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Josephson emission with frequency span 1-11 THz from small Bi2Sr2CaCu2O8+δ mesa structures
E A Borodianskyi1, V M Krasnov2
1Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91, Stockholm, Sweden.
Nature Communications
|November 25, 2017
Summary
Small Bi2Sr2CaCu2O8+δ mesas emit tunable terahertz waves up to 11 THz. This Josephson emission, requiring ~100 junctions, shows superradiant behavior and approaches theoretical limits.
Area of Science:
- Condensed Matter Physics
- Superconductivity
- High-Frequency Electronics
Background:
- Mesa structures of Bi2Sr2CaCu2O8+δ act as stacks of intrinsic Josephson junctions.
- These structures are investigated for high-frequency electromagnetic wave generation.
Purpose of the Study:
- Analyze Josephson emission from small-but-high mesas.
- Investigate tunable terahertz emission properties and efficacy.
Main Methods:
- Studied Josephson emission from mesas with numerous stacked junctions.
- Analyzed emission spectra across a wide frequency range (1-11 THz).
Main Results:
- Observed tunable terahertz emission with good efficacy from 1-11 THz.
- Emission maxima linked to in-phase cavity modes, indicating superradiant emission.
- Identified a threshold of approximately 100 junctions for terahertz emission.
Conclusions:
- Terahertz emission in these mesas exhibits coherent superradiant characteristics.
- The observed threshold behavior suggests laser-like cascade amplification.
- The findings approach the theoretical upper frequency limit for this superconductor.
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