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Chapter 07&08 & 09 & 10. PHOTONIC-CRYSTAL OPTICS. 下几页列出重 要的概 念,需掌握. WaVE Transfer Matrix. Scattering Matrix. Airy's formulas. Fabry -Perot Etalon. Bragg Grating. Bloch Modes. Chapter 8. Comments…why?. Comments…integration circuits. 在小空间里控制光场的传播 , 用 于信息交换及应用!.
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PHOTONIC-CRYSTAL OPTICS • 下几页列出重要的概念,需掌握
Comments…integration circuits 在小空间里控制光场的传播,用于信息交换及应用!
Photonic Crystals Metamaterials 尺寸更小,亚波长,<200nm • From a similar consideration
Firstly, from ray optics… • Reflection by mirrors • Correct in microwave frequency
Why?... At microwave • Perfect electric conductor (PEC) • ε = ― • n= j • |r|=1 • Phase change: 0 or π (半波损) • 0: 边界场强极大 • π: 边界场强为零
Dispersion Relation 截止频率f0。f <f0 (波长大时)模式消失,无法传播。在截止频率处,群速度为零,即慢光效应。
Group Velocity c.cosθ c 一种特殊的光学延迟线 θπ/2, 越慢
Field Distributions 正交归一本征模式
Comments • m=1,2,3… • How about m=0? • Infinite field amplitude, not allowed • Cutoff size: d>dc=/2 But coaxial PEC waveguide supports m=0 TEM mode, which in non-cutoff!
Comparing to Section 1 No longer PEC boundary conditions • With field outside the core • With non-zero/pi reflection phase Now Electromagnetic optics
Field Distributions … with EM boundary conditions!
Group Velocity Goos-Hänchenshift 当相位为常数时,v=c.cosθ
Goos-Hänchen shift • Usually… positive and very small, <0.05λ • Could be negative and with large value in left-handed metamaterials • Backward energy flux • Strong dispersion in LHM
GH shift can make a cavity nature_450_397
Input Couplers 尽可能大的交叠积分
Prism & Grating Side Couplers To match the wavevectorm…
Fibers 圆柱对称二维光波导,选择性阅读
Resonator • From waveguide • Spatial confinement of EM waves • select specific frequencies from a signal • To generate stronger EM field intensity • For applications that need strong EM field • Laser • Quantum Physics • ……
Resonator Modes Interference … standing wave …
Similar to 1D waveguides … Smaller d larger vf (uncertainty principle)
As Traveling waves Multiple interference…
Traveling-Wave Resonator 驻波的缺点:场强分布不均匀,例如E~cos(kz)。 Traveling wave? 场强均匀分布,优点: 例如可以充分利用增益介质等。