An Ultrabroadband Mid-Infrared Pulsed Optical Switch Employing Solution-Processed Bismuth Oxyselenide

Pulsed lasers operating in the mid-infrared (3-25 mu m) are increasingly becoming the light source of choice for a wide range of industrial and scientific applications such as spectroscopy, biomedical research, sensing, imaging, and communication. Up to now, one of the factors limiting the mid-infrared pulsed lasers is the lack of optical switch with a capability of pulse generation, especially for those with wideband response. Here, a semiconductor material of bismuth oxyselenide (Bi2O2Se) with a facile processibility, constituting an ultrabroadband saturable absorber for the mid-infrared (actually from the near-infrared to mid-infrared: 0.8-5.0 mu m) is exhibited. Significantly, it is found that the optical response is associated with a strong nonlinear character, showing picosecond response time and response amplitude up to approximate to 330.1% at 5.0 mu m. Combined with facile processibility and low cost, these solution-processed Bi2O2Se materials may offer a scalable and printable mid-infrared optical switch to open up the long-sought parameter space which is crucial for the exploitation of compact and high-performance mid-infrared pulsed laser sources.