Active terahertz time differentiator using piezoelectric micromachined ultrasonic transducer array

Abstract

The rapid growth of information technology is closely linked to our ability to modulate and demodulate a signal, whether in the frequency or in the time domain. Recent demonstrations of terahertz (THz) modulation involve active semiconductor metamaterial surfaces or use of a grating-based micromirror for frequency offset tuning. However, a wideband and active differentiator in the THz frequency band is yet to be demonstrated. Here, we propose a simple method to differentiate a THz pulse by inducing tiny phase changes on the THz beam path using a piezoelectric micromachined ultrasonic transducer array. We precisely demonstrate that the modulated THz signal detected after the piezoelectric device is proportional to the first-order derivative of the THz pulse. The proposed technique will be able to support a wide range of THz applications, such as peak detection schemes for telecommunication systems.

Reconfigurable terahertz metamaterials: From fundamental principles to advanced 6G applications

“…Microelectromechanical system (MEMS) technology enables micro/nanoscale mechanical manipulation, which is suitable for meta-atom construction in the THz region, bringing various applications in THz functional devices. The reconfigurable MEMS metamaterials can be further classified by their actuator mechanisms, such as piezoelectric ( Willatzen and Christensen, 2014 ; Amirkhan et al., 2020 ; Le et al., 2022 ), electrothermal ( Lee and Wu, 2005 ; Lee and Yeh, 2005 ; Lee, 2005 ; Lee, 2006 ; Lee, 2007 ; Pitchappa et al., 2017 ), and electrostatic ( Pitchappa et al., 2015a , 2015b , 2015c , 2016a , 2016c ; Shih et al., 2017 ) ( Pitchappa et al., 2021a , 2021b ), and so on ( Lee et al., 2005 ; Lee, 2005 ; Yeh et al., 2006 ). Combining with metamaterial resonator designs, the deformed structures can effectively modify the electromagnetic field distribution inside the resonators.…”

“…Microelectromechanical system (MEMS) technology enables micro/nanoscale mechanical manipulation, which is suitable for meta-atom construction in the THz region, bringing various applications in THz functional devices. The reconfigurable MEMS metamaterials can be further classified by their actuator mechanisms, such as piezoelectric (Willatzen and Christensen, 2014;Amirkhan et al, 2020;Le et al, 2022), electrothermal Lee, 2005;Lee, 2006;Lee, 2007;Pitchappa et al, 2017), and electrostatic (Pitchappa et al, 2015a(Pitchappa et al, , 2015b(Pitchappa et al, , 2015c(Pitchappa et al, , 2016a(Pitchappa et al, , 2016cShih et al, 2017)…”

Time‐Domain Integration of Broadband Terahertz Pulses in a Tapered Two‐Wire Waveguide

“…Additionally, a more recent work has showed that the phase‐modulation induced by a piezoelectric micromachined device onto a THz pulse could lead to its time differentiation. [ 38 ] We note that, in both cases, the subwavelength feature of the employed devices is the key aspect allowing for a broadband operation. Nevertheless, such solutions have been implemented in a free space configuration, which makes difficult to realize full, compact and portable THz systems.…”

A Nonlinear Pulse Shaping Method Using Resonant Piezoelectric MEMS Devices

“…ultrasonic transducers (MUTs), and that new applications are enabled thanks to their properties. For example, it has been shown that PMUTs can act as an active terahertz time differentiator [11][12][13], in which case the periodic displacement of the membrane is of interest to affect the terahertz signal.…”