1996 Fiscal Year Annual Research Report

超短光パルス励起による新型高温超伝導テラヘルツ波発振器の開発

Research Project

Project/Area Number	08405028
Research Category	Grant-in-Aid for Scientific Research (A)
Research Institution	Osaka University
Principal Investigator	萩行正憲大阪大学, 超伝導エレクトロニクス研究センサー, 教授 (10144429)
Co-Investigator(Kenkyū-buntansha)	村上博成大阪大学, 工学部, 助手 (30219901) 青木亮三大阪大学, 工学部, 教授 (70037175)
Keywords	高温超伝導体 / 超高速光応答 / テラヘルツ波 / 超伝導発振器 / フェムト秒レーザー / 超短レーザーパルス / 非平衡超伝導 / 磁束
Research Abstract	本年度は、1.テラヘルツ波放射効率増大のための素子構造及びシステムの最適化、2.テラヘルツ波の時間領域波形を支配している非平衡超伝導状態での準粒子の超高速ダイナミクスの解析、3.磁場下での放射特性、について研究を行った。その結果 1.(a)超伝導薄膜の膜質向上、(b)素子膜厚の最適化、(c)アンテナ構造として初期のダイポール型にかえてボウタイ型の採用、(d)集光システムにMgO超半球レンズを付加等の改良を行った結果,初期の出力に比べて100倍の出力が得られ、超伝導発振器としては異例の0.5μWの電磁波を空間に放射できるようになった。 2.放射波形をレート方程式で解析することにより、高温超伝導体では、光により励起された準粒子が0.5ピコ秒以下の短時間で再結合するということがわかった。また、この再結合時間は超伝導転移温度附近で発散的に増大することが明らかになった。この結果は、高温超伝導機構と密接に関連していると予想される。 3.外部磁場を印加することにより,バイアス電流を流さないでもテラヘルツ波が発生するという興味ある現象を見出した。さらに、外部磁場を取り去った後もテラヘルツ波が発生することから、磁束捕獲に伴う超伝導電流の光変調がその原因であることが明らかとなった。この現象を利用した超伝導光メモリーを提案した。

Research Products
(19 results)

All Other

All Publications (19 results)

