Pub Date : 2025-07-24DOI: 10.1109/TTHZ.2025.3592354
Sota Mine;Kodo Kawase;Kosuke Murate
To advance real-time spectroscopy based on terahertz (THz) parametric generation, we achieved the simultaneous generation of more than ten THz wavelengths. We used higher order Stokes beams generated at multiple wavelengths via a cascaded process within a nonlinear optical crystal as both the pump and seed beams for THz parametric generation. This allowed concurrent generation of up to 13 THz wavelengths. This facilitated real-time spectroscopy of various reagents. The ability to generate 13 THz wavelengths in the 1–2 THz range simultaneously greatly aids in reagent identification despite the presence of obstructions and holds significant potential for future spectroscopic applications.
{"title":"Multiwavelength Terahertz Parametric Generation Using Higher Order Stokes Beams","authors":"Sota Mine;Kodo Kawase;Kosuke Murate","doi":"10.1109/TTHZ.2025.3592354","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3592354","url":null,"abstract":"To advance real-time spectroscopy based on terahertz (THz) parametric generation, we achieved the simultaneous generation of more than ten THz wavelengths. We used higher order Stokes beams generated at multiple wavelengths via a cascaded process within a nonlinear optical crystal as both the pump and seed beams for THz parametric generation. This allowed concurrent generation of up to 13 THz wavelengths. This facilitated real-time spectroscopy of various reagents. The ability to generate 13 THz wavelengths in the 1–2 THz range simultaneously greatly aids in reagent identification despite the presence of obstructions and holds significant potential for future spectroscopic applications.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 5","pages":"781-786"},"PeriodicalIF":3.9,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144998241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-24DOI: 10.1109/TTHZ.2025.3592353
William F. McGrew;James Greenberg;Keisuke Nose;Brendan M. Heffernan;Antoine Rolland
We report a comprehensive theoretical analysis of the instability achievable by using phase modulation spectroscopy to lock a terahertz (THz) terahertz local oscillator to an absorptive reference consisting of the rotational transition of molecules at room temperature. We find that the signal-to-noise ratio of the THz detector provides the limitation to the instability that can be achieved and analyze a number of viable candidate molecules, identifying several as being of particular interest, including OCS and HI. We find that a 1-s instability in the $10^{-13}$ decade is achievable for molecules confined to waveguide, while instability at the $10^{-14}$ level can be reached for molecules in free space. We also present calculations of the intermodulation effect for spectroscopy taking place far outside the quasi-static regime and find that this source of noise presents constraints on which THz local oscillators are appropriate to be used for such frequency references.
{"title":"Terahertz Molecular Frequency References: Theoretical Analysis of Optimal Instability","authors":"William F. McGrew;James Greenberg;Keisuke Nose;Brendan M. Heffernan;Antoine Rolland","doi":"10.1109/TTHZ.2025.3592353","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3592353","url":null,"abstract":"We report a comprehensive theoretical analysis of the instability achievable by using phase modulation spectroscopy to lock a terahertz (THz) terahertz local oscillator to an absorptive reference consisting of the rotational transition of molecules at room temperature. We find that the signal-to-noise ratio of the THz detector provides the limitation to the instability that can be achieved and analyze a number of viable candidate molecules, identifying several as being of particular interest, including OCS and HI. We find that a 1-s instability in the <inline-formula><tex-math>$10^{-13}$</tex-math></inline-formula> decade is achievable for molecules confined to waveguide, while instability at the <inline-formula><tex-math>$10^{-14}$</tex-math></inline-formula> level can be reached for molecules in free space. We also present calculations of the intermodulation effect for spectroscopy taking place far outside the quasi-static regime and find that this source of noise presents constraints on which THz local oscillators are appropriate to be used for such frequency references.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 6","pages":"1068-1074"},"PeriodicalIF":3.9,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145435684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-23DOI: 10.1109/TTHZ.2025.3591922
Nguyen H. Ngo;Feifan Han;Yuta Inose;Masayuki Fujita;Safumi Suzuki
To meet the growing need for higher data rates with improved energy efficiencies, this article demonstrates the application of resonant tunneling diodes (RTDs) for wireless communications at a frequency of approximately 860 GHz. By incorporating a low-loss air-bridge transmission line to form a cavity resonator and a ring-slot antenna, a two-RTD oscillator realized coherent terahertz radiation with a power output of 0.23 mW and a dc-to-RF efficiency of 0.2%. Experimental validation confirmed wireless data transmission for data rates up to 1.2 Gbit/s using on-off keying modulation with bit error rates below 10−9. To the best of our knowledge, this is the first reported demonstration of all-electronic oscillators for wireless communication beyond 850 GHz, paving the way for next-generation networks and advanced integrated circuits in the artificial intelligence-driven era.
