Terahertz wave emission from intrinsic Josephson junctions in high- T c superconductors

2011 XXXth URSI General Assembly and Scientific Symposium

Köseoğlu

et al. 2011

We work on a frequency tunable solid state device to meet the needs of continuous, coherent, powerful terahertz emission sources that fill practically important terahertz gap. High temperature superconducting (HTS) coherently oscillating Josephson junctions in Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212) crystal make this approach very promising. Since doping dependence of Bi2212 is an important parameter, Bi2212 crystals are annealed in vacuum or purified argon gas flow at 425 o C. For further processing we pattern both single and double rectangular mesa structures by using electron beam lithography on the cleaved surface of the crystal. Resistance-temperature (R-T), and current-voltage behavior (I -V) measurements achieved.

Section: Methodsmentioning

confidence: 99%

“…It is shown that THz emitting mesas are below a certain underdoped level, which has relatively small critical current in contrast to optimally doped and overdoped Bi2212 [7]. More recently, emission powers of 5 µW and frequencies at the higher harmonics up to 2.5 THz have been obtained.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of double mesa structures by E-beam lithography from high temperature superconducting Bi<inf>2</inf>Sr<inf>2</inf>CaCu<inf>2</inf>O<inf>8+δ</inf> (Bi2212) for powerful terahertz emission

2011 XXXth URSI General Assembly and Scientific Symposium

Köseoğlu

et al. 2011

“…They found that standing waves of the electric field are created through interactions with a hot spot and this effect may have an active role in generating synchronized radiation from intrinsic Josephson junction stacks. In [14] we discussed the dependence of the characteristics of the mesa structures on the oxygen doping level of the Bi2212 crystals and reported that the THz emitting mesas are below a certain underdoped level, which has a relatively small critical current in contrast to optimally doped and overdoped Bi2212. Minami et al [15] reported the radiation characteristics of terahertz radiation emitted from rectangular mesa structures of Bi2212 and they concluded that these devices exhibit enough frequency purity, intensity, and controllability to be suitable for device applications.…”

Section: Introductionmentioning

confidence: 99%

Interferometer measurements of terahertz waves from Bi₂Sr₂CaCu₂O_8+dmesas

Köseoğlu

Supercond. Sci. Technol.

et al. 2012

Self Cite

We fabricated rectangular mesa structures of superconducting Bi 2 Sr 2 CaCu 2 O 8+d (Bi2212) using e-beam lithography and Ar ion beam etching techniques for terahertz (THz) emission. c-axis resistance versus temperature (R-T), current-voltage (I-V) characteristics and bolometric THz power measurements were performed to characterize Bi2212 mesas. The emission frequency of mesas was determined using a Michelson interferometer setup which also demonstrates polarized emission. Interference patterns of THz radiation from Bi2212 mesas were detected by various detectors such as a liquid helium cooled silicon composite bolometer, a Golay cell and a pyroelectric detector. An emitted power as high as 0.06 mW was detected from Bi2212 mesas. For the first time, most of the pumped power was extracted as THz emission from a Bi2212 mesa. The radiation at 0.54 THz was detected using the Michelson interferometric setup.

“…Therefore, 1 mV corresponds to 0.483 THz. However, the operation frequency is restricted by the superconducting gap, so it cannot exceed several hundred gigahertz for the devices made of conventional superconductors [2]. Also, the power emitted from a single junction is too small for practical applications, typically in the order of pW.…”

Section: Introductionmentioning

confidence: 99%

Terahertz wave emission from layered superconductors: Interferometer measurements

Özyüzer

2011 XXXth URSI General Assembly and Scientific Symposium

et al. 2011

Rectangular Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212) mesa structures were fabricated on as-grown Bi2212 single crystal superconductors using standard photolithography and Ar ion beam etching techniques. We have performed c-axis resistance versus temperature (R-T), current-voltage (I-V) characteristics and bolometer measurements. Furthermore, in contrast to previous studies, the emission frequency was determined using interferometer set up instead of FTIR. The interference patterns were detected outside the cryostat after traveling long way through ambient space. The emission frequency calculated by Fourier transform of interference data is consistent with Josephson frequencyvoltage relation.