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Proceedings ArticleDOI

Resonant cavities based on substrateless dielectric waveguide platform for terahertz integrated systems

TL;DR: In this paper , a disk resonator and a photonic crystal cavity based on a sub-strateless dielectric waveguide platform are proposed for terahertz applications.
Abstract: In the past two decades, terahertz technology has been steadily improved with a wide range of scientific studies to develop terahertz applications. Recently, a substrateless dielec-tric waveguide platform based on effective medium has been proposed. Waveguiding on this silicon-based platform can be realized with low loss and low dispersion. One important series of components for this platform includes resonant cavities of different characteristics that are crucial for terahertz integrated systems. In this article, we present one design of a disk resonator, and one design of a photonic crystal cavity based on this sub-strateless dielectric waveguide platform. These cavities operate within the frequency range of 220–330 GHz. The simulation and measurement results of these resonant cavities show a strong resonant behavior, with a resonance Q-factor that can be tuned. These cavities can be employed in various terahertz applications including sensing, switching, and modulation.
References
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Journal ArticleDOI
B. B. Hu1, Martin C. Nuss1
TL;DR: This work presents what is to their knowledge the first imaging system based on optoelectronic terahertz time-domain spectroscopy, and demonstrates applications to package inspection and chemical content mapping in biological objects.
Abstract: We present what is to our knowledge the first imaging system based on optoelectronic terahertz time-domain spectroscopy Terahertz time-domain waveforms are downconverted from the terahertz to the kilohertz frequency range, and the waveform for each pixel is frequency analyzed in real time with a digital signal processor to extract compositional information at that point We demonstrate applications to package inspection and chemical content mapping in biological objects

1,628 citations

Journal ArticleDOI
TL;DR: In this paper, the state-of-the-art technologies on photonics-based terahertz communications are compared with competing technologies based on electronics and free-space optical communications.
Abstract: This Review covers the state-of-the-art technologies on photonics-based terahertz communications, which are compared with competing technologies based on electronics and free-space optical communications. Future prospects and challenges are also discussed. Almost 15 years have passed since the initial demonstrations of terahertz (THz) wireless communications were made using both pulsed and continuous waves. THz technologies are attracting great interest and are expected to meet the ever-increasing demand for high-capacity wireless communications. Here, we review the latest trends in THz communications research, focusing on how photonics technologies have played a key role in the development of first-age THz communication systems. We also provide a comparison with other competitive technologies, such as THz transceivers enabled by electronic devices as well as free-space lightwave communications.

1,238 citations

Journal ArticleDOI
TL;DR: This work demonstrates 0.8-dB/cm transmission loss for a single-mode, strip Si/SiO(2) waveguide with submicrometer cross-sectional dimensions, which is to their knowledge the smallest reported lost for a high-index-difference system such as a Si/ SiO( 2) strip waveguide.
Abstract: We demonstrate 0.8-dB/cm transmission loss for a single-mode, strip Si/SiO(2) waveguide with submicrometer cross-sectional dimensions. We compare the conventional waveguide-fabrication method with two smoothing technologies that we have developed, oxidation smoothing and anisotropic etching. We observe significant reduction of sidewall roughness with our smoothing technologies, which directly results in reduced scattering losses. The rapid increase in the scattering losses as the waveguide dimension is miniaturized, as seen in conventionally fabricated waveguides, is effectively suppressed in the waveguides made with our smoothing technologies. In the oxidation smoothing case, the loss is reduced from 32 dB/cm for the conventional fabrication method to 0.8 dB/cm for the single-mode waveguide width of 0.5 microm . This is to our knowledge the smallest reported loss for a high-index-difference system such as a Si/SiO(2) strip waveguide.

600 citations

Journal ArticleDOI
TL;DR: In this article, experimental verification of analytic formulas for the dispersion and attenuation of electrical transient signals propagating on coplanar transmission lines is performed in the frequency domain over a terahertz range although the experiments are in the time domain.
Abstract: Experimental verification of analytic formulas for the dispersion and the attenuation of electrical transient signals propagating on coplanar transmission lines is presented. The verification is done in the frequency domain over a terahertz range although the experiments are in the time domain. The analytic formulas are obtained from fits to the full-wave analysis results. It is quantitatively verified that the full-wave steady-state solutions can be directly applied to the transient time-domain propagation experiments. Subpicosecond electrical pulses and an external electrooptic sampling technique are used to obtain the time-domain propagation data. From the Fourier transforms of the time-domain data both the attenuation and the phase information as a function of frequency are extracted. The dispersion and the attenuation characteristics are investigated for both coplanar waveguide and coplanar strip transmission lines. The investigation is carried out on both semiinsulating semiconductor and dielectric substrate materials. No observable losses caused by the semiconductor material are indicated. >

354 citations

Journal ArticleDOI
TL;DR: The results show the potential of photonic crystals for application as terahertz integration platforms and an error-free uncompressed high-definition video transmission by using a photonic-crystal waveguide with a length of as long as 50 cm and up to 28 bends thanks to the low-loss properties.
Abstract: We pursued the extremely low loss of photonic-crystal waveguides composed of a silicon slab with high resistivity (20 kΩ-cm) in the terahertz region. Propagation and bending losses as small as <0.1 dB/cm (0.326–0.331 THz) and 0.2 dB/bend (0.323–0.331 THz), respectively, were achieved in the 0.3-THz band. We also developed 1.5-Gbit/s terahertz links and demonstrated an error-free uncompressed high-definition video transmission by using a photonic-crystal waveguide with a length of as long as 50 cm and up to 28 bends thanks to the low-loss properties. Our results show the potential of photonic crystals for application as terahertz integration platforms.

134 citations