Kinetic inductance in thin film superconductors has been used as the basis for low-temperature, low-noise photon detectors. In particular thin films such as NbTiN, TiN, NbN, the kinetic inductance effect is strongly non-linear in the applied current, which can be utilized to realize novel devices. We present results from transmission lines made with these materials, where DC (current) control is used to modulate the phase velocity thereby enabling an on-chip spectrometer. The utility of such compact spectrometers are discussed, along with their natural connection with parametric amplifiers.
Spectral characterization and performance of SPT-SLIM on-chip filterbank spectrometers
University of Chicago（芝加哥大学）；Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙物理研究所）；Cardiff University（卡迪夫大学）；McGill University（麦吉尔大学）；Fermi National Accelerator Laboratory（费米国家加速器实验室）；Enrico Fermi Institute, University of Chicago（芝加哥大学恩里科·费米研究所）；Argonne National Laboratory（阿贡国家实验室）；Boston University（波士顿大学）
Superconducting On-chip Fourier Transform Spectrometers (SOFTS) are broadband, compact and electronic interferometers. Being extremely compact, SOFTS can fit into standard antenna coupled detector architectures. SOFTS will enable kilo-pixel spectro-imaging focal planes enhancing sub-millimeter science; particularly cluster astrophysics / cosmology, CMB-science and line intensity mapping. This proceeding details the development, design and bench-marking of RF on-chip architecture of SOFTS for Ka and W bands.
Terahertz spectrometers with a wide instantaneous frequency coverage for passive remote sensing are enormously attractive for many terahertz applications, such as astronomy, atmospheric science and security. Here we demonstrate a wide-band terahertz spectrometer based on a single superconducting chip. The chip consists of an antenna coupled to a transmission line filterbank, with a microwave kinetic inductance detector behind each filter. Using frequency division multiplexing, all detectors are read-out simultaneously creating a wide-band spectrometer with an instantaneous bandwidth of 45 GHz …
Systematic effects in polarizing Fourier transform spectrometers for cosmic microwave background observations
探测到宇宙微波背景（CMB）的原始B模偏振信号将为暴胀提供证据。然而，越来越清楚的是，检测这样一个微弱的信号需要一个仪器，既有宽的频率覆盖范围，以拒绝前景和良好的控制仪器系统的影响。使用偏振傅里叶变换光谱仪（FTS）进行CMB观测符合这两个要求。在这项工作中，我们提出了偏振傅里叶变换光谱仪中的仪器系统效应的分析，使用原始通货膨胀探测器（PIXIE）作为一个工作的例子。我们解析解决固有的FTS发射光学元件，未对准的光学元件，采样和相位误差，和自旋同步效应的最重要的系统效应-并证明，校正后的残留系统误差条款将全部在子nK水平，远低于预测的100 nK B模式信号。
The QUIJOTE Experiment was developed to study the polarization in the Cosmic Microwave Background (CMB) over the frequency range of 10-50 GHz. Its first instrument, the Multi Frequency Instrument (MFI), measures in the range 10-20 GHz which coincides with one of the naturally transparent windows in the atmosphere. The Tenerife Microwave Spectrometer (TMS) has been designed to investigate the spectrum between 10-20 GHz in more detail. The MFI bands are 2 GHz wide whereas the TMS bands will be 250 MHz wide covering the complete 10-20 GHz range with one receiver chain and Fourier spectral filter …
Superconducting on-chip filter-banks provide a scalable, space saving solution to create imaging spectrometers at millimetre and sub-millimetre wavelengths. We present an easy to realise, lithographed superconducting filter design with a high tolerance to fabrication error. Using a capacitively coupled $λ/2$ microstrip resonator to define a narrow ($λ/Δλ= 300$) spectral pass band, the filtered output of a given spectrometer channel directly connects to a Lumped Element Kinetic Inductance Detector (LEKID). We show the tolerance analysis of our design, demonstrating $<11\%$ change in filter qual…
A superconducting microstrip half-wavelength resonator is proposed as a suitable band-pass filter for broadband moderate spectral resolution spectroscopy for terahertz (THz) astronomy. The proposed filter geometry has a free spectral range of an octave of bandwidth without introducing spurious resonances, reaches a high coupling efficiency in the pass-band and shows very high rejection in the stop-band to minimize reflections and cross-talk with other filters. A spectrally sparse prototype filter-bank in the band 300-400 GHz has been developed employing these filters as well as an equivalent c…
SuperSpec is an on-chip filter-bank spectrometer designed for wideband moderate-resolution spectroscopy at millimeter wavelengths, employing TiN kinetic inductance detectors. SuperSpec technology will enable large-format spectroscopic integral field units suitable for high-redshift line intensity mapping and multi-object spectrographs. In previous results we have demonstrated noise performance in individual detectors suitable for photon noise limited ground-based observations at excellent mm-wave sites. In these proceedings we present the noise performance of a full $R\sim 275$ spectrometer me…
We develop a time-ordered data simulator and map-maker for the proposed PIXIE Fourier transform spectrometer and use them to investigate the impact of polarization leakage, imperfect collimation, elliptical beams, sub-pixel effects, correlated noise and spectrometer mirror jitter on the PIXIE data analysis. We find that PIXIE is robust to all of these effects, with the exception of mirror jitter which could become the dominant source of noise in the experiment if the jitter is not kept significantly below $0.1μm\sqrt{s}$. Source code is available at https://github.com/amaurea/pixie.
