DFG-RSF: Polytype and isotope engineering of silicon carbide for quantum microwave amplifiers

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Masers are known as one of the best microwave (MW) amplifiers. The functionality of masers is based on a purely quantum effect - stimulated microwave emission - and this is the reason why maser (or quantum) amplifiers have extremely low intrinsic noise levels. However, the application of masers is up to now limited to a few niche uses only. The reason is that modern masers require specific conditions for operation, such as cryogenic temperatures or ultra high vacuum. A new type of maser, that can operate at ambient conditions and is compatible with standard manufacturing technology, would have enormous impact on our every-day life, similar as semiconductor lasers have at present. The purpose of this project is to solve the main problem, i.e., to demonstrate quantum MW amplification at room temperature. To achieve this goal, we use vacancy-related defects in silicon carbide (SiC), where optically generated population inversion and stimulated emission have been demonstrated. We will consider theoretically the fine structure of color centers in SiC having different symmetry, and investigate experimentally the pumping mechanism of the vacancy-related color centers in various polytypes using electron spin resonance (ESR) and optically-detected magnetic resonance (ODMR) techniques. We will use various planar MW resonators/waveguides and highly sensitive techniques to reduce losses and detect MW amplification based on the maser effect in our optimized samples.