Abstract
Photoconductive antenna (PCA), as the most widely used emitter
(or detector) in Terahertz time-domain spectroscopy (TDS) system, virtually
acts as a semiconductor switch, whose electrical conductivity controlled by
pump light. At the same time, the heat caused by the pump light and the
electrical bias will be stacked in a tiny area. Inevitably, the thermal effects,
which may reduce the performance of PCA and the operational lifetime of
device, need to be considered, especially for that generated by a compact
package fiber-pigtailed photoconductive antenna. Nonetheless, there still
lacks of relevant reports about real-time temperature monitoring for PCA.
This paper proposes a method to obtain the temperature information by
observing the temperature dependent frequency drifting of radiation
spectroscopy. In other words, it converts the temperature information via
analyzing the radiation spectrum of the conventional TDS system. In this
work, we simulate a design of meta-atom-loaded PCA with indium
antimonide (InSb). As a kind of temperature-dependent permittivity of the
semiconductor, InSb is stuffed into the gap of split-ring resonator (SRR).
When the temperature increases from 300K to 380 K, the resonance
frequency shifts from 0.582THz to 0.678THz (a shift more than 16%),
calculated by the commercial software-CST. The significant blue shift is
caused by the SRR loading temperature sensitive materials, well analyzed
by the LC resonant circuit model. Then, one can clearly obtain the actual
antenna temperature from the radiation spectrum through the relationship
between temperature and resonance frequency. Always, this simply method
could be applied to shift the peak frequency of spectrum for various
applications.
