Modulators for mid-infrared and terahertz light

Abstract

The rise of mid-infrared and terahertz wave technology over the past two decades has led to incredible insights and potential applications for next-generation optoelectronics. Modulators, which control amplitude, phase, and/or polarization of incident light, are widely used in communications, imaging, and sensing and are crucial for further development of technology functioning in the mid-infrared and terahertz frequency regimes. The lack of natural materials with optical responses in these frequency regimes has led to a surge in engineering efforts to create novel devices and architectures for achieving control over the properties of mid-infrared and terahertz radiation. Major efforts in the field have been devoted to studying carrier concentration modulation, liquid crystals, phase-change materials, and micro-electromechanical systems for controlling the light–matter interaction. Although there has been considerable progress in realizing mid-infrared and terahertz modulators, novel approaches are seeking higher modulation speed, more functionality, and miniaturized size. In this perspective, we review the recent advancements of modulators for mid-infrared and terahertz wavelengths. We discuss various modulation mechanisms, along with their relative performance, and consider future architectures to improve upon the current technology for mid-infrared and terahertz modulation.

Recent Progress of Terahertz Spatial Light Modulators: Materials, Principles and Applications

“…Overviews of reconfigurable metamaterials were provided for spectrally or spatially manipulating the intensity, phase and polarization of terahertz waves [ 38 ]. The progress of THz modulators has been summarized in the terahertz band with the main focus on spatially uniform temporal modulation [ 39 , 40 , 41 , 42 ]. Some other reviews pay more attention to applications in single pixel imaging [ 31 ].…”

Mid-infrared all-optical modulators based on an acetylene-filled hollow-core fiber

“…MIR modulators has a wealth of applications, including actively Q-switched laser generation, environmental pollution monitoring, chemical and biosensing, industrial processes control, multispectral thermal imaging, and medical diagnostics of early disease, etc 1,2,6 . To date, most of the MIR modulators are established on waveguide-integrated or free-space platforms [7][8] . On-chip integrated devices have attracted great attention due to it s flexible waveguide geometry and complementary metal oxide semiconductor compatibility.…”

Design and analysis of a high-performance terahertz photoconductive modulator enhanced by photonic crystal cavity

“…THz modulators based on tuning the conductivity of a semiconductor with an external electrical signal or optical power are one of the most desirable structures which have received considerable attention [22,23]. In this mechanism, modulating of free carrier density changes the conductivity of the substance.…”