Abstract
We report the generation mechanism associated with nano-grating electrode photomixers fabricated on Fe-doped InGaAsP substrates. Two different emitter designs incorporating nano-gratings coupled to the same broadband antenna were characterized in a continuous-wave terahertz (THz) frequency system employing telecommunications wavelength lasers for generation and coherent detection. The current-voltage characteristics and THz emission bandwidth of the emitters is compared for different bias polarities and optical polarisations. The THz output from the emitters is also mapped as a function of the position of the laser excitation spot for both continuous-wave and pulsed excitation. This mapping, together with full-wave simulations of the structures, confirms the generation mechanism to be due to an enhanced optical electric field at the grating tips resulting in increased optical absorption, coinciding with a concentration of the electrostatic field.
Highlights
The development of terahertz (THz) frequency technologies has received extensive interest over the last decade, for the study of fundamental science [1,2,3], and for applications including biomedical imaging [4], drug sensing [5], non-destructive testing [5], security screening [6] and gas spectroscopy [7]
We report the generation mechanism associated with nano-grating electrode photomixers fabricated on Fe-doped InGaAsP substrates
This mapping, together with full-wave simulations of the structures, confirms the generation mechanism to be due to an enhanced optical electric field at the grating tips resulting in increased optical absorption, coinciding with a concentration of the electrostatic field
Summary
The development of terahertz (THz) frequency technologies has received extensive interest over the last decade, for the study of fundamental science [1,2,3], and for applications including biomedical imaging [4], drug sensing [5], non-destructive testing [5], security screening [6] and gas spectroscopy [7].
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