forum for electromagnetic research methods and application … · 2017. 1. 16. · conference on...

2nd International Conference on

Telecommunications and Remote Sensing

INTERNATIONAL CONFERENCE ON FOUNDATIONS AND FRONTIERS IN

COMPUTER, COMMUNICATION AND ELECTRICAL ENGINEERING

January 9, 2015

Forum for Electromagnetic Research Methods and Application Technologies (FERMAT)

Abstract— The electromagnetic waves at frequencies from 0.1 THz (100 GHz) to 10 THz is referred to as terahertz (THz) waves, which are located between microwaves and infrared light waves, and have remained unutilized for our life. Thanks to tremendous efforts of research and development over two decades, THz technologies have proven lots of capabilities which are not available with conventional radio waves and/or light waves. In this paper, we describe how efficiently THz waves can be generated and detected by contemporary photonics technologies, and present recent emerging applications including wireless communications, spectroscopy, and imaging.

Keywords—terahertz; photonics; generation; detection; communication; spectroscopy; imaging; measurement.

byTadao Nagatsuma

http://discoverlosangeles.com/getting-around/air/things-to-do-near-lax-los-angeles-airport.htmlhttp://discoverlosangeles.com/getting-around/air/things-to-do-near-lax-los-angeles-airport.html

C2E2 2015 Page 2 9 January 2015

About Osaka


Outline

Challenges to exploring millimeter- and terahertz waves (electro-magnetic waves at frequencies

from a few tens gigahertz to terahertz) with use of “photonics” technologies.

Background & motivation

Approaches

Enabling devices

Recent applications



Approaches

Enabling devices

Recent applications


Until 19th Century

Late 19th Century

Experiment of Radio Transmission: Marconi (1895-1898)

20th Century

21st Century

Higher Frequency Optical Fiber（1.3 - 1.5mm)

Undeveloped (Terahertz gap)

100GHz - 10THz

Radio Wave Lightwave

Wireless Communications Fiber-optic Commun.

Discovery of E-M waves: J.C. Maxwell (1864) Experiment: H. Hertz(1888)

Discovery of X-ray: Roentgen

Only visible light utilized

History of Exploring E-M Waves

1895


m mm mm nm

10 1 100 10 1 100 10 1 100 10 1 100 10 1

3 30 300 3 30 300 3 30 3003 30 300

M (106) Hz T (1012) HzG (109) Hz P (1015) Hz

Wavelength

l

Frequencyf

Microwave

Raido Wave

km

30 300

k (103) Hz

Lo

ng

wave

Mediu

mw

ave

Short

wave

Ultra

short

wave

Mic

row

ave

(narr

ow

definitio

n)

Far

Infr

are

d

(TH

z)

Near/

Med

ium

Infr

are

d

Vis

ible

UV

X-r

ay

Extr

em

ely

Ultra

short

wave

Mil

lim

ete

r-

wave

Su

bm

illi

me

ter-

wa

ve

Light Region

Microwave Photonics/

THz photonics

Radio Wave and Light Wave


“Millimeter-waves”

(MMW)

30 GHz – 300 GHz

10 mm – 1 mm

Frequency

f

Wavelength

l

“Terahertz waves”

(THz Waves)

0.1 THz (100 GHz)

– 10 THz

3 mm – 30 mm

Definitions


Why Undeveloped?

Technically difficult for us…

“Signal generation”

“Transmitter”

output power

stability

controllability

“Signal detection”

“Receiver”

sensitivity

bandwidth

Generation is more crucial !!


