Report In Japan 20060613 Liuxu

Department of Optical Engineering Department of Optical Engineering Zhejiang University, Hangzhou, China Zhejiang University, Hangzhou, China 2006. 10. 12 2006. 10. 12

The New Developments on OpThe New Developments on Optical and Photonic Technology tical and Photonic Technology

in Zhejiang Universityin Zhejiang University

Professor Xu LIU Professor Xu LIU

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJU

Contents:1. Brief Introduction of ZJU and OED

2. New Development in the Research of Optical Engineering

Nano-photonics

Photonic Crystals (PC) and Thin film devices

Optical Coherent Tomography (OCT) and applications

3. Conclusion

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJU1. Brief Introduction

of ZJU

Locate in Hangzhou Locate in Hangzhou

one of the most beautone of the most beaut

iful cities at east coasiful cities at east coas

t of Chinat of China

100 miles south-west 100 miles south-west

of Shanghai.of Shanghai.

ZhejiangUniversity

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJUZhejiang

University

-- ranked among the top 3 Chinese universities-- ranked among the top 3 Chinese universities 6 campuses in City of Hangzhou6 campuses in City of Hangzhou 30,000 undergraduate students30,000 undergraduate students 12,000 graduate students 12,000 graduate students 5,000 PhD candidates5,000 PhD candidates 8,000 faculty and staff members8,000 faculty and staff members


Dept. of Optical Dept. of Optical EngineeringEngineering

1952 ： The first division of optical engineering in China

1960 ： The first Dept. of Optical Engineering in China

1984: Ph.D Programs

1986: Post-doctoral Programs

1988 ： Selected National Key Academic Discipline

1990 ： State Key Lab. of Modern Optical Instrumentati

on

1993: National E&T Center of Optical Instrumentation

1995: International Joint Laboratory of Photonics with

Hamamatsu Photonics

2002: Selected National Key Academic Discipline

2005 ： No:1 Discipline in China


Education:Undergraduate program: ( 4 year program) 720 students Optical Engineering

Program for MS degree: ( 2~2.5 year program) 219 students Optical Engineering Instrumentation Science and Technology

Program for Ph.D: ( 3 year program) 107 students Optical Engineering Instrumentation Science and Technology

Faculty and staff members:Total 98 faculty/staff in the department

Including: 28 professors, 37 associate professors

16 Post doctors & assistant professors


Constitution

State Key Lab. of Modern Optical Instrumentation

International Joint Laboratory of Photonics

National R&D center of Optical Instrumentation

For technical development and transform

For bio-optics and bio-photonics

For applied science researches


The State Key Laboratory of Modern Optical Instrumentation Lab of optical instrumentation

Lab of optical thin films and display

Lab of opto-electronics

Lab of opto-electric information detection

Center for optics and electromagnetic wave

Cover all the Department


In past 50 years, the Department has brought upIn past 50 years, the Department has brought up

4800 Bachelors 4800 Bachelors

850 Masters850 Masters

200 Ph.Ds200 Ph.Ds

In the same time, more than 300 engineers have also been trained by continuing education programs.

The Cradle of Chinese optical The Cradle of Chinese optical EngineersEngineers

History of Education


Annual Funds for Research:

0

5

10

15

20

25

30

35

40

2001 2002 2003 2004 2005 2006

Mil

lion

yu

an R

MB

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJUPublications in the last

years

Totally 196 papers on scientific journals and

2 books are published SCI collected ： 73 papers EI collected ： 125 paper

s Foreign journal ： 51 papers

23 patents opened74%

26%

forei gndomesti c

37%63%

SCI Others


Research fields in the

Optical Engineering

Department

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJUA. Precision detection and

instrumentation

Precision optical detection Position detection Wave-front & Surface roughness testing Optical coherent tomography (OCT)

