The Experts below are selected from a list of 9774 Experts worldwide ranked by ideXlab platform
Withawat Withayachumnankul - One of the best experts on this subject based on the ideXlab platform.
-
characteristics of effective medium clad Dielectric Waveguides
IEEE Transactions on Terahertz Science and Technology, 2021Co-Authors: Weijie Gao, Wendy S L Lee, Masayuki Fujita, Tadao Nagatsuma, Christophe Fumeaux, Withawat WithayachumnankulAbstract: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.
-
effective medium cladded Dielectric Waveguides for terahertz waves
Optics Express, 2019Co-Authors: Weijie Gao, Masayuki Fujita, Tadao Nagatsuma, Christophe Fumeaux, Withawat WithayachumnankulAbstract:Terahertz integrated platforms with high efficiency are crucial in a broad range of applications including terahertz communications, radar, imaging and sensing. One key enabling technology is wideband interconnection. This work proposes substrate-less all-Dielectric Waveguides defined by an effective medium with a subwavelength hole array. These self-supporting structures are built solely into a single silicon wafer to minimize significant absorption in metals and Dielectrics at terahertz frequencies. In a stark contrast to photonic crystal Waveguides, the guiding mechanism is not based on a photonic bandgap but total internal reflections The Waveguides are discussed in the context of terahertz communications that imposes stringent demands on performance. Experimental results show that the realized Waveguides can cover the entire 260–400 GHz with single dominant modes in both orthogonal polarizations and an average measured attenuation around 0.05 dB/cm. Limited by the measurement setup, the maximum error-free data rate up to 30 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. The proposed concept can potentially benefit integrated optics at large.
-
effective medium cladded Dielectric Waveguides for terahertz communications
arXiv: Optics, 2019Co-Authors: Weijie Gao, Masayuki Fujita, Tadao Nagatsuma, Christophe Fumeaux, Withawat WithayachumnankulAbstract: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.
Klaus J Boller - One of the best experts on this subject based on the ideXlab platform.
-
linewidth narrowing via low loss Dielectric waveguide feedback circuits in hybrid integrated frequency comb lasers
Optics Express, 2019Co-Authors: Jesse Mak, Albert Van Rees, Youwen Fan, Peter J M Van Der Slot, E J Klein, Dimitri Geskus, Klaus J BollerAbstract:We present an integrated hybrid semiconductor-Dielectric (InP-Si3N4) waveguide laser that generates frequency combs at a wavelength around 1.5 μm with a record-low intrinsic optical linewidth of 34 kHz. This is achieved by extending the cavity photon lifetime using a low-loss Dielectric waveguide circuit. In our experimental demonstration, the on-chip, effective optical path length of the laser cavity is extended to 6 cm. The resulting linewidth narrowing shows the high potential of on-chip, highly coherent frequency combs with direct electrical pumping, based on hybrid and heterogeneous integrated circuits making use of low-loss Dielectric Waveguides.
Kin Seng Chiang - One of the best experts on this subject based on the ideXlab platform.
-
Analysis of the effective-index method for the vector modes of rectangular-core Dielectric Waveguides
IEEE Transactions on Microwave Theory and Techniques, 1996Co-Authors: Kin Seng ChiangAbstract:The approximations involved in the effective-index method for analyzing the vector modes of rectangular-core Dielectric Waveguides are examined in detail. It is shown that the effective-index method does not solve the full vector-wave equation that governs the modes. Instead, it solves the reduced vector-wave equation, which is accurate only for approximately linearly polarized waves. Furthermore, in solving the reduced vector-wave equation, the method of separation of variables is used, which leads to additional errors as the waveguide being analyzed is a mathematically nonseparable structure. To characterize the performance of the effective-index method, asymptotic expressions are derived for the errors in the calculation of propagation constants. Apart from separating the effects of different approximations involved, these expressions show explicitly how the accuracy of the method depends on the mode type, the normalized frequency, the mode orders, the dimensions of the waveguide, and the relative refractive-index differences between the core and the surrounding media. With the help of these expressions, it is demonstrated that more accurate results can be obtained by combining various effective-index solutions.
