Last updated in 23th, November
Titles and abstracts of presentation can be found below the list.
|First name||Last name||Title||Affiliation & Email|
|1||Ting-Hang||Pei||Terahertz Microlamp-Light Source for the Detector Calibration of the SAFARI Instrument in SPICA Project||Academia Sinica
|3||Chao-Te||Li||Developing a cryogenic diplexer for wSMA||ASIAA
|4||CHUN-LUN||WANG||High Performance THz Integrating Sphere||Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan
|5||Hsiao Wen||Chang||Densely Rotational Twins in Epitaxial Superconducting δ-NbN on 4H-SiC Substrates||Academia sinica
|6||Akira||Kawakami||Fabrication of 2 THz Wave-guide Type Hot Electron Bolometer Mixer||NICT Japan
|7||Yoshihisa||Irimajiri||Development of a waveguide-type hot electron bolometer mixer (HEBM) at 2 THz||NICT
|8||Hajime||Ezawa||National Astronomical Observatory of Japan
|9||Shohei||Ezaki||Development of Vacuum Windows with Anti-reflection Structures||National Astronomical Observatory of Japan
|10||Makoto||Nagai||Design of correlation polarimeter with superconducting circuit for Radio Point Diffraction Interferometer||NAOJ
|14||Tac||Nakajima||Research on a Next-Generation Ground-Based Millimeter-Wave Atmospheric Radiometer||Nagoya University
|16||Wenlei||Shan||A Millimeter-wave Multibeam Receive Implemented with Superconducting MMICs||National Astrononmical Observatory, Japan
|17||Jihoon||Choi||Axion Dark Matter Search around 6.7 μeV||KASI
|18||T.S.Sachin||Venkatesh||Delhi Technological University
|19||Daekeun||Yoon||National Chiao Tung University
|20||Sooyeon||Kim||Design of Oscillator in 65 nm CMOS Technology||ETRI
|21||Wei||Liu||Purple Mountain Observatory
|22||Naeun||Shin||Seoul National University
|23||Taehyun||Jung||Korean VLBI Network (KVN): Current Status and Future Plan||Korea Astronomy and Space Science Instit ute
|24||Jongsoo||Kim||GPU Spectrometer for the ALMA Total Power Array||KASI
|25||Seog-Tae||Han||The development of the compact triple band receiver for Italian radio telescopes||KASI
|26||Kee-Tae||Kim||Mid-term Development Plan of KASI Radio Astronomy Division||KASI
|27||JiangQiao||Ding||High Efficiency and Powerful 260-340Ghz Frequency Doublers based on Schottky Diodes||Purple Mountain Observatory|
|28||Wen||Zhang||Optical/infrared superconducting transition-dege single photon detectors||Purple Mountain observatory|
|29||Zhi||Li||IQ Mixer Calibration for 8x8 Al MKIDS Detection||Purple Mountain Observatory|
|30||Zheng||Lou||Purple Mountain Observatory|
|31||Yuan||Ren||Enhanced two-dimensional phase gratings at terahertz frequencies||Purple Mountain Observatory
|32||YENPIN||CHANG||Sub-millimeter Wave Devices on Thin Silicon Substrates||Institute of Astronomy and Astrophysics, Academia Sinica, Taipei Taiwan
|33||Ayako||Niwa||Development of Compact 0.8 K Sorption Coolers for THz Photon Counting Detectors||University of Tsukuba
|34||Ming-Jye||Wang||The Current Status of wSMA Receiver||AISAA
|36||Keiko||KANEKO||National Astronomical Observatory of Japan
|37||Ryo||Sakai||Development of a measurement system for permittivity materials in millimeter-wave band and verification of validity of the measurement results||National Astronomical Observatory of Japan
|45||Kazushige||Ohtawara||ALMA Project, NAOJ
|47||Sho||Masui||Osaka Prefecture University
|49||Ryohei||Kawabe||Recent Progress of LST and AtAST projects||
The SAFARI of SPICA, an imaging Fourier transform spectrometer  on a proposed IR space telescope, requires a radiation source at THz for calibrating the transition-edge sensor regularly. Due to the limitation of thermal loading (total power < 1mW), the regular cavity-type black body is not adequate as the hot source for the calibration. We designed and fabricated microlamps, a hot micro-island suspended by long and thin legs is necessary to fulfill the requirement of calibration source of SAFARI . The microlamps consist of a micro-island (260x260 μm2) with film heater and four SiNx legs which connect to the thermal reservoir (Si chip). The microlamp can be heated up to a temperature higher than 150 K at base temperature of 4K with a power of several tens μW. The time constants of fabricated microlamps switching between different temperatures are around a couple of hundred milliseconds, which are too long for the requirement of modulation. Shorter legs are necessary to reduce the time constant. We also simulated the temperature distribution of the microlamp and legs