Nano-scale lasers and optical amplifiers are the core devices of optoelectronic integration of chips in the fu-ture. Rare-earth optical materials with large optical gain are of great importance for a wide variety of applica-tions in photonics and quantum information, especially in the realization of efficient lasers and amplifiers. Until now, such materials have achieved a gain of less than a few dB/cm, rendering them unsuitable for applications in nanophotonic integrated circuits.