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Mutually Synchronized Macroscopic Josephson Oscillations Demonstrated by Polarization Analysis of Superconducting Terahertz Emitters
摘要： We demonstrate mutual synchronization of Josephson oscillations in multiple stacks of intrinsic Josephson junctions of the cuprate superconductor Bi2Sr2CaCu2O8+δ. Detailed analysis of the full polarization parameters allows the determination of a phase correlation between the stacks: a simultaneous emission state is described by a linear combination of individual emission states with a phase retardation. This proves that the stacks are coupled via a Josephson plasma in a superconducting substrate and that the coupling matrices can be extracted from polarization analyses. Our findings suggest a route towards the realization of high-power terahertz sources based on the synchronization of a large number of intrinsic Josephson junctions.
关键词： polarization analysis,Josephson oscillations,superconducting terahertz emitters,terahertz sources
更新于2025-09-23 15:21:01
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Investigation of GaAsBi epitaxial layers for THz emitters pumped by long-wavelength fiber lasers
摘要： Herein we report the studies on the GaBiAs terahertz emitters. The molecular beam epitaxy grown thin films were subjected to structural and optical characterization. Inhomogeneity of Bi concentration in the samples is confirmed by XRD, PL and EDS studies. Investigations on the generation characteristics of the fabricated bow-tie photoconductive antennas were carried out via the Fourier Transform Infrared Spectroscopy. The collected data indicate a pattern of change in the shape of the spectra with increasing bismuth concentration, namely, a sharp drop in the low-frequency part (0.1–0.2 THz) simultaneously with a noticeable increase in intensity in the range 0.3–1 THz with a pronounced maximum at frequencies of ~0.4 THz. The deterioration of the THz power to average photocurrent ratio can be explained by a general decrease in the electron mobility, caused both by a large number of structural defects and by a large local heating of the crystal.
关键词： terahertz emitters,photoconductive antennas,molecular beam epitaxy,GaBiAs,Fourier Transform Infrared Spectroscopy
更新于2025-09-23 15:19:57
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Current‐Enhanced Broadband THz Emission from Spintronic Devices
摘要： An ultra-broadband terahertz (THz) emitter covering a wide range of frequencies from 0.1 to 10 THz is highly desired for spectroscopy applications. So far, spintronic THz emitters have been proven as one class of efficient THz sources with a broadband spectrum while the performance in the lower THz frequency range (0.1–0.5 THz) limits its applications. In this work, a novel concept of a current-enhanced broad spectrum from spintronic THz emitters combined with semiconductor materials is demonstrated. A 2–3 order enhancement of the THz signals in a lower THz frequency range (0.1–0.5 THz) is observed, in addition to a comparable performance at higher frequencies from this hybrid emitter. With a bias current, there is a photoconduction contribution from semiconductor materials, which can be constructively interfered with the THz signals generated from the magnetic heterostructures driven by the inverse spin Hall effect (ISHE). These findings push forward the utilization of metallic heterostructure-based THz emitters on the ultra-broadband THz emission spectroscopy.
关键词： spintronic devices,broadband spectrum,photoconduction,terahertz emitters
更新于2025-09-04 15:30:14