Design, Demonstration, and Simulation of the Diode-Pumped Thulium/Holmium (Tm/Ho) Composite Fiber 2.1-μm Laser

How using a designable hybrid photonic crystal cavity (HPCC) polariton system can contribute to advancing the fundamental understanding and technological innovation in semiconductor photonics.

Army Research Laboratory, Adelphi, Maryland

Coherence properties are what distinguish a laser from other sources of light and make it useful. This research demonstrates for the first time a polariton laser with coherence reaching the intrinsic limit of single-mode matter-wave lasers. It further demonstrates intensity coherence at the shot-noise limit expected of an ideal coherent state (Figure 1, left), and phase coherence revealing interactions within the polariton condensate due to its matter-wave nature (Figure 1, right).

This research also demonstrates a new mechanism of frequency comb generation using coupled polariton condensates. It results from the dynamic interplay between on-site nonlinearity and inter-site couplings. This is distinct from other systems, such as microtoroidal resonators and quantum cascade lasers that are based on cascaded four-wave mixing process. A unique feature of this form of frequency comb generation is that the comb spacing is not given by the cavity transverse mode spacing and can be engineered from GHz to THz without having to drastically change the physical dimension of the system. Furthermore, since it is based on polariton condensation, the polariton comb allows a very low threshold and an incoherent pump, including electrical injection.