Nanolasers, high speed modulation, and energy efficiency

We study the general issue of energy-data-rate efficiency and high-speed modulation of semiconductor nanolasers for future on-chip interconnects. Recent progress in nanolasers will be presented including semiconductor membrane lasers and plasmonic enhanced lifetime shortening. This talk tries to address several important issues related to semiconductor nanolasers. The first is the feasibility of faster modulation than conventional semiconductor lasers due to smaller sizes as a result of Purcell enhancement of radiative recombination. The focus here is the data rate under large signal modulation and the effects of noise^[1]. We found out that the noise or bit-error-rate poses a severe limit to the extremely high bandwidth predicted previously. But the noise-limited bandwidth is still significantly larger than the achievable bandwidth in a large laser. The second issue we address is the energy-data-rate efficiency. While this issue has received significant attention recently, we tried to address this issue in a more general theoretical framework of rate equations with special attention to the relationship to device sizes.^[1] We will show that the future requirement of energy efficiency limits the size of semiconductor lasers for on-chip applications. The interplay of modulation rate, energy data efficiency, and device sizes will be considered in a comprehensive fashion. In addition to above theoretical consideration, we will also present our recent experimental results on improving existing semiconductor nanolasers.^[2] Our recent approach is based on semiconductor membrane transfer. Semiconductor thin membrane as thin as 250 nm can be transferred from the original growth substrate for subsequent device fabrication. Results of recent fabrication and characterization will be presented. To study the plasmonic enhanced radiative processes in a metal-plasmonic laser, a series of plasmonic-semiconductor composite structures are studied in a systematic manner in order to determine the proximity effects of plasmonic resonance to operating wavelengths on lifetime shortening and enhancement of radiative and non-radiative processes.