UC San Diego

Wavelength-scale nanolasers are a crucial component of future photonic systems integrated on chip. As nanolasers progress from their first proof-of-concept demonstrations to robust designs working at room temperature far above their lasing threshold, their thermal behavior, as well as the effects of fabrication imperfections, need to be better understood. This dissertation presents the first integrated optical, electrical, thermal, and material analysis of wavelength-scale nanolaser performance, and uses these results to analyze a failed laser design, as well as to suggest design changes to improve robustness and performance. The dissertation begins by describing methods for optical and thermal analysis, including methods to automate long sweeps of operating current and/ or geometry parameters. Next, a nanolaser with poor laboratory performance is analyzed, and the performance- limiting parameter is found not to be thermal issues, as had been expected, but the sloped sidewalls of the fabricated laser. The next chapter expands the analysis of sloped sidewalls and finds that, although this effect is very detrimental to laser performance, an increase in the amount of undercut etching can render the laser insensitive to sidewall slope, with no significant Joule heating penalty near threshold. Finally, the analysis of laser performance is applied to lasers designed to operate well above threshold, showing the thermal benefits of using heat-conducting dielectric shield layers, and analyzing the effect of shield material choice on optimal shield thickness