The SPIRE FTS Spectral Feature Finder (FF), developed within the Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) instrument team, is an automated spectral feature fitting routine that attempts to find significant features in SPIRE FTS spectra. The $^3$P$_1$ - $^3$P$_0$ and $^3$P$_2$ - $^3$P$_1$ neutral carbon fine structure lines are common features in carbon rich far-infrared astrophysical sources. These features can be difficult to detect using an automated feature detection routine due to their typically low amplitude and line blending. In thi…
Enhanced electron-beam lithography to reduce the frequency scatter of 200-400 GHz superconducting microstrip resonators for on-chip filterbank spectrometers
Delft University of Technology（代尔夫特理工大学）；SRON — Space Research Organisation Netherlands（荷兰空间研究所）；Universität zu Köln（科隆大学）
Development and validation of a cryogenic far-infrared diffraction grating spectrometer used to post-disperse the output from a Fourier transform spectrometer
Context. Millimetre-wave astronomy is an important tool for both general astrophysics studies and cosmology. A large number of unidentified sources are being detected by the large field-of-view continuum instruments operating on large telescopes. Aims. New smart focal planes are needed to bridge the gap between large bandwidth continuum instruments operating on single dish telescopes and the high spectral and angular resolution interferometers (e.g. ALMA in Chile, NOEMA in France). The aim is to perform low-medium spectral resolution observations and select a lower number of potentially intere…
The ESA Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF) project is an automated spectral feature fitting routine developed within the SPIRE instrument team to extract all prominent spectral features from all publicly available SPIRE FTS observations. In this work, we demonstrate the use of the FF information extracted from three observations of the edge-on spiral galaxy NGC 891 to measure the rotation of NII and CI gas at Far-infrared frequencies in complement to radio observations of the HI 21cm line and the CO(1-0) …
In this study, a novel type of Fourier transform radio spectrometer (termed as all-digital radio spectrometer; ADRS) has been developed in which all functionalities comprising a radio spectrometer including a sampler and Fourier computing unit were implemented as a soft-core on a field-programmable gate array (FPGA). A delay-line-based ramp-compare analog-to-digital converter (ADC), one of completely digital ADC, was used, and two primary elements of the ADC, an analog-to-time converter (ATC) and a time-to-digital converter (TDC), were implemented on the FPGA. The sampling rate of the ADRS $f$…
The Herschel SPIRE FTS Spectral Feature Finder (FF) detects significant spectral features within SPIRE spectra and employs two routines, and external references, to estimate source radial velocity. The first routine is based on the identification of rotational CO emission, the second cross-correlates detected features with a line template containing most of the characteristic lines in typical far infra-red observations. In this paper, we outline and validate these routines, summarise the results as they pertain to the FF, and comment on how external references were incorporated.
