Integral Submillimeter-Wave Spectrometers
Development and Study of Integrated Receivers for Operation Frequencies 0.5-1 THz
Tech Area / Field
- ENV-MIN/Monitoring and Instrumentation/Environment
- INS-DET/Detection Devices/Instrumentation
- PHY-RAW/Radiofrequency Waves/Physics
- PHY-SSP/Solid State Physics/Physics
8 Project completed
Senior Project Manager
Mitina L M
Russian Academy of Sciences / Institute of Radioengineering and Electronics, Russia, Moscow
- Institute of Physics of Microstructures, Russia, N. Novgorod reg., N. Novgorod
- Space Research Organization Netherlands, The Netherlands, Utrecht\nChalmers University of Technology, Sweden, Göteborg\nTechnical University of Denmark, Denmark, Copenhagen\nUniversity of Erlangen-Nurnberg, Germany, Erlangen
Project summaryLightweight and compact ultra sensitive superconducting integrated receivers (SIRs) are very attractive for remote monitoring of the Earth atmosphere using air-crafts, balloons and satellites, where low weight, low power consumption and limited volume are vitally required. Remote study of atmospheric pollution is possible using onboard submm wave spectrometers for detection of the spectral lines of ozone, chlorine and other elements. It is worth noticing that successful completing of this program will allow the Integrated Spectrometer to be used both in the laboratory and for distant monitoring of the atmosphere to detect different contaminations and Chemical Warfare Agents (CWA). As a result of the project new methods and equipment for detection of the complicated chemical compounds (like components of the chemical weapons and explosive substances) will be developed; expected sensitivity of this method will allow the measurements of these substances on the level down to 10-7.
The main project objective is to develop and test a family of integrated superconducting quantum-limited high-resolution receiver for submm wave frequencies (up to 1 THz). The concept of submm Superconducting Integrated Receiver (SIR) has been developed and experimentally proven in collaboration between IREE and SRON. The SIR is a single-chip device, which comprises an SIS-mixer with a quasioptical antenna and a superconducting local oscillator (flux-low oscillator, FFO). A prototype of an airborne integrated spectrometer with a noise temperature close to the quantum limit hf/k, intended for monitoring ozone, chlorine compounds and industrial contaminants in the atmosphere is under development. The desired parameters of this instrument are as follows: frequency range 500-650 GHz, noise temperature (DSB) below 250 K, spectral resolution better than 1 MHz. An important application of this spectrometer will be a heterodyne balloon mission launched to study the Earth atmospheric chemistry and physics in the Terahertz limb-sounding mode (TELIS). The TELIS project is a pre-cursor for future satellite space missions.
Integrated receivers developed in the course of the project realization would be a prototype for planned missions aimed at the investigation of submm radiation using space borne radio telescopes. It is important that new ambitious radio-astronomy multi-dish ground-based projects (like ALMA) would benefit from using single chip spectrometers due to their lower price and better serviceability in comparison with conventional approaches. There is also a large niche for applications of Integrated Receivers for the detection of radiation from the newly developed semiconducting and superconducting sources of submm waves. This receiver would detect radiation as weak as 10-12 W in the frequency range 300-700 GHz (provided exchangeable Integrated Receiver chip mounts). When mass-produced the estimated cost of a microcircuit for an Integrated Spectrometer would be of the order of 1000 USD, much lower than 20-25,000 USD presently paid for a conventional oscillator in this frequency range, usually based on a BWO with powerful magnet and high-voltage power supply or a Gunn oscillator with a harmonic multiplier. Mass production of integrated spectrometers gives a chance for their application for analysis of the breathed out air at medical survey. Spectral lines mostly important for medical analysis can be detected at adsorption of submillimeter waves.