1 THz ～ 1 ps ～ 300 mm ～ 4 meV ～ 50 K

Approach with “Electron”

(via Radio waves)

↓

Barrier of electron velocity

Approach with “Photon”

(via Light waves)

↓

Barrier of temperature/band gap

Electrode

Active

layer

Electrode

P N+

N

Base

electrode

Insulator(SiO2)

Planar Transistor

Emitter

electrode

Collector electrode

N+

Semiconductor Laser

E = hf = kT

Limits of Electronic and Photonic Devices


10

100

0.1 1

GaAs HEMT

GaAs PM-HEMT

InP H EMT

InP PM- HEMT

GaAs MESFET

calculated

0.05 2

500

0.2 0.5

20

50

200

0.02

1000

Gate Length (mm)

Cu

rre

nt-

Gain

Cu

toff

Fre

q. (G

Hz)

0.1mm

DNA

Cutoff Frequency vs. Gate Length

InP-based HEMT Scaling


IMPATT

Gunn

RTD

Multiplexer

BWO

MMIC

Frequency (THz)

0.01 0.1 1 10 100 1000

Ou

tpu

tP

ow

er

(mW

)

0.001

0.01

0.1

1

10

100

1000

104

105

Photomixer

(UTC-PD)

III-V Laser

Lead Salt Laser

QCL

THz QCL

TUNNET

RC, t : Transport Transition: hn/kT

THzGap

Electronics Photonics

Power Limitation of Current Devices

http://upload.wikimedia.org/wikipedia/commons/2/2f/Hubble_ultra_deep_field.jpghttp://upload.wikimedia.org/wikipedia/commons/2/2f/Hubble_ultra_deep_field.jpg


Evolution of Stars

Young StarRed Giant

Birth and Death

of Stars

X R

ay

MMW

Visible/Infrared

SM

MW

Light

Star

Heavy

Star

Interstellar

Particles

Ball of Gas

Pulsar

Cloud of

Molecules

Proto-star

Supernova

Black Hole

Stars emits many

E-M waves


Atacama Large Millimeter/submillimeter Array

>18 km

Largest Telescope to Explore Universe

http://www.almaobservatory.org/images/three-antennas-2.jpghttp://www.almaobservatory.org/images/three-antennas-2.jpg


Hot at pressure points!

My hand emits….


Any object with temperature emits E-M waves

10 15

Infrared, NIR

10 13 10 11 10 9 10 7 10 5

Re

lati

ve

Ra

dia

tio

n P

ow

er

Frequency (Hz)

MMW, THz Wave

Microwave

Planck’s equation c 2

2hf 3 1B

bb = exp (hf / kT ) -1･

Black-body Radiation

310 K


Wireless

(radio wave)

technology

Ultra-low power

electronic devices

Highly functional digital

electronic signal processing

Ultra-fast, broadband

electronic/photonic devices,

and photonic signal

processing

Optical fiber

(light wave)

communication

technology

Now, We Have Two Technologies!!


Radio wave

space “Transparent” fiber network

Started to be Combined in Communications

Radio wave

space

“Radio-over (on)-fiber (RoF) technology”


Radio-over-Fiber (RoF) Technology

Relay

amplifier

Mixer

Divider

Base station

Antenna Antenna

ISDN

ISDN

Remote

base station

Remote

base station Underground

Shopping malls

Stations

Vehicle/train tunnels

Divider

EO

OE

OE

EO

Radio

Light

Optical fiber

Optical fiber


Use of Photonics in Exploring THz Waves

Photonics

Technology

Radio-wave

(THz-Wave)

Technology

based on

Electronics

Advantages: wide bandwidth, tunability, stability

distribution at long distances


Optical

Signal

Source

Photonic

Millimeter-

/Terahertz-

wave

Emitter

Photonic

Millimeter-

/Terahertz-

wave

Detector

Object

Under

Test

Optical

Delay

Photoconductive Antenna

Electro-optic Crystal

Pulse/CW

Detected

Signal

“Breakthrough”: Photonic Generation & Detection

Setup for spectroscopy and/or imaging

Photodiode




0 50 100 150 200

Pulsed MMW/THz Technology

Pulselaser

AmplitudeTime

Optical delay

Probe pulse

Trigger pulse THz pulse

Emitter

Detector

Emitter/detector

Electro-optic (EO) crystal

Photoconductive (PC) antenna

Photodiode (PD)