Nano-scale detection & metrology AFM Nano-scale probe Near field detection

Fiber sensor and application Fiber grating Nano-fiber and application


B. Imaging Techniques and Hybrid optical imaging system

Diffractive component CAD

Laser direct writing system

Digital image processing

Imaging systems and techniques

High resolution imaging

Auto focus for digital imaging

Dynamic range expending


C. Projection display

Transmit liquid crystal projection display

Reflective liquid crystal projection display

Helmet display system

LED based display technique

Volumetric 3D display


D. Photonics Technology Photonic crystal design

Photonic crystal antenna

Photonic crystal wave-guide

Metamaterials design and development

Left hand materials

Negative refractive index effect in optical region

Passive integrated optical circuit on silicon

Optical system on chip

Integrated optical circuit

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJUE. Laser and nonlinear optics

technology

Fiber laser technique

Phase conjugation technique

Nonlinear optics

Semiconductor laser pumping

New type organic dye tunable laser

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJUF. Optical Thin film

Techniques Optical thin film coatings for extreme cases

Thin film coatings based on 1D PC

“Thin film Grating” super-prism effect

Structured thin film devices

Tunable thin film devices

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJUG. Optical radiation and color

detection

Optical radiation

metrology technique

Color matching model

and instrumentation

Spectrometry


2. The New Development

in the Research of

Optical Engineering

Nanometer optical fiber and new potential application Photonic Crystal and potential application OCT techniques & application

LabLabLabLab 浙江大学光学工程浙江大学光学工程


Micro- and Nano-fibers for Micro- and Nano-photonics


9 μm

125 μm

4-μm diameter

150-nm diameter

L. Tong et al., Nanotechnology 16, 1445 (2005).

Micro- and Nanofibers Standard optical fibers

Shrinking optical fibers into nanofibers


a. Laser-assisted VLS growth

1-2. Morales, A.M. & Lieber, C.M. A laser ablation method for the synthesis of crystalline semiconductor nanowires. Science 279, 208–211 (1998).

b. Photolithographic or electron beam lithography

problems:Surface roughness

Optical lose


Nano wire situationNano wire situation


Taper drawing of silica fibers

L. Tong et al., Nature 426, 816 (2003).

2. Fabrication of Nanofibers


we developed a simple method to

fabricate sub-micrometer- or nano

meter-diameter silica wires with e

xtraordinary uniformities. The pri

ncipal motivation for studying the

se optical- quality wires is their us

efulness as low-loss optical wavegu

ides for future micrometer- or nan

o-scale photonics, and as

tools and materials for

many other researches.

20um

SEM of a 560-nm diameter silica wire

Optical micrograph of a 360-nm diameter silica wire guiding He-Ne light



Diameter: 50 nm several micrometers

Length:

L ~ 1 mm (D < 100 nm)

L can go up to 100 mm for D > 200 nm

D ~ 50 nmD ~ 50 nm



SEM images

Silica nanofibers

D = 50 nm

D = 70 nmD = 450 nm

D = 260 nm

Nature 426, 816 (2003)

Nature 426, 816 (2003)

D = 480 nm

Small dimension

Uniform diameter

Large length

Circular cross section

2. Fabrication of Nanofibers


More than 30% of the total energy is guided outside the core

x (µm) y (µm)

Sz

Field distribution in

the sub-wavelength

fiber


Light coupling between the nano-fibersLight is sent into a silica wire by means of evanescent coupling. As shown here, He-Ne laser (633-nm wavelength) transfers from a 390-nm diameter wire to a 450-nm diameter wire.

100µm100µm

390-nm diameter wire 390-nm diameter wire

450-nm diameter wire 450-nm diameter wire


More recently

< 0.01dB/mmL. Tong et al., Nature 426, 816-819 (2003).

G. Brambilla et al., Opt. Express 12, 2258-2263 (2004).

3. Optical wave guiding with nanofibers

Fibre taper 2

Fibre taper 1 Silica SGFs

Bonding Loss measurement

Light launching ： Evanescent coupling

Loss measurement

Optical microscope image of coupling light from a 390-nm-diameter wire to a 450-nm-diameter wire.

Schematic diagram for loss measurement of nanofibers


100µm

(D=360 nm, λ= 633 nm)

L. Tong et al., Nano Lett. 5, 259 (2005)

Optical wave guiding along silica nanofibers on aerogel substrate

Optical wave guiding with nanofibers


633-nm-wavelength light guided along a 260-nm-diameter tellurite nanofiber on a MgF2 substrate with guiding loss <0.1 dB/mm

Optical wave guiding along typical glass nanofibers

L. Tong et al., Opt. Express 14, 82 (2006).

Optical wave guiding with nanofibers

Up-conversion photoluminescence in a 320-nm-diameter Er-doped ZBLAN nanofiber excited by a 975-nm-wavelength light


Light propagation in fiber bending Minimum bending radius ~ 5.6 µm

100µm

Minimum bending radius ~ 9.0 µm

Light output


4. Micro- and nanofibers for photonic devices

Fiber diameter ： 350&450 nm

Wavelength ： 633 nm

Transfer length ：＜ 5 μm

Microcoupler assembled with tellurite nanofibers

Ultra-compact photonic integration and devices

3-dB splitter

Substrate: SilicaNo excessive loss!

