Analogue of electromagnetically induced absorption in the microwave domain using stimulated Brillouin scattering

Abstract

Electromagnetically induced transparency/absorption (EIT/EIA) tailor the amplitude and phase response of an absorption resonance to create large dispersion, which has been exploited for applications in slow- and fast-light, and quantum information science. Since EIA enhances (induces) absorption of an already existing absorption (transmission) profile, it leads to a significant reduction in output signal power. Induction of a narrow absorption feature within a gain resonance can compensate for the signal loss while creating large dispersion at the EIA feature frequency. However, the demonstration of an analogue of EIA exploiting gain resonances has remained elusive. Here, we exploit coherent interaction between the Brillouin gain resonances in orthogonal polarization states to demonstrate controlled excitation of an analogue of EIA over microwave frequency range of 2.5–43 GHz. We induce a narrow absorption feature (~6 MHz), with controllable depth and frequency, within Brillouin gain resonance, demonstrating a novel technique for microwave photonic processing.