at transit and steady state by a commercial software, ANSYS. With the thermal properties of materials, we had simulation results consistent with experimental data in terms of required heating power and time constant. Based on the simulation, the radiation power of microlamp with leg length of 300 μm, the radiation power is less 5% and 10% than the idea values at temperature of 80 K and 22.8 K. This simulation model will be used for the design of microlamp with optimized radiation power and time constant. Reference: . W. M. Laauwen, C. de Jonge, L. Ferrari, and P. Dieleman, A Calibration Source For SAFARI on-ground Calibration – Design and Design Supporting Tests. https://asd.gsfc.nasa.gov/conferences/FIR/posters/Roelfsema_SAFARI-Calibration.pdf . Ming-Jye Wang and SPICA-Taiwan Team, SPICA and Taiwan Participations, Annual Meeting of the Physical Society of Taiwan (2020).
To exploit more IF bandwidth of wSMA, a diplexer is proposed to separate the current 4 to 16+ GHz IF and that below 4 GHz. A configuration of low pass/high pass filters, instead of low pass/band pass, would be adopted due to the large bandwidth (~ 16 GHz) above 4 GHz. For a good out of band rejection, high impedance ratios and more sections would be used. To reduce loss, superconducting materials would be applied.
The SAFARI/SPICA, a proposed IR space telescope, requires a radiation source for calibrating the transition-edge sensor regularly. In order to offer a spatially uniform light source covering the full dynamic wavelength range (30-250 um), integrating sphere working at terahertz (THz) is essential. We have developed high performance integrating spheres operating at 1~10 THz. Early report from SRON group, Netherlands, revealed strong absorption of integrating sphere with sandblasted and gold plated aluminum surface . The performance of integrating sphere is significantly improved by introducing a aluminum wet-etch process. In this presentation, we show the fabrication details of our integrating sphere working at 1-10 THz. The 3D topography of the surface demonstrates that the complex substructure, causing the strong surface absorption, were removed by the wet-etch process. The FFT (fast Fourier transform) analysis of line profile confirms the significant reduction of FFT amplitude in the FFT wavelength of 7-100 um. The surface reflectance of the surfaces with wet-etch process is 0.91 which is close to the reflectance of flat gold surface of 0.96 and much larger than that without wet-etch (0.67). The output uniformity of the integrating sphere with wet-etch process was measured by a scanning system. The detected spatial distribution is consistent with the simulation result based on spatially uniform radiation power at the output port, indicating that the scattering on the inner surface is Lambertian-like. Reference:  Laauwen, W. M., de Jonge, C., Ferrari, L. & Dieleman, P. (2014, May 12-13). A Calibration Source for SAFARI on-ground Calibration - Design and design supporting tests - [Poster presentation]. Mission Concepts and Measurement Requirements for a Future Far-Infrared Space Mission, Goddard Space Flight Center, NASA, Greenbelt, Maryland, U.S. (https://asd.gsfc.nasa.gov/conferences/FIR/posters/Roelfsema_SAFARI-Calibration.pdf)
The superconductivity of hexagonal ε-NbN was reported recently . A reported Tc of 11.6 K in hexagonal ε-NbN powder prepared under 10 GPa pressure. Kou et. al. calculated the band structures of NbN polymorphs and found that the ε-NbN should be an insulator with topological properties . To date, no further reports on the superconductivity of ε-NbN are published. We intentionally deposited NbN film on (0001) 4H-SiC substrate, with good lattice match, at 750°C by magnetron sputtering method to grow the hexagonal NbN superconductor. Rather than the hexagonal ε-NbN, the deposited films are identified as (111)-orientated δ-NbN phase with densely rotational (60°) twins. The HRTEM and HAADF-STEM images confirm the existence of nano-twins in the (111)-orientated δ-NbN film. Odd diffraction spots in SAED images are reconstructed through the vector analysis method of the double diffraction model . Having high density of twin in (111)-orientated δ-NbN film is natural because of no preference in bonding energy with the Si-face substrate for both rotational twins. In comparing with the (001)-orientated δ-NbN films, the (111)-orientated δ-NbN films have a higher normal state resistivity and lower Tc. Their Tc, normal state resistivity, and thickness follow the scaling law well but with a larger coefficient . The STM results show excellent spatial uniformity of superconducting energy gap although the deposited (111)-orientated δ-NbN films have densely rotational twins.  