Space-charge modulation in vacuum microdiodes at THz frequencies

Tunability of the THz space-charge modulation in a vacuum microdiode

Under certain conditions, space-charge limited emission in vacuum microdiodes manifests as clearly defined bunches of charge with a regular size and interval. The frequency corresponding to this interval is in the Terahertz range. In this computational study it is demonstrated that, for a range of parameters, conducive to generating THz frequency oscillations, the frequency is dependant only on the cold cathode electric field and on the emitter area. For a planar micro-diode of given dimension, the modulation frequency can be easily tuned simply by varying the applied potential. Simulations of…

Terahertz pulsed photogenerated current in microdiodes at room temperature

Space-charge modulation of the current in a vacuum diode under photoemission leads to the formation of beamlets with time periodicity corresponding to THz frequencies. We investigate the effect of the emitter temperature and internal space-charge forces on the formation and persistence of the beamlets. We find that temperature effects are most important for beam degradation at low values of the applied electric field, whereas at higher fields intra-beamlet space-charge forces are dominant. The current modulation is most robust when there is only one beamlet present in the diode gap at a time, …

Synchronization in arrays of vacuum microdiodes

Simulations have shown that space-charge effects can lead to regular modulation of photoemitted beams in vacuum diodes with gap sizes on the order of 1 micron and accelerating voltage on the order of 1V. These modulations are in the THz regime and can be tuned by simply changing the emitter area or accelerating vacuum field. The average current in the diode corresponds to the Child-Langmuir current, but the amplitude of the oscillations is affected by various factors. Given the small size and voltage of the system, the maximum radiated AC power is expected to be small. In this work we show tha…

激光光丝阵列太赫兹发射的频率调制

Frequency modulation of THz emission from a laser filament array

本研究采用行波天线模型理论研究横向与纵向激光光丝阵列的太赫兹发射，揭示周期性横向阵列通过干涉效应将单丝宽带频谱调制为离散频率谱，为太赫兹信号频率调控提供了新途径。

径向和纵向射频场的时空太赫兹发射：由共传播的啁啾激光在磁化不规则等离子体中产生

Spatiotemporal THz emission from radial and longitudinal wakefields by copropagating chirped lasers in magnetized rippled plasma

研究通过FBPIC模拟探讨了共传播啁啾激光脉冲在磁化不规则等离子体中激发径向和纵向射频场的时空演化及其在太赫兹辐射生成中的作用，发现啁啾、脉冲持续时间和等离子体密度显著影响射频场振幅和相干性。