Generation of Submillimeter Terahertz Radiation by Ultrafast Optical-Field-Emission

Terahertz wave science and technology have been recognized as an emerging key frontier of research, showing potential applications in a much wider spectrum, particularly for recent topics such as terahertz wireless communication and terahertz radar. However, to date there is an obvious mismatch between potential application and available technology. To meet the rapid increase in interest of broadening potential applications, effort has been increased to search for new physical mechanism underlying terahertz radiation. In this study, we reveal a new physical mechanism, i.e. generation of submillimeter radiation by ultrafast optical-field-emission. We demonstrate that femtosecond optical-field-emission electrons radiate terahertz waves in the range of 0.3 to 5.36 THz, and that the periodical pulses of terahertz waves may be produced. The method is simple and efficient with unique technological property, potentially being crucial to terahertz radar and terahertz wireless communication.