavelength gain media to reduce two-photon absorption by orders of magnitude. When coupled with a new pulse shaping mechanism and pulse stacking, it is anticipated that this approach will enable kW peak powers and femtosecond pulses on a chip-scale semiconductor platform. The impact of the project will be further enhanced through a number of engagements and outreach activities and undergraduate research opportunities.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.