電磁波工学 xiigt_ils.ils.uec.ac.jp/em_wave_lec/denjiha_10.pdf電磁波工学xii 米田仁紀...
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1916 誘導放出 Einstein1924 逆転分布 Tolman
負の吸収 van Vleck1940 吸収観測の可能性 Fabrikant1946 NMRで自然放出確率がQ倍に Purcell1951 負の吸収観測 Ladenburg1954 Maser Gordon, Zeiger, Townes1956 3準位Maser Bloembergen1957 Ruby Maser Kikuchi1960 Ruby Laser Maiman1961 He-Ne laser(1.15mm) Javan1961 Nd:Ca-tungstate laser Johnson, Nassau1962 He-Ne laser (632.8nm) Rigden, White1962 Diode laser Hall, Fenner, Kingsley1964 Nd: YAG laser Geusic, Uitert1965 CO2 laser KuGordon, Labuda1971 FEL Madey1975 Excimer laser, Searles, Ewing, Ault, Tisone,..
Lasersの誕生前後
霜田、矢島、量子エレクトロニクス 裳華房
OUTPUT of THE FIRST LASER IN THE HISTORY (1960)
T.H. Maiman et al.
Flash Lamp Pumped Ruby Laser
The output was unexpectedly
like a random set of pulsed noises
10 ms/div
Graphene transistorsIllustration of the high-speed graphene transistor designed by UCLA researchers led by Xiangfeng Duan. The cylinder across the middle of the transistor is the self-aligning nanowire gate.
Matthias C. Hoffmann et al., Journal of Physics D: Applied Physics 44, 8 (2011) 83001
発生方法
光伝導スイッチ
E r, 𝑡 = −1
4𝜋휀0 𝑉′
−∞
𝑡 3 J ∙ R R
𝑅5−
J
𝑅3𝑑𝑡′𝑑𝑣′
+1
4𝜋휀0 𝑉′
3 J ∙ R R
𝑅4−
J
𝑐𝑅2𝑑𝑣′
+1
4𝜋휀0
1
𝑐2 𝑉′
𝜕𝜕𝑡
J × R × R
𝑅3𝑑𝑣′
Auston switch
THz pulse generation by optical rectification
𝑃𝑡 =
𝑗𝑘
𝜒𝑗𝑘𝐸𝑗𝐸𝑘
𝛻 × 𝛻 × 𝐸 +1
𝑐2
𝛿2
𝛿𝑡2휀𝐸 = −
4𝜋
𝑐2
𝛿2𝑃
𝛿𝑡2
𝐸1 = 𝐸0cos𝜔1𝑡, 𝐸2 = 𝐸0cos𝜔2𝑡
𝑃2𝑛𝑙 = 𝜒2𝐸1𝐸2 = 𝜒2
𝐸02
2cos 𝜔1 − 𝜔2 𝑡 + cos 𝜔1 + 𝜔2 𝑡
n
E(n)
t
E(t)phase
0
∞
𝐸(𝜔)𝑒𝑖𝜔𝑡𝑑𝜔 = 𝐸(𝑡)
n
E(n)
t
E(t)phase
0
∞
𝐸(𝜔)𝑒𝑖𝜔𝑡+𝜙(𝜔)𝑑𝜔 = 𝐸′(𝑡)
f(n)
f(n)
Δ𝜈Δ𝑡~1
𝐹 𝜔 =1
2𝜋 −∞
∞
𝑓(𝑡)𝑒−𝑖𝜔𝑡𝑑𝑡 =𝜏
𝜋
sin𝜔𝜏
𝜔𝜏2t幅の矩形波形のフーリエ変換
T 観測時間範囲
Δt 観測時間分解能
ωmax - ωminスペクトル範囲
Δω スペクトル分解能
L/c = T
フーリエ変換
Temporal domain spectrometry
ΔL/c = Δt
例えば、L=1m, 観測ステップ0.01mmで行えば
Δω ~ 300MHzωmax - ωmin ~ 30THz