A solution-processed 1.53 μm quantum dot laser with temperature- invariant emission wavelength

Sources of coherent, monochromatic short-wavelength infrared (1-2 μm) light are essential in telecommunications, biomedical diagnosis, and optical sensing. Today's semiconductor lasers are made by epitaxial growth on a lattice-matched single-crystal substrate. This strategy is incompatible with direct growth on silicon. Colloidal quantum dots synthesized in solution can, in contrast, be coated onto any surface. Here we show a 1.53 μm laser fabricated using a remarkably simple process: dipping a glass capillary into a colloidal suspension of semiconductor quantum dots. We developed the procedures to produce a smooth, low-scattering-loss film inside the capillary, resulting in a whispering gallery mode laser with a well-defined threshold. While there exist three prior reports of optical gain in infrared-emitting colloidal quantum dots [1, 2, 3], this work represents the first report of an infrared laser made using solution processing. We also report dλ_max/dT, the temperature-sensitivity of lasing wavelength, of 0.03 nm/K, the lowest ever reported in a colloidal quantum dot system and 10 times lower than in traditional semiconductor quantum wells.