Optical Microfluidic Waveguides and Solution Lasers of Colloidal Semiconductor Quantum Wells

• DOI: 10.1002/adma.202007131
• Publication Date: 2021-01-25T11:59:29Z
• Authors: Joudi Maskoun; Negar Gheshlaghi; Furkan Isik; Savas Delikanli; Onur Erdem; Emine Yegan Erdem; Hilmi Volkan Demir
• Keywords: :Physics [Science]; Microfluidics; Semiconductor Quantum Wells; 02 engineering and technology; 0210 nano-technology; 7. Clean energy

AbstractThe realization of high‐quality lasers in microfluidic devices is crucial for numerous applications, including biological and chemical sensors and flow cytometry, and the development of advanced lab‐on‐chip (LOC) devices. Herein, an ultralow‐threshold microfluidic single‐mode laser is proposed and demonstrated using an on‐chip cavity. CdSe/CdS@CdxZn1−xS core/crown@gradient‐alloyed shell colloidal semiconductor quantum wells (CQWs) dispersed in toluene are employed in the cavity created inside a poly(dimethylsiloxane) (PDMS) microfluidic device using SiO2‐protected Ag mirrors to achieve in‐solution lasing. Lasing from such a microfluidic device having CQWs solution as a microfluidic gain medium is shown for the first time with a record‐low optical gain threshold of 17.1 µJ cm−² and lasing threshold of 68.4 µJ cm−² among all solution‐based lasing demonstrations. In addition, air‐stable SiO2 protected Ag films are used and designed to form highly tunable and reflective mirrors required to attain a high‐quality Fabry–Pérot cavity. These realized record‐low thresholds emanate from the high‐quality on‐chip cavity together with the core/crown@gradient‐alloyed shell CQWs having giant gain cross‐section and slow Auger rates. This microfabricated CQW laser provides a compact and inexpensive coherent light source for microfluidics and integrated optics covering the visible spectral region.