Transcript Ultra Stable Terahertz Frequency Synthesizers and

Ultra Stable Terahertz
Frequency Synthesizers and
Extremely Sensitive HEB
Detectors up to 70 THz.
Mikhail L. Gershteyn
President, Insight Product Co.
www.insight-product.com
Phone: (617) 965-8151
E-mail: [email protected]
Overview
• 1. Advancing frequency stabilization techniques to Terahertz range.
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1.1 Applications of frequency stabilized sources.
1.1.1 Narrow band phenomena’s in Nature.
1.1.2 Narrow band systems technologies.
1.2 Stabilized sources in MMW and THz.
1.2.1 Comparison of Stabilized Sources.
1.2.2 THz synthesizers from Insight Product Co.
• 2. Superconducting Hot Electron Bolometer (HEB) Mixers &
Detectors
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2.1 Applications of HEB Mixers & Detectors
2.2 Direct Detectors and Mixers
2.3 Comparison of Detectors & Mixers in THz area.
2.4 Superconducting Hot Electron Bolometer (HEB) detectors and mixers from
Insight Product
• 3. Conclusions
• 4. Acknowledgments
Applications of Synthesized
Sources
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Gas Spectroscopy
Security: Gas detection systems
Accessing water content in tissue
Medical imaging: cancer tissue identification
Heterodyne Receiving Systems
Astrophysics
Material characterization and testing
NMR/ MRI, EPR, quantum computers
Plasma diagnostics, Gyrotron cold testing
Communications: high bandwidth channels
Naturally occurring physical
narrow-band phenomena
• Absorption and emission spectrum of various molecules
• It is well know that each molecule has a distinctive frequency
fingerprint of emitting and absorbing electromagnetic waves. There
are very sharply, narrow-band frequency effects observed, called
“absorption lines”.
• Security Application: The THz absorption spectrum of various
gases yields distinct regions of absorption which could be used to
differentiate hazardous gases from benign ones.
• Applications: Air Monitoring
• Atmospheric Monitoring via satellite.
• Monitoring of emissions from Industrial Chemical Processing.
• Real-time monitoring of chemical processes in gas phase.
• Scientific Application: Gas Spectroscopy
Naturally occurring physical
narrow-band phenomena II
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Resonance of mediums with minuscule absorption
Mechanical resonance: quartz. Quartz vibrates because it basically does
not absorb acoustic wave.
Professor H. Frohlich’s concept: cell membranes participate in synchronized
coherent high-frequency oscillations (10s of GHz up to 100s of GHz) :
therefore dynamic biological functionality can be influenced by weak EM
radiation at certain narrow-band frequency.
Biological Coherence & Response to External Stimuli (Springer, 1988)
edited by H. Frohlich
First experimental demonstration of the effect of weak specific mm-wave
frequencies on living organisms was obtained in the early 1970s by
Academician N. N. Devatkov et al. group in USSR.
One of the latest reviews on the subject, entitled “Non-thermal Biological
Effects of Microwaves” (Microwave Review, November 2005) was published
by Dr. Igor Y. Belyaev (Department of Genetics, Microbiology and
Toxicology, Stockholm University, Sweden)
http://www.mwr.medianis.net/pdf/Vol11No2-03-IBelyaev.pdf
Biomedical Applications: Millimeter Wave Therapy
Naturally occurring physical
narrow-band phenomena III
• EPR (Electron Paramagnetic Resonance) and
NMR/DNP (Nuclear Magnetic Resonance/
Dynamic Nuclear Polarization)
• NMR enhancement by EPR
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Applications:
Material characterization
Medical Imaging
Biological & Chemical Research.
Naturally occurring physical
narrow-band phenomena IV
Frequency shift effects.
– Doppler effect: frequency change of EM coming from a moving
source depending on the velocity of motion. Also the reflection of
EM against a moving target causing a frequency shift in reflected
signal.
– Frequency shift is proportional to velocity over speed of light.
• ∆f/f= v/c
• General Applications: Motion detectors and velocity
estimators.
• Security Applications: Intruder detection by motion.
