Sensitive optomechanical transduction of electric and magnetic signals to the optical domain

We report a radio-frequency-to-optical converter based on an electro-optomechanical transduction scheme where the electrical, optical, and mechanical interface was integrated on a chip and operated with a fiber-coupled optical setup. The device was designed for field tests in a magnetic resonance scanner where its small form-factor and simple operation is paramount. For the appurtenant magnetic resonance detection circuit at 32MHz, we demonstrate transduction with an intrinsic magnetic field sensitivity of 8 fT/root Hz, noise figure 2.3 dB, noise temperature 210K, voltage noise 99 pV/root Hz, and current noise 113 pA/root Hz, all in a 3 dB-bandwidth of 12 kHz. Such sensitivity and bandwidth make the transducer a valuable alternative to conventional electronic preamplifiers that additionally is directly compatible with fiber communication networks. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement