Monolithic Patch-Antenna THz Lasers with Extremely Low Beam Divergence and Polarization Control

Abstract

Arrays of patch antennas have impacted modern telecommunications in the RF range significantly, owing to their versatility in tailoring the properties of the emitted radiation such as beam width and polarization, along with their ease of fabrication. At higher frequencies, in the terahertz (THz) range, there is a pressing need for a similar monolithic platform to realize and enable the advanced functionalities available in the RF technology. This platform would benefit a wide variety of fields such as astronomy, spectroscopy, wireless communications, and imaging. Here, we demonstrate THz lasers made of arrays of 10 × 10 patch antenna microcavities that provide up to 25 mW output power with robust single mode frequency and spatial mode. This device architecture leads to an unprecedented beam divergence, better than 2° × 2°, which depends only on the number of resonators. This allows to functionalize the device while preserving a high quality far-field pattern. By interconnecting the symmetric square microcavities with narrow plasmonic wires along one direction, we introduce an asymmetry into the originally degenerate and cross-polarized TM01 and TM10 modes, leading to a precise control of the resonant frequency detuning between the TM modes. This feature allows devices to be designed that radiate with any coherent polarization states from linear to circular. Large-scale full-wave simulations of the emission from entire arrays support our experimental results. Our platform provides a solution to finally achieve monolithic terahertz emitters with advanced integrated functionalities such as active beam steering and polarization control.

Recent Advances of 5G Technology Based on Patch Antenna: A Literature Review

“…Various operations can be performed on patch antennas due to the integration of RF modules, making it more functional and effective than ever before. For example, with a use of MEMS switches and bias network in patch antennas, switchable slots that work at several frequencies with acceptable return losses and directivities are achieved [47]. Another approach is to place RFIC inside the inner cavity of antennas-in-package (AiP) which increases bandwidth by arranging ground vias appropriately thus improving overall performance [48].…”

Relative phase locking of a terahertz laser system configured with a frequency comb and a single-mode laser

“… – 18 Highly stabilized THz radiation sources are of great importance for the various applications mentioned above. Among different THz radiation sources, the electrically pumped THz quantum cascade laser (QCL), showing high output power, 19 wide emission frequency range, 20 , 21 high operation temperature, 22 – 24 high-quality far-field beam, 25 , 26 and narrow intrinsic linewidth, 27 is an ideal candidate for high-precision frequency comb operation 28 , 29 . Although the intrinsic linewidth of THz QCLs is narrow, the practical devices normally show broad linewidths due to the disturbances such as temperature drift, current variation, optical feedback and other environmental noises.…”