Compact High- Tc Superconducting Terahertz emitter operating up to 86 K

Abstract

We report on a Stirling-cooled compact Bi 2 Sr 2 CaCu 2 O 8+δ intrinsic Josephson-junction stack with very high critical current density and improved cooling, operating at bath temperatures T b up to 86 K. The square stand-alone stack is embedded between two sapphire substrates. For bath temperatures between 27.8 and 86 K emission is observed at frequencies from 0.356 to 2.09 THz. The emission power exceeds 1 μW at bath temperatures between 60 and 80 K for emission frequencies between 0.5 and 0.88 THz. A record high value of 0.577 THz is obtained for the emission frequency at T b = 80 K, which is important for potential applications using liquid nitrogen as a coolant. We also compare our experimental results with numerical simulations based on three-dimensional coupled sine-Gordon equations combined with heat diffusion equations.

Superconductor Electronics: Status and Outlook

“…The understanding of various coherence promoting and emission-limiting mechanisms is still in progress. Bestattained coherent emission data are frequencies up to 2 THz, linewidths down to several megahertz, and emitted power of over 0.2 mW from a single mesa [47] and up to 0.6 mW from an array of three synchronized mesas [48]. By now, efforts in application as terahertz sources reached the stage of laboratory demonstrations, e.g., of terahertz imaging [49] or portable terahertz source ( [50] and refs.…”

Study of Radiation Characteristics of Intrinsic Josephson Junction Terahertz Emitters with Different Thickness of Bi2Sr2CaCu2O8+δ Crystals

“…It is known that and become smaller with decreasing the carrier doping level of the crystals. In addition, in the previous works for higher bath temperature operation of Bi2212-THz emitters [ 38 , 67 ], the mesa structures made of Bi2212 single crystals with ∼ 90 K were used. They observed clear emission and the wide area of hysteresis loop of IVCs with large at around 80 K. Our observed results discussed here are consistent with such studies.…”

“…The characteristics of the electromagnetic waves radiating from these Bi2212-THz emitters are that they are coherent, continuous, widely tunable from 0.3 to 2.4 THz [ 21 , 30 , 31 , 32 ], with even higher frequencies that can be generated up to 11 THz [ 33 ], their narrow spectral linewidth is less than 0.5 GHz [ 34 ], and has even been reported to be as low as 20 MHz [ 35 ], and they are highly polarized, either linearly or circularly [ 36 , 37 ]. Furthermore, Bi2212-THz emitters can be operated at temperatures up to 86 K [ 38 ]. To date, the maximum intensity observed from a single mesa device is about 30∼100 W [ 30 , 39 , 40 , 41 , 42 , 43 ].…”

“…Several device structures have been proposed to overcome the heating effect [ 30 , 31 , 41 , 43 , 65 ]. Due to these improvements in the design of Bi2212-THz emitters by adding heat exhausting structures, the device characteristics such as the radiation intensities, frequencies [ 30 , 31 , 43 ], and the device working bath temperatures [ 38 , 66 , 67 ] have also improved. According to these results and the related previous studies [ 68 , 69 , 70 , 71 , 72 ], it is certain that thermal managements, such as adding heat exhaust structures, control of the number of active Josephson junctions in mesa structures, position of the hot-spot on mesa structures, and contact resistance of electrodes on mesa structures, are one of the important factors to improve the device characteristics.…”

Design aspects of Bi2Sr2CaCu2O8+δ THz sources: optimization of thermal and radiative properties

“…The layered high-temperature superconductor Bi-2212 (Bi 2 Sr 2 CaCu 2 O 8+δ ) may provide an alternative possibility for the creation of cryogenic CW THz sources [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Bi-2212 represents a natural stack of atomic scale intrinsic Josephson junctions (IJJs) [23][24][25][26].…”