L. Tong et al., Opt. Express 14, 82 (2006).


Micro- and nanofibers for photonic devicesHigh-quality microfiber knot resonators

(2) Knot resonators in air

1570 1575 1580-18

-15

-12

-9

-6

-3

0

Tra

nsm

issio

n(d

B)

Wavelength(nm)

1573.2 1573.6-12

-6

0

Transmission spectra of a 850-μm-diameter microfiber knot assembled using a 1.73-μm-diameter microfiber. The inset shows a single resonance peak.

Transmission spectra of a microfiber knot with diameter of (a) 1.84 mm, (b)1.38 mm, (c) 1.08mm, (d) 239μm and (e) 196μm. The knot is assembled with a 2.5-μm-diameter microfiber and is freestanding in air during the test.

1561 1562 1563 1564 1565 1566 1567-50

-40

-30

-20

-10

0

(e)

(d)

(c)

(b)

Tra

nsm

issi

on(d

B)

Wavelength(nm)

(a)

High quality factor (Q=57,000) Changing FSR with knot diameter

X. Jiang et al., Appl. Phys. Lett. 88, 223501(2006).


Micro- and nanofibers for photonic devicesHigh-quality microfiber knot resonators

(4) Microfiber knot lasers

Laser emission spectrum of a 2-mm-diameter microfiber knot. The knot is assembled with a 3.8-μm-diameter microfiber. (a) Laser emission spectrum with pump power around threshold. (b) Laser emission spectrum with pump power much higher than threshold.

1536 1538 1540 1542 1544 1546-80

-70

-60

-50

-40

-30

-20

-10

Pow

er (

dBm

)

Wavelength (nm)

a

b

Optical microscope image of the green up-converted photoluminescence from a 5.74-mm-length microfiber knot. The knot is assembled with a 2.7-μm-diameter Er:Yb-doped phosphate glass microfiber.

Optical microscope image Laser emission spectrum


Potential applications

C. Girard, “Near fields in nanostructures”, Rep. Prog. Phys. 68, 1883-1933(2005)]

Nanofiber is a promising solution for future photonic devices


5. OutlookNanofiber research is among the “TOP FIVE IN PHYSICS”

J. Giles, Nature 441, 265 (2006)

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJUA 450-nm diameter silica wire wraps on a hair

and guides light around it.

100µm


Photonic Crystal & Optical Thin films devices


Photonic CrystalThe concept was proposed by E.Yablonovitch and S.John in 1987 independently （ Phys.Rev.Lett,1987,58,2059 Phys.Rev.Lett,1987,58,2486 ） PC is an artificial material with periodic refractive index distribution in the scale of wavelength.


PC in the nature worldSea mouse spine hair

Butterfly


Properties of PC

Photonic band gap

Transparent

Polarization

Isotropy

Super dispersion

Band edge effectDFB


Applications of PC

super dispersion

Reflector & filter PC waveguide

PC lens

PC fiber

Recent development ：•Nonlinear PC device•Out coupling devices

……..


Fabrication methods• Film adding+ hole etching• Self-assembly• Pulse laser machine• Holographic imaging


Thin film techniques for PC

Self clone films by Tohoku Univ.Film micro column structure by Robbie. K &. Brett.M.J


Omni-directional reflector in visible or violet region

Dispersion equation of 1D PC

1 2

1 21 2

2 1

cos cos( )cos( )

1( )sin( )sin( )

2

x x

x x

K k a k b

k a k b

2 11 1 2 2

2 2 1 1 1 21 22 2

2 1 1 2 2 11 1 2 22 2

2 2 1 2 1 1 2

cos cos

cos cos

/ cos / cos

/ cos / cos

x x

x x

x x

x x

k kn nTE

n n k k

n k n kn nTM

n n n k n k

1 D photonic crystal


1D PC Band width Ratio of refractive index

Relative band wide vs. index ratio PC frequency vs. wave vector

In case of low index ratio <3, no perfect band gap ， only exits partial gap for certain incident angle.

