Peter H. Siegel

Faculty Associate: Engineering and Applied Science
Senior Scientist: Beckman Institute, Division of Biology
Technical Supervisor: Submillimeter Wave Advanced Technology
Senior Research Scientist: Jet Propulsion Laboratory

B.A. Astronomy, 1976, Colgate University, Hamilton, NY
M.S. Physics, 1978, Columbia University, NY
Ph.D. Electrical Engineering, 1983, Columbia University, NY

Email contact phs AT caltech DOT edu

Research in Terahertz Technology and Applications: Earth and Space Science, Biology, Medicine, Defense and related Civilian opportunities

To view Dr. Siegel's current research.

Link to 33rd International Conference on Infrared, Millimeter and Terahertz Waves to be held at Caltech in September 15-19, 2008.

Background and Philosophy: Dr. Siegel’s research group specializes in the invention, development and delivery of a wide range of specialized sensor and source devices, components, and instruments spanning the frequency range between 100 and 5000 GHz which includes the millimeter, submillimeter and far infrared wavelength regimes: the terahertz bands. Emphasis is placed on a cross disciplinary approach which brings together a diverse range of backgrounds and skills that can be directly applied towards progress in bridging the electronic and optical regimes, one of the last remaining technology gaps in the electromagnetic spectrum. Students and staff working with Dr. Siegel include electrical engineers, physicists, biologists and chemists from a wide range of backgrounds and countries. Research work is conducted both at Caltech and at the nearby Jet Propulsion Laboratory, where the emphasis is on Earth, space science and planetary applications of THz technology.

Over the past 20 years Dr. Siegel and his Submillimeter Wave Advanced Technology team at JPL and Caltech have developed and delivered critical sensor hardware for four space flight missions: NASA’s Upper Atmospheric Research Satellite Microwave Limb Sounder, the first instrument to directly measure the anti-correlation between chlorine monoxide build up and ozone depletion on a global scale; NASA’s Earth Observing System Aura Microwave Limb Sounder currently measuring a wide range of stratospheric molecular species involved in ozone depletion, global water distribution, climate change and pollution monitoring across the earth; European Space Agency’s Microwave Instrument on the Rosetta Orbiter (MIRO), scheduled to rendezvous with comet Churyumov-Gerasimenko in 2014 and measure nuclear temperature and out gassing rates of carbon monoxide, water, ammonia and methanol; and most recently the Heterodyne Instrument for the Far Infrared (HIFI) on the European Space Agency’s Herschel Space Telescope, an ambitious astrophysics mission to record thousands of molecular signatures between 300 and 1900 GHz in and around star forming regions and in external galaxies, as a means of understanding the composition and evolution of the universe. Future mission opportunities include a Discovery class instrument for Venutian cloud measurements, Vesper; a Mars orbiter searching for volcanic emission and life signatures, Marvel/SIGNAL (Submillimeter Investigation of Geothermal Networks and Life); and a Europa orbiter previewing a new technique, Terahertz Radar Absorption Chemistry Experiment (TRACE) being pioneered in the SWAT group, to detect signatures from chemicals sputtered off the Europan surface by the high intensity radiation environment around Jupiter. Third generation Earth science and several new astrophysics missions are also in the near and long term planning and proposal phases.

In addition to Earth, planetary and space science, Dr. Siegel is interested in terrestrial applications of terahertz imaging and spectroscopy and has been actively pursuing several related initiatives in the health and biological sciences at Caltech as well as defense and security applications at both Caltech and JPL. The very first National Institute of Health program in the terahertz field, granted to Dr. Siegel in 2002, is just finishing up with the goal of developing high signal-to-noise imaging and spectroscopy instruments for disease diagnostics. A second THz NIH program to develop low loss terahertz waveguide for endoscopy applications is also in its final year. A proposal applying this newly established terahertz frequency and time domain instrumentation to skin cancer, in the first US health science application of terahertz in a clinical environment is currently pending. Additional work has also just begun on the thermal and non thermal effects of terahertz radiation on cellular systems. This work is being undertaken in conjunction with the Caltech biology division and a neurophysiologist at the Huntington Medical Research Institute. Significant expansion of the health science work at Caltech is planned for 2008 partially through a new National Science Foundation instrumentation grant for terahertz spectroscopy awarded to the Caltech department of astrogeochemistry (Professor Geoff Blake) which is partnered with the division of biology on the grant.

