Highly Flexible RF Filter Responses Using Stimulated Brillouin Scattering With Bandwidth up to 1 GHz

In this article, a novel approach to realize a switchable RF filter with analogous electromagnetically induced absorption (EIA) responses, electromagnetically induced transparency (EIT) responses, and spectral hole burning responses with tunable central frequency, suppression ratios, and bandwidth using two Brillouin loss resonances are proposed. EIA induces absorption in a gain profile, resulting in attenuation of signal power in the absorption bandwidth. In contrast, EIT induces amplification in a loss profile, leading to signal amplification in the transmission bandwidth. EIA-like filters with an absorption depth of up to 50 dB, bandwidth tunability of up to 1 GHz, and an absorption depth of up to 63 dB with bandwidth tunability of up to 600 MHz have been demonstrated. EIT-like filters with transmission depths of 51 dB, bandwidth tunability of up to 1.1 GHz, and spectra hole-burning with a hole depth of up to 36 dB have been achieved. Bandwidth tailoring is achieved by only frequency shifting of one of the pump lasers and harnessing the Brillouin phase profile and is thus highly power-efficient.