Frequency (THz)

M. Ashida et al., IRMMW/THz 2008.

I. Katayama et al., APL, 27, 2010.

Am

plit

ude (

a.u

.)Emitter: DAST crystal

Detector: (a) PC antenna

(b) Filter & Power detector

Laser pulse: 5 fs

(a)

(b)


Recent: From Pulse to CW: “T” to “F”

Laser-Pulse MMW/Terahertz: Proven to be powerful and useful over 2 decades since

early1980s Established as early industry-standards

Because of unprecedented ultra-short “Time”

CW MMW/Terahertz: With accurately controlled “Frequency” Offers more functionality

Generation/Signal Processing (formatting, modulation, etc)

Detection/Signal Processing (demodulation, signal recover, A/D, etc)

Extends application areasCommunication, Sensing, and Measurements


My First Encounter with MMW & sub-MMW

J. Appl. Phys. 54 (6), pp.3302-3309 (1983) .


Applied magnetic field

Quantized flux

Vdc Idc

Insulator

Superconductor

Superconductor

F0

F0

F0

f = Vdc/F0483.6 GHz/mV

AC current

Flux-Flow Oscillator (FFO)

Load(100GHz~700GHz)


“FFO”-Integrated MMW/THz ReceiversIntegrated superconducting receiver for atmosphere monitoring at 500-650 GHz

(TELIS project: TErahertz and submm LImb Sounder)

ISEC 2007 “Integrated Receivers for Space” by V. Koshelets

FFO(Local

oscillator)400 x

8~16 mm2

Antenna and mixer (0.8 mm2)

LO

IF

RF


History…1980 1990 2000 2010

1st MWP(1996)

FFO(1983)

UTC-PD(1997)

120Gwireless(2002)

ExternalEOS

(1989)

DAST(2002)

IC tester(1992)

WG-PD(1994)

Networkanalyzer(1998)

SARtesting(2006)

Spectro-scopy(2008)

PhotonicLO

(2003)

MMWimaging(2002)

Opticalsampler(1997)

EOpolymer(1991)

THz imaging(1995)

Electro-opticsampling: EOS

(1982)

THz TDS(1990)

Microwave photonics

Terahertz photonics

Optical MWinteractions

(1993/94)

Materials/devices

Measurement

Systems

300Gwireless(2009)

Tomo-graphy(2011)



Approaches

Enabling devices

Recent applications


CW MM/THz-wave Emission by Photonics

Optical

Fiber

Optical Signal

Source

(CW/Modulated)

Optical-to-

Electrical

Converter

Antenna

(Lens)

PhotodiodePhotoconductor


Enhancing the bandwidth of RF electronics

• Extremely wideband

• Widely and precisely Tunable

• Low-loss transmission with optical fibers

• Small size of frontend

Features


Laser DiodeDC

Laser DiodeDC

Coupler

(Combiner)

l1 (f1)

l2 (f2)

f1-f2

Wavelength ll2l1

ｔ

Dｆ = cDl/l2

fbeat= f1- f2

OE converter

(Photodiode/

Photoconductor)

Radio wave frequency

(1GHz ~ 1THz)

“Photo-mixing”, or “Optical heterodyning”

CW Optical MM/THz-wave

Sources


Df

Optical Noise Source(ASE Noise)

fOpticalfilter

Df

Noise Sources(Low-coherent Sources)

Wavelength l

f0

Nf0

Wavelength l

Optical Frequency Comb Generator

f0

RF

l

Optical

Filter

Highly Coherent Sources

CW Optical MM/THz-wave Sources


Photodiode Technologies

Light absorption layer (InGaAs)

C. B.

V. B.

p-contact

P+

Hole

Electron

N+

Light

Band diagram

Photocarriers+ -

ab

so

rptio

n

Ca

rrie

r d

rift

Absorption layer

Layer structure

Light

+ - + -+ - + -

+

+

+ +

++

+

-

-

--

---

Conventional pin PD “Surface illuminated”


Structure design: higher efficiency, bandwidth Refracting facet Waveguide PD, evanescently coupled Traveling-wave, distributed

Carrier transport design: higher current UTC-PD, PDA, etc.