Narrow band Systems in
Technology
• Systems in Technology and Science use
narrow-band signals in order to achieve:
high selectivity
high frequency resolution
high sensitivity
high stability
phase detection
Narrow band Systems in
Technology II
• Communications – we use synthesized
sources to differentiate one channel from
another and to inhibit interference. Also
the narrow-frequency band allows the
utilization of heterodyne receiving systems
which offer exceptional sensitivity. This
also enables broad receiving range with
limited transmitted power.
Narrow band Systems in
Technology III
• Radars - Time for reflected signal to reach the
sensor is used to calculate distance. Narrow
band pulses are used to increase sensitivity, at
the receiver end, and in Doppler shift radars to
measure velocity. In FM (frequency modulation)
radars the distance to the target if inferred from
the change in frequency between reflected
signal and current signal. In this case the
frequency must be very accurately defined for
every time point, so a narrow-banded time
dependent signal is necessary.
Narrow band Systems in
Technology IV
• Selective receivers in Astrophysics and
Atmosphere Investigations
• We need to receive a signal in a certain
frequency range corresponding to
emission of various molecules in space.
Heterodyne receivers are used, since they
yield excellent sensitivity. The heterodyne
LO (local oscillator) needs to have high
frequency stability.
Narrow band Systems in
Technology V
• Imaging system for medical and security
applications.
• In imaging systems, narrow-band signals
together with heterodyne receiving technique
increase the sensitivity of reception of the signal,
expedite the frame rate, and boast resolution.
• An example in THz area, I’d like to refer to the
latest results of Peter Siegel et al. (JPL)
Heterodyne Active Imager
Courtesy of Dr. Peter H. Siegel, JPL
Heterodyne Active Imager
Courtesy of Dr. Peter H. Siegel, JPL
Narrow band Systems in
Technology VI
• Systems for material characterization and
plasma diagnostics :
• Narrow-band signal allows:
• a ) increased sensitivity
• b) selectivity by frequency
• c) phase measurements (especially relevant in
plasma diagnostics)
• d) increased temporal resolution (faster
measurements)
• e) introduce monitoring capability
Narrow band Systems in
Technology VII
• Gas absorption spectrometers and gas detectors.
• The natural absorption phenomena are narrow-banded.
• The typical “absorption line” width of any gas at a
pressure of 1 Torr and standard temperature is 10-6
(∆f/f) in the terahertz range.
• Therefore to match the “absorption line” we need to have
a probing signal which has at least 10-6 (∆f/f) frequency
stability (both long and short term stability).
• Security Application: Local atmosphere monitoring for
specific known substances, biological agents, or gases.
• Monitoring of chemical reactions.
• Monitoring of technological processes.
Sources of frequency stable
signal in THz range
• Synthesized frequency stable sources in microwaves (up to 20
GHz) are well developed and widely available. One of the latest
reviews was written by Jack Browne.
Reference:
“Frequency Synthesizers Generate Clean Signals:
Frequency synthesizers come in many shapes and sizes, although
the ultimate goal in any design is to generate stable output
frequencies with minimal spurious and phase noise.”
Jack Browne Microwaves & RF [Systems & Subsystems]
ED Online ID #10016 March 2005
(http://www.mwrf.com/Articles/Index.cfm?ArticleID=10016&pg=2)
Sources of frequency stable
signal in THz range II
• Lasers (C02 pumped)
• Pros: High output power (~10-100 mW) & high
frequency stability (better than 300 KHz line).
• Cons: Fixed frequency, lacks tunability, limited
possibility for frequency and phase modulation
and manipulation, large bulky devices, available
on only several specific frequencies.
Sources of frequency stable
signal in THz range III
• Stabilized Quantum Cascade Lasers
(QCL)
• Pros: High output power (1-50 mW),
good stability (less than 300 kHz)
• Cons: Small tuning bandwidth (~10 GHz),
Not available on all frequencies.
Sources of frequency stable
signal in THz range IV
• Photo-mixers
• Pros: wide tunable bandwidth (several
hundred GHz)
• Cons: low output power (1 microWatt at 1
THz, 0.1 microWatt at 3 THz), large bulky
devices.
