X-ray communications in space called XCOM
X-rays have much shorter wavelengths than both infrared and radio. This means that, in principle, XCOM can send more data for the same amount of transmission power. The X-rays can broadcast in tighter beams, thus using less energy when communicating over vast distances.
gigabytes-per-second data transmission throughout the solar system.
Gamma ray communication
In the more distant future gamma rays could be used.
A two-millisecond gamma ray burst could carry 1,000,000,000,000,000,000 (1x10 to the power of 18) bits of information.
“So far as we know, gamma rays offer the widest practical communications bandwidth in the electro-magnetic spectrum and the only feasible way to send large quantities of information over intergalactic distances.” John A. Ball (MIT)