Circuit design: higher bandwidth Matching circuit canceling capacitance Antenna integration Array, power combiner

Approaches to Enhancing Performance


(A)

(C)

(D)

Carrier

drift

Optical waveguide

(WG)

Carrier

drift

Absorption

Light

Refracting facet S.I. InP

(B)

Absorption layer

Abs. Abs.

L


Carrier Transport Engineering

Lig

ht

absorp

tion

layer

(p-I

nG

aA

s)

Carr

ier

colle

ction

layer

(InP

)

Diffu

sio

n b

lockin

g

layer

p-contact

P+

electrons

Light

non-

absorbed

N+

C. B.

V. B.

holes

UTC-PD: Uni-Traveling-Carrier-Photodiode


p

i (InGaAs)

n(b) Conventional pin

non-

absorbedi (InP)

(a) Dual depletion pin

i (InGaAs)

p

n

p-dopedabsorber

(p-InGaAs)

non-

absorbed

(c) UTC

i (InP)

hole

electron

Light

i (InGaAs)

non-

absorbed

(e) Modified UTC (composite)

i (InP)

(d) Partially doped absorber

n-dopedabsorber

(n-InGaAs)

p-dopedabsorber

(p-InGaAs)

Light

Menu of “Hamburgers”


p-doped

absorption layer

un-doped

collection

layer

n-contact

layer

p-contact

layer

diffusion block layer

(C.B.)

(V.B.)

200 300 400 500 600

Frequency (GHz)

0

-5

-10

-15

-20

-25

un-doped

absorption layer

Outp

ut

pow

er

(dB

m)

500 mW @20 mA

Modified UTC-PD (Composite Structure)

A. Wakatsuki et al.,

IRMMW-THz 2008.


C

G

G

DCbias

Stub

UTC-PD

RFout

100 µm

CPW 3

C

CPW 2(stub)

CPW 1

UTC-PD

50 Ω

DCbias

(2-3 V)

RFout

(A) W-band (75~110 GHz)

(B) Equivalent circuit

(C) J-band (220~325 GHz)

UTC-PDStub

C

100 µmRF out

DCbias

Circuit Techniques

“relax CR time constraint”


w/o RC-time

limitation

0.4 0.6 0.8 1.0 2.0

with RC-time

limitation

0.75 THz

1.05 THz

1. 5 THz

100

10

1

0.1

Frequency (THz)

Dete

cte

d p

ow

er

(mW

)

(-2 V, 8 mA)

Twin dipoleantenna

DC bias

RF ChokeRF Choke

100 mm

With log-periodic

antenna

Maximum 11 mW at 1 THz

(14 mA)

Integrated with Antenna


Output Power from PDs

10 -3

10 -1

10

10 3

10 5

0.1 1

Maxim

um

de

tecte

d p

ow

er

(mW

)

Frequency (THz)

f -4

LT-GaAs

20 dB

pin PD

NTTUTC-PD(resonant)4)

1)

3)

4)

0.3 0.5

UCLUTC-PD

(resonant)3)

NTTUTC-PD(resonant)2)

NTTUTC-PD

(wideband)1)

2)


Enhancing Output Power by Combiner

PD

Combiner

Chip Structure

PD

Output

Ou

tpu

t p

ow

er (

dB

m)

1 10 100

0

6

Photocurrent per PD (mA)

1 mW @300 GHz@ 18 mA per PD

-6

-12

-18

H. J. Song et al., 2012 Asia-Pacific Microwave Photonics Conference.

K. Arakawa et al., ibid.

H. J. Song et al., IEEE Micro. Wireless Compo. Lett., Vol. 22, No. 7, pp. 363-365, 2012.


Commercially Available from NEL

1550 nm

6 mAAntenna-integrated

J-band (WR-3 waveguide)

0

-10

-20

-30

-40

0 200 400 600 800 1000

Frequency (GHz)

W-band F-band D-band

1550 nm

7 mA

60 100 140 180

10

0

-10

-20

-30

-40

Frequency (GHz)

Ou

tput

pow

er

(dB

m)


O/E

Conv.