Sources of frequency stable
signal in THz range III
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Direct Multiplier chains
These devices use multipliers and amplifiers to go from microwave stable
source (up to 20 GHz) to THz range.
Pros: Solid-state, high frequency stability when input signal is from a
frequency synthesizer, compact, commercially available, wide tunability
(~15%).
Cons: Complex design. Amplifier and multi-cascaded chains (FEMs) are
required to reach THz frequencies.
Output power drops exponentially with increasing frequency.
Low output power (1-2 microWatt at 1.25 THz)
Do not go higher than 1.7 THz.
Low efficiency (less than 0.5%)
Multiple component spectrum of output signal with different harmonics.
Possibility for frequency and phase modulation and manipulation is limited
by what’s available in the driving microwave source.
Sources of frequency stable
signal in THz range IV
• PLL (Phase-lock loop) Systems based on BWO (Backward
Wave Oscillator, a.k.a. “carcinotron” or “backward wave tube”)
• BWO by PLL locked to harmonic of microwave stable source.
• Pros: Wide tunability band (~20 %)
• Relatively high output power (2-8 milli-Watt at 1 THz)
• Possibility of quick frequency and phase modulation and
manipulation.
• Simple (“one line”) output spectrum.
• Cons:
• Need high voltage power supply and magnet
• Do not go above 1.5 THz
Sources of frequency stable
signal in THz range V
• Hybrid systems – PLL locked Sources plus
Multipliers (in development)
• PLL locked BWO sources (200-300 GHz) are multiplied
to THz region.
• Pros: Wide tunability band.
• Possibility of quick frequency and phase modulation and
manipulation.
• Projected cover from 1 up to 3 THz with power of about
10 microWatt.
• Cons: Need high voltage power splay and magnet.
Insight Product Synthesizers
(Insight FS) 36 GHz – 1.25 THz
• Typical Output Power (in milliWatt) and
Tuning Frequency Range.
• 370 - 535 GHz: 4-15 mW
• 526 - 714 GHz: 4-15 mW
• 667 - 857 GHz: 4-15 mW
• 789 - 968 GHz: 3-8 mW
• 882 - 1,111 GHz: 2-8 mW
• 1,034 – 1,250 GHz: 0.5-2 mW
Insight FS Synthesizers II
Advantages:
 Extremely high frequency stability (up to 10-11 =∆f/f).
 High output power (several mW at 1 THz).
 Each synthesizer covers a full waveguide band.
 Each synthesizer operates independently in free
running mode as generator or with microwave signal
generator as synthesizer.
 Insight FS provides several options for frequency and
amplitude modulation (analog FM/AM modulation,
frequency manipulation, pulses modulation).
 Insight FS are compact in size and controlled by IEEE,
analog input, or manually.
Insight FS Synthesizers III
“For millimeter-wave frequencies, Insight Product Co. (www.insight-product.com) offers
a line of frequency synthesizers in full waveguide bands from 120 to 180 GHz,
with output-power levels of 30 mW or more. Ideal for measurement and astronomy applications,
these synthesizers can be equipped with optional AM and FM capabilities and GPIB remote control.”
March 2005, Microwaves & RF Journal
Schematics of direct vs.
heterodyne detection
Courtesy of Drs. Peter H. Siegel and Robert J. Dengler, CALTECH & JPL
650 GHz: typical bolometer NEP @ 300 degrees K = 10-11 W/Hz2
650 GHz: typical mixer NEP @ 300 degrees K = 10-15 - 10-14 W/Hz2
Superconducting Hot Electron
Bolometer (HEB) Mixers
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Terahertz Spectroscopy
Terahertz RadioAstronomy
Remote sensing of Earth Atmosphere
Active Terahertz Imaging
Security Imaging and Monitoring
Superconducting Hot Electron
Bolometer (HEB) Mixers II
• Currently the following large-scale projects
may benefit from HEB mixers:
• Large-scale government projects such as
SOFIA, FIRST, & ALMA.
• Astronomy projects: SMILES, EOS-MLS.
• Planetary science projects: ROSETTA,
Mars explorer.
