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Journal ArticleDOI

Effective-medium-cladded dielectric waveguides for terahertz communications

TL;DR: This work proposes substrate-less all-dielectric waveguides defined by an effective medium with a subwavelength hole array built solely into a single silicon wafer to minimize significant absorption in metals and dielectrics at terahertz frequencies.
Abstract: Terahertz communications is a promising modality for future short-range point-to point wireless data transmission at rates up to terabit per second. A milestone towards this goal is the development of an integrated transmitter and receiver platforms with high efficiency. One key enabling component is a planar waveguiding structure with wide bandwidth and low dispersion. This work proposes substrate-less all-dielectric waveguides cladded by an effective medium for low-loss and low dispersion terahertz transmission in broadband. This self-supporting structure is built solely into a single silicon wafer with air perforations to mitigate significant absorptions in metals and dielectrics at terahertz frequencies. The realized waveguides can cover the entire 260 to 400 GHz with single dominant modes in both orthogonal polarizations. The simulation shows that for the E_11^x mode the attenuation ranges from 0.003 to 0.024 dB/cm over the entire band, while it varies from 0.008 to 0.023 dB/cm for the E_11^y mode. Limited by the measurement setup, the maximum error-free data rate of 28 Gbit/s is experimentally achieved at 335 GHz on a 3-cm waveguide. We further demonstrate the transmission of uncompressed 4K-resolution video across this waveguide. This waveguide platform promises integration of diverse active and passive components. Thus, we can foresee it as a potential candidate for the future terahertz integrated circuits, in analogy to photonic integrated circuits at optical frequencies.
Citations
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Book
01 Jan 2006
TL;DR: Theorems and Formulas used in this chapter relate to theorems in optical waveguides and lightwave Circuits that describe the behaviour of Planar Waveguides through the response of the E-modulus effect.
Abstract: Preface 1. Wave Theory of Optical Waveguides 2. Planar Optical Waveguides 3. Optical Fibers 4. Couple Mode Theory 5. Nonlinear Optical Effects in Optical Fibers 6. Finite Element Method 7. Beam Propagation Method 8. Staircase Concatention Method 9. Planar Lightwave Circuits 10. Theorems and Formulas Appendix

359 citations

Journal ArticleDOI
TL;DR: In this article, the waveguides are monolithically integrated within a supporting silicon frame, with which they are fabricated together from the same silicon wafer in a single-mask etching process.
Abstract: A practical approach to realize substrateless, unclad, micro-scale intrinsic silicon waveguides for the terahertz range is presented. The waveguides are monolithically integrated within a supporting silicon frame, with which they are fabricated together from the same silicon wafer in a single-mask etching process. This establishes an integration platform to house many diverse components and facilitates packaging. Effective medium techniques are deployed to prevent the frame from interfering with the waveguide's functionality. Straight waveguides of this sort are experimentally found to be efficient and broadband. Elementary components including Y-junctions and evanescent couplers are developed, and deployed in demonstrations of applications for terahertz waves including sensing and communications. This is a promising pathway to realize future microphotonic devices for diverse applications of terahertz waves.

47 citations


Cites background from "Effective-medium-cladded dielectric..."

  • ...are very closely related to that of the effective medium-clad terahertz waveguides that are presented in [22]....

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  • ...For these reasons, recent years have seen the photonic crystal replaced with effective medium, in order to lower the effective index of the silicon that surrounds the waveguide, and achieve in-plane field confinement using the broadband phenomenon of total internal reflection, rather than a photonic bandgap [22]....

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Journal ArticleDOI
TL;DR: In this paper, effective medium-clad dielectric waveguides with low loss and low dispersion were investigated for terahertz-integrated platforms, and the results showed an average measured attenuation coefficient of 0.075 dB/cm and a group velocity dispersion ranging from around 10ps/THz/mm across the whole band.
Abstract: Effective-medium-clad dielectric waveguides are purely built into a single high-resistivity float-zone silicon wafer with their claddings defined by deep subwavelength perforations. The waveguides are substrate-free while supporting both $E_{11}^x$ and $E_{11}^y$ modes with low loss and low dispersion. This article extends the investigations of the waveguides by analyzing the dispersion, cross-polarization, and crosstalk together with the characteristics of bends and crossings over an operation frequency range of 220–330 GHz (WR-3 band). Taking the $E_{11}^x$ mode as an example, the experimental results show an average measured attenuation coefficient of 0.075 dB/cm and a group velocity dispersion ranging from around $\pm$ 10 ps/THz/mm across the whole band. A crosstalk level below $-$ 10 dB is measured for parallel waveguides with a separation of 0.52 $\lambda _{0}$ at 300 GHz. The realized waveguides show a bending loss ranging from 0.500 to 0.025 dB per bend and a crosstalk at crossing below $-$ 15 dB from 220 to 330 GHz. Due to the different dispersion characteristics, the $E_{11}^y$ mode has similar performances but with its operation frequency range reduced to 260–330 GHz. Limited by the measurement setup, a cross-coupling between the $E_{11}^x$ and $E_{11}^y$ modes is measured to be below $-$ 20 dB over the whole band. This in-depth investigation of effective-medium-clad waveguides will form a basis for terahertz-integrated platforms.