CW-THz Detectors

Antenna Diode AntennaElectronic

Mixer

LO Signal

AntennaElectronic

Mixer

Photonic

LO Signal

Antenna

(Lens)

Photonic

Mixer

Photonic

LO Signal

SBD/Bolometer

SBD/SIS PC/EO/PD

SBD/Bolometer


Outline


Approaches

Enabling devices

Recent applications

Wireless communications

Spectroscopy

Imaging


Ethernet

FTTx

FTTH

ISDN

ADSL LTE

USB2.0

USB3.0

802.11b

WiMAX2

802.11a802.11g Bluetooth

802.11ad802.11ac

WiGig

100 G

10 G

1 G

100 MUWB

802.11n

LTE-A

10 M

1 M

1990 2000 2010 2020

Wired

Wireless

Trends in Communications


Wireless LAN

802.11 a/g/n

Carrier frequency (GHz)

TransferJet

0.56 Gbit/s

60-GHz band

Wireless HD/

WiGig

4-7 Gbit/s

120-GHz band

10-20 Gbit/s

Bluetooth 3.0

0.054 Gbit/s

Data

rate

(Gbit/s

)

275GHz

300-GHz band

40 Gbit/s

Not yetallocated

0.1

1

10

100

10 100 1000

0.3 Gbit/s

1

Present

Future

Carrier vs. Data Rate


1 THz

Radio comms

Marconi

Satellite comms LMDS

WPAN

60 GHz LAN

1 GHz

1 MHz

1900 1940 20201980

THz

T. S. Bird (CSIRO), Keynote talk at

Asia-Pacific Microwave Conference

2011, Melbourne, Australia,

December 2011.

Car

rier

Fre

quen

cy

120 GHz

Jan. 2014~

Carrier vs. Year


First Field Demonstration


Broadcasters’ Needs


Success in Beijing Olympic 2008

-45 -40 -35

10-2

Bit E

rror

Rate

Received Power (dBm)

10-4

10-6

10-8

10-10

10-12

Data rate:10.3125 Gbit/s

Minimum receivedpower: -38 dBm


Shannon Proves…

THz wavesMicrowaves

VS.

Increasing power, complexity and cost

Energy efficient, cost

effective, and ….

Frequency

= Space

Shannon theory

R (bit/s) = B (Hz) log2 (1 + S/N)


Who Pays for THz?

1) Broadcasting

uncompressed HD x N:1.5 Gbit/s x N

uncompressed UHD (SHV):72Gbit/s, 144 Gbit/s

uncompressed 3D w/ HD or UHD >200 Gbit/s

2) Medical

more reality in color and increased resolution for diagnosis

huge image data handled at real time for surgery

wireless data transfer required in surgery rooms

no latency for remote medicine

3) General consumer ??

cheaper and smaller


Wireless

energy transfer

We do not bring notebook PCs.

Memory

devices

Smart

phone

Ultra fast: >100Gbit/s wireless ☞>12.5GB/s+ Low-power operation

+ Small in size (including antennas)

Data

transfer

Future NFC


Data Rate vs. Carrier FrequencyT. Nagatsuma et al., Optics Express, 21, Issue 20, Page 23736 (2013).

