ABSTRACT
The importance of terahertz (THz) wave techniques has been demonstrated in various fields, and the range of applications is now expanding rapidly. However, the practical implementation of THz science to solve the real-world problems is restricted due to the lack not only of convenient high power THz wave emitters and sensitive detectors but also of efficient quasi-optical active devices such as amplifiers. In this work, we demonstrate the direct amplification of THz waves in room temperature using magnesium oxide-doped lithium niobate (MgO:LiNbO3) crystals as the nonlinear gain medium. The input THz wave is injected as a seed beam along with the pump beam into the nonlinear crystal and it is amplified by the optical parametric process. We report gain in excess of 30 dB with an input THz pulse energy of less than 1 pJ. We believe that this demonstration will contribute to the convenience and further applicability of THz frequency techniques.
ABSTRACT
A 76-year-old woman underwent laparotomy at another hospital because of acute abdomen. Owing to strong attachment and dissemination of the tumor, it was unresectable. Adult-type granulosa cell tumor (AGCT) was diagnosed based on pathological examination. Considering her poor condition, she was advised to receive total supportive care. However, she was lost to follow-up after a few months. Subsequently, she visited our hospital with abdominal distension. A large abdominal tumor and liver metastasis was observed on abdominal computed tomography (CT). We selected palliative radiotherapy to relieve her of the symptoms. External beam radiotherapy was delivered to the affected data. No acute adverse effects were observed. We observed reduction in tumor size on postoperative abdominal CT. She is still alive with no signs of tumor progression for 30 months. Palliative radiotherapy is effective for patients with advanced-stage AGCT and abdominal complaints.
