Design and characterization of microstrip patch antennas for high-T superconducting terahertz emitters.

We designed and characterized a microstrip pattern of planar patch antennas compatible with a cuprate high-T superconducting terahertz emitter. Antenna parameters were optimized using an electromagnetic simulator. We observed repeatable sub-terahertz emissions from each mesa fabricated on identical BiSrCaCuO base crystals in a continuous frequency range of 0.

Study of Radiation Characteristics of Intrinsic Josephson Junction Terahertz Emitters with Different Thickness of BiSrCaCuO Crystals.

The radiation intensity from the intrinsic Josephson junction high-Tc superconductor Bi2Sr2CaCu2O8+δ terahertz emitters (Bi2212-THz emitters) is one of the most important characteristics for application uses of the device. In principle, it would be expected to be improved with increasing the number of intrinsic Josephson junctions in the emitters. In order to further improve the device characteristics, we have developed a stand alone type of mesa structures (SAMs) of Bi2212 crystals.

Cavity mode enhancement of terahertz emission from equilateral triangular microstrip antennas of the high-T superconductor BiSrCaCuO.

We study the transverse magnetic (TM) electromagnetic cavity mode wave functions for an ideal equilateral triangular microstrip antenna (MSA) exhibiting C point group symmetry. When the C operations are imposed upon the antenna, the TM(m,n) modes with wave vectors [Formula: see text] are much less dense than commonly thought. The R operations restrict the integral n and m to satisfy [Formula: see text], where [Formula: see text] and [Formula: see text] for the modes even and odd under reflections about the three mirror planes, respectively.

Applications using high-Tc superconducting terahertz emitters.

Using recently-developed THz emitters constructed from single crystals of the high-Tc superconductor Bi2Sr2CaCu2O8+δ, we performed three prototype tests of the devices to demonstrate their unique characteristic properties for various practical applications. The first is a compact and simple transmission type of THz imaging system using a Stirling cryocooler. The second is a high-resolution Michelson interferometer used as a phase-sensitive reflection-type imaging system.

Cavity mode identification for coherent terahertz emission from high-Tc superconductors.

Stacks of intrinsic Josephson junctions in BiSrCaCuO emit intense and coherent terahertz waves determined by the internal electromagnetic cavity resonance. We identify the excited transverse magnetic mode by observing the broadly tunable emissions from a nearly square stack and simulating the scattering spectrum. We employ a wedge-type interferometer to measure spatially-integrated power independently of the far-field pattern.

Broadly tunable subterahertz emission from internal branches of the current-voltage characteristics of superconducting Bi2Sr2CaCu2O(8+δ) single crystals.

Continuous, coherent subterahertz radiation arises when a dc voltage is applied across a stack of the many intrinsic Josephson junctions in a Bi2Sr2CaCu2O(8+δ) single crystal. The active junctions produce an equal number of I-V characteristic branches. Each branch radiates at a slightly tunable frequency obeying the Josephson relation.

High-power terahertz electromagnetic wave emission from high-T(c) superconducting Bi2Sr2CaCu2O(8+δ) mesa structures.

In this paper, we report intense electromagnetic wave emissions generated by the rectangular mesa structure of intrinsic Josephson junctions with high-T(c) superconducting Bi2Sr2CaCu2O(8+δ). The radiated power is an order of magnitude stronger than that of the previously observed power of a few μW. Two emission regions, reversible (R-type) and irreversible (IR-type), with comparable intensities can be observed at different I-V curve locations in the same mesa.

Geometrical resonance conditions for THz radiation from the intrinsic Josephson junctions in Bi(2)Sr(2)CaCu(2)O(8+δ).

Subterahertz radiation emitted from a variety of short rectangular-, square-, and disk-shaped mesas of intrinsic Josephson junctions fabricated from a Bi(2)Sr(2)CaCu(2)O(8+δ) single crystal was studied from the observed I-V characteristics, far-infrared spectra, and spatial radiation patterns. In all cases, the radiation frequency satisfies the conditions both for the ac Josephson effect and for a mesa cavity resonance mode. The integer higher harmonics observed in all spectra imply that the ac Josephson effect plays the dominant role in the novel dual-source radiation mechanism.

[A case of dedifferentiated liposarcoma of the spermatic cord].

A 61-year-old man was referred to our department because of painless and stony hard mass beside the left testis. Serum levels of lactate dehydrogenase, alpha-fetoprotein and human chorionic gonadotropin were within normal ranges. The ultrasonography of the mass showed almost homogenous and relatively low intensity echogram.

Renal cell carcinoma with hemorrhagic cyst formation in a 4-year-old boy.

We report on a case of renal cell carcinoma (RCC) with hemorrhagic cyst formation in a 4-year-old boy. The patient presented with asymptomatic macrohematuria. Abdominal ultrasound, computed tomography and magnetic resonance imaging demonstrated a left renal complicated cyst, 18 mm in diameter.