光致动态可调太赫兹超材料吸收器

Photoinduced dynamically tunable terahertz metamaterial absorber

设计了一种具有偏振不敏感和广角吸收的光激发可切换单/双波段太赫兹超材料吸收器.通过调制嵌入谐振器中的光敏砷化镓的电导率实现功能切换,并提取不同砷化镓电导率下的表面电流,对超材料吸收器的吸收机理进行了物理解释.结果表明,该吸收器可以实现从0.568和1.442 THz的双波段吸收(吸收率为99.08%和99.56%)到0.731 THz的单波段吸收(吸收率为95.43%)的切换.该器件强度调制深度为61.4%,频率调谐带宽为60.6%,可制作太赫兹频段的强度调制器和频率选择吸收器.此外,所提出的吸收器对横电(TE)和横磁(TM)偏振波都具有与偏振无关的广角吸收.可调谐超材料吸收器的实现为成熟的半导体技术以及有源太赫兹调制器和开关的潜在应用提供了机会.

A photoexcited switchable single-band/dual-band terahertz metamaterial absorber with polarization-insensitive and wide-angle absorption is reported.The function switching is realized by modulating the conductivity of the photosensitive GaAs embedded in the resonator,and the surface currents at different GaAs conductivities are extracted to physically explain the absorption mechanism of the metamaterial absorber.The results show that the absorber can realize switching from dual-band absorption at 0.568 and 1.442 THz with 99.08%and 99.56%absorptivity,respectively,to a shift single-band absorption at 0.731 THz with 95.43%absorptivity.The device has an intensity modulation depth of 61.4%and a frequency tuning bandwidth of 60.6%.With these values,the device can be used to fabricate intensity modulators and frequency-selective absorbers in the terahertz band.In addition,the proposed absorber exhibits polarization-independent and wide-angle absorption for transverse electric(TE)and transverse magnetic(TM)polarization waves.The realization of tunable metamaterial absorbers offers opportunities for mature semiconductor technologies and potential applications in active terahertz modulators and switchers.