We present an overview of SITELLE, an Imaging Fourier Transform Spectrometer (iFTS) available at the 3.6-meter Canada-France-Hawaii Telescope. SITELLE is a Michelson-type interferometer able to reconstruct the spectrum of every light source within its 11' field of view in filter-selected bands of the visible (350 to 900 nm). The spectral resolution can be adjusted up to R = 10 000 and the spatial resolution is seeing-limited and sampled at 0.32 arcsec per pixel. We describe the design of the instrument as well as the data reduction and analysis process. To illustrate SITELLE's capabilities, we…
We describe an update to the Herschel-SPIRE Fourier-Transform Spectrometer (FTS) calibration for extended sources, which incorporates a correction for the frequency-dependent far-field feedhorn efficiency, $η_\mathrm{FF}$. This significant correction affects all FTS extended-source calibrated spectra in sparse or mapping mode, regardless of the spectral resolution. Line fluxes and continuum levels are underestimated by factors of 1.3-2 in the Spectrometer Long-Wavelength band (SLW, 447-1018 GHz; 671-294 $μ$m) and 1.4-1.5 in the Spectrometer Short-Wavelength band (SSW, 944-1568 GHz; 318-191 $μ$…
We have constructed a Fourier-transform spectrometer (FTS) operating between 50 and 330 GHz with minimum volume (355 x260 x64 mm) and weight (13 lbs) while maximizing optical throughput (100 $\mathrm{mm}^2$ sr) and optimizing the spectral resolution (4 GHz). This FTS is designed as a polarizing Martin-Puplett interferometer with unobstructed input and output in which both input polarizations undergo interference. The instrument construction is simple with mirrors milled on the box walls and one motorized stage as the single moving element. We characterize the performance of the FTS, compare th…
A 3D-Printed Millimeter-Wave Inline Waveguide-to-Coplanar-Waveguide Transition to Enable Dense Spectrometer Arrays for Intensity Mapping Surveys
University of Chicago（芝加哥大学）；Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙物理学研究所）；Dept. of Physics, University of Chicago（芝加哥大学物理系）；Dept. of Astrophysics, University of Chicago（芝加哥大学天体物理学系）；Argonne National Laboratory（阿贡国家实验室）；Dept. of Aeronautics and Astronautics, Massachusetts Institute of Technology（麻省理工学院航空航天系）；NVIDIA Corporation（英伟达公司）
The ESA Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF) project is an automated spectral feature fitting routine developed within the SPIRE instrument team to extract all prominent spectral features from all publicly available SPIRE FTS observations. We present the extension of the FF to include the off-axis detectors of the FTS in sparsely sampled single-pointing observations, the results of which have been ingested into the catalogue. We also present the results from an automated routine for identifications of the a…
The Fourier transform spectrometer (FTS) is a core instrument for solar observation with high spectral resolution, especially in the infrared. The Infrared System for the Accurate Measurement of Solar Magnetic Field (AIMS), working at 10-13 $μm$, will use a FTS to observe the solar spectrum. The Bruker IFS-125HR, which meets the spectral resolution requirement of AIMS but just equips with a point source detector, is employed to carry out preliminary experiment for AIMS. A sun-light feeding experimental system is further developed. Several experiments are taken with them during 2018 and 2019 to…
Calibration of the Herschel SPIRE Fourier Transform Spectrometer
Herschel SPIRE仪器由成像光度照相机和成像傅里叶变换光谱仪（FTS）组成，两者都在450-1550 GHz的频率范围内工作。在本文中，我们简要地回顾了FTS的设计，操作和数据处理，并详细描述了相对校准（去除仪器签名）和绝对校准对标准天文源的方法。校准方案假设一个空间扩展的源，并使用赫歇尔望远镜作为主要的校准器。从扩展到点源校准的转换是使用天王星的观测进行的。望远镜发射的模型被证明是精确到6%以内，可重复性好于0.06%，与火星和海王星的模型相比，天王星模型被证明是精确到3%以内。对多个点源的多次观测表明，在校正卫星绝对指向误差（APE）的影响后，定标的重复性优于1%。卫星APE导致导出的通量减少，在任务的第一部分中，在SPIRE范围的高频端，其可以高达~10%（1 sigma），并且在Herschel操作第1011天之后为~4%。由于较大的波束尺寸，SPIRE频带的较低频率范围不受此指向误差的影响。总体而言，对于指向良好的点状源，绝对通量校准优于6%，对于需要映射的扩展源，绝对通量校准优于7%。
We describe the Fourier Transform Spectrometer (FTS) used for in-field testing of the POLARBEAR receiver, an experiment located in the Atacama Desert of Chile which measures the cosmic microwave background (CMB) polarization. The POLARBEAR-FTS (PB-FTS) is a Martin-Puplett interferometer designed to couple to the Huan Tran Telescope (HTT) on which the POLARBEAR receiver is installed. The PB-FTS measured the spectral response of the POLARBEAR receiver with signal-to-noise ratio (SNR) $>20$ for $\sim$69% of the focal plane detectors due to three features: a high throughput of 15.1 steradian cm$^{…
We provide a detailed description of the Herschel-SPIRE Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF). The FF is an automated process designed to extract significant spectral features from SPIRE FTS data products. Optimising the number of features found in SPIRE-FTS spectra is challenging. The wide SPIRE-FTS frequency range (447-1568 GHz) leads to many molecular species and atomic fine structure lines falling within the observed bands. As the best spectral resolution of the SPIRE-FTS is ~1.2 GHz, there can be significant line blending, depending on the source type. In order…
SuMAC: On-sky demonstration of multi-pixel on-chip millimeter-wave spectroscopy at the Large Millimeter Telescope
Cardiff University（卡迪夫大学）；Jet Propulsion Laboratory（喷气推进实验室）；Dalhousie University（达尔豪斯大学）；Instituto Nacional de Astrofísica, Óptica y Electrónica（国家天体物理学、光学和电子学研究所）；California Institute of Technology（加州理工学院）；Boston University（波士顿大学）；The University of Chicago（芝加哥大学）；University of California Santa Barbara（加州大学圣巴巴拉分校）