{"title":"Wireless Communications of Resonant Tunneling Diode Transmitter and Receiver at 860 GHz","authors":"Nguyen H. Ngo;Feifan Han;Yuta Inose;Masayuki Fujita;Safumi Suzuki","doi":"10.1109/TTHZ.2025.3591922","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3591922","url":null,"abstract":"To meet the growing need for higher data rates with improved energy efficiencies, this article demonstrates the application of resonant tunneling diodes (RTDs) for wireless communications at a frequency of approximately 860 GHz. By incorporating a low-loss air-bridge transmission line to form a cavity resonator and a ring-slot antenna, a two-RTD oscillator realized coherent terahertz radiation with a power output of 0.23 mW and a dc-to-RF efficiency of 0.2%. Experimental validation confirmed wireless data transmission for data rates up to 1.2 Gbit/s using <sc>on-off</small> keying modulation with bit error rates below 10<sup>−9</sup>. To the best of our knowledge, this is the first reported demonstration of all-electronic oscillators for wireless communication beyond 850 GHz, paving the way for next-generation networks and advanced integrated circuits in the artificial intelligence-driven era.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 5","pages":"763-770"},"PeriodicalIF":3.9,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145011333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-21DOI: 10.1109/TTHZ.2025.3591312
Zengwen Wang;Shaozhe Zhang;Houxiu Xiao;Xianfei Chen;Zhenxing Wang;Yvting Lu;Xiaotao Han
We demonstrate a terahertz (THz) pulse slicer composed of two laser-driven semiconductor switches (LDSSs) that enables the generation of high-power, nanosecond-scale narrowband THz pulses for many applications. To slice the THz waves precisely and efficiently, a tunable LDSS featuring a double semiconductor wafer structure is proposed to improve the isolation and reduce the insertion loss. By adjusting the distance between the wafers, the phase shift of the THz waves propagating within the LDSS can be precisely controlled. This allows the reflected waves to interfere destructively, resulting in near-zero off-state reflection across a broad frequency range. This approach applies to THz waves of any polarization and propagation direction, significantly enhancing the flexibility of quasi-optical system design and reducing propagation losses in the pulse slicer. In simulations and experiments, the performance of the double-wafer LDSS and the pulse slicer is analyzed. The results show that, over a frequency range of 230 to 260 GHz for both s-polarized and p-polarized waves, each LDSS achieves an isolation exceeding 17.5 dB and an insertion loss below 0.15 dB, with a response time of approximately 4 ns. With the pulse width about 8 ns or longer, the overall insertion loss of the THz pulse slicer can reach as low as 0.2 dB, which is much better compared to that reported in the literature.