Participants of the project have long-term experience of joint development and application of high sensitive receivers of mm and submm waves on the basis of SIS junctions. For example, the SIS receiver created in IAP-IPM on the base of SIS mixers made at IREE was used for observations on radio telescope in Crimea. In cooperation with National Institute of Space Researches of the Netherlands the quasioptical SIS receiver based on Nb-AlOx-Nb junctions with aluminum tuning structures has been developed and tested. For frequency of 930 GHz the noise temperature (DSB) of 250 K has been measured, that was the best of all published results. Together with National Institute of an Industrial Science and Technology (Tsukuba, Japan) the researches of integrated receiving structures on the basis of NbN films are started. Part of the IREE team from MPSU is the recognized leader in development of low noise HEB mixers (based on the effect of electron heating in superconductors) for frequencies up to 5 THz. Recently MPSU (together with Harward-Smithsonian Center for Astrophysics) has manufactured and installed the waveguide receiver with the central frequency of 1.037 THz on 10-meter radio telescope of a submillimeter observatory (Arizona, USA).
There are some reasons, which limit the working frequency of superconducting circuits with Nb-AlOx-Nb junctions and niobium matching structures below 700 GHz. First, energy of photons at frequencies higher than 700 GHz exceeds the superconducting gap of Nb; it results in essential losses in Nb matching structures. Second, for working frequencies of about 1 THz junctions of sub-micron size with very high current density ( > 104 А/cm2) are required. Till now the problem of producing of high quality Nb-AlOx-Nb junctions with such parameters and reasonable yield is still unsolved. Thus, for substantial increase of sensitivity of 1 THz receivers both the essential reduction in losses in matching structures due to use of superconducting NbN films, and use of SIS junctions with high current density on the basis of AlN barriers are required. An ultimate goal of the project is manufacturing and study of all basic elements of the integrated receiver for frequencies up to 1 THz.
To accomplish all these tasks the following researches will be carried out:
· Development and optimization of technological process for Nb-AlN-Nb tunnel junctions’ fabrication. Development of the process for fabrication of Nb-AlN-Nb junctions of sub-micron size using methods of direct electron beam lithography (EBL) and chemical-mechanical polishing (CMP).
· Development and optimization of the process for sputtering of NbN thin films with critical temperature of 15 K as well as for Nb-AlN-NbN and NbN-AlN (MgO)-NbN junctions fabrication. The purpose is fabrication of junctions, which are efficient at frequencies up to 1 THz.
· Fabrication and study of long Josephson junctions (FFO) with NbN electrodes for further implementation as integrated local oscillator, capable of pumping of an SIS mixer. Study of a possibility of integration of an FFO with low noise HEB mixer based on effect of electron heating.
· Development and numerical simulation of mixing elements with working frequency up to 1 THz, calculation of parameters for matching circuits. Design and numerical simulation of superconducting integrated circuit for operation frequencies up to 1 THz.
· Development and verifications of the methods for detection of the complicated chemical compounds (including the components of chemical weapons and explosive substances); the goal is to improve sensitivity of this method down to 10-7.
There are a number of new approaches in the basis of this proposal. The idea of integration of different superconducting components in a single-chip integrated receiver has been developed by IREE scientists. This concept has been experimentally proven in collaboration of the SRON and IREE. A novel and reliable technique, recently proposed by project groups, will be used for precision linewidth measurements and phase locking of superconducting oscillator. One of the project issues is a further development of the method for the microwave spectroscopy of rotary and oscillatory molecules spectra, which provides the best sensitivity and spectral resolution. It is enough to register only one line of absorption for unambiguous identification of substance and its analytical investigation.
It is important to emphasize that most of the project study will be done in the collaboration with the leading western scientific institutions, which are interested in project results and will provide their own unique technological and measuring facilities for project execution (see appended Letters of Support). Unique microwave cryogenic measuring set-ups available at National Institute of Space Researches (Groningen, the Netherlands - SRON), Technical University of Denmark (Lyngby), Chalmers University of Technology (Gothenburg, Sweden) and National Institute of an Industrial Science and Technology (Tsucuba, Japan) will be involved. Furthermore, some of the foreign collaborators are ready to supply Russian partners (using the ISTC infrastructure) by a set of modern equipment in case of funding of the project by ISTC.
The project undoubtedly fits the aims and tasks of ISTC. It allows a large group of Russian scientists and engineers from IREE and IPM, having great knowledge and qualification in development of military applications, to be reoriented completely onto the peaceful applications. Thereby any possibilities of contacts with the developing countries on transferring special knowledge and research results for military applications will be completely cancelled.
The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.
ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.