Y. Zou, X. Qi, C. Zhang, S. Ma, W. Zhang, Y. Li, et al., "Discovery of Superconductivity in Hard Hexagonal epsilon-NbN," Sci Rep, vol. 6, p. 22330, Feb 29 2016.  K. R. Bahu and G.-Y. Guo, "Electron-phonon coupling, superconductivity, and nontrivial band topology in NbN polytypes," Phys. Rev. B, vol. 99, 104508, 2019.  L. A. Tietz, C. B. Carter, and S. McKernan, "Top-bottom effects in double diffraction," Ultramicroscopy, vol. 60, pp. 241-246, 1995.  Y. Tao, "Scaling Laws for Thin Films near the Superconducting-to-Insulating Transitio," Sci. Rep., vol. 6, 23863, 2016.
We are working to develop a 2 THz-band waveguide-type Ni-HEBM by using Si3N4 membrane structure. The mixer is built on a 55 μm-wide, 800 μm-long, and 1 μm-thick silicon nitride thin-film bridge, which is supported by a 200 μm-thick silicon frame. Fabrication methods and I-V characteristics of waveguide-type Ni-HEBM will be described.
We are developing a waveguide-type HEBM (Hot Electron Bolometer Mixer) at 2 THz in collaboration with ASIAA. I will talk about the current status of the development of the WG-type HEBM mainly on the design(HFSS simulation), fabrication of the mixer mount, and chip alignment.
We have been developing vacuum windows with antireflection (AR) structures for sub-millimeter wave receivers. We designed and fabricated the AR structures on a high resistivity silicon surface by using a deep reactive ion etching. A silicon on insulator (SOI) wafer was introduced for the highly uniform AR structures. The AR structure height can be precisely controlled because of the buried oxide layer of the SOI wafer which stops the device layer silicon etching. In this presentation, we will report the fabrication processes and the optical characteristics of the AR structures.
Radio point diffraction interferometer (RPDI) is a new type of point diffraction interferometer in radio frequency. RPDI is proposed for mirror surface measurement of submilimeter and THz telescopes. Setup of RPDI consists of a polarizer with a pinhole (PP) and a detector array. The PP makes a test beam and a reference beam whose polarizations are orthogonal while the detector array produces interferogram images with different phase shifts. We are developing a correlation polarimeter with superconducting circuit, which can be a pixel of an RPDI detector array. In this presentation, we will show a design of a correlation polarimeter at 100 GHz.
Microwave remote sensing for atmosphere was started in 1980s, and that was also started in Nagoya University at the same time. The instrument and technique of observation with microwave radiometer are based on those in radio astronomy. In fact, our millimeter-wave atmospheric radiometers are almost same design with astronomical radio telescope. Recently, some new remarkable technologies and techniques in the millimeter-wave have been proposed and applied to the receiver in worldwide radio telescopes. I am making an attempt to apply the new ideas to a next-generation radiometer based on such newly developed technologies and techniques. In this presentation, I will talk about the important parameters to reach for realization of the new radiometer and will introduce some ideas to improve the accuracy and efficiency of observation.
This presentation is concerned with the experimental evidence that proves technical feasibility of the hybrid planar integration (HPI) scheme to construct SIS mixer focal plane arrays of unprecedented compactness. The scheme is characterized by the adoption of silicon membrane-based waveguide probes, which allows superconducting monolithic microwave integrated circuits (MMICs) to couple signal and LO from CNC-machined waveguides through multiple paths. A 2 x 2 dual-polarization balanced SIS mixer array has been implemented with this scheme and assessed at 2 mm wavelengths. This compact array has demonstrated uniform LO distribution and low crosstalk between pixels. The RF performance of component pixels has been confirmed to be little affected by the high degree integration. The potential implementation of the HPI scheme at THz frequencies is also discussed.
