EAGER: Moire Cavity Single Emitter Lasers (MOCSELs)

Harvard University, Cambridge MA

Investigators

Abstract

Periodic patterns of holes etched into semiconductor slabs can serve as efficient cavities for microscale and nanoscale lasers by controlling the interaction between input energy and the emitters in the cavity. This research focuses on the possibilities of a new kind of semiconductor laser cavity, formed of two such slabs, where control of the lasing threshold and frequency may be done by changing the angle of one slab with respect to the other. Such cavities are called moiré photonic crystal cavities, because of the moiré patterns that are formed by the combined patterns of the two slabs. This exploratory research will be multi-facetted and strongly integrated, combining cavity simulation and design, nanofabrication of the moiré cavities, development of the means of controllable adjustment of the twist angle, and analysis of the lasing behavior of these new devices. Beyond the achievement of a suite of new efficient, tunable microscale and nanoscale lasers, this exploration will provide important insights into the details of the lasing process itself. The integrative and collaborative approach will provide an exceptionally rich research and education environment for the postdocs and graduate students involved in the project. We also expect that the multidisciplinary and collaborative aspects of this EAGER project will be amplified by the participation of undergraduates and high-school students. Photonic crystal slabs permit increasing the efficiencies and dramatically lowering the threshold of micro-scale and nanoscale semiconductor lasers. The proposed EAGER program on Moiré Cavity Single Emitter Lasers (MOCSELs) will further push the limits of lasing efficiency by fabricating moiré photonic crystal cavities, where two photonic crystal slabs are twisted relative to each other. The twist angle will be used to tune the quality factor, resonant frequency, and spatial distribution of the cavity modes, matching modes to atomic-scale emitters, such as InGaN quantum dots to achieve targeted and tunable non-linear cavity coupling to single quantum dots. This multi-facetted yet tightly integrated program will develop the simulations and design of the appropriate cavity structure, matched to the materials and emitters, implement the nanoscale fabrication processes needed to realize the design and match cavities to emitters, and as well, explore and implement Micro-electromechanical means to tune the twist angle, achieving optimal coupling across a range of quantum dot frequencies and spatial locations. Beyond demonstrating proof-of-concept of new, tunable, and highly efficient nanoscale lasers, the program research should provide transformational insights into the mechanisms of lasing, and cavity-emitter interactions, and therefore tunable lasers at the single-emitter level. 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.