Superconducting Terahertz Sources with 12% Power Efficiency

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

“…For whisker-based mesas the ratio between emission and self-heating responses is quantitatively different: The emission peak R det (P get ) is much larger than the monotonic self-heating background. This indicates a much larger RPE in whisker-based devices [40].…”

“…Figure 2c shows the ac resistance of the detector mesa, R det , as a function of dissipation power in the generator mesa, P gen = I gen V gen . It is anticipated that selfheating is monotonic (approximately linear) with the dissipation power, while the emission is nonmonotonic [14,40] because it occurs at certain bias voltages, corresponding to geometrical resonances in the mesa [14,16,24,26]. From Figure 2c it is seen that a profound EMW emission occurs in a whisker-based mesa, leading to more than an order of magnitude enhancement of R det .…”

“…Radiative properties of our whisker-based devices were analyzed in [40]. A significant EMW emission at f ≃ 4.2 THz with a record-high RPE reaching 12% was reported.…”

“…The emission occurs in a specific bias range, corresponding to the step in the I-V marked in Figure 2a. To avoid repetitions we address the reader to [40] for more details.…”

“…Self-heating limits the maximum bias voltage that can be reached without critical overheating of a mesa and, therefore, the maximum achievable frequency and emission power. Furthermore, as pointed out in [40], self-heating creates a general limitation for the maximal achievable emission power for any cryogenic device (not only superconducting). Taking into account the limited cooling power of compact cryorefrigerators (sub-watt at low T), a device with RPE ≈ 1% would not be able to emit significantly more than 1 mW.…”