A 270 GHz triple-push ring oscillator with coupled lines was designed and measured in a 65 nm CMOS process. A design procedure focusing on the single unit amplifier is explained, and this method uses power-dependent Z-parameters of transistors. In addition, triple-push sub-harmonic injection-locked ring tripler is described. The circuit employs a tri-layer double coupled line, which is composed of three layers of metal stack. The injection through the tri-layer dual coupled line structure reduces the Q-factor, widening a locking range.
As a dedicated mm-VLBI facility, the Korean VLBI Network (KVN) equips a multi-frequency receiving system enabling observations at 22, 43, 86 and 129 GHz simultaneously and carries out VLBI observations by itself or with other network and telescopes. In this talk, we will introduce current activities and future plans of the Korean VLBI Network.
The feature size of device for microwave frequency application is usually proportional to the wavelength, which can be made by the precision CNC machine. As the wavelength becomes shorter, the difficulty and cost of machining increase dramatically. The demand of devices at sub-mm wavelength, such as orthogonal mode transducer (OMT), directional coupler, power combiner, and other passive components, grows quickly in astronomical instrument. Fabricating such devices massively and cheaply are an important issue. We have developed the fabrication process of sub-mm devices on the thin silicon substrate. Such devices are mounted in the host blocks with lower machining precision requirement. Furthermore, the properties of whole device can be adjusted by replacing the chip with different design parameters. The fabricating process of device on thin silicon substate combines the techniques of deep silicon etching, mechanical lapping and polishing, and the regular RIE etching. The deep silicon etching process can ensure the dimension of silicon substrate with accuracy better than 1 um. Mechanical lapping/polishing process incorporating with regular RIE can push the thickness accuracy better than 2 um. Two kinds of devices have been fabricated successfully, attenuator and directional coupler. These devices have been tested and demonstrate excellent performance at frequency bands of 230 and 340 GHz and will be used in the new receiver of sub-millimeter Array (SMA). In this presentation, we will describe the details of fabricating process and the performance of deviecs. Reference: Lingzhen Zeng, Wei-Chun Luy, Paul K. Grimes, Tse-Jun Cheny, Yen-Pin Changy, C. Edward Tong Member, IEEE and Ming-Jye Wangy ”A Silicon Chip-Based Waveguide Directional Coupler for Terahertz Applications” IEEE Transactions on Terahertz Science and Technology, pp. 698-703, November 2020.
Radio astronomy, especially THz, requires high resolution observation. THz intensity interferometry makes images by photon bunching using photon counting detectors to identify a single photon. This detector becomes the best sensitivity below at 0.8 K and generates 200 µW at cryogenic readout circuit. Our compact sorption cooler kept approximately 0.70 K for over three hours and has 400 µW cooling capacity at 0.80 K. We plan to extend duration time by running two of this cooler alternately. This talk shows that coolers have enough duration time for alternating operation even when 200 µW is applied.
The SubMillimeter Array (SMA) is the first interferometer with 8 six-meter dishes operating at sub-millimeter wavelength. Some receivers have served more than 20 years with upgrades gradually. To keep the SMA competitive, new cryostats and receivers will be constructed with the latest technologies. The new SMA receiver will have wide IF-bandwidth (4-18 GHz, 0.5-20 GHz optional), so called wSMA receiver. Two cartridge-type receivers cover the low band (240GHz) and high band (320GHz) with dual polarization capability. A selecting wheel provides the different observation modes. In this presentation, I will report the current status of the wSMA.
We are developing a system to measure the dielectric properties in order to improve the design accuracy of the receiver optical system. In this study, in order to verify the validity of the developed measurement system, the beam pattern measurement results of the optical system consist of the lens which designed using measured permittivity are compared with the beam pattern simulation results using commercial software, WASP-NET. The measurement result of the beam pattern and antenna efficiency were in good agreement with simulation results, demonstrating the validity of the dielectric constant obtained by the developed measurement system. Moreover, the results of this analysis also suggest that the error in the design value of the permittivity of the lens has a significant effect of the antenna efficiency, emphasizing the importance of accurate permittivity measurement in optical system design.
