Room-Temperature Planar Lasers Based on Water-Dripping Microplates of Colloidal Quantum Dots

The solution-processable colloidal quantum dots (CQDs) attract great interests in small-size laser applications because of the high quantum yields and the tunable emission wavelengths. The small CQD lasers based on the microplates are of importance in the highly integrated photonic circuits, and the simple and low-cost manufacturing methods to obtain the CQD microplates are greatly desired and appealing in applications. Here, by employing the simple drop-casting and water-dripping method, the high-quality CQD microplates with various shapes and sizes are experimentally manufactured under the proper solvents and solvent ratio as well as environment temperature. Evidently, this manufacturing method does not require any expensive or special instruments. Because of both the large gain coefficients and the high quality factors of the CQD microplates, the room-temperature planar multi- and single-mode CQD lasers with p-polarized emissions are experimentally realized under low pump thresholds. Moreover, it is demonstrated that the planar CQD microplate laser is easy to be integrated with the waveguides on chips. This simple and low-cost method to manufacture the CQD microplates opens a wide range of possible activities in the area of solid-state small lasers, which are important building blocks for the true integration of optoelectronic circuitry.