{"title":"Tunable Double-Wafer Laser-Driven Semiconductor Switch for Nanosecond THz Pulse Slicing Across a Broad Frequency Range","authors":"Zengwen Wang;Shaozhe Zhang;Houxiu Xiao;Xianfei Chen;Zhenxing Wang;Yvting Lu;Xiaotao Han","doi":"10.1109/TTHZ.2025.3591312","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3591312","url":null,"abstract":"We demonstrate a terahertz (THz) pulse slicer composed of two laser-driven semiconductor switches (LDSSs) that enables the generation of high-power, nanosecond-scale narrowband THz pulses for many applications. To slice the THz waves precisely and efficiently, a tunable LDSS featuring a double semiconductor wafer structure is proposed to improve the isolation and reduce the insertion loss. By adjusting the distance between the wafers, the phase shift of the THz waves propagating within the LDSS can be precisely controlled. This allows the reflected waves to interfere destructively, resulting in near-zero off-state reflection across a broad frequency range. This approach applies to THz waves of any polarization and propagation direction, significantly enhancing the flexibility of quasi-optical system design and reducing propagation losses in the pulse slicer. In simulations and experiments, the performance of the double-wafer LDSS and the pulse slicer is analyzed. The results show that, over a frequency range of 230 to 260 GHz for both s-polarized and p-polarized waves, each LDSS achieves an isolation exceeding 17.5 dB and an insertion loss below 0.15 dB, with a response time of approximately 4 ns. With the pulse width about 8 ns or longer, the overall insertion loss of the THz pulse slicer can reach as low as 0.2 dB, which is much better compared to that reported in the literature.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 6","pages":"1092-1101"},"PeriodicalIF":3.9,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145435681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-21DOI: 10.1109/TTHZ.2025.3591305
Tobias Doeker;Thomas Kürner
In low terahertz communications ($0.1 ,{mathrm{THz}}$–$1 ,{mathrm{THz}}$), highly directive antennas with high antenna gains are essential to overcoming the significant losses during wireless propagation. Consequently, precise alignment between the transmitter and receiver is mandatory, making the device discovery phase—a crucial step in such communication systems—extremely important. A promising approach involves an iterative search in which both the transmitter and receiver scan the entire angular range to find the orientation that results in the highest received power. Since this process requires a substantial number of measurement steps, the approach is enhanced by combining the scanning process with compressed sensing. It is shown that the device discovery method can be represented as an underdetermined linear system, and because the signal to be reconstructed is sparse, compressed sensing techniques can be utilized. In this work, this compressed sensing-assisted device discovery approach is presented and evaluated using simulation-based data. To optimize the method, various solvers are tested, with orthogonal matching pursuit appearing to be the most suitable in this case. Furthermore, different improvement strategies are examined, showing that a sectorized application can significantly enhance the proposed device discovery process. Finally, the proposed method is verified through channel sounder measurements.
{"title":"Compressed Sensing-Assisted Device Discovery for Low Terahertz Communications","authors":"Tobias Doeker;Thomas Kürner","doi":"10.1109/TTHZ.2025.3591305","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3591305","url":null,"abstract":"In low terahertz communications (<inline-formula><tex-math>$0.1 ,{mathrm{THz}}$</tex-math></inline-formula>–<inline-formula><tex-math>$1 ,{mathrm{THz}}$</tex-math></inline-formula>), highly directive antennas with high antenna gains are essential to overcoming the significant losses during wireless propagation. Consequently, precise alignment between the transmitter and receiver is mandatory, making the device discovery phase—a crucial step in such communication systems—extremely important. A promising approach involves an iterative search in which both the transmitter and receiver scan the entire angular range to find the orientation that results in the highest received power. Since this process requires a substantial number of measurement steps, the approach is enhanced by combining the scanning process with compressed sensing. It is shown that the device discovery method can be represented as an underdetermined linear system, and because the signal to be reconstructed is sparse, compressed sensing techniques can be utilized. In this work, this compressed sensing-assisted device discovery approach is presented and evaluated using simulation-based data. To optimize the method, various solvers are tested, with orthogonal matching pursuit appearing to be the most suitable in this case. Furthermore, different improvement strategies are examined, showing that a sectorized application can significantly enhance the proposed device discovery process. Finally, the proposed method is verified through channel sounder measurements.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 6","pages":"1020-1032"},"PeriodicalIF":3.9,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145435685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-15DOI: 10.1109/TTHZ.2025.3588056
Yifeng Wang;Zhengping Zhang;Xiong Wang
In recent years, nondiffracting beams such as Airy beams and Bessel beams have garnered widespread attention due to their unique propagation characteristics. Among them, Airy beams exhibit exceptional imaging capabilities, including enhanced resolution, increased penetration depth, and improved contrast in complicated scattering environments. While research works on amplitude imaging with Airy beams has been extensive, the potential of Airy beams in phase imaging remains largely underexplored. This article proposes an Airy-beam-based through-scattering-media phase imaging technique in the THz band, which is referred to as Airy beam phase imaging (ABPI) technique. We design dielectric lenses to generate a THz Airy beam working from 190 to 210 GHz and investigate the imaging of some printed dielectric samples. We make scattering layers by glass beads to test the ABPI technique. We perform imaging experiments and have the following findings. First, the phase images obtained by the ABPI method bear much higher quality than the amplitude images. Second, the images reconstructed using broadband information outperform the single-frequency images. Third, the thickness of the dielectric samples can be estimated with high accuracy and three-dimensional (3-D) images of the samples can be reconstructed. Furthermore, the advantages of the ABPI technique are more obvious when scattering media is present in the propagation path of the Airy beam. This work provides a novel paradigm for accurate imaging of dielectric samples involving scattering media in the THz regime and paves the way for advanced 3-D imaging applications in nondestructive examination, biomedical imaging, food inspection, and security screening.
