Parametric amplification and oscillation using an inverted maser material

Experimental results are reported demonstrating the possibility of achieving parametric gain in an inverted paramagnetic medium. In this case the parametric pump frequency may be lower than the signal frequency. The authors used chromium-doped rutile as the active material, a pump frequency of 150 MHz, and a signal frequency of 4.25 GHz. The parametric effect is strongly supported by adjusting the idling circuit for high master gain.