After successful responses to several recent research calls, Dr. Siegel and his group have begun applying submillimeter wave imaging to security and defense. In these applications radar techniques are being applied in the submillimeter wave frequency regime for the very first time. A new class of phenomenology and instrumentation is now emerging that shows great promise for undergarment and threat detection imaging. This application is expected to expand dramatically over the next few years with strong involvement from both JPL and Caltech.

Finally, Dr. Siegel and his research team are dedicated to the long term development of novel devices and components that can push terahertz instruments into mainstream applications. This includes in-house design and fabrication of THz superconductor and semiconductor devices, carbon nanotube based electron tube sources (high efficiency cathodes) and detectors (CNT Schottky diodes), planar array antennas and monolithic circuits as well as similar programs involving collaborations with research groups and commercial enterprises around the world.

Current Research:

THz Imaging for Biomedical Applications (Caltech): This research is funded under an NIH cross training grant, the first in this research area, and involves the application of terahertz imaging techniques to problems in the biomedical sciences. Specifically Dr. Siegel has been developing and utilizing the RF instrumentation that was pioneered under his former NASA programs for disease diagnosis, measurements of tissue properties, enhancing contrast through common biomedical staining techniques, and most recently to the impact of THz radiation on cellular processes.

THz Low Loss Flexible Waveguide (Caltech/CAS): This program is a collaboration between Caltech and California Advanced Systems (Dr. Cavour Yeh and Dr. Fred Shimabukura) to develop the first low loss dielectric based waveguide for THz applications. The work involves analysis, fabrication and testing of three types of new waveguide media specifically tailored for the submillimeter bands: ribbon guide, photonic-band gap waveguide and a new concentric cylinder guide, all based on quartz fiber technology. Dr. Nuria Llombart Juan, a Caltech post-doctoral fellow and a JPL SWAT team member, is collaborating on the task.

THz Effects on Cellular Systems (Caltech/HMRI): This new program attempts to quantitatively examine THz (and millimeter wave) radiation impact on cells and cellular processes. It blends biological, optical and RF instrumentation in a novel way to examine RF dosimetry effects while directly monitoring cell lines and will establish one of the first IR Raman/optical/RF test instruments for microscopic evaluation of thermal and chemical processes at the cellular level. A proposal to continue the work is currently in preparation with collaborator Dr. Victor Pikov, a neurophysiologist at the Huntington Medical Research Institute and Professor Jan Stake, of Chalmers University, Sweden.

THz Detection of BC & SC Carcinoma (Caltech/USC): THz imaging has already been proven to be effective in delineating tumor margins on areas of the body that are near the surface, i.e. skin or surgically exposed regions. Our efforts involve establishing real time video imaging instruments in the THz bands (using pulsed time domain techniques) and then applying these in an actual clinical environment – University of Southern California Medical Center – to establish efficacy for diagnosing, and perhaps someday thermally treating, skin lesions, specifically basal and squamous cell carcinoma. This work has been proposed through NIH but has not yet received funding. The work has been ongoing at a low level in the hopes of acquiring sufficient data to bolster future proposal efforts. Collaborators include Professor Warren Grundfest, a surgeon and bioengineer at UCLA, Professor Scott Fraser at Caltech and Dr. David Peng, a clinical dermatologist at USC.

THz Radar Imaging (Caltech/JPL): Using our NASA developed source and sensor technologies we have started the first work on THz FMCW radar. In this very exciting program we have designed, fabricating and begun testing a 600 GHz FMCW radar imager that can mechanically scan and 3D reconstruct (using radar ranging) objects between 1 and 25 meters distance with cm resolution in all three dimensions. Since THz waves can pass through many dielectrics, the system is being applied to undergarment threat detection. However significant phenomenologic breakthroughs have already been established through the use of this established technique in this new frequency range. The ultimate goal of the program is to demonstrate near video rate imaging over a modest angular scene scale. The work is being supported by the DoD and most of the instrumentation resides at JPL. Program participants include a number of JPL SWAT team members, particularly Dr. Ken Cooper, Dr. Goutam Chattopadhyay and Mr. Robert Dengler. Other contributors are Caltech post doctoral fellows Dr. Nuria Llombart Juan and Dr. Tomas Bryllert as well as JPL’s Dr. Imran Mehdi, Dr. Choonsup Lee, Dr. Anders Skalare and Dr. Erich Schlecht.