Weijie Gao - One of the best experts on this subject based on the ideXlab platform.
-
characteristics of effective medium clad Dielectric Waveguides
IEEE Transactions on Terahertz Science and Technology, 2021Co-Authors: Weijie Gao, Wendy S L Lee, Masayuki Fujita, Tadao Nagatsuma, Christophe Fumeaux, Withawat WithayachumnankulAbstract: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.
-
effective medium cladded Dielectric Waveguides for terahertz waves
Optics Express, 2019Co-Authors: Weijie Gao, Masayuki Fujita, Tadao Nagatsuma, Christophe Fumeaux, Withawat WithayachumnankulAbstract:Terahertz integrated platforms with high efficiency are crucial in a broad range of applications including terahertz communications, radar, imaging and sensing. One key enabling technology is wideband interconnection. This work proposes substrate-less all-Dielectric Waveguides defined by an effective medium with a subwavelength hole array. These self-supporting structures are built solely into a single silicon wafer to minimize significant absorption in metals and Dielectrics at terahertz frequencies. In a stark contrast to photonic crystal Waveguides, the guiding mechanism is not based on a photonic bandgap but total internal reflections The Waveguides are discussed in the context of terahertz communications that imposes stringent demands on performance. Experimental results show that the realized Waveguides can cover the entire 260–400 GHz with single dominant modes in both orthogonal polarizations and an average measured attenuation around 0.05 dB/cm. Limited by the measurement setup, the maximum error-free data rate up to 30 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. The proposed concept can potentially benefit integrated optics at large.
-
effective medium cladded Dielectric Waveguides for terahertz communications
arXiv: Optics, 2019Co-Authors: Weijie Gao, Masayuki Fujita, Tadao Nagatsuma, Christophe Fumeaux, Withawat WithayachumnankulAbstract: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.
C Leone - One of the best experts on this subject based on the ideXlab platform.
-
exploiting the optical quadratic nonlinearity of zinc blende semiconductors for guided wave terahertz generation a material comparison
IEEE Journal of Quantum Electronics, 2010Co-Authors: Matteo Cherchi, Alberto Taormina, Alessandro Busacca, Roberto Luigi Oliveri, S Bivona, Alfonso Carmelo Cino, Salvatore Stivala, Stefano Riva Sanseverino, C LeoneAbstract:We present a detailed analysis and comparison of Dielectric Waveguides made of CdTe, GaP, GaAs and InP for modal phase matched optical difference frequency generation (DFG) in the terahertz domain. From the form of the DFG equations, we derived the definition of a very general figure of merit (FOM). In turn, this FOM enabled us to compare different configurations, by taking into account linear and nonlinear susceptibility dispersion, terahertz absorption, and a rigorous evaluation of the waveguide modes properties. The most efficient Waveguides found with this procedure are predicted to approach the quantum efficiency limit with input optical power in the order of kWs.
-
exploiting the optical quadratic nonlinearity of zincblende semiconductors for guided wave terahertz generation a material comparison
arXiv: Optics, 2009Co-Authors: Matteo Cherchi, Alberto Taormina, Alessandro Busacca, Roberto Luigi Oliveri, S Bivona, Alfonso Carmelo Cino, Salvatore Stivala, Stefano Riva Sanseverino, C LeoneAbstract:We present a detailed analysis and comparison of Dielectric Waveguides made of CdTe, GaP, GaAs and InP for modal phase matched optical difference frequency generation (DFG) in the terahertz domain. From the form of the DFG equations, we derived the definition of a very general figure of merit (FOM). In turn, this FOM enabled us to compare different configurations, by taking into account linear and nonlinear susceptibility dispersion, terahertz absorption, and a rigorous evaluation of the waveguide modes properties. The most efficient Waveguides found with this procedure are predicted to approach the quantum efficiency limit with input optical power in the order of kWs.