Dresden 2026 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 26: Poster II
HL 26.29: Poster
Wednesday, March 11, 2026, 09:30–11:30, P1
Stokes, Anti-Stokes and selective excitation of Si-vacancies in SiC — •Emilian Eisermann, Vladimir Dyakonov, and Andreas Sperlich — Experimental Physics 6, University of Würzburg, 97074 Würzburg, Germany
Our group has demonstrated a room temperature continuous-wave maser that uses the silicon vacancy (V2) in silicon carbide (4H-SiC) (arXiv:2312.08251). Stimulated emission arises from an optically pumped population inversion in these spin defects. However, only a low output power could be achieved and laser heating caused instabilities. To enhance the maser characteristics, we investigate the fundamental pumping behavior of V2 (zero phonon line at 916.2 nm). Hereby, we distinguish between common Stokes excitation (CSE) (<916.2 nm), Anti-Stokes excitation (ASE) (>916.2 nm) and selective excitation (=916.2 nm). Using electron paramagnetic resonance spectroscopy, we resolve microwave absorption and emission signals due to the optical polarization of Zeeman split states. By analyzing these features, we calculate the population inversion and hence the pump efficiency. At low temperatures selective excitation is particular efficient and CSE outcompetes ASE, which requires thermally driven phonons. At room temperature, the increased phonon activity and the shortened T1 lifetime cause ASE (λ=950 nm) to have an efficiency of around 50 % compared to CSE. ASE however allows for a very targeted excitation of V2 and we identify an optical pumping sweet spot that is promising for future maser implementations.
Keywords: 4H-SiC; Si-vacancy; Zero-phonon line; Anti-Stokes excitation; EPR