Development of Highly Directional and Efficient THz Photonic Transmitters
Date Issued
2012
Date
2012
Author(s)
Huang, Yu-Ru
Abstract
Many Terahertz (THz) radiation devices have been created for the reason of upcoming THz applications, e.g., resonant-tunneling diodes (RTDs), photoconductive (PC) switch antennas, uni-traveling-carrier photodiodes (UTC-PDs), traveling-wave photodetector-(TWPD) based photonic transmitters, THz quantum cascade lasers, InP-based high electron mobility transistors and heterojunction bipolar transistors etc. As a THz radiation source, its directivity and efficiency should be of great concern for specific purposes. For instance, a handheld THz probe head needs a highly concentrated THz beam to enhance the sensitivity of instant detections. Low excitation power is critical for on-chip biosensing due to the thermal effects. A highly efficient THz source for such an application is thus eagerly desired. In this dissertation, we have proposed to use the rampart slot array antenna design to achieve highly directional THz radiation patterns without any focusing medium. A 3dB beam width less than 30° in both E and H planes at ~0.9THz was demonstrated by exciting single radiation source. To enhance radiation efficiency and high-frequency performances, we modified the circuit design of the THz photonic transmitter where a grounded coplanar waveguide structure was utilized to collect more resonating waves in the substrate. Besides, a broadband THz excitation was also performed to study the on-chip THz wave propagation, resonance, and radiation phenomena. The good agreement of circuit design and THz wave characteristics shows a great potentiality for the present circuit to be utilized as an on-chip detection device, where phase-sensitive detection could be realized.
We also proposed a fiber-based coherent control system for THz photonic generation. For handheld devices or tabletop systems, combination with an optical fiber is a promising way to save the THz information from environmental disturbances. Long-range communication relies on a fiber-optic communication system as well. Here we utilized a large-mode-area photonic crystal fiber to realize a neat tunable narrow-band THz excitation system with lower hardware cost and higher flexibility. The tunable range was demonstrated from 0.15 to ~3.7 THz. In the future applications, we are convinced that a high-efficiency/low power consuming THz system could benefit from our newly proposed device design and neat THz excitation system.
Subjects
terahertz photonic transmitter
rampart slot array antenna
coplanar waveguide
optoelectronic integrated circuits
optical fiber
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-101-F94941015-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):ec2e4cdec69629d3bc6edb67aee68e4e