THz Radar Imaging using Integrated Planar Arrays (Caltech/JPL): Although not yet funded, this program is a follow-on to the radar imaging program already described. In this approach novel planar array architectures are envisioned for the realization of staring THz imaging arrays that can record thousands of pixels with a single transceiver architecture. Applications go well beyond the security screening field and spill over into multipixel spectrometers for both the space science and biomedical areas. A low level design effort is ongoing as a precursor to future proposal opportunities that may materialize in the coming year. Primary collaborators include Caltech post doctoral fellows Dr. Nuria Llombart Juan and Dr. Tomas Bryllert and JPL SWAT members Dr. Anders Skalare and Dr. Ken Cooper.

 Source and Sensor Development: This ongoing set of tasks has been the core of the JPL SWAT team work for more than 15 years and represents the major thrust of the Earth, planetary and space science applications. A continually evolving set of technical goals and spectroscopic techniques and applications derive from the devices and components that are being developed. These span the frequency range from 100 GHz to 5 THz and include two and three terminal semiconductor devices, passive waveguide and quasi optical components, novel planar and planar array antennas, superconducting detectors, carbon nanotube based sensors and sources, many varieties of upconverter and downconverter circuits and any components that might be critical for achieving a particular instrument goal. The work spans both development and actual delivered flight components, subsystems and instruments. The team works with scientists, engineers and flight systems people to propose, plan, and implement NASA missions and collaborates with space agencies and institutions world wide. The team has so far delivered flight hardware for four major programs including two Earth science, one planetary and one space science mission. Major participants include JPL’s Dr. Imran Mehdi, Dr. Lorene Samoska, Dr. John Ward, Dr. Erich Schlecht, Dr. Goutam Chattopadhyay, Dr. Anders Skalare, Dr. Ken Cooper, Dr. Hamid Javadi, Dr. Andy Fung, Dr. Harish Manohara, Dr. Frank Maiwald, Dr. John Gill, Dr. Choonsup Lee, Mr. Robert Dengler, Mr. Robert Lin, Mr. Alex Peralta, Mr. David Pukala, Mr. Seth Sin, Mr. Ed Luong, Mr. William Chun, and Ms. Karen Lee.

Facilities:

Dr. Siegel manages six separate laboratory facilities at JPL containing a large range of terahertz test and measurement equipment. These include microwave, millimeter, submillimeter and optical components and instruments as well as sophisticated microassembly and inspection equipment and some biologic processing equipment. He also is a supervisor of, and has access to the JPL Micro Device Laboratory (MDL) with a 100,000+ square foot clean room housing direct write e-beam, wet and dry etching, sputter and thermal coating, bonding, MBE and a wide variety of chemical and optical processing equipment. At Caltech Dr. Siegel is working in the millimeter wave MMIC lab in Moore where he has epi-fluorescence inverted and upright microscopes, an incubator, and an RF exposure system for studying cell level responses and processes and access to the laboratory and animal facilities in the Caltech Beckman Institute where he works with the staff under the direction of Professor Scott Fraser, Anna Rosen Professor of Biology and Director of the Biological Imaging Center.

Recent and review papers describing current work:

