Nanoplasmonics enhanced terahertz sources

Abstract

Arrayed hexagonal metal nanostructures are used to maximize the local current density while providing effective thermal management at the nanoscale, thereby allowing for increased emission from photoconductive terahertz (THz) sources. The THz emission field amplitude was increased by 60% above that of a commercial THz photoconductive antenna, even though the hexagonal nanostructured device had 75% of the bias voltage. The arrayed hexagonal outperforms our previously investigated strip array nanoplasmonic structure by providing stronger localization of the current density near the metal surface with an operating bandwidth of 2.6 THz. This approach is promising to achieve efficient THz sources.

Nanostructure‐Enhanced Photoconductive Terahertz Emission and Detection

“…Reproduced with permission. [51] Copyright 2012, Optical Society of America. c) Schematic of the photoconductive antenna with a transferred LT-GaAs layer and nanodisk arrays and its peak-to-peak radiated electric field in comparison with similar photoconductive antennas without the transferred LT-GaAs layer and nanodisk arrays.…”

Enhancement of terahertz photoconductive antenna operation by optical nanoantennas

“…Recombination of thermal and photoinduced carriers in subsequent cycles of charge carriers generation prevents the stable operation of the photoconductive antenna. Recently it has been shown that the optical NAs embedded in a THz photoconductive antenna can improve the thermal stability of the latter due to the large thermal conductivity of metals . For example, gold has the thermal conductivity of 3.14 W/cm· K that is six times larger than the thermal conductivity of GaAs (0.55 W/cm· K).…”

“…Usually, this amount is rather small, taking into account the high values of the semiconductor refractive index at optical frequencies, leading to a high reflection coefficient. Moreover, the effectiveness of conventional photoconductive antennas is limited by low drift velocities of the photoinduced charge carriers in semiconductor substrates and material breakdown threshold .…”

Photoconductive Terahertz Near-Field Detector with a Hybrid Nanoantenna Array Cavity

“…The use of nanostructures for enhancing optical absorption has enabled optically thin semiconductor photonic devices for a wide range of applications, including high-efficiency, lowcost solar cells (1,2) and photo-detectors based on two-dimensional (2D) atomically thin crystals (3). Nanostructures can also make an impact on development of photoconductive (PC) terahertz (THz) emitters and detectors (4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Substantial increase in the conversion efficiency has been achieved in PC THz emitters by coupling the photo-excitation to localized plasmonic modes supported by nanostructured electrodes (5)(6)(7).…”