The demonstration of electrically-driven continuous wave (CW) laser operation at room temperature and at wavelengths lying in the third telecommunication band in few-cell point photonic crystal nanocavities may lead to the development of densely integrated miniature laser sources for optical communication applications. The main difficulty in realizing nanolasers with these operating characteristics is the inherent low-quality factors of cavities with few-point defects and, in turn, the associated high gain thresholds for CW laser oscillation at room temperature. Now, a collaboration led by Eiichi Kuramochi reports a route to overcome this impediment, which involves the realization and use of InP L_x (x = 1,2…5) cavities with InGaAs/AlGaInP multi-quantum-wells (MQW) heterostructures, buried in the point-defects having Q values that exceed 10⁶ and active volumes that are smaller than 10^–14 cm³. The miniature sources developed required a maximum DC current injection and a bias voltage as low as 10 μA and 1 V, respectively, to generate CW laser emission at 23°C, thereby indicating the potential of this approach to enable the realization of arrays of low-threshold nanolasers based on CMOS-compatible photonic crystal platforms. They also represent an excellent example of the ability of green photonics approaches in providing energy-efficient solutions for optical communication applications.

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