{"title":"Phase Imaging Through Scattering Media Based on a THz Airy Beam","authors":"Yifeng Wang;Zhengping Zhang;Xiong Wang","doi":"10.1109/TTHZ.2025.3588056","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3588056","url":null,"abstract":"In recent years, nondiffracting beams such as Airy beams and Bessel beams have garnered widespread attention due to their unique propagation characteristics. Among them, Airy beams exhibit exceptional imaging capabilities, including enhanced resolution, increased penetration depth, and improved contrast in complicated scattering environments. While research works on amplitude imaging with Airy beams has been extensive, the potential of Airy beams in phase imaging remains largely underexplored. This article proposes an Airy-beam-based through-scattering-media phase imaging technique in the THz band, which is referred to as Airy beam phase imaging (ABPI) technique. We design dielectric lenses to generate a THz Airy beam working from 190 to 210 GHz and investigate the imaging of some printed dielectric samples. We make scattering layers by glass beads to test the ABPI technique. We perform imaging experiments and have the following findings. First, the phase images obtained by the ABPI method bear much higher quality than the amplitude images. Second, the images reconstructed using broadband information outperform the single-frequency images. Third, the thickness of the dielectric samples can be estimated with high accuracy and three-dimensional (3-D) images of the samples can be reconstructed. Furthermore, the advantages of the ABPI technique are more obvious when scattering media is present in the propagation path of the Airy beam. This work provides a novel paradigm for accurate imaging of dielectric samples involving scattering media in the THz regime and paves the way for advanced 3-D imaging applications in nondestructive examination, biomedical imaging, food inspection, and security screening.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 5","pages":"831-842"},"PeriodicalIF":3.9,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11079283","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144998375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-14DOI: 10.1109/TTHZ.2025.3588765
Runzhou Chen;Hao-Yu Chien;Mau-Chung Frank Chang
This work presents the design and analysis of a compact D-band × 9 frequency multiplier chain, using taiwan semiconductor manufacturing company limited (TSMC) 16 nm technology with the radio frequency (RF) p-FinFET device. The unique high $mathbf {f_{max}}$ feature of the p-FinFET device sets the foundations for this design. To accommodate the short-channel effects in the fin field-effect transistor (FinFET) devices, a time domain double-clipped piece-wise linear model is proposed to analyze the current waveform of the frequency tripler, which proves to be accurate in predicting the harmonic generation behavior of FinFET by comparing with the simulation. The optimal load impedance and the matching conditions at 3f$_{0}$ are also examined to improve the efficiency. The frequency multiplier chain consists of an inductor-less active balun for single-to-differential conversion and mismatch compensation, two frequency tripler cells, an interstage amplifier, and a two-stage driving amplifier at the output. The proposed model was applied to find the optimal bias condition when designing the frequency triplers. The proposed multiplier was measured under two bias conditions; the first achieves a conversion gain of 1.6 dB, a $mathbf {P_{sat}}$ of -2.8 dBm and a harmonic rejection ratio of 44 dBc while consuming 58 mW dc power. The second bias point achieves a higher conversion gain and $mathbf {P_{sat}}$ at 4.7 and 1.8 dBm with 102 mW dc power. The multiplier chip occupies a core area of only 0.068 $mathbf {mm^{2}}$ and the phase noise degradation is 19.8 dB at 1-MHz frequency offset.
