Emission of Circularly Polarized Terahertz Wave From Inhomogeneous Intrinsic Josephson Junctions

Abstract

Abstract-We have theoretically demonstrated the emission of circularly-polarized terahertz (THz) waves from intrinsic Josephson junctions (IJJs) which is locally heated by an external heat source such as the laser irradiation. We focus on a mesastructured IJJ whose geometry is slightly deviate from a square and find that the local heating make it possible to emit circularlypolarized THz waves. In this mesa, the inhomogeneity of critical current density induced by the local heating excites the electromagnetic cavity modes TM (1,0) and TM (0,1), whose polarizations are orthogonal to each other. The mixture of these modes results in the generation of circularly-polarized THz waves. We also show that the circular polarization dramatically changes with the applied voltage. The emitter based on IJJs can emit circularly-polarized and continuum THz waves by the local heating, and will be useful for various technological application.

Control of circularly polarized THz wave from intrinsic Josephson junctions by local heating

“…Figure 4 (a) shows the frequency spectrum of the EM wave from the IJJ mesa at 0.932 mV. As we reported in our previous work, we can see that the peak frequency of the emission is 0.451 THz, according to the AC Josephson relation f J = 2eV /h, and the emission frequency is almost the average of the resonant frequencies of the TM(1,0) mode and TM(0,1) mode [26]. Finally, to clarify the dependence of the state of the polarization on the heating position, we investigated the THz emissions from the IJJ mesa by varying the heating position.…”

“…Stacks of these natural Josephson junctions, which are referred to as intrinsic Josephson junctions (IJJs), can generate an AC Josephson current in the THz frequency range by application of a voltage, and the THz wave emission is attributed to the generation of this current. Intense THz emissions have been reported for IJJs fabricated in a mesa geometry, which itself behaves as a cavity resonator, and thus, a number of studies on such IJJ mesas have been carried out both experimentally [4][5][6][7][8][9][10][11][12][13][14][15] and theoretically [16][17][18][19][20][21][22][23][24][25][26]. However, in the previous studies, little attention was given to the state of the polarization of the THz waves.…”

Monolithic Superconducting Emitter of Tunable Circularly Polarized Terahertz Radiation

“…3(a). These peaks, at frequencies of 544.3 and 608.6 GHz, may correspond to the excitation of the two cavity modes [25]. The detected power (P), estimated in accordance with bolometer sensitivity, is found to be of the order of Pmax ≈ 176.5 nW.…”

“…Waves emitted from rectangular IJJ-based sources have been known to be linearly polarized [2]. However, recent numerical studies [14,25,26] have proposed the possibility of realizing circularly polarized emissions from IJJ devices. This paper reports the first experimental demonstration of the generation of circularly polarized sub-THz waves from a monolithic source-a superconducting IJJ stack-wherein the ellipticity and evolution direction are tuned by mesa shape and bias conditions.…”

Recent advances in metamaterial split-ring-resonator circuits as biosensors and therapeutic agents

“…Although with the polarization direction of the incident electric field being parallel to the bottom bars of the asymmetric structure, two absorption dips are seen corresponding to the low frequency LC resonance and high frequency dipole resonance respectively; three absorption dips have been seen with the polarization direction of incidence being perpendicular to the design structure, as depicted in Fig 7(c) (Yang et al, 2016). Devices incorporating terahertz metamaterial attract attention for its great prospects in THz imaging, filtering and modulation in various biological sensing applications (Yang et al, 2016) with terahertz electromagnetic waves having huge potential to open up unique applications in medical diagnosis and bio sensing coupled with high-speed wireless-communication (Asai and Kawabata, 2016).…”