50 100 150 200 250 300 350 Carrier frequency (GHz)

Data

rate

(G

bit/s

)

Real time

Off-line DSP

40 Gbit/s

(SISO)

100

10

1

48 Gbit/s

(PMUX)c

20 Gbit/s

(QPSK)

10 Gbit/s

(SISO)NO allocation


Towards 100-Gbit/s Wireless

75-110 GHz 40 Gbit/s: 16QAM BER= 1.9x10E-3 (off-line DSP)

A. Kannno et al., Opt. Lett.,19, 2011.

100 Gbit/s: 16QAM+Pol. MUX BER=2x10E-3 (off-line DSP)S. Pang et al., Opt. Express, 19, 2011.

108 Gbit/s: 2x2 MIMO BER=3.3x10E-3 (off-line DSP)

X. Li et al., Optics Lett., 37, 2012.

120 GHz 10 Gbit/s: ASK (SISO) Error free (BER


Enabling Technologies: TxDATA signal

Post-amplifier

Optical RF signalgenerator

Opticalmodulator

O/Econverter

Electricalmodulator

Opticalamplifier

Electrical RF signal generator

DATA signal DATA signal

Diode

mixer Gunn diode + multiplier

Oscillator IC, RTD, etc.

EDFA

SOA EOM

EAM

PD

Amplifier IC

Amplifier IC Infrared

lasers, etc.

AntennaElectronics based Tx

Photonics (O/E) based Tx


Enabling Technologies: Rx

DATA signal

Pre-amplifier

Electricaldemodulator

Diode detector

Amplifier IC

Antenna

Baseband IC

DATA signal

Pre-amplifier

Electricaldemodulator

Diode mixer

Photodiode Amplifier IC

Antenna

IF/baseband IC

LO signalsource Gunn diode + multiplier, etc.

Photonically-generated LOs

Direct detection

Coherent detection


Role of Photonics in THz Wireless

• Technology driver for THz wireless research

Early demonstrator to explore applications

Key components mostly available

High performance

• Convergence with fiber-optic systems

Seamless bit rate between wired and wireless NW

Merit of analog RoF: no latency, low cost, low power

• To be a “winner”

Integration makes competitive with electronics

(Silicon photonics, InP photonics, Hybrid intergarion)


Application of Photonics-based Tx

Base-band

Photodiode

l1

Data

Data

Fiber-optic link

ｆRF = cDl/l2

Dl =l1 - l2

l2RF

Photodiode

Photo-mixing

RF

Receiver Data

Wireless link

Seamless between fiber-optic and wireless

Optical

Modulator


Oscillo-

scope

Optical amp.

Schottky-

barrier

diode

Optical

modulator

Photo-

diode

THz wave

Pulse-pattern

generator

Wavelength

tunable laser

Wavelength

tunable laser

Horn anttenaPreamp.

Limit amp.

Error

detector

Dielectric lens

Tx Rx

Optical freq.

Optical freq.

f

fRF freq.

l2

l1

Baseband freq.

BasebandFreq.

300-GHz Photonics-based Tx


0

20

40

60

80

100

120

260 300 340 380 420

6 mA

10 mA

Frequency (GHz)

Dete

cte

d P

ow

er

(mW

)

140 GHz

270 410

90 Gbit/s w/ ASK

Large Bandwidth of PDs


Limitation by Receiver BW

Output

[1] Antenna [2] Matching circuit [4] Low-pass filter

[3] Schottky

barrier diode

(SBD)

[1] [2]

[3]

[4]


Photo of Setup

ReceiverTransmitter

THz wave


SISO Transmission at 300 GHz

Bit e

rro

r ra

te

1E-12

1E-10

1E-8

1E-6

1E-4

Photocurrent (mA)6.0 7.0 8.05.0

42 Gbit/s

40 Gbit/s

~100 mW


30 Gbit/s 32 Gbit/s 35 Gbit/s

40 Gbit/s 45 Gbit/s 50 Gbit/s

Use of Wideband Detector at 300 GHz


Use of Higher Carriers: 600-GHz Band

450 GHz

500 GHz

550 GHz

600 GHz

650 GHz

720 GHz

1.6 Gbit/s

Usable BW: 270 GHz 160 Gbit/s, >105 Ch. HDTV


Outline


Approaches

Enabling devices

Recent applications


Spectroscopy

Imaging


THz Spectroscopy: Motivation

3THz1.5 THz0.9THz

1 cm-1= 30 GHz

Absorption peaks or finger prints exist…


Optical

Signal

Source

Photonic

Terahertz-

wave

Emitter

Photonic

Terahertz-

wave

Detector

Object

Under

Test

Optical

Delay

Photodiode


Electro-optic CrystalPulse/CW

Detected

Signal

Setup for spectroscopy

Photodiode



Ultra-broadband Only by Photonics


Commercial Spectroscopy Systems

AispecTeraView(UK)