{"title":"Design of a D-Band Multiply-by-9 Frequency Multiplier Chain in 16 nm p-FinFET Technology With Waveform Modeling","authors":"Runzhou Chen;Hao-Yu Chien;Mau-Chung Frank Chang","doi":"10.1109/TTHZ.2025.3588765","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3588765","url":null,"abstract":"This work presents the design and analysis of a compact D-band × 9 frequency multiplier chain, using taiwan semiconductor manufacturing company limited (TSMC) 16 nm technology with the radio frequency (RF) p-FinFET device. The unique high <inline-formula><tex-math>$mathbf {f_{max}}$</tex-math></inline-formula> feature of the p-FinFET device sets the foundations for this design. To accommodate the short-channel effects in the fin field-effect transistor (FinFET) devices, a time domain double-clipped piece-wise linear model is proposed to analyze the current waveform of the frequency tripler, which proves to be accurate in predicting the harmonic generation behavior of FinFET by comparing with the simulation. The optimal load impedance and the matching conditions at 3f<inline-formula><tex-math>$_{0}$</tex-math></inline-formula> are also examined to improve the efficiency. The frequency multiplier chain consists of an inductor-less active balun for single-to-differential conversion and mismatch compensation, two frequency tripler cells, an interstage amplifier, and a two-stage driving amplifier at the output. The proposed model was applied to find the optimal bias condition when designing the frequency triplers. The proposed multiplier was measured under two bias conditions; the first achieves a conversion gain of 1.6 dB, a <inline-formula><tex-math>$mathbf {P_{sat}}$</tex-math></inline-formula> of -2.8 dBm and a harmonic rejection ratio of 44 dBc while consuming 58 mW dc power. The second bias point achieves a higher conversion gain and <inline-formula><tex-math>$mathbf {P_{sat}}$</tex-math></inline-formula> at 4.7 and 1.8 dBm with 102 mW dc power. The multiplier chip occupies a core area of only 0.068 <inline-formula><tex-math>$mathbf {mm^{2}}$</tex-math></inline-formula> and the phase noise degradation is 19.8 dB at 1-MHz frequency offset.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 5","pages":"864-876"},"PeriodicalIF":3.9,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144998097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-14DOI: 10.1109/TTHZ.2025.3588749
Jun Xiao;Jing Wu;Tongyu Ding;Chong-Zhi Han;Qiubo Ye
In this article, a low-temperature cofired ceramic-based E-shaped planar inverted-F antenna is proposed for circularly polarized (CP) at D-band (110—170 GHz). For stable CP radiation characteristic, a densified self-sequential rotation feeding technique is applied for 2 × 2 subarray. Certain perturbance of field distribution is achieved by arranging the coupling feed disks properly. Hence, a TE410-mode/quasi-TE330 high-order-mode substrate integrated waveguide cavity is excited with four coupling feeding slots properly arranged to obtain equal amplitudes and sequential 90°-phase shifts, which can be deemed as high-order-mode-based densified self-sequential rotation feeding (HOM-DSRF) configuration. Thanks to the proposed HOM-DSRF configuration, the overall dimension of the 2 × 2 CP subarray is only 1.05λ × 1.05λ with a simulated aperture efficiency up to 96%, which is significantly superior to conventional sequentially rotation feeding methods in terms of overall dimension and aperture efficiency. Finally, a 4 × 4 antenna array is designed, fabricated, and measured. The measured impedance bandwidth and 3-dB axial ratio bandwidth are 10.4% from 145.7 to 161.7 GHz and 10.5% from 144 to 160 GHz, respectively. The measured peak gain is 15.1 dBic, with measured aperture efficiency up to 71%. The measured results agree well with the simulated ones. The proposed HOM-DSRF configuration has potential applications for terahertz CP antenna array designs.
