  Electro-optical transducers are utilized for upconvertion of radio frequency
(RF) signals to the optical frequency domain to study the RF signals with
optical tools. The transducers frequently impact on the RF system and introduce
additional noise, including optical shot noise as well as quantum back action
noise, limiting the measurement accuracy. In this paper we theoretically study
a technique based on a high efficiency electro-optical phase modulation effect
that allows back action evading detection of an RF field quadrature. The main
idea of proposed method is independent homodyne detection of two (Stokes and
anti-Stokes) optical modes. It allows subsequent postprocessing of the detected
signals, which, in turn, results in a broadband back action evading measurement
leading to the high sensitivity evaluation of the RF signals.
