Terahertz artificial birefringence device based on periodic chirped grating

Abstract

The invention discloses a terahertz artificial birefringence device based on a periodic chirped grating. According to the terahertz artificial birefringence device, an artificial birefringence effect is formed through etching a submillimeter-scale relief grating structure on the surface of a high-resistance silicon chip, thereby realizing functions of terahertz wave phase shift and polarization state transition. According to the device, a specific period chirped structure is adopted. Not only is periodicity of the grating kept, but also the chirped structure is introduced. Compared with a common periodic grating, the terahertz artificial birefringence device is advantageous in that the birefringence coefficient and the birefringence bandwidth of the device are improved; a high birefringence coefficient which is larger than 0.35, broadband birefringence flatness and a good linear phase shift characteristic are realized in a terahertz waveband; a highest phase shift coefficient reaches deltaphi=1.6pi; and polarization conversion rate exceeds 99% when the terahertz artificial birefringence device is used as a one-half wave plate. Compared with a metal grating and a metal hypersurface structure, the terahertz artificial birefringence device is made of a full dielectric material and greatly improves transmittance of the device; low loss and broad band are realized; and the terahertz artificial birefringence device can be widely used for regulating terahertz wave phase and polarization.

Description

technical field [0001] The invention belongs to the field of terahertz science and technology, and in particular relates to a terahertz artificial birefringence device based on a periodically chirped grating. Background technique [0002] Terahertz wave refers to the frequency between 0.1-10THz (1THz=10 12 THz, corresponding to electromagnetic waves with a wavelength in the range of 3 mm to 30 μm, this band is between microwaves and light waves, and is an intersecting field between electronics and photonics. Due to its special position in the electromagnetic spectrum, terahertz waves have many superior characteristics such as perspective, safety, and high signal-to-noise ratio, and have very important academic and application values ​​in the fields of spectroscopy, imaging, and communication. These terahertz application systems are inseparable from the support of terahertz functional components such as filtering, modulation, phase shifting, and polarization conversion. Pha...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a terahertz artificial birefringent device based on a periodically chirped grating, which solves the problem of terahertz phase delay and polarization conversion devices with small birefringence coefficient, large dispersion, narrow working bandwidth and nonlinear phase delay in the background technology. Key technical issues such as high effect and loss

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