{"title":"An LTCC-Based Antenna Array With Densified Self-Sequential Rotation Feeding Configuration for Circularly Polarized Terahertz Communications","authors":"Jun Xiao;Jing Wu;Tongyu Ding;Chong-Zhi Han;Qiubo Ye","doi":"10.1109/TTHZ.2025.3588749","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3588749","url":null,"abstract":"In this article, a low-temperature cofired ceramic-based E-shaped planar inverted-F antenna is proposed for circularly polarized (CP) at D-band (110—170 GHz). For stable CP radiation characteristic, a densified self-sequential rotation feeding technique is applied for 2 × 2 subarray. Certain perturbance of field distribution is achieved by arranging the coupling feed disks properly. Hence, a TE<sub>410</sub>-mode/quasi-TE<sub>330</sub> high-order-mode substrate integrated waveguide cavity is excited with four coupling feeding slots properly arranged to obtain equal amplitudes and sequential 90°-phase shifts, which can be deemed as high-order-mode-based densified self-sequential rotation feeding (HOM-DSRF) configuration. Thanks to the proposed HOM-DSRF configuration, the overall dimension of the 2 × 2 CP subarray is only 1.05<italic>λ</i> × 1.05<italic>λ</i> with a simulated aperture efficiency up to 96%, which is significantly superior to conventional sequentially rotation feeding methods in terms of overall dimension and aperture efficiency. Finally, a 4 × 4 antenna array is designed, fabricated, and measured. The measured impedance bandwidth and 3-dB axial ratio bandwidth are 10.4% from 145.7 to 161.7 GHz and 10.5% from 144 to 160 GHz, respectively. The measured peak gain is 15.1 dBic, with measured aperture efficiency up to 71%. The measured results agree well with the simulated ones. The proposed HOM-DSRF configuration has potential applications for terahertz CP antenna array designs.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 5","pages":"934-939"},"PeriodicalIF":3.9,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144997976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-10DOI: 10.1109/TTHZ.2025.3588046
Sven van Berkel;Alain E. Maestrini;Robert Lin;Choonsup Lee;Goutam Chattopadhyay;Raquel Rodriguez Monje;Ken B. Cooper
In this article, we report on the development of a high-performance, tunable, solid-state, single-pole-single-throw (SPST) switch operating in $G$-band for radar applications. Future space-borne, high-power $G$-band radars may require an SPST switch for receiver protection. We explore a novel solid-state switching architecture based on planar GaAs Schottky diodes. The switch, optimized for operation from 158 to 175 GHz, achieves high isolation by absorbing, reflecting, and frequency multiplying the input power to the second harmonic. A first demonstrator is characterized with an on-state insertion loss <0.86>20 dB at 0 dBm input power. The off-state isolation exceeds 43 dB at 0 dBm input power and remains above 30 dB at +17 dBm input power. Depending on the required isolation, the switch is tunable with an instantaneous bandwidth ranging from 300 MHz (for 30 dB isolation) to 13 GHz (for 15 dB isolation). The switch is successfully demonstrated to operate at an ultra-fast 4 MHz switching rate with a switching speed of a few nanoseconds.