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJUSuperposition of angular

band PCPC1 ， PC2 with periods of 106.11nm and 118.84nm

From λ1 ＝ 328.95nm to λ2 ＝ 352.11nm ， relative bandgap reach to6.80% 。

Bandgap shematic

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJU1D photonic

crystal

300 400 500 600 700 800 900

020406080

100300 400 500 600 700 800 900

020406080

100300 400 500 600 700 800 900

020406080

100

refle

ctio

n(%

)Wavelength(nm)

80

refle

ctio

n(%

)

60

refle

ctio

n(%

)

0 Omni-directional mirror

Angular Zone overlap to increase the frequency range, decrease the condition of the big refractive index ratio in PC

Biqin Huang, Peifu Gu, Ligong Yang, Construction of one-dimensional photonic crystals based on the incident angle domain, Physical Review E, 2003, Vol.68, No.4, 046601



The design of reflector0=365nm ， Sub/(HL)20 (1.12H1.12L) 20/Air ， nsub=1.416

0˚ ～ 56˚ ， PC1 band 332.0 ～ 345.6nm ；56˚ ～ 80 ˚ ， PC2 band 335.2 ～ 351.2nm ；PC1/PC2 band 332.0nm~350.4nm. Relative wide 5.39%

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJU“Thin film grating” superprism

effect

gxv

Group delay GD ：

Spatial dispersion ：

gxS v

, 2 tan

,2

gS L

KL

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJUFor high reflection

coatingsHigh reflector mirror coating: Glass/(HL)30/Glass ， n0=1.52 ， angle of incide

nt of θ0=39° ， n1=2.0 、 n2=1.5,d1=225nm ， d2=300nm 。

800 1000 1200 1400 1600 1800 20000

10

20

30

40

50

60

70

80

90

100

Wavelength(nm)

Reflecta

nce(%

)

EH

For TE light form 800nm to 1315nm is pass band, and for region >1315nm is rejection band, the superdispersion effect appears at the edage of the pass band.


Examples

800 900 1000 1100 1200 1300 1400

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

Wavelength(nm)

Gro

up D

elay

(ps)

RT

800 900 1000 1100 1200 1300 1400

-1

-0.5

0

0.5

1

Wavelength(nm)G

roup

Del

ay(p

s)

RT

Glass/(LH)30/Glass,39°incident angleGlass /(LH)30/ Air, 39°incident angle

There exists negative group delay, means negative spatial dispersion. And the superdispersion is sensitive for the incident media,


For Thin film F-P filterGlass/ H （ LH) 5(6L) （ HL)5H /Air, H － TiO2 , L － SiO2, thickness105nm, nglass=1.52, TE wave, incident angle=30.26°

At the wavelength of minimum reflectance, maximum phase change


Positive spatial dispersion

At wavelength of 747.57nm and 745nm ，incident angle=30.26° ， g=600μm

At the wavelength of 747.57nm and 745nm ，入 z ＝ 0 su

rface light distribution


Negative dispersion0

0

(Air/ (HL) 6(4L)(LH)6 /Glass) ， incident angle

=50°for air

At the wavlength=747.57nm


Numerical simulation

a) At 747.57nm b) at 747.3nm

At 747.3nm, dispersion +9.75μm, at 747.57nm dispersion is － 151.5μm 。

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJUReflective beam

separation For F-P filter, with incident angle of 30.26° ， from air, at the wavelength of 747.57nm 。

0 200 400 600 800 10000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

X(m)

(a.u

.)归

一化

光强

入射光反射光

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJUReflective light beam

separated

(a) At 747.57nm ， (2) at 745nm


Experimental results

746.5 747 747.5 748 748.5 749 749.5 7500

50

100

150

200

250

300

Wavelength(nm)

Shi

ft( m

)


Potential application

“Thin film grating” Very narrow band filter Possible used in some fluorescence spectra

analysis In DWDM system


Dielectric thin film polarizer


Bend gap

TE mode form0.208 to 0.291exist rejected band ； and TM mode does not exist band ， relative band wide is 33.1 ％ .


spectra

At normal incident, infect for TE mode is always reflected


Thin film imaging effectGrating period Lx＝ a＝ 0.44μm ， thin film period Lz ＝ Lx ， Si thick T ＝ 0.14 μm ， 45°

