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High temperature superconductors have unique properties that can be useful in the THz region, single crystal constituted from superconducting CuO2-layers could sustain high voltages across the junctions and they are coupled through the intrinsic Josephson Effect this maintains the potential for very intense, coherent radiation which spreads over the THz gap. We investigated various experimental techniques to fabricate THz sources, bolometers and filters for efficient THz emission and detection. Rectangular mesa structures were fabricated on Bi2Sr2CaCu2O8-x (Bi2212) single crystal superconductors using standard e-beam lithography and Ar ion beam etching systems and an emitted power as high as 60 μW at frequencies up to 0.85 THz was detected from micron sized continuous wave terahertz sources. We also fabricated bolometric microchips for THz detection purpose from Bi2212 single crystals. Bi2212 microchips detected the signals and response time were calculated, our results have clearly shown that Bi2212 single crystals are potential candidates for THz detection. The detection properties and sensitivity of bolometer chips can be further improved by integrating an antenna and filter structures. In order to investigate this we have fabricated metamaterial THz filters based on metals and YBa2Cu3Ox superconducting thin films with metal-mesh shape and a unique fourcross shape pattern. Both a THz time domain spectrometer and a Fourier transform infrared spectrometer (FTIR) were used to investigate the performance of these filters and the results were compared with simulations done with a commercially available electromagnetic simulation software.

Terahertz (THz) radiation is in powerful region of electromagnetic spectrum because of prosperous application areas yet deficiency still exists about sources and detectors in despite of improvements of the research field in this range. This gap can be filled by focusing on development of THz detectors. Therefore, bolometers were preferred through many detectors due to detection sensitivity above 1 THz. In this study, Bi2Sr2CaCu2O8+δ (Bi2212) single crystals were used to fabricate THz bolometric detector. Bi2212 single crystals were transferred on sapphire substrate by cleavage process and e-beam lithography and ion beam etching were used to fabricate the microchip clean room facilities. Custom-designed cryogenic cryostat was used for a-b axis electrical and THz response measurements with liquid nitrogen cooled system. After electrical measurements, Bi2212 microchips detected the signals using Stefan-Boltzmann Lamp and response time were calculated. This study have shown with our experimental results that Bi2212 single crystals are potential candidates for THz bolometric detectors.

The as-grown Bi2Sr2CaCu2O8+δ (Bi2212) crystals were heat-treated at various temperatures either in Argon atmosphere or in vacuum. Bi2212 triple mesa structures were fabricated by electron beam lithography and Ar ion beam etching processes. A set of samples has identical size (50 × 300 μm2) are vertically mounted in vacuum on the cold finger of an optical LHe continuous-flow cryostat and resistance versus temperature and current-voltage measurements achieved. We investigated and compared characteristics of three mesas which are on same chip and next to each other. By this way, we searched the crystal inhomogenity in triple mesa structures and studied how critical current density varies with the doping conditions.

Rapid increase in applications of the electromagnetic waves in the terahertz frequency range requires new techniques to obtain continues-wave terahertz radiation sources. It is shown that rectangular shaped mesa structure from Bi2Sr2CaCu2O8+d (Bi2212) is a good source for generation of terahertz radiation. In this study, we have fabricated triple mesa structures using e-beam lithography and argon ion beam etching techniques. Our aim is to find the critical current density dependence of mesa area to obtain maximum emission power for the terahertz radiation.