Highly efficient optical pumping of spin defects in silicon carbide for stimulated microwave emission

TL;DR

This paper demonstrates highly efficient optical pumping of silicon vacancy spins in silicon carbide, achieving significant population inversion and potential for continuous-wave maser operation at room and cryogenic temperatures.

Contribution

It presents the first detailed analysis of pump efficiency in silicon carbide spins, highlighting conditions for maser development and quantum microwave amplification.

Findings

Spin population inversion factor of 75 at room temperature

Pump efficiency increases at cryogenic temperatures due to long relaxation times

Potential for continuous-wave silicon carbide maser operation

Abstract

We investigate the pump efficiency of silicon vacancy-related spins in silicon carbide. For a crystal inserted into a microwave cavity with a resonance frequency of 9.4 GHz, the spin population inversion factor of 75 with the saturation optical pump power of about 350 mW is achieved at room temperature. At cryogenic temperature, the pump efficiency drastically increases, owing to an exceptionally long spin-lattice relaxation time exceeding one minute. Based on the experimental results, we find realistic conditions under which a silicon carbide maser can operate in continuous-wave mode and serve as a quantum microwave amplifier.