development of thz tds system on the basis of the s...
TRANSCRIPT
NA-PAC 2013@Pasadena, 2nd October, 2013
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Ryunosuke Kuroda
Senior Researcher, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
Development of THz TDS system on the basis of the S-band compact electron linac
(Visiting lecturer, Waseda University, Tokyo, Japan)
Y.Taira, M. Tanaka, H. Toyokawa, K. Yamada (AIST)M. Kumaki1, M. Tachibana1, K.Sakaue1, K. Kan2, M. Yoshida3, H. Tomizawa4
1 RISE, Waseda University, Japan, 2 ISIR, Osaka University, Japan3 KEK, Japan4 RIKEN, SPring-8 Center, Japan
Colleagues of THz research
NA-PAC 2013@Pasadena, 2nd October, 2013
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Outline• Introduction
• Instruction of THz region
• Methods of THz generation
• Coherent THz radiation (CSR, CTR in our case)
• S-band compact electron linac and THz beam lines at AIST
• Measurement of THz-CTR characteristicsTHz-CTR Profile, Polarization, Frequency-range measurements
with THz real-time camera, Polarizer and BPFs
• Present status of THz-CTR Time-domain spectroscopy (TDS)Setup of THz-CTR-TDS, Preliminary experiment results of THz-TDS with samples
• Summary
In collaborating with Central Custom Laboratory(Japan Custom)
of Ministry of Finance Japan
NA-PAC 2013@Pasadena, 2nd October, 2013
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Spin excitation Molecular vibration electronic transition Molecular rotation
Frequency
Wavelength
IR UV
CO2
1nm1μm1mm1m
ArF
Radio wave Light wave
101810151012109106
(0.1~10THz)
THz region :(0.1 ~ 10 THz; 30μm ~ 3mm)
Terahertz (THz) LaserLasercm-
wavem-
waveVHF
Imaging
Science Vol. 297, 761 (2002 )20 40 60 80 100
0.6 1.2 1.8 2.4 3.0 Frequency/THz
HMX
PETNRDX
PE4
TNT
Semtex
Abso
rban
ce
Wavenumber/cm-1
Nature PhotonicsVol. 2, 541 (2008)
Finger-print spectrumof explosives
Inspection
THz GAP for security fields Hz
NA-PAC 2013@Pasadena, 2nd October, 2013
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• Photoconductive antenna with fs-laser (B)
• Nonlinear crystal with fs-laser (B) or (M)
Methods of THz generation
• Parametric Oscillation(TPO, is-TPG) (M)
100nw~10mW
10mW~1W
• Free electron laser(FEL) (M) > 1 kW (up to MW)
Peak power
Academic : Measurement of complex dielectric constant, reflective index(organic electroluminescence(EL), polymer…) …etc
Security : Inspection of explosives, illegal drug, handgun, knives …etcMedical : Diagnostics of skin/ breast cancer …etc
• Coherent radiation with ultra-short electron bunch (B) > 1 kW (up to MW)
High Peak Power
For the in-situ measurement and the solvation sample measurement,High peak-power THz source is strongly required.
Type: Broadband (B), Monochromatic (M)
Application Fields
Therefore
However, THz radiation is strongly absorbed by the atmosphere (water)!Low peak power THz source can not be applied to industrial uses.
Laser based
Accelerator based
NA-PAC 2013@Pasadena, 2nd October, 2013
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Coherent THz radiation
Coherent Transition radiation (CTR)
Coherent Synchrotron radiation (CSR)
))()1(1( fNII inctot
lc c /Intensity of Coherent radiation
Critical frequencyωcCoherent radiation methods
Frequency (THz)
Inte
nsity
(a.u
.)
To generate the coherent THz radiation, the electron bunch should be compressed to less than 0.5 ps.
THz CSR has been developed for THz imaging (only measure intensity deference
THz CTR has been developed for THz time domain spectroscopy (TDS) . (Fourier limited pulse, small spot size)
In our case
forwardbackward
@40MeV
NA-PAC 2013@Pasadena, 2nd October, 2013
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THz freq.: 0.1 ~ 2 THz (up to 5 THz)Pulse energy: >100 nJPeak power: >10 kWSource: CSR for imaging
CTR for spectroscopy
THz specificationFreshness measurement
S-band comapct electron linac at AIST
THz beamlines
Solvation sample measurement
Explosive inspection Inside of Envelope
Envelope
2,4 2,6 3,4 DNTIsomers
0.1THz
0.6THz
@2THz
0.3THz
THz beam lines summary at AIST
NA-PAC 2013@Pasadena, 2nd October, 2013
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Outline• Introduction
• Instruction of THz
• Generation methods of THz wave
• S-band compact linac and THz beamlines at AIST
• Coherent THz radiation source and its applicationsTHz-CTR Profile, Polarization, Frequency-range measurements
with THz real-time camera, Polarizer and BPFs
• Present status of THz-CTR Time-domain spectroscopy (TDS)Setup of THz-CTR-TDS, Preliminary experiment results of THz-TDS with samples
• Summary
• Introduction • Instruction of THz
• Methods of THz generation
• Coherent radiation (CSR, CTR in our case)
• S-band compact linac and THz beam lines summary at AIST
• Measurement of THz-CTR characteristicsTHz-CTR Profile, Polarization, Frequency-range measurements
with THz real-time camera, Polarizer and BPFs
• Present status of THz-CTR Time-domain spectroscopy (TDS)Setup of THz-CTR-TDS, Preliminary experiment results of THz-TDS with samples
• Summary
NA-PAC 2013@Pasadena, 2nd October, 2013
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Measurement of THz-CTR characteristicsTHz-CTR Profile measurement
with THz Camera (made by NEC corp.)
