Terahertz Waves Emission From Two Bi Sr CaCu O Mesas in Series

Thedependenceofterahertz(THz)emissionpoweron thethicknessofseriesBi Sr CaCu O (BSCCO)mesasisstudied in this letter. An intrinsic Josephson junction (IJJ) array with two BSCCO mesas in series is proposed. The current-voltage charac- teristics of the IJJs, the powers, and Fourier spectra of the THz emissionaremeasuredfordifferentthicknessesofthemesas,which is gradually mounted by the argon ion beam milling. Experiment resultsindicatethattheTHzemissionpowergrowsasthethickness of the mesas is increasing. The power reaches a maximum value of about 0.502 W at a frequency of 0.708 THz when the thickness is 1200 nm. However, the THz emission power decreases while the thickness of the mesas keeps increasing. This nonlinearity between the THz emission power and the thickness of the mesas is due to the cavity resonance of the mesas and the self-heating generated by the IJJs in the mesas. The structure of connecting two mesas in series can be extended to form an IJJ array of multiple series mesas, which could further improve th eT Hz emission power.