提取光栅耦合的高电子迁移率晶体管中的太赫兹辐射

借助于傅立叶光谱仪,在具有耦合光栅的高电子迁移率晶体管中观察到了波长在400um左右的微弱的太赫兹辐射。同时使用了一种调制探测技术,从而使得太赫兹辐射的绝对功率能够被提取计算出来。并且发现器件的太赫兹辐射功率正比于源漏电流,而黑体辐射功率则与器件电功率有密切关系。此外,太赫兹辐射对于源漏偏置电压及栅压的依赖性,说明太赫兹辐射是由加速电子与光栅的相互作用而引起的。     

二维电子气等离激元太赫兹波器件

固态等离激元太赫兹波器件正成为微波毫米波电子器件技术和半导体激光器技术向太赫兹波段发展和融合的重要方向之一。本综述介绍AlGaN/GaN异质结高浓度和高迁移率二维电子气中的等离激元调控、激发及其在太赫兹波探测器、调制器和光源中应用的近期研究进展。通过光栅和太赫兹天线实现自由空间太赫兹波与二维电子气等离激元的耦合,通过太赫兹法布里-珀罗谐振腔进一步调制太赫兹波模式,增强太赫兹波与等离激元的耦合强度。在光栅-谐振腔耦合的二维电子气中验证了场效应栅控的等离激元色散关系,实现了等离激元模式与太赫兹波腔模强耦合产生的等离极化激元模式,演示了太赫兹波的调制和发射。在太赫兹天线耦合二维电子气中实现了等离激元共振与非共振的太赫兹波探测,建立了太赫兹场效应混频探测的物理模型,指导了室温高灵敏度自混频探测器的设计与优化。研究表明,基于非共振等离激元激发可发展形成室温高速高灵敏度的太赫兹探测器及其焦平面阵列技术。然而,固态等离激元的高损耗特性仍是制约基于等离激元共振的高效太赫兹光源和调制器的主要瓶颈。未来的研究重点将围绕高品质因子等离激元谐振腔的构筑,包括固态等离激元物理、等离激元谐振腔边界的调控、新型室温高迁移率二维电子材料的运用和高品质太赫兹谐振腔与等离激元器件的集成等。     

Extraction of terahertz emission from a grating-coupled high-electron-mobility transistor

In a grating-coupled high-electron-mobility transistor,weak terahertz emission with wavelength around 400μm was observed by using a Fourier-transform spectrometer.The absolute terahertz emission power was extracted from a strong background blackbody emission by using a modulation technique.The power of terahertz emission is proportional to the drain-source current,while the power of blackbody emission has a distinct relation with the electrical power.The dependence on the drain-source bias and the gate voltage suggests that the terahertz emission is induced by accelerated electrons interacting with the grating.     

Tunable terahertz plasmon in grating-gate coupled graphene with a resonant cavity

Plasmon modes in graphene can be tuned into resonance with an incident terahertz electromagnetic wave in the range of 1–4 THz by setting a proper gate voltage.By using the finite-difference-time-domain(FDTD)method,we simulate a graphene plasmon device comprising a single-layer graphene,a metallic grating,and a terahertz cavity.The simulations suggest that the terahertz electric field can be enhanced by several times due to the grating–cavity configuration.Due to this near-field enhancement,the maximal absorption of the incident terahertz wave reaches up to about 45%.