Axion is one of the dark matter candidates that can solve the strong CP problem. Axion dark matter can be converted into photons under a strong magnetic field. P. Sikivie proposed an experiment for axion search using microwave resonance cavities applied with an external magnetic field, and many experiments are attempting to search for axion. The CAPP-8TB experiment performed in IBS/CAPP is one of the axion dark matter search experiments, dedicated to a mass around 6.7 ueV is presented. The experiment aimed the most sensitive axion dark matter search in this axion mass range, where the sensitivity could reach the QCD axion band. In this presentation, we discuss the overview of the experiment and present the result. We will also discuss ways to improve the efficiency and sensitivity of axion search experiments.
The development project of the ACA (Atacama Compact Array) Spectrometer based on GPU technology is led by the KASI (Korea Astronomy and Space Science Institute) in collaboration with the NAOJ (National Astronomical Observatory of Japan). The project successfully finished the CDMR (Concept Design and Manufacturing Review) on October 2020. The ACA Spectrometer is supposed to be used for science from Cycle 9. The ACA Spectrometer is designed to provide auto-correlation power spectra for science targets and cross-correlation outputs for calibrations of the Total Power Array. The hardware of the ACA Spectrometer is composed of 4 GPU servers. Each server has 4 NVIDIA TITAN V cards and two data acquisition cards, all of which are plugged into the PCIe (Peripheral Component Interconnect Express) slots of the server. One GPU card has enough performance to process the 2 GHz bandwidth of one baseband pair. The prototype of the ACA Spectrometer successfully obtained SiO spectral lines using Nobeyama 45-m Telescope.
The compact triple band receiver system has been developing under the mutual collaboration between INAF, Italy and KASI, Korea. Those will be installed on the 64 m Sardinia radio telescope, 32 m Noto and Medicina radio telescopes, respectively. It enables simultaneous observations in the three frequency intervals K(18–26 GHz/8 GHz IF bandwidth) band, Q(34–50 GHz/16 GHz IF bandwidth) band, and W(85–116GHz/32 GHz IF bandwidth) band. An integrated quasi-optical circuit incorporating a more compact triple-band receiver in single cryostat is chosen in order to circumvent difficulties in installation and beam alignment. A frequency-independent quasi-optical circuit for each band is adopted to obtain constant aperture efficiency as a function of the observed frequencies. We present the design details of the compact wideband quasi-optical circuit and the properties of the triple-band receiver optimized for simultaneous multi-frequency observations. It is expected that it dedicates to conduct the millimeter wave VLBI and Sun observations.
High efficiency and accuracy phase gratings are of crucial importance for large format heterodyne array receivers at terahertz frequencies. Here, by developing a design approach that can create gratings with arbitrary two-dimensional diffraction distributions, we have realized a reflective metallic phase grating that generates 2×2 diffraction beams at 0.85 THz. The measured total power efficiency of the diffraction beam pattern is 81.9%, which demonstrates at least 17% improvement in efficiency compared with the standard 2D Fourier phase grating.
Superconducting transition-edge (TES) single-photon detectors exhibit high detection efficiency and photon-number resolving capability at optical and infrared wavelengths, and they have been applied in astrophysics, quantum information, biologic imaging. Here we are developing titanium-based superconducting TES single photon detectors at three wavelengths ( 450, 780 and 1550 nm). Our TES can revolve at least 9 photons at 450 nm with an energy resolution (ΔEFWHM) of 1.62 eV while ΔEFWHM is reduced to 0.75 eV at 780 nm. We integrated an optical cavity, which makes the absorption efficiency is as high as 90%. The measured system detection efficiency is 65% with ΔEFWHM of 0.51eV. Higher detection efficiency will be expected for better absorption and alignment of single-mode fiber to TES.
We are proposiing future 50-m class submillimeter single disk telescopes in Japan and Europe and planning to built united single disk telescope jointly at the ALMA pleateau; i.e, Large Submillimeter Telescope (LST) in Japan, and Atacama Large Aperture Telescope (AtLAST) in Europe. We will report on the recent progress of activities in both sides.