Low Power Dissipation Goblet Quantum Cascade Laser

ABSTRACT Mid‐infrared low‐power‐dissipation quantum cascade lasers are key components for the next‐generation portable sensing and high‐speed free‐space communication systems. Common methods to reduce power dissipation consist of reducing the device size with the help of lateral Fe: InP regrowth to suppress the optical loss and facilitate the current injection. However, the lateral regrowth inevitably complicates the fabrication process and raises the cost. Herein, a regrowth‐free quantum cascade laser with a Goblet‐shaped waveguide cross‐section is proposed, which features a much narrower active region than the top and bottom claddings. By selectively etching the active region, the Goblet quantum cascade laser enables the fabrication of ridges with a width < 2 µm while still maintaining an excellent current injection. Combined with the high‐reflection coating, the devices threshold power dissipations of 0.85 W and 1 W are achieved for pulsed and continuous wave operations at 20°C, respectively. Our work provides a conceptually different routine to mid‐infrared quantum cascade lasers that are both low‐cost and ultra‐low‐dissipation, with a drastically simplified fabrication process. This paradigm holds great importance to the advances of mid‐infrared active nonlinear micro‐resonators, high‐speed communication systems, and miniature spectrometers.