Effect of hotspot on THz radiation from Bi2Sr2CaCu2O8 intrinsic Josephson junctions

Abstract

We investigate hot spot effects on increasing THz emission of the frequency modes in a square mesa structure with constant hot spot size in different positions, without applying magnetic field. We show that in the presence of hot spot at any position, the average of emitted power intensity level is increased. The frequency modes that the position of their field concentration is more matched with hot spot position are more excited. Accordingly, in the case with hot spot located at center of a-axis or b-axis, frequency modes TM(m,n) with even indices m or n is more excited and in the case in which hot spot is located at the corner of a-axis or b-axis, frequency modes TM(m,n) with odd indices m or n is more excited. We also show that in the presence of hot spot, the excited frequencies are independent of hot spot temperature and critical current attenuation ratio. Increase of the emission intensity of excited modes and average power intensity has a little dependency on critical current density attenuation ratio of hot spot region.