View area :7.5mm×5.6mmFrame rate: 30Hz
Ultra-short electron beam
Rotating Polarizer, Band Pass Filter(BPF) etc
Al Al2O3
ForwardTHz-CTR
Backward
NA-PAC 2013@Pasadena, 2nd October, 2013
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THz-CTR Profile measurement
Ultra-short electron beamTHz-CTR Polarization measurement
with THz Camera (made by NEC corp.)
NA-PAC 2013@Pasadena, 2nd October, 2013
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THz-CTR Profile measurement
Ultra-short electron beam
Linearly Polarizer
THz-CTR Polarization measurementwith THz Camera (made by NEC corp.)
NA-PAC 2013@Pasadena, 2nd October, 2013
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THz-CTR Profile measurement
Ultra-short electron beam
Linearly Polarizer
THz-CTR Polarization measurementwith THz Camera (made by NEC corp.)
NA-PAC 2013@Pasadena, 2nd October, 2013
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THz-CTR Profile measurement
Ultra-short electron beam
Linearly Polarizer
with Linearly Polarizer
THz-CTR Polarization measurementwith THz Camera (made by NEC corp.)
NA-PAC 2013@Pasadena, 2nd October, 2013
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THz-CTR Profile measurement
Ultra-short electron beam
Linearly Polarizer
with Linearly Polarizer
THz-CTR Polarization measurementwith THz Camera (made by NEC corp.)
Radial polarization
NA-PAC 2013@Pasadena, 2nd October, 2013
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THz-CTR Profile measurement with BPF
Ultra-short electron beamTHz-CTR measurement
with THz Camera (made by NEC corp.)
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THz-CTR Profile measurement with BPF
Ultra-short electron beamTHz-CTR measurement
with THz Camera (made by NEC corp.)
BPF
NA-PAC 2013@Pasadena, 2nd October, 2013
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THz-CTR Profile measurement with BPF
Ultra-short electron beamTHz-CTR measurement
with THz Camera (made by NEC corp.)
1.0THz
BPF
NA-PAC 2013@Pasadena, 2nd October, 2013
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THz-CTR Profile measurement with BPF
Ultra-short electron beamTHz-CTR measurement
with THz Camera (made by NEC corp.)
1.0THz
BPF (1.0 – 5.0 THz)
NA-PAC 2013@Pasadena, 2nd October, 2013
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Outline• Introduction
• Instruction of THz region
• Methods of THz generation
• Coherent THz radiation (CSR, CTR in our case)
• S-band compact linac and THz beam lines summary at AIST
• Measurement of THz-CTR characteristicsTHz-CTR Profile, Polarization, Frequency-range measurements
with THz real-time camera, Polarizer and BPFs
• Present status of THz-CTR Time-domain spectroscopy (TDS)Setup of THz-CTR-TDS, Preliminary experiment results of THz-TDS with samples
• Summary
In collaborating with Central Custom Laboratory(Japan Custom)
of Ministry of Finance Japan
NA-PAC 2013@Pasadena, 2nd October, 2013
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-5 0 5 10 15 20 25 30 35
-1
0
1
2
3
4
Am
plitu
de, n
A
Time, ps
0 2 4 6
1E-13
1E-12
1E-11
1E-10
Frequency, THz
Am
plitu
de, a
.u.
Fourier transform
Time domain Frequency domain
THz time-domain spectroscopy (THz-TDS) has recently emerged as a useful probe for the investigation of illegal materials such as explosives and drugs.
THz-CTR Time Domain Spectroscopy(TDS)with EO sampling method
fs-laser based THz-TDS system
(Temporal decoding)
NA-PAC 2013@Pasadena, 2nd October, 2013
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Principle of EO sampling method for THz-TDS
[0,0,1]
[-1,1,0]
Ellipsoid of Refractive index THz E_field
Probe laser E_field(horizontaly linear
polarized)
Irradiated THz can make Pockels effect in EO crystal
< 1 1 0 > oriented ZnTe crystal
Measurement of the phase difference Γ
x
y
・ Initial E_field of probe laser
・ Output E_field of probe laser
←horizontal←vertical
←vertical
←horizontal
NA-PAC 2013@Pasadena, 2nd October, 2013
In Vacuum In Air
EO crystal(ZnTe 1mmt)
Ultra-short electron beam
Probe beam(fs laser)
PD
PD
THz-CTRSample
Polarizer
Frequency domain
FTTHz Spectrum
Time domain
Setup of THz-CTR Time-domain spectroscopy (TDS)
with EO sampling method (pump-probe technique)
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NA-PAC 2013@Pasadena, 2nd October, 2013
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THz-TDS Result with Polyethylene(PE) sampleTo demonstrate the THz-TDS system, the refractive index measurement has been done using the well-known sample (PE)It is well-known that PE has about 1.5 refractive index from optical to THz region.
