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Apparatus and methods for generating electromagnetic radiation

專利號
US10785858B2
公開日期
2020-09-22
申請人
Massachusetts Institute of Technology（US MA Cambridge）
發(fā)明人
Ido Kaminer; Liang Jie Wong; Ognjen Ilic; Yichen Shen; John Joannopoulos; Marin Soljacic
IPC分類
H05G2/00
技術(shù)領(lǐng)域
graphene,electron,in,radiation,spp,gp,electrons,can,plasmon,beam
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

? v f ≈ 10 6 ? m s )
are considered possible, even in relatively large sheets of graphene (10 μm and more). On the other hand, plasmons in graphene can have an exceptionally slow phase velocity, down to a few hundred times slower than the speed of light. Consequently, velocity matching between charge carriers and plasmons can be possible, allowing the emission of GPs from electrical excitations (hot carriers) at very high rates. This can pave the way to new devices utilizing the ?E on the nanoscale, a prospect made even more attractive by the dynamic tunability of the Fermi level of graphene. For a wide range of parameters, the emission rate of GPs can be significantly higher than the rates previously found for photons or phonons, suggesting that taking advantage of the ?E allows near-perfect energy conversion from electrical energy to plasmons.

In addition, contrary to expectations, plasmons can be created at energies above 2Ef—thus exceeding energies attainable by photon emission—resulting in a plasmon spectrum that can extend from terahertz to near infrared frequencies and possibly into the visible range.

Furthermore, tuning the Fermi energy by external voltage can control the parameters (direction and frequency) of enhanced emission. This tunability also reveals regimes of backward GP emission, and regimes of forward GP emission with low angular spread; emphasizing the uniqueness of ?E from hot carriers flowing in graphene.

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