  A GHz maser beam with Gaussian-type distribution passing through a homogenous
static magnetic field can be used to detect gravitational waves (GWs) with the
same frequency. The presence of GWs will perturb the electromagnetic (EM)
fields, giving rise to perturbed photon fluxes (PPFs). After being reflected by
a fractal membrane, the perturbed photons suffer little decay and can be
measured by a microwave receiver. This idea has been explored to certain extent
as a method for very high frequency gravitational waves. In this paper, we
examine and develop this method more extensively, and confront the possible
detection with the predicted signal of relic gravitational waves (RGWs). A
maser beam with high linear polarization is used to reduce the background
photon fluxes (BPFs) in the detecting direction as the main noise. As a key
factor of applicability of this method, we give a preliminary estimation of the
sensitivity of a sample detector limited by thermal noise using currently
common technology.
  The minimal detectable amplitude of GWs is found to be
$h_{\rm{min}}\sim10^{-30}$. Comparing with the known spectrum of the RGWs in
the accelerating universe for $\beta=-1.9$, there is still roughly a gap of
$4\sim 5$ orders. However, possible improvements on the detector can further
narrow down the gap and make it a feasible method to detect high frequency
RGWs.

General Relativity and Quantum Cosmology