Terahertz (THz) frequencies of the electromagnetic spectrum have been underutilized when compared to neighboring microwave and infrared frequencies, largely due to the difficulties controlling and detecting these fields. In a step toward gaining control over THz frequencies, my advisor Dr. Yun-Shik Lee’s group experimentally demonstrated optical-pulse THz-control over a plasmonic...
This dissertation presents nonlinear terahertz (THz) properties of carbon nanomaterials investigated by time-resolved high-field THz spectroscopy. In order to determine THz characteristics of nanomaterials, we performed THz power spectrum measurement, THz raster imaging, THz time-domain spectroscopy (THz-TDS) and time-resolved pump-probe experiment on two different types of single layer graphene and...
This thesis will cover work that I have completed relating to the field of terahertz (THz) science. My work has consisted of generating tunable, narrowband THz pulses in a table-top optical setup and using both narrow- and broadband THz pulses to study various material systems. Broadband THz pulses were used...
In this thesis, I present studies in the field of terahertz [THz] spectroscopy. It covers both the generation and detection of ultra-fast broadband THz pulses, as well as the transmission properties of vertically grown multi-walled carbon nanotube forests [MWCNTs]. We have found that these vertically grown MWCNTs respond strongly to...
Plasmon induced transparency (PIT) describes a spectral response of coupled plasmonic resonators in that coupling between bright and dark modes leads to a destructive interference resulting in a narrow transparency window. This process has many applications in material characterization and advanced optical devices such as slow light devices or ultrafast...
Gallium arsenide shows excellent promise for terahertz generation using mid infrared.
This is for two reasons. First, the indices of refraction for the terahertz (nTHz=3.61 at 1 THz) and mid infrared (nopt=3.431 at 2 μm) are close allowing a long interaction length.
Second, the linear absorption is low at terahertz...
High field time-domain terahertz spectroscopy (TDS) is used to determine the time dependent transmission and the time-delay and optical-power dependent conductivity of a wafer of gallium arsenide (GaAs). Gallium arsenide is a direct band-gap semiconductor and has potential as a computer processor component. Analysis of the transmission of terahertz (THz)...
Semiconductors serve an integral role in our technologies today. However, with new advancements in ultra-fast electronics, we are approaching the fundamental speed limits of traditional silicon-based semiconductors. Silicon-based semiconductors typically exhibit photocarrier dynamics in nanosecond timescales. Transition metal dichalcogenides (TMDs) are 2D materials shown to exhibit photocarrier dynamics in picosecond...
In this thesis I studied several THz components that can be used for potential THz
technology. THz waves were generated in nonlinear medium via optical rectification
of femtosecond optical pulses. Utilizing the phase matching condition between the
optical and THz waves in a ZnTe crystal, single-cycle broad-band THz pulses were...