An electro-optical modulator utilizing high-energy electrons in the free-space

Gaining access to the ultrawide bandwidth of optical channels through a suitable electro-optical interface is an important issue for future optoelectronic technology. Considering the broad-bandwidth nature of relativistic free-electron generators of violet and ultraviolet radiation, it would be reasonable to devise a scheme based on the same principles for electro-optical interfacing in the near infrared and even soft X-ray regime. Realisation of such a device does not seem to be unrealistic considering the growing advances in electron-beam injection and microsystems technology. For optoelectronic applications, such as those for very-high bit-rate data communication, the device must be compatible to an existing system. Therefore, the interaction design in a small and economic size has to be considered. On this basis, we initiated a search for a device by looking for potential schemes which take advantage of relativistic electrons and electromagnetic field interaction. We previously adopted a characteristic interaction model with small dimensions and studied the electronic to optical transition/modulation process. The operating characteristics, e.g., coupled wavelengths and gain, associated with the electro-optical coupling process were derived in terms of model parameters and the challenges were defined accordingly. As a continuation of this work, here we explore an interaction design based on the use of cyclotron relativistic electrons. One important advantage of this scheme is that electrons can be easily re-used for another interaction cycle. Another advantage is that for the same physical dimensions, this design offers a longer interaction length which results in gain and power enhancement.