A new type of optical-microwave conversion system has been proposed as high-stabilized oscillators and optical interfaces for superconducing circuits. The photomixer with heterodyne mixing of two lasers was applied to generate the electromagnetic waves and high-T<sub>C</sub> grain boundary Josephson junction detector was used to monitor the frequency of electromagnetic waves in real time. The current-voltage properties of Josephson junction detector were examined and the system operation up to 50 GHz was demonstrated. We also described in detail the two types of optical-microwave conversion system.
We have proposed and demonstrated a nondestructive and non-contact inspection method for electrical faults using laser-Terahertz (THz) emission microscopy (LTEM). By measuring the position dependence of the amplitude of the THz emission from integrated circuits (IC) excited with femtosecond (fs) laser pulses, it is possible to investigate the electrical faults in IC. By improving the spatial resolution of the system, we successfully observed the THz emission
image of a microprocessor on standby mode. The LTEM system has a spatial resolution about 3µm and it can localize electrically defective sites in the chip to within a ten square microns.
Magnetic flux letters are visualized by a laser terahertz emission microscope (LTEM). LTEM excites terahertz (THz) radiation from electronics materials with a femtosecond laser and maps the amplitude of the THz waves while scanning laser beam on the sample. Magnetic flux letters written in high-Tc superconductors are successfully imaged without destroying them.