1. K.B. Cooper, R. J. Dengler, G. Chattopadhyay, E. Schlecht, A. Skalare, I. Mehdi and P. H. Siegel, “A High-Resolution Imaging Radar at 580 GHz ,” to appear in IEEE Microwave and Wireless Component Letters, 2008
2. P.H. Siegel, “THz Instruments for Space,” IEEE Transactions on Antennas and Propagation, v. 55, no. 11, pp. 2957-65, Nov 2007.
3. P.H. Siegel and R.J. Dengler, “Terahertz Heterodyne Imaging: Instruments,” Int. Journal of Infrared and Millimeter Waves, v.27, no. 5, pp. 631-656, May 2006.
4. P.H. Siegel and R.J. Dengler, “Terahertz Heterodyne Imaging: Introduction and Techniques,” Int. Journal of Infrared and Millimeter Waves, v.27, no. 4, April 2006.
5. J.W. Waters, L. Froidevaux, R.S. Harwood, R.F. Jarnot, H.M. Pickett, W.G. Read, P.H. Siegel, et.al., “The Earth Observing System Microwave Limb Sounder (EOS MLS) on the Aura satellite,” IEEE Trans. Geoscience and Remote Sensing, v. 44, no. 5, pp. 1075-1092, May 2006. One of Sci-Bytes most highly cited papers
6. Harish M. Manohara, Eric Wong, Erich Schlecht, Brian D. Hunt, P. H. Siegel, “Carbon Nanotube Schottky Diodes Using Ti-Schottky and Pt-Ohmic Contacts for High Frequency Applications,” Nanoletters, vol. 5, no. 7, pp. 1469-1474, 2005.
7. C. Yeh, F. Shimabukuro, P.H. Siegel, “Low Loss Terahertz Ribbon Waveguides,” Applied Optics, v. 44, no. 28, pp. 5937-46, Oct. 2005.
8. P.H. Siegel, “THz Technology in Biology and Medicine,” IEEE Trans. Microwave Theory and Techniques, vol. 52, no. 10, pp. 2438-2448, Oct. 2004.
9. A. Barkan, F. K. Tittel, D. M. Mittleman, R. Dengler, P. H. Siegel, G. Scalari, L. Ajili, J. Faist, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, “Linewidth and tuning characteristics of terahertz quantum cascade lasers,” Optics Letters, v. 29, no. 6, pp. 575-577, March 2004.
10. P.H. Siegel, “THz Technology,” IEEE Trans. Microwave Theory and Techniques 50th Anniversary Issue, vol. 50, no. 3, pp. 910-928, March 2002. Special Invited paper.
11. Michael C. Gaidis, H.M. Pickett, C.D. Smith, R.P. Smith, S.C. Martin and P.H. Siegel “A 2.5 THz Receiver Front-End for Spaceborne Applications,” IEEE Transactions Microwave Theory and Techniques,MTT-48, no. 4, April 2000, 733-739.
12. P.H. Siegel, R.P. Smith, S. Martin and M. Gaidis, “2.5 THz GaAs Monolithic Membrane-Diode Mixer”, IEEE Transactions Microwave Theory and Techniques, vol. 47, no. 5, pp. 596-604, May 1999.

Honors, Activities

• Distinguished Microwave Lecturer, Institute of Electrical Engineers (IEEE)
  Fellow, IEEE
• Former Chair IEEE Microwave Theory and Techniques Committee 4 - Terahertz Technology
• Vice-Chair Organizing Committee: International Conference on Infrared, Millimeter and Terahertz Waves
• Chair IRMMW-THz 2008 33rd International Conference on Infrared and Millimeter Waves and 16th International Conference on Terahertz Electronics (to be held at Caltech Sept. 15-19, 2007)
• Editorial Board, International Journal of Infrared and Millimeter Waves
• Technical Program Committee, IEEE International Microwave Symposium
• International Organizing Committee, International Symposium on Space THz Technology
• Seven NASA Group Achievement Awards
• NASA Space Act Award
• More than 50 NASA Certificates of Recognition for Technology Development
• Three time winner of JPL Award for Technical Excellence (1998, 2000, 2001)
• Four JPL Team Awards for Technical Achievement
• Two JPL Technical Commendation Certificates
• Organizer and Chair of seven Special Technical Sessions on Terahertz Technology and Applications at the IEEE International Microwave Symposium (2000-2007)
• 12 Keynote and Plenary talks, more than 50 Invited presentations.
  
  

Featured in:
ChemMatters, “Peter Siegel: Studying the Energy of the Universe,” an interview article for the American Chemical Society, Sept. 2002, pp. 6-7
NIH e-Advances, “Retooling a Research Career - From Engineering to Biology and Back,” an e-interview for the National Institute of Health, June 2006.
Co-author of Best Paper of the Decade award, Indium Phosphide and Related Materials Conference, 1998
100+ professional staff and student hires
Supervisor of 1 Doctoral, 1 Masters, 2 Senior theses
PI or co-I on 65+ research programs totaling more than $50M spanning 20 years
1000+ pages of technical reports!

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Last updated January 9, 2008.