EMCore

Zomega

Toptica PhotonicsNikon Otsuka

PNP Advantest BATOP


Towards Low-cost and Compact System

S. Hisatake et al., IEEE Sensor J., Vol. 13, No. 1, pp. 31-36, 2012.

Wavelengthfixed laser

Wavelengthtunable laser

Splitter

FS

CombinerEmitter: UTC-PD

Detector:

Photoconductor

or UTC-PD

Oscilloscope

Optical spectrumanalyzer

Object

Lock-inamplifier

Amplitude

Phase

0.1 Hz 2 kHz

Current amplifier


Photo of Setup

Detector

EmitterTHz wave


Frequency Characteristics: SNRWater vapor absorption @ 556.936 GHz


Standard deviation of measurement 67 MHz

Frequency Resolution & Accuracy

𝐴THz = −𝐵

2

𝜔 − 𝜔0𝜔 − 𝜔0

2 + 𝛾2𝜙THz =

𝐵

2

𝛾

𝜔 − 𝜔02 + 𝛾2

520 540 560 580 600

1000

0

0

500-60

-120

SN

R

Ph

ase

(d

eg

ree

)

Frequency (GHz) Frequency (GHz)

experimental

calculated

520 540 560 580 600


J.-Y. Kim et al., IEEE Trans. Terahertz Science Tech., Vol. 3, No. 2, pp. 158-166,

2013.

Spectroscopic imaging of two tablets composed of pure

polyethylene (PE) and 20% theophyline (Thp) in PE at 950 GHz.

Spectroscopic Imaging


Future: Spectroscopic Tomography

Measured by Advantest TAS7000 based on

pulsed THz imaging.


Outline


Approaches

Enabling devices

Recent applications


Spectroscopy

Imaging


Imaging: What Can be Seen with THz?


At the airport…


3-D Imaging with THz Pulse

delay


What THz can See?

Multi-layer Coating of Paints

Skins Paiting Art

Tablet Coatings


L1

L2

L1

Inte

nsi

ty

DepthL1 L2

L2

L2

L2

L1

L1

Low-coherence

signal source

Power

detector

Mirror

ObjectHalf Mirror

T. Isogawa et al., IEEE Trans.

THz, vol. 2. No. 5, 485 (2012).

Our Approach: THz OCT


Experimental Setup: TD-OCT

Optical

Amplifier

UTC-PD

PC

Object

Pre-

Amplifier

Lock-in-

Amplifier

Beam Splitter

Reference Mirror

Movable

Low-coherence Signal Source Detector

SBD

Terahertz Waveoptical

electric

UTC-PD : Uni-Traveling Carrier PD / SBD : Schottky Barrier Diode

(10kHz) Horn

Antenna

Output

Signal

UTC-PD

Optical

Modulator

ASE noise


Theoretical Depth Resolution

Path length differenceFrequency

Broadband THz Source

(Low-coherence Signal)

Interference Signal

Δf

ΔZ=2ln(2)

π Δλ

λc

The theoretical depth resolution is

Δz = 1.1 mm(fC = 350 GHz, Δf = 120 GHz) λC ：center wavelength

Δλ：bandwidth of wave length

2λc

fc

= fc2

C


Applicable to tomography with 1-mm depth resolution.

Waveform “Interferogram”

0

0.2

0.4

0.6

0.8

1

-10 -5 0 5 10

Rel

ativ

e In

tensi

ty (

a.u

.)

