Abstract
A diffractive grating is a well-known optical component and is extensively used in many applications. This research work explores application of the diffractive grating in a photoconductive antenna (PCA) of a terahertz time domain spectroscopy (THz-TDS) system, by utilizing benefits of a sub-wavelength grating structure. The grating PCA structure was modeled and simulated by COMSOL Multiphysics software (COMSOL, Inc., Burlington, MA, USA). Performance of the proposed PCA design is studied in terms of its induced photocurrent. The effects of geometrical parameters of the grating are also investigated and analyzed through its optical and electrical responses. Thanks to the increase in absorption of the incident laser’s electric field, the simulation results show a 63% increment of the induced photocurrent in the grating PCA, compared with the conventional planar PCA.
Highlights
A grating is a periodic array of lines, slits, grooves, or other variations that split and diffract light into several beams travelling in different directions
We explore a new application of an incorporating its structure in a photoconductive antenna (PCA)
Theeffective effectiveindex index isisaffected affectedby bythe thegrating gratingparameters, parameters,the thepolarization polarizationofofthe theincident incidentlight, light,and andthe therefractive refractiveindex index ofofthe thesurrounding surroundingmedium
Summary
A grating is a periodic array of lines, slits, grooves, or other variations that split and diffract light into several beams travelling in different directions. The optical properties, including its refractive index, of a subwavelength grating could be engineered by varying grating parameters [7,8]. As a result, these grating were used as an anti-reflection surface, a polarization-selective device, and a guided-mode resonance filter [9]. We explore a new application of an anti-reflective subwavelength grating by photovoltaic devices, such as solar cell [10,11,12]. Of a terahertz time domain spectroscopy anti-reflective subwavelength grating by incorporating its structure in a photoconductive antenna (THz-TDS).
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