33 citations


Cites background from "Effective-medium-cladded dielectric..."

  • ...The relatively stronger fluctuations in the measurements represent standing waves caused by the misalignment between the inserted tapers and the feeding hollow waveguides [31]....

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  • ...Recently, we have proposed a type of substrate-free dielectric waveguides clad by in-plane effective media [31], [32], which are defined by subwavelength periodic perforations....

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  • ...surrounded by in-plane effective-medium claddings [31]....

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  • ...thus achieving extremely low loss and low dispersion over 260–400 GHz [31]....

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Journal ArticleDOI
TL;DR: Experiments indicate that a slab-mode beam is launched with ∼86% efficiency, over a broad 3 dB bandwidth from ∼260 to ∼390 GHz, although these reported values are approximate due to obfuscation by variation that arises from reflections within the device.
Abstract: Currently, optics such as dielectric lenses and curved reflector dishes are commonplace in terahertz laboratories, as their functionality is of fundamental importance to the majority of applications of terahertz waves. However, such optics are typically bulky and require manual assembly and alignment. Here we seek to draw inspiration from the field of digital electronics, which underwent rapid acceleration following the advent of integrated circuits as a replacement for discrete transistors. For a comparable transition with terahertz optics, we must seek mask-oriented fabrication processes that simultaneously etch multiple interconnected integrated optics. To support this goal, terahertz beams are confined to two dimensions within a planar silicon slab, and a gradient-index half-Maxwell fisheye lens serves to launch such a slab-mode beam from a terahertz-range photonic crystal waveguide that is coupled to its focus. Both the optic and the waveguide are implemented with through-hole arrays and are fabricated in the same single-etch process. Experiments indicate that a slab-mode beam is launched with ∼86% efficiency, over a broad 3 dB bandwidth from ∼260 to ∼390 GHz, although these reported values are approximate due to obfuscation by variation that arises from reflections within the device.

29 citations

Journal ArticleDOI
TL;DR: In this paper, the authors provide an overview of recent progress in terahertz (THz) technologies based on silicon photonics or hybrid silicon photonic, including THz generation, detection, phase modulation, intensity modulation, and passive components.
Abstract: In the last couple of decades, terahertz (THz) technologies, which lie in the frequency gap between the infrared and microwaves, have been greatly enhanced and investigated due to possible opportunities in a plethora of THz applications, such as imaging, security, and wireless communications. Photonics has led the way to the generation, modulation, and detection of THz waves such as the photomixing technique. In tandem with these investigations, researchers have been exploring ways to use silicon photonics technologies for THz applications to leverage the cost-effective large-scale fabrication and integration opportunities that it would enable. Although silicon photonics has enabled the implementation of a large number of optical components for practical use, for THz integrated systems, we still face several challenges associated with high-quality hybrid silicon lasers, conversion efficiency, device integration, and fabrication. This paper provides an overview of recent progress in THz technologies based on silicon photonics or hybrid silicon photonics, including THz generation, detection, phase modulation, intensity modulation, and passive components. As silicon-based electronic and photonic circuits are further approaching THz frequencies, one single chip with electronics, photonics, and THz functions seems inevitable, resulting in the ultimate dream of a THz electronic-photonic integrated circuit.

