Faster nanolaser modulation using mode-field switching

Nanolasers have the potential to enable a diverse range of photonic applications, such as optical interconnects, sensors, and artificial optical neural networks. For many applications involving data communication, high-speed modulation is required of the nanolasers. However, existing nanolaser modulation methods, such as gain switching, rely on the injection of short current pulses into the nanolaser gain medium, which causes unwanted parasitics that limit the maximum achievable speed.

Pellegrino et al. developed a modulation technique for nanolasers known as mode-field switching, and demonstrated its capability in a three-cavity system. Their method overcomes traditional limitations by exploiting a controllable electromagnetic field in coupled nanocavities, which in turn allows the control of light-matter interactions at the nanoscale.

“This research demonstrates experimental switching of a nanolaser, and shows that the implementation of fast detuning techniques leads to production of short laser pulses in the 10 picosecond timescale,” said author Daniele Pellegrino. “This feature places mode-field tuning potentially among the techniques able to generate laser pulses together with gain-switching, Q-switching and mode-locking.”

Their mode-field switching technique enables nanolaser modulation from a target cavity by thermally tuning the control cavity resonances, without having to adjust the pump level, which would otherwise slow down the system. The three-coupled cavity system can also be tuned from bright to dark, enabling the inhibition of all radiative processes, including stimulated emission. According to the authors, the technique can be applied to any system with tunable resonances.

“The natural evolution of this research includes the generation of short laser pulses for applications in many fields,” said Pellegrino. “Additionally, mode-field tuning can also be exploited in quantum information, as it potentially enables controllable single-photon sourcing.”

Source: “Mode-field switching of nanolasers,” by Daniele Pellegrino, Pierre Busi, Francesco Pagliano, Bruno Romeira, Frank W. van Otten, Andrei Yu. Silov, and Andrea Fiore, APL Photonics (2020). The article can be accessed at https://doi.org/10.1063/5.0006767 .