| Project/Area Number |
13450142
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
電子デバイス・機器工学
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| Research Institution | Osaka University |
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Principal Investigator |
YAMAMOTO Sadahiko Osaka University, Graduate School of Engineering Science, Professor, 大学院・基礎工学研究科, 教授 (00029448)
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| Co-Investigator(Kenkyū-buntansha) |
SHIOMI Hidehisa Osaka University; Graduate School of Engineering Science, Assistant Professor, 大学院・基礎工学研究科, 助手 (00324822)
TANAKA Takuo Osaka University, Graduate School of Engineering Science, Assistant Professor, 大学院・基礎工学研究科, 助手 (40283733)
MURATA Hiroshi Osaka University, Graduate School of Engineering Science, Associate Professor, 大学院・基礎工学研究科, 助教授 (20239528)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥13,400,000 (Direct Cost: ¥13,400,000)
Fiscal Year 2002: ¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 2001: ¥8,800,000 (Direct Cost: ¥8,800,000)
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| Keywords | Optical Mixing / Microwave Transistors / HEMT / Microwave Circuits / Side-gating Effect / Sub-carrier Mixing / 近接場光 |
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| Research Abstract |
Recently, optical mixing by high-speed transistors has been attracted much interest for broadband mobile communication systems by combining the optical fiber and the microwave technologies because of their wide bandwidth and inherent isolations between RF signals. Until now, the optical mixing and the photodetection mechanisms of high-speed transistors such as high-electron mobility transistors (HEMTs) or MESFETs have been studied. However, there have not been reported about the change of the polarities of optical responses by light irradiation conditions. In this research, we tried to do the selective optical beam irradiation to the HEMT by use of a microscope and a laser beam and we found its positive and negative optical responses depending on irradiation position. We also studied the application of these optical responses to optically controlled microwave oscillators.
A commercially available InGaAs HEMT for low noise amplification in the L- to K-band was mounted on a microstripline
… More
of 50Ω. An optical beam from a laser diode was focused and injected onto the surface of the HEMT. The spot size of the focused optical beam was about 3μm. The position of the beam spot on the HEMT was monitored by using a microscope and a CCD camera, and adjusted by using an XY-stage.
When we set the CW laser beam spot with 50μW from a laser diode of 635nm near the gate electrodes and supplied appropriate DC-bias voltages to the HEVIT, increases of the drain current up to 8mA and the small signal gain up to 20dB were obtained. While we set the beam spot apart from the gate electrodes, decreases of the drain current and the gain were observed clearly. We believe that this negative optical response was due to the capture of carriers in the deep traps, called as the "side-gating effect". We applied these interesting characteristics by light illumination to the optically controlled microwave are oscillators.
We designed and fabricated a series feedback microwave oscillator with an oscillating frequency of 11.7GHz by using the HEMT. The HEMT in the oscillator was irradiated by optical pulse beams selectively and the changes of the microwave oscillation were measured. By changing the irradiated position of an optical pulse to the HEMT between the positive and the negative response regions on an appropriate DC-bias condition, the gain of the HEMT was controlled optically and the 11.7GHz microwave oscillation was triggered by the irradiation of a light pulse to the positive response region and stopped by the irradiatinn to the negative response region. By tuning the DC-bias condition, the modulation of the microwave oscillation by the optical beam was also obtained. Less
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