Terahertz emission from mutually synchronized standalone Bi2Sr2CaCu2O8+x intrinsic-Josephson-junction stacks

Abstract

Suitably patterned single crystals made of the cuprate superconductor Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+x}$ (BSCCO), intrinsically forming a stack of Josephson junctions, can generate electromagnetic radiation in the lower terahertz regime. Due to Joule heating the emission power of single stacks seems to be limited to values below 100 $\mu$W. To increase the radiation power, mutually synchronized arrays situated on the same BSCCO base crystal have been studied. Mutual electromagnetic interactions via a connecting BSCCO base crystal have been considered essential for synchronization, but the approach still suffers from Joule heating, preventing the synchronization of more than three stacks. In the present paper we show, on the basis of two emitting stacks, that mutual synchronization can also be achieved by stand-alone stacks contacted by gold layers and sharing only a common gold layer. Compared to BSCCO base crystals, the gold layers have a much higher thermal conductivity and their patterning is not very problematic. We analyze our results in detail, showing that the two oscillators exhibit phase correlations over a range of $\pm$0.4 GHz relative to their center frequencies, which we mainly studied between 745 GHz and 765 GHz. However, we also find that strong phase gradients in the beams radiated from both the mutually locked stacks and the unlocked ones play an important role and, presumably, diminish the detected emission power due to destructive interference. We speculate that the effect arises from higher-order cavity modes which are excited in the individual stacks. Our main message is that the mutual interaction provided by a common gold layer may open new possibilities for relaxing the Joule-heating-problem, allowing the synchronization of a higher number of stacks. Our findings may boost attempts to substantially increase the output power levels of the BSCCO terahertz oscillators.

References in corpus (34)

• Coherent THz emission of Bi_2Sr_2CaCu_2O_8 intrinsic Josephson junction stacks in the hot spot regime
• Hot spots and waves in Bi2Sr2CaCu2O8 intrinsic Josephson junction stacks -a study by Low Temperature Scanning Laser Microscopy
• Geometrical Resonance Conditions for THz Radiation from the Intrinsic Josephson Junctions in Bi2Sr2CaCu2O8+d
• Possible Dynamic States in Inductively Coupled Intrinsic Josephson Junctions of Layered High-$T_c$ Superconductors
• Powerful terahertz emission from Bi2Sr2CaCu2O8+delta mesa arrays
• Radiation Due to Josephson Oscillations in Layered Superconductors
• Tunable terahertz emission from Bi2Sr2CaCu2O8+δ mesa devices
• Interaction of hot spots and THz waves in Bi_2Sr_2CaCu_2O_8 intrinsic Josephson junction stacks of various geometry
• Unusual linewidth dependence of coherent THz emission measured from intrinsic Josephson junction stacks in the hot-spot regime
• Evidence for a Dual-Source Mechanism of THz Radiation from Rectangular Mesas of Single Crystalline \bm{$\mathrm{B}{\mathrm{i}}_2\mathrm{S}{\mathrm{r}}_2\mathrm{CaC}{\mathrm{u}}_2{\mathrm{O}}_{8+\delta }$} Intrinsic Josephson Junctions
• Radiation from a Josephson STAR-emitter
• Effect of thermal inhomogeneity for THz radiation from intrinsic Josephson junction stacks of Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$
• Hot-spot formation in stacks of intrinsic Josephson junctions in Bi2Sr2CaCu2O8
• Local SiC photoluminescence evidence of non-mutualistic hot spot formation and sub-THz coherent emission from a rectangular Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$ mesa
• Direct imaging of hot spots in Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} mesa terahertz sources
• Stability of dynamic coherent states in intrinsic Josephson-junction stacks near internal cavity resonance
• THz emission from a stacked coherent flux-flow oscillator: non-local radiative boundary conditions and the role of geometrical resonances
• Three-Dimensional Phase-Kink State in Thick Stack of Josephson Junctions and Terahertz Radiation
• Counterintuitive Consequence of Heating in Strongly-Driven Intrinsic-Junctions of Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$ Mesas
• Superconducting THz sources with 12% power efficiency
• Thermal and electromagnetic properties of Bi${}_2$Sr${}_2$CaCu${}_2$O${}_8$ intrinsic Josephson junction stacks studied via one-dimensional coupled sine-Gordon equations
• In-plane dissipation as a possible synchronization mechanism for terahertz radiation from intrinsic Josephson junctions of layered superconductors
• Cavity mode identification for coherent terahertz emission from a nearly square stack of intrinsic Josephson junctions
• Monolithic superconducting emitter of tunable circularly polarized terahertz radiation
• 3D simulations of the electrothermal and THz emission properties of Bi${}_2$Sr${}_2$CaCu${}_2$O${}_8$ intrinsic Josephson junction stacks
• Mutually synchronized macroscopic Josephson oscillations demonstrated by polarization analysis of superconducting terahertz emitters
• Direct visualization of phase-locking of large Josephson junction arrays by surface electromagnetic waves
• Synchronization of Josephson oscillations in mesa array of BSCCO single crystal through the Josephson plasma waves in base crystal
• Design aspects of Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$ THz sources: optimization of thermal and radiative properties
• Control of Circularly Polarized THz Wave from Intrinsic Josephson Junctions by Local Heating
• Mutual synchronization of two stacks of intrinsic Josephson junctions in cuprate superconductors
• Wave functions for high-symmetry, thin microstrip antennas and two-dimensional quantum boxes
• Instability of flux flow and production of vortex-antivortex pairs by current-driven Josephson vortices in layered superconductors
• A distributed, active patch antenna model of a Josephson oscillator

Cited by in corpus (1)

• Fingerprint of $T_c$ advancement in Li-doped Bi-2223 superconductors prepared by cationic molecular mixing within Pechini sol-gel synthesis