[Publications] M.Hangyo: "Terahertz Radiation from Superconducting YBa_2Cu_3O_<7-δ> Thin Films Excited by Femtosecond Optical Pulses" Applied Physics Letters. 69・14. 2122-2124 (1996)
[Publications] M.Tonouchi: "Ultrashort Electromagnetic Pulse Radiation from YBCO Thin Films Excited by Femtosecond Optical Pulse" Japan Journal of Applied physics. 35・5A. 2624-2632 (1996)
[Publications] M.Tani: "Enhanced Sub-Picosecond Electromagnetic Radiation from YBa_2Cu_3O_<7-δ> Thin-Film Bow-Tie Antennas Excited with Femtoseconds Laser Pulses" Japan Journal of Applied physics. 35・9B. L1184-L1187 (1996)
[Publications] M.Hangyo: "Subpicosecond Electromagnetic Pulse Generation from High-T_c Superconducting Thin Films by Femtosecond Laser Pulse Excitation" Czechoslovak Journal of Physics. 46・Suppl.S5. 2767-2768 (1996)
[Publications] M.Tonouchi: "Novel Dynamic Diagnosis of Femtosecond Time-Transient Nonequilibrim State in Optically Excited YBCO Thin Films" Czechoslovak Journal of Physics. 46・Suppl.S5. 1095-1096 (1996)
[Publications] T.Nagashima: "Interplane Electromagnetic Response of a-Axis Oriented YBCO Thin Films in the Millimeter-Wave Region and Its Dependence on Weak Magnetic Field" Czechoslovak Journal of Physics. 46・Suppl.S2. 1097-1098 (1996)
[Publications] T.Nagashima: "Inter-Plane Electromagnetic Response of a -Axis Oriented YBCO Films in the Millimeter-Wave Region" Physica C. 271. 365-372 (1996)
[Publications] M.Tonouchi: "Terahertz Emission Syudy of Femtosecond Time-Transient Nonequilibrium State in Optecally Excited YBa_2Cu_3O_<7-δ> Thin Films" Japan Journal of Applied physics. 35・12A. L1578-L1581 (1996)
[Publications] M.Tonouchi: "Novel Terahertz Radiation form Flux-Trapped YBa_2Cu_3O_<7-δ> Thin-Films Excited by Femtosecond Laser Pulses" Japan Journal of Applied physics. 36・2A. L93-L95 (1997)
[Publications] M.Tani: "Emission Properties of YBa_2Cu_3O_<7-δ> Film Photoswitches as Terahertz Radiation Sources" Japan Journal of Applied physics. 36・3B. (1997)
[Publications] M.Hangyo: "YBCO Thin Film Teraherts Radiator Excited by Femtosecond Laser Pulse" Proc.16th Int.Cryogenic Eng.Conf./Int.Cryogenic Mat.Conf.(ICEC16/ICMC). (出版予定).
[Publications] N.Wada: "YBCO Thin Film Bow-Tie Antenna for Terahertz Radiator" Proc.16th Int.Cryogenic Eng.Conf./Int.Cryogenic Mat.Conf.(ICEC16/ICMC). (出版予定).
[Publications] M.Tonouchi: "Characterization of Femtosecond Time-Transient Nonequilibrium State in YBCO Thin Films" Proc.16th Int.Cryogenic Eng.Conf./Int.Cryogenic Mat.Conf.(ICEC16/ICMC). (出版予定).
[Publications] M.Hangyo: "THz Emission from High-T_c Superconductors by Optical Pulse Excitaiton" IEEE Transaction of Applied Superconductivity. (出版予定).
[Publications] M.Hangyo: "Ultrafast Photoexcited Quasiparticle Dynamics in YBCO Films Observed by THz Emission" IEEE Transaction of Applied Superconductivity. (出版予定).
[Publications] M.Tonouchi: "Enhanced THz Radiation from YBCO Thin Film Bow-Tie Antennas with Hyper-Hemispherical MgO Lens" IEEE Transaction of Applied Superconductivity. (出版予定).
[Publications] M.Hangyo: "Ultrashort Electromagnetic Pulse Radiation from YBCO Thin Films by Femtosecond Laser Pulse Irradiation" Advances in Superconductivity IX. (出版予定).
[Publications] M.Hangyo: "Terahertz Radiation from High-T_c Superconducting Films Excited by Femtosecond Optical Pulses" SPIE Proceedings. 2999(出版予定).
[Publications] M.Hangyo: "Ultrafast Optical Response and Terahertz Radiation from High-T_c Superconductor" IEICE Trans.Commun.(出版予定).

1996 Fiscal Year Annual Research Report

超短光パルス励起による新型高温超伝導テラヘルツ波発振器の開発

Principal Investigator

萩行 正憲 大阪大学, 超伝導エレクトロニクス研究センサー, 教授 (10144429)

Research Products

[Publications] M.Hangyo: "Terahertz Radiation from Superconducting YBa_2Cu_3O_<7-δ> Thin Films Excited by Femtosecond Optical Pulses" Applied Physics Letters. 69・14. 2122-2124 (1996)

[Publications] M.Tonouchi: "Ultrashort Electromagnetic Pulse Radiation from YBCO Thin Films Excited by Femtosecond Optical Pulse" Japan Journal of Applied physics. 35・5A. 2624-2632 (1996)

[Publications] M.Tani: "Enhanced Sub-Picosecond Electromagnetic Radiation from YBa_2Cu_3O_<7-δ> Thin-Film Bow-Tie Antennas Excited with Femtoseconds Laser Pulses" Japan Journal of Applied physics. 35・9B. L1184-L1187 (1996)