Superconducting Hot Electron
Bolometer (HEB) Mixers III
• “Superconducting hot electron bolometer (HEB) mixers are the
choice of device for the frequencies between 1.5 and 6 THz. They
are complementary to SIS mixers which work as quantum noise
limited detectors up to about 1 THz. An HEB consists of a niobiumnitride (NbN) superconducting bridge with nanometer or submicron
dimensions, contacted by thick gold pads. THz radiation signals are
coupled into the bridge through a lens and an on-chip antenna
(quasi optical). The heterodyne mixing process makes use of the
resistive transition between the superconducting state and the
normal state of the superconducting bridge, induced by the heating
of THz radiation signals. Click for a schematic of the detector
principle. To reach a high intermediate frequency (IF) bandwidth, an
extremely thin NbN film with a high critical temperature is used,
optimized for phonon cooling.”
–SRON (Netherlands Institute for Space Research)
Hot Electron Bolometer
(HEB) Mixers IV
• HEB Mixers, Advantages
• Above about 1 THz Hot Electron
Bolometer mixers offer the best sensitivity
and lowest noise of all the technology for
the coherent detection of radiation.
• Wide converstion gain bandwidth and
noise bandwidth ( both up to 4.5 GHz).
• Low Heterodyne source power (about 1
microW).
Superconducting Hot Electron
Bolometer (HEB) Detectors
• Applications of Superconducting HEB
Detectors:
• Fast and/or wide range pulses of terahertz
radiation for biological investigations, and
real-time monitoring.
• Passive Imaging
• Active Imaging with short pulses
Schematic of Superconducting S.
HEB Mixer/Detector
HEB receiver in Chile
Courtesy of Dr. Gregory Goltsman
Comparison of Mixers
Courtesy of Dr. Gregory Goltsman
S. HEB mixer System at .7-.9 THZ
w/ components and LHe cryostat
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Quasioptical NbN mixers
Hyper-hemispherical Si lens
Mixer holder with SMA connector
Bias-T adapter
Cryogenically cooled HEMT amplifiers (four options)
Liquid helium cryostats (3 options)
Cryogenically cooled IR filter
Teflon input cryostat window
Room-temperature (RT) amplifiers (3 options)
HEMT amplifier power supply
RT amplifier power supply
Mixer power supply
S. HEB mixers specs
• 1 THz: ~800 ° K = Noise Temperature
• 2 THz: ~1,000 ° K = Noise Temperature
• 4 THz: ~1,200 ° K = Noise Temperature
• LO Power required < 1µW
• Bandwidth ~ 4.5 GHz
S. HEB Detectors specs
• 0.3 – 3.0 THz Detectors:
• NEP= 3-5*10-13 W*Hz-0.5; Response time=
50 ps
• NEP= 5-7*10-14 W*Hz-0.5; Response
time=1 ns
S. HEB Detectors specs II
• 0.1 – 30 THz Detectors:
• NEP= 1-2*10-10 W*Hz-0.5; Response time=
50 ps
• NEP= 6-8*10-11 W*Hz-0.5; Response
time=1 ns
S. HEB Detectors specs III
• 25 – 70 THz Detectors:
• NEP= 4-5*10-12 W*Hz-0.5; Response time=
50 ps
• NEP= 1-2*10-12 W*Hz-0.5; Response
time=1 ns
S. HEB detector system
S.HEB detector input window
S. HEB detector inside view
Conclusions
• THz band synthesized sources and ultra
sensitive detectors are well developed are
commercially available.
• Most of the applications thus far lie in scientific
research and government R&D.
• Technology is ready designing more widely
used commercial applications, for security,
medical imaging, air pollution monitoring, and
biomedical therapy, and real-time monitoring of
chemical and industrial processes.
Acknowledgments
• Special thanks to the following individuals:
• Dr. Peter H. Siegel for discussions, and
materials.
• Dr. Gregory Goltsman for discussions, and
materials.
• Dr. Lev I. Gershteyn for discussions.
• Arkady Gershteyn for discussions, and help with
presentation of content.
• Matt Thomas, for organizing SURA conference.
© Insight Product Co. 2006