Recently, Some scientists in Lawrence Livermore National Laboratory has converted highest frequency sounds into light by inverting a process shifting electrical signals to sound.
They have used piezo-electric speakers those of which can be found in cell phones, also works at lower frequencies that human ears can hear.
The institution heads says "This technology can go to better computer chip developments"
Moreover; it's said that the producement of THz radiation for security, medical and many other purposes will be "easy" by using this technique.