{"title":"Ultra-Fast Low-Loss SPST Switch Using Planar GaAs Diodes for $G$-Band Radar Receiver Protection","authors":"Sven van Berkel;Alain E. Maestrini;Robert Lin;Choonsup Lee;Goutam Chattopadhyay;Raquel Rodriguez Monje;Ken B. Cooper","doi":"10.1109/TTHZ.2025.3588046","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3588046","url":null,"abstract":"In this article, we report on the development of a high-performance, tunable, solid-state, single-pole-single-throw (SPST) switch operating in <inline-formula><tex-math>$G$</tex-math></inline-formula>-band for radar applications. Future space-borne, high-power <inline-formula><tex-math>$G$</tex-math></inline-formula>-band radars may require an SPST switch for receiver protection. We explore a novel solid-state switching architecture based on planar GaAs Schottky diodes. The switch, optimized for operation from 158 to 175 GHz, achieves high isolation by absorbing, reflecting, and frequency multiplying the input power to the second harmonic. A first demonstrator is characterized with an <sc>on</small>-state insertion loss <0.86>20 dB at 0 dBm input power. The <sc>off</small>-state isolation exceeds 43 dB at 0 dBm input power and remains above 30 dB at +17 dBm input power. Depending on the required isolation, the switch is tunable with an instantaneous bandwidth ranging from 300 MHz (for 30 dB isolation) to 13 GHz (for 15 dB isolation). The switch is successfully demonstrated to operate at an ultra-fast 4 MHz switching rate with a switching speed of a few nanoseconds.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 5","pages":"852-863"},"PeriodicalIF":3.9,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144998184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Staphylococcus aureus (S. aureus) represents a major threat to global health, and its sensitive and accurate detection is highly demanded in disease diagnosis and food safety. Here, a flexible terahertz (THz) metasurface based on bound states in the continuum (BIC) is proposed and experimentally demonstrated for the trace analysis of S. aureus. The unit cell structure incorporates a metallic square with two opening gaps, supporting a resonance transition from BIC to quasi-BIC states by introducing a symmetry perturbation to one opening gap location. First, the refractive index (RI) spectra of the drip-dried S. aureus solution at different concentrations are characterized using THz-TDS. The frequency point possessing a maximum linearity between RI and S. aureus concentrations is selected as the resonance frequency of designed sensing quasi-BIC. Moreover, an experimental demonstration of the sensing performance is conducted by monitoring spectral evolution after target loading. The measured results indicate that the constructed biosensor exhibits a detection limit down to 200 cfu/mL and RI sensing sensitivity up to 267.1 GHz/RIU for S. aureus measurement. Hence, the flexible, easy manufacturing, and highly-sensitive quasi-BIC metasurface biosensor paves a new way toward developing novel bacteria sensors and BICs-related optoelectronic devices.
{"title":"Flexible Terahertz Metasurface Supporting Bound State in the Continuum for Refractive Index Based Staphylococcus Aureus Sensing","authors":"Zijie Dai;Can Yan;Ying Liang;Jitao Li;Xiaoxian Song;Jingjing Zhang;Zhen Yue;Zhang Zhang;Xinghua Zhu;Yunxia Ye;Xudong Ren","doi":"10.1109/TTHZ.2025.3587427","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3587427","url":null,"abstract":"<italic>Staphylococcus aureus</i> (<italic>S. aureus</i>) represents a major threat to global health, and its sensitive and accurate detection is highly demanded in disease diagnosis and food safety. Here, a flexible terahertz (THz) metasurface based on bound states in the continuum (BIC) is proposed and experimentally demonstrated for the trace analysis of <italic>S. aureus</i>. The unit cell structure incorporates a metallic square with two opening gaps, supporting a resonance transition from BIC to quasi-BIC states by introducing a symmetry perturbation to one opening gap location. First, the refractive index (RI) spectra of the drip-dried <italic>S. aureus</i> solution at different concentrations are characterized using THz-TDS. The frequency point possessing a maximum linearity between RI and <italic>S. aureus</i> concentrations is selected as the resonance frequency of designed sensing quasi-BIC. Moreover, an experimental demonstration of the sensing performance is conducted by monitoring spectral evolution after target loading. The measured results indicate that the constructed biosensor exhibits a detection limit down to 200 cfu/mL and RI sensing sensitivity up to 267.1 GHz/RIU for <italic>S. aureus</i> measurement. Hence, the flexible, easy manufacturing, and highly-sensitive quasi-BIC metasurface biosensor paves a new way toward developing novel bacteria sensors and BICs-related optoelectronic devices.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 6","pages":"1041-1047"},"PeriodicalIF":3.9,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145435675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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