Information-Measuring Complex to Detect High Frequency Gravitational Waves

Abstract

The gravitational waves predicted by the general theory of relativity and detected by the Laser Interferometer Gravitational-wave Observatory (LIGO) have typical frequencies in the range of 30 ... 300 Hz. Current theories of gravity predict the existence of high-frequency gravitational waves with frequencies of 10 ... 100 MHz, including those of cosmological origin, induced by quantum fluctuations of the scalar field at the stage of cosmological inflation in the early Universe.Multi-beam optical resonators, in particular the Fabry-Perot interferometers, can be used to detect high-frequency gravitational waves. When using multi-beam optical resonators, it is possible to use the phenomenon of low-frequency optical resonance, which allows us to have a selective response to the gravitational wave effect. The gravitational-optical resonance in a multi-beam interferometer occurs if the condition is fulfilled that an integer number of half-waves of gravitational radiation is along the length of the resonator.The use of a multi-beam interferometer to detect high-frequency gravitational waves does not require the creation of a complex system for decoupling mirrors used for gravitational antennas operating in the low-frequency part of the spectrum. This is due to the fact that the frequency of mechanical vibrations of the interferometer mirrors is significantly less than the frequency of the gravitational wave.The paper considers possible optical schemes of a high-frequency gravitational antenna: based on the traditional Michelson interferometer, in the arms of which two Fabry-Perot interferometers are available, and on the basis of the Mach-Zehnder optical scheme, where Fabry-Perot interferometers can be made in the form of two perpendicular arms, with reflecting mirrors at the bend of the beam. The advantage of the second scheme is that three photo-detectors, one being main and two others being auxiliary, can be used, and there is a possibility to detect radiation transmitted by Fabry-Perot interferometers.To prove that detection of high-frequency gravitational waves is possible, a potential sensitivity of the high-frequency gravitational antenna has been estimated in the paper.