Path Length Difference (mm)

Δz = 1.2 mm

Experimental

Gaussian fitting


Experimental Depth Resolution

1.0 mm

3.1 mm

4.5 mm

7.0 mm

9.9 mm

Plastic

d : thickness

0 20 40 (mm)

0

60

40

20

(mm

) Intensity MapingObject

Inte

nsi

ty

Depth

Predicted Waveform

Front side Back side

Back sideFront side

0 40302010

Rel

ativ

e In

tensi

ty (

a.u

.)

Path Length of the Reference Mirror (mm)

Z

d = 3.1 mm

4.5 mm

7.0 mm

9.9 mm


LEGO Giraffe

Front Side Backside

Thick Paper Metal

3D Imaging : TD-OCT


Unit；mm0

100

0

65

2-D Image

0

65

0

50

3-D Image

0

65

50

3D Imaging : Results


Single Signal

Detector

Wavelength Sweep Source

𝐿

𝑧1 𝑧2

k

𝜋𝑐

𝑧1 − 𝐿

k

𝜋𝑐

𝑧2 − 𝐿

FFT

z𝑧1 − 𝐿 𝑧2 − 𝐿

Reference Mirror

Object

Beam Splitter

𝑘

T. Ikeou et al., Tech. Dig. Microwave

Photonics (MWP), 2012.

THz Swept-source (SS) OCT


250 300 350 400 450

1.0

0.8

0.6

0.4

0.2

0

Frequency (GHz)

Sig

nal P

ow

er

(arb

.U

nit)

0 5 10 15 20

1.0

0.8

0.6

0.4

0.2

0

Optical Path Length Difference (mm)

Sig

nal P

ow

er

(arb

.U

nit)

Detected Signal: SS-OCT(300 GHz)

Raw data

(frequency spectra)

Position data

(point spread function)

FFT


3-D Imaging of Object

1 mm10 mm

3 mm

Incident waveT

HZ

Reflectedwave

Plastic plates with holes of letters


Z

H

T

x

z

y

High

Low

Reflectio

n

x

z

y

Incident

wave

Top and back surfaces can be discriminated.

Cross sectional view for x-z face

Tomographic View


Optical

Amplifier

UTC-PD

Wavelength

Tunable LaserWavelength

Fixed Laser

A

B

Optical

Modulator

A

B

t

l0 l1 l2

t=0.5mm

Sig

na

l P

ow

er

(a.u

.)

0 5 10

15 Optical Path Length (mm)

Incident

Reflected

Swept-source OCT at 600 GHz

450~750 GHz


Application Examples

0

0.5

1

0 2 4 6Sig

na

l P

ow

er

(a.u

.)

Depth Distance (mm)

0

0.5

1

0 2 4 6

Sig

na

l P

ow

er

(a.u

.)

Depth Distance (mm)

Front side

Back side

(a)

(b)

(c)

A

B

A

B

Air

Water

0.9-mm thickness can be detected

Plastic bottle


Application Examples


Summary

Photonics accelerates MMW/THz applications and empowers their capabilities

• THz Wireless Communications

“Error-free” 30-50 Gbit/s @ 300 GHz only by photonics

> 100 Gbit/s @ 600 GHz is expected

• THz Spectroscopy

Telecom-wavelength based CW system

higher resolution, compact, low-cost

• THz Imaging

tomography based on OCT with sub-millimeter resolution

using 300/600-GHz band


Spacescience

Earth

environment

Broadcasting

EMC

Disaster recovery

Photonics Empowers MMW/THz Applications

Access network

Security

Medical Test & measurement


Thank you for your attention.

C2E2 2015 Page 100 9 January 2015

http://www.iject.org/C2E2-2015/5-Tadao-Nagatsuma.pdf

International Journal of Electronics & Communication

Technology VOL 6.1, Spl-1 Jan – Mar 2015

Full Paper Published

forum for electromagnetic research methods and application … · 2017. 1. 16. · conference on...

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