Intraband Optical Gain in Colloidal Nanoplates

Colloidal nanoplatelets show some of the most promising optical gain characteristics of any materials. Using a modified quantum fountain design, thresholdless intraband optical gain at near-infrared wavelengths is demonstrated in using colloidal nanoplatelets. This is the first demonstration of unipolar gain in a colloidal system, requiring only electrons in this case. Stimulated emission wavelength depends on the thickness of the samples and can be tuned to technologically important wavelengths such as 1.3 and 1.5 μm. The modal gain, gain bandwidth, and gain lifetime of this intraband gain may be manipulated using excitation energy and temperature. Unlike bipolar laser media which competes with non-radiative Auger recombination, intraband stimulated emission must compete with intraband relaxation via longitudinal optical and surface phonons.