At the wavelength λ=1533nm


Sub-wavelength imagingAt the distance of the surface of 0.68a, two point sources, with interval of 0.83λ


MicroDisplay devices based on MOEMS

G la s s S u b s tra te

S i3 N 4

C r

A g

Inc id e nt light

A ir ga p

R e fle c te d light

V o lta ge S u p o o rt la y e r

Based on the induced admittance concept, the thin film device has admittance Z=X+iY:

the reflectance of Air|Ag Airgap is

2 2

2 2

2 2 2( (2 )) ( )

2 2 2( (2 )) ( )

s s s

s s s

n n dY X d nk n dX YR

n n dY X d nk n dX Y

X→0 、 Y→0 ， R→0 ， Max abs.X→∞ 、 Y→∞ ， R→1 ， Max refl.

'00

(2 1)( )

4 2

karctg k D

The center reflection wavelength

input

/4 SiNx

Silicon

PSG

reflect

transmit

Vdrive


400 450 500 550 600 650 700

0

10

20

30

40

50

60

70

80

90

100

Airgap=295nm

Airgap=520nm

Ref

lect

ivity

(%)

Wavelength(nm)

Airgap=425nm

Airgap=83nm

G la s s S u b s tra te

S i3 N 4 (4 2 .7 9 nm )

C r(1 0 nm )

Inc id e nt light

A ir ga p

R e fle c te d light

S i3 N 4 (3 3 .7 8 nm )

A g(1 0 0 nm )

scheme of the device

400 450 500 550 600 650 700

0

20

40

60

80

100

Airgap=0nm

Airgap=240nmAirgap=425nm

Ref

lect

ivity

(%)

Wavelength(nm)

Airgap=335nm

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80.0

0.2

0.4

0.6

0.8

Airgap=335nm(Blue)

Airgap=425nm(Green)

Airgap=240nm( Red)

CIE 1931

诱导反射光谱的色品图插入 Si3N4 后不同空气腔高度下的反射率曲线


Process

substrate

(1) 硅基板准备

substrate

(2) 热氧化 100nm SiO2 作为绝缘层

substrate

(3) 沉积 1.3μm 厚的多晶硅作牺牲层

substrate

(4) 沉积 250nm 厚的氮化硅作结构层

substrate

(5) 离子束刻蚀氮化硅

substrate

(6)KOH 溶液腐蚀释放氮化硅粱

substrate

(7) 电子束蒸发 50nm 的 Al


(a) (b)


Dynamic performance

在 100Hz 的方波驱动下的光学响应

上：电压驱动信号，下：光学响应信号响应时间 1~2ms 。

(a)250Hz 方波； (b)200Hz 正弦波(b)(a)

0 200 400 600 800 1000 1200 14000.0

0.2

0.4

0.6

0.8

1.0

optic

al in

tens

ity(a

.u)

frequency(Hz)

器件的频率响应，方波电压保持 20V

电容 C=ε0εrS/d=6.941×10-9F ，电阻 R=105KΩ ，电容充放电常数 0.73ms ，限制了器件的动态性能。


Devices testing

wyko 白光干涉仪的测试图，测得腔长 1.512μm

CCD 拍摄图


Optical Coherent Tomography and application


OCT system & Michelson interferometer


Cross-sectional imaging

Axial Axial ScanningScanning(Depth)(Depth)

Backscattering IntensityBackscattering Intensity


Time domain OCT

MirrorSource

Detector

Pre-ampBand-pass

FilterDemodulator

AD ConverterInterferometer Output Signal


Spectrum domain OCT

I(k)

k

Spectrum

a(z)

z

Amplitudes

FFT

Source

Sample

Static reference mirror

Diffractive Grating

(1200lp/mm)(1200lp/mm)

Detector Array

VR

eg. L103K-2K （ BASLER ）2048pixels 10um×10um 40Mhz 18.7Khz


System photo


Image of fish eye

LabLabLabLab Dept Opt. Eng. Dept Opt. Eng. ZJUZJUThe retina cross-section of

a rabbit


Esophagus‘s （食道） image

超生波 Ultrasonic OCT


4. Conclusion Optical techniques have developed so fast, that lots of new techniques have bean demonstrated, the Nanophotonic, Photonic Crystal, and so call optical meta － materials will bring us lots of new possibilities, including new imaging technique, new optical devices, etc. Optics has shown most important role in the future.


Thank you!