YBCO超電導薄膜スイッチによる24GHz空洞からのパルス抽出

抄録

A microwave pulse source using a Y-Ba-Cu-O (YBCO) superconducting thin film switch was studied. The YBCO thin film with a thickness of 0.2μm and a critical temperature of about 90K was fabricated by a laser ablation technique. It was installed in a cylindribcal TE011 mode cavity made of copper with a resonant frequency of 24.0GHz. The cavity was set inside a cryostat and cooled to 20K. The unloaded Q values of the cavity and the CW microwave power transmitted through the film were measured. Microwave pulses were extracted from the cavity by the switching from superconducting to normal states in the film, using a 1.06μm pulsed Q-switched Nd; YAG laser with a duration of 10ns. The peak power of the output pulses obtained below 40K at the incident laser energy density of 76.0mJ/cm2 was larger than the CW input power of 7.0mW.