Apparatus and methods for generating electromagnetic radiation
地域：
MA
MA Cambridge
摘要
An apparatus includes at least one conductive layer, an electromagnetic (EM) wave source, and an electron source. The conductive layer has a thickness less than 5 nm. The electromagnetic (EM) wave source is in electromagnetic communication with the at least one conductive layer and transmits a first EM wave at a first wavelength in the at least one conductive layer so as to generate a surface plasmon polariton (SPP) field near a surface of the at least one conductive layer. The electron source propagates an electron beam at least partially in the SPP field so as to generate a second EM wave at a second wavelength less than the first wavelength.
說明書
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where F(ω) is the complex spectral distribution, ε0 is the permittivity of free space, zi>0 is the initial pulse position of the backward-propagating pulse, and the frequency dependence of each component is explicitly shown. Subscripts denoting layer have been omitted for convenience. A large confinement factor normally implies a very small group velocity vg (e.g., vg=2×105 m/s for confinement factor n=300 and a substrate of SiO2 of refractive index 1.4446 at free space wavelength 1.5 μm), which can be negligible compared to the speed of free electrons from standard electron microscopes and DC electron guns. Hence, the counter-propagating pulses practically approximate a stationary, standing wave grating.
When the GP pulse duration is large, a simplified form for Equation (12) can be:
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