[Publications] M.Hangyo: "Subpicosecond Electromagnetic Pulse Generation from High-T_c Superconducting Thin Films by Femtosecond Laser Pulse Excitation" Czechoslovak Journal of Physics. 46・Suppl.S5. 2767-2768 (1996)

[Publications] M.Tonouchi: "Novel Dynamic Diagnosis of Femtosecond Time-Transient Nonequilibrim State in Optically Excited YBCO Thin Films" Czechoslovak Journal of Physics. 46・Suppl.S5. 1095-1096 (1996)

[Publications] T.Nagashima: "Interplane Electromagnetic Response of a-Axis Oriented YBCO Thin Films in the Millimeter-Wave Region and Its Dependence on Weak Magnetic Field" Czechoslovak Journal of Physics. 46・Suppl.S2. 1097-1098 (1996)

[Publications] T.Nagashima: "Inter-Plane Electromagnetic Response of a -Axis Oriented YBCO Films in the Millimeter-Wave Region" Physica C. 271. 365-372 (1996)

[Publications] M.Tonouchi: "Terahertz Emission Syudy of Femtosecond Time-Transient Nonequilibrium State in Optecally Excited YBa_2Cu_3O_<7-δ> Thin Films" Japan Journal of Applied physics. 35・12A. L1578-L1581 (1996)

[Publications] M.Tonouchi: "Novel Terahertz Radiation form Flux-Trapped YBa_2Cu_3O_<7-δ> Thin-Films Excited by Femtosecond Laser Pulses" Japan Journal of Applied physics. 36・2A. L93-L95 (1997)

[Publications] M.Tani: "Emission Properties of YBa_2Cu_3O_<7-δ> Film Photoswitches as Terahertz Radiation Sources" Japan Journal of Applied physics. 36・3B. (1997)

[Publications] M.Hangyo: "YBCO Thin Film Teraherts Radiator Excited by Femtosecond Laser Pulse" Proc.16th Int.Cryogenic Eng.Conf./Int.Cryogenic Mat.Conf.(ICEC16/ICMC). (出版予定).

[Publications] N.Wada: "YBCO Thin Film Bow-Tie Antenna for Terahertz Radiator" Proc.16th Int.Cryogenic Eng.Conf./Int.Cryogenic Mat.Conf.(ICEC16/ICMC). (出版予定).

[Publications] M.Tonouchi: "Characterization of Femtosecond Time-Transient Nonequilibrium State in YBCO Thin Films" Proc.16th Int.Cryogenic Eng.Conf./Int.Cryogenic Mat.Conf.(ICEC16/ICMC). (出版予定).

[Publications] M.Hangyo: "THz Emission from High-T_c Superconductors by Optical Pulse Excitaiton" IEEE Transaction of Applied Superconductivity. (出版予定).

[Publications] M.Hangyo: "Ultrafast Photoexcited Quasiparticle Dynamics in YBCO Films Observed by THz Emission" IEEE Transaction of Applied Superconductivity. (出版予定).

[Publications] M.Tonouchi: "Enhanced THz Radiation from YBCO Thin Film Bow-Tie Antennas with Hyper-Hemispherical MgO Lens" IEEE Transaction of Applied Superconductivity. (出版予定).

[Publications] M.Hangyo: "Ultrashort Electromagnetic Pulse Radiation from YBCO Thin Films by Femtosecond Laser Pulse Irradiation" Advances in Superconductivity IX. (出版予定).

[Publications] M.Hangyo: "Terahertz Radiation from High-T_c Superconducting Films Excited by Femtosecond Optical Pulses" SPIE Proceedings. 2999(出版予定).

[Publications] M.Hangyo: "Ultrafast Optical Response and Terahertz Radiation from High-T_c Superconductor" IEICE Trans.Commun.(出版予定).

萩行正憲大阪大学, 超伝導エレクトロニクス研究センサー, 教授 (10144429)