Ultrashort laser pulses can be used to generate X-rays. Normally, however, only certain specific frequencies are produced. A team from TU Wien and the University of California San Diego has developed a method that makes it possible to tune the frequency continuously.

Using a six-meter-long gas-filled waveguide (20 feet long) containing the appropriate gas, the researchers can “detune” the light frequencies so that, in the end, exactly the required X-ray frequency is produced. The results have been published in the journal Communications Physics.