Gravitational Spectrum Transformer

In this work, we propose the concept of a gravitational spectrum transformer -- a passive method for converting an optical electromagnetic signal into the radio range without the use of electronic devices. The method is based on the effect of gravitational redshift near a massive cold astrophysical object, such as a neutron star. It is shown that under certain conditions the gravitational field is capable of changing the frequency of laser radiation so significantly that it can be registered by an ordinary antenna. Physical limitations, requirements for the signal source, and possible applications of the proposed approach in deep space communications and fundamental physics are discussed.