THz temporal waveform
THz spectrum
Phase Sample: Polyethylene(PE) plate
(1 mmt)
Calculated
Refractive index
FT
NA-PAC 2013@Pasadena, 2nd October, 2013
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PE: n = [email protected] - 2THz
THz-TDS Result with Polyethylene(PE) sampleTo demonstrate the THz-TDS system, the refractive index measurement has been done using the well-known sample (PE)It is well-known that PE has about 1.5 refractive index from optical to THz region.
THz temporal waveform
THz spectrum
Phase Sample: Polyethylene(PE) plate
(1 mmt)
Calculated
Refractive index
FT
NA-PAC 2013@Pasadena, 2nd October, 2013
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PE: n = [email protected] - 2THz
THz-TDS Result with Polyethylene(PE) sampleTo demonstrate the THz-TDS system, the refractive index measurement has been done using the well-known sample (PE)It is well-known that PE has about 1.5 refractive index from optical to THz region.
THz temporal waveform
THz spectrum
Phase Sample: Polyethylene(PE) plate
(1 mmt)
Calculated
Refractive index
FT
We have checked the performance of THz-CTR-TDS.
NA-PAC 2013@Pasadena, 2nd October, 2013
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Pellet (1 mmt) ofMethoxyphenamine hydrochloride (MPA)
(Imitation Drug of Methamphetamine)
THz temporal waveform
THz spectrum
FT
Calculated
Absorption spectrum
THz-TDS Result with drug sample (MPA)
NA-PAC 2013@Pasadena, 2nd October, 2013
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Pellet (1 mmt) ofMethoxyphenamine hydrochloride (MPA)
(Imitation Drug of Methamphetamine)
THz temporal waveform
THz spectrum
FT
Calculated
Absorption spectrum
THz-TDS Result with drug sample (MPA)
NA-PAC 2013@Pasadena, 2nd October, 2013
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Pellet (1 mmt) ofMethoxyphenamine hydrochloride (MPA)
(Imitation Drug of Methamphetamine)
THz temporal waveform
THz spectrum
FT
Calculated
Absorption spectrum
THz-TDS Result with drug sample (MPA)
The sample absorption has been successfully measured in atmosphere. However, the accuracy of the THz-TDS system should be improved.One of the solutions is the single-shot measurement
with the chirped pulse laser (spectral decoding).Now, we are preparing the single-shot scheme.
NA-PAC 2013@Pasadena, 2nd October, 2013
In near future, single-shot measurement (Spectral decoding) will be performed.
Y.Taira, M. Tanaka, H. Toyokawa, K. Yamada (AIST)M. Kumaki1, M. Tachibana1, K.Sakaue1, K. Kan2, M. Yoshida3, H. Tomizawa4
1 RISE, Waseda University, Japan, 2 ISIR, Osaka University, Japan3 KEK, Japan4 RIKEN, SPring-8 Center, Japan
Colleagues of THz research
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Summary
THz frequency range: 0.1 – 5.0 THz
In-situ Security Inspection (Investigation of explosives
and illegal drugs)
1. High peak power THz source has been developed with CSR, CTR techniqueson the basis of the S-band compact electron linac at AIST.
2. THz-CTR characteristics (Profiles, Polarization, Frequency range) have been measured with the real-time THz camera, Polarizer and BPFs
3. THz-CTR Time-domain spectroscopy (TDS) has been demonstrated in freq. range between 0.1 – 2 THz. The refractive index (PE) and the absorption (MPA) measurements have also successfully performed in atmosphere.
NA-PAC 2013@Pasadena, 2nd October, 2013
In near future, single-shot measurement (Spectral decoding) will be performed.
Y.Taira, M. Tanaka, H. Toyokawa, K. Yamada (AIST)M. Kumaki1, M. Tachibana1, K.Sakaue1, K. Kan2, M. Yoshida3, H. Tomizawa4
1 RISE, Waseda University, Japan, 2 ISIR, Osaka University, Japan3 KEK, Japan4 RIKEN, SPring-8 Center, Japan
Colleagues of THz research
31
Summary
THz frequency range: 0.1 – 5.0 THz
In-situ Security Inspection (Investigation of explosives
and illegal drugs)
Thank you for your attention !
1. High peak power THz source has been developed with CSR, CTR techniqueson the basis of the S-band compact electron linac at AIST.
2. THz-CTR characteristics (Profiles, Polarization, Frequency range) have been measured with the real-time THz camera, Polarizer and BPFs
3. THz-CTR Time-domain spectroscopy (TDS) has been demonstrated in freq. range between 0.1 – 2 THz. The refractive index (PE) and the absorption (MPA) measurements have also successfully performed in atmosphere.
NA-PAC 2013@Pasadena, 2nd October, 2013
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REFERENCES
Methamphetamine Methoxyphenamine