X-ray communication (XCOM) is a novel space communication method with great potential. X-rays have much shorter wavelengths than both infrared and radio. In principle, XCOM can send more data for the same amount of transmission power, which could permit more efficient gigabits-per-second data rates for deep space missions.

Besides, X-rays can pierce the hot plasma sheath that builds up as spacecraft hurdle through Earth’s atmosphere at hypersonic speeds. However, some current technical limitations have made X-ray communication unable to fully release its theoretical advantages in space communications. Among them, the modulation of X-ray emission impacts significantly.

For the requirements of high-flux, collimation, quasi-monochromatic X-ray emissions, as well as the exploration of X-ray frequency modulation, a research team led by Prof. Dr.SHENG Lizhi from Xi'an Institute of Optics and Precision Mechanics (XIOPM) of the Chinese Academy of Sciences (CAS) propose an X-ray frequency modulation method for generating different energy X-rays by controlling the electron beam deflection based on an external electrostatic field.

It is different from all traditional on-off control methods, this scheme uses two specific X-ray energies indicate the digital signal 0 and 1, which makes X-ray frequency modulation possible. Based on this, we simulated the emission flux and energy distribution of two different targets.

Simulation results indicate that this X-ray modulation method produce X-rays with up to 50？GHz modulation frequency, 1014 cps X-ray emission flux, 99% monochrome, and 1.5？mrad divergence angle. Through this modulator, not only the communication distance and communication speed experience significant increases, but also the concept of X-ray communication, X-ray ranging and X-ray navigation can be realized as a three-in-one mission.

 X-ray modulation source method. (Image by XIOPM)

(Original research article " OPTIK (Volume 199, December 2019, 163263) https://doi.org/10.1016/j.ijleo.2019.163263 "）