21 citations

References
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Book
01 Jan 2005

9,038 citations

Book
01 Jan 1992
TL;DR: In this article, the authors present an overview of the main components of WDM lightwave communication systems, including the following: 1.1 Geometrical-Optics Description, 2.2 Wave Propagation, 3.3 Dispersion in Single-Mode Fibers, 4.4 Dispersion-Induced Limitations.
Abstract: Preface. 1 Introduction. 1.1 Historical Perspective. 1.2 Basic Concepts. 1.3 Optical Communication Systems. 1.4 Lightwave System Components. Problems. References. 2 Optical Fibers. 2.1 Geometrical-Optics Description. 2.2 Wave Propagation. 2.3 Dispersion in Single-Mode Fibers. 2.4 Dispersion-Induced Limitations. 2.5 Fiber Losses. 2.6 Nonlinear Optical Effects. 2.7 Fiber Design and Fabrication. Problems. References. 3 Optical Transmitters. 3.1 Semiconductor Laser Physics. 3.2 Single-Mode Semiconductor Lasers. 3.3 Laser Characteristics. 3.4 Optical Signal Generation. 3.5 Light-Emitting Diodes. 3.6 Transmitter Design. Problems. References. 4 Optical Receivers. 4.1 Basic Concepts. 4.2 Common Photodetectors. 4.3 Receiver Design. 4.4 Receiver Noise. 4.5 Coherent Detection. 4.6 Receiver Sensitivity. 4.7 Sensitivity Degradation. 4.8 Receiver Performance. Problems. References. 5 Lightwave Systems. 5.1 System Architectures. 5.2 Design Guidelines. 5.3 Long-Haul Systems. 5.4 Sources of Power Penalty. 5.5 Forward Error Correction. 5.6 Computer-Aided Design. Problems. References. 6 Multichannel Systems. 6.1 WDM Lightwave Systems. 6.2 WDM Components. 6.3 System Performance Issues. 6.4 Time-Division Multiplexing. 6.5 Subcarrier Multiplexing. 6.6 Code-Division Multiplexing. Problems. References. 7 Loss Management. 7.1 Compensation of Fiber Losses. 7.2 Erbium-Doped Fiber Amplifiers. 7.3 Raman Amplifiers. 7.4 Optical Signal-To-Noise Ratio. 7.5 Electrical Signal-To-Noise Ratio. 7.6 Receiver Sensitivity and Q Factor. 7.7 Role of Dispersive and Nonlinear Effects. 7.8 Periodically Amplified Lightwave Systems. Problems. References. 8 Dispersion Management. 8.1 Dispersion Problem and Its Solution. 8.2 Dispersion-Compensating Fibers. 8.3 Fiber Bragg Gratings. 8.4 Dispersion-Equalizing Filters. 8.5 Optical Phase Conjugation. 8.6 Channels at High Bit Rates. 8.7 Electronic Dispersion Compensation. Problems. References. 9 Control of Nonlinear Effects. 9.1 Impact of Fiber Nonlinearity. 9.2 Solitons in Optical Fibers. 9.3 Dispersion-Managed Solitons. 9.4 Pseudo-linear Lightwave Systems. 9.5 Control of Intrachannel Nonlinear Effects. Problems. References. 10 Advanced Lightwave Systems. 10.1 Advanced Modulation Formats. 10.2 Demodulation Schemes. 10.3 Shot Noise and Bit-Error Rate. 10.4 Sensitivity Degradation Mechanisms. 10.5 Impact of Nonlinear Effects. 10.6 Recent Progress. 10.7 Ultimate Channel Capacity. Problems. References. 11 Optical Signal Processing. 11.1 Nonlinear Techniques and Devices. 11.2 All-Optical Flip-Flops. 11.3 Wavelength Converters. 11.4 Ultrafast Optical Switching. 11.5 Optical Regenerators. Problems. References. A System of Units. B Acronyms. C General Formula for Pulse Broadening. D Software Package.

4,125 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied the transmission properties of a guide consisting of a dielectric rod with rectangular cross section, surrounded by several dielectrics of smaller refractive indices.
Abstract: We study the transmission properties of a guide consisting of a dielectric rod with rectangular cross section, surrounded by several dielectrics of smaller refractive indices. This guide is suitable for integrated optical circuitry because of its size, single-mode operation, mechanical stability, simplicity, and precise construction. After making some simplifying assumptions, we solve Maxwell's equations in closed form and find, that, because of total internal reflection, the guide supports two types of hybrid modes which are essentially of the TEM kind polarized at right angles. Their attenuations are comparable to that of a plane wave traveling in the material of which the rod is made. If the refractive indexes are chosen properly, the guide can support only the fundamental modes of each family with any aspect ratio of the guide cross section. By adding thin lossy layers, the guide presents higher loss to one of those modes. As an alternative, the guide can be made to support only one of the modes if part of the surrounding dielectrics is made a low impedance medium. Finally, we determine the coupling between parallel guiding rods of slightly different sizes and dielectrics; at wavelengths around one micron, 3-dB directional couplers, a few hundred microns long, can be achieved with separations of the guides about the same as their widths (a few microns).

1,620 citations

Book
01 Jan 2000

1,493 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