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24 th COOC 단기강좌 극초단 레이저 기반 투명 재료 가공기술

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Page 1: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

24th COOC 단기강좌

극초단 레이저 기반 투명 재료 가공기술

Page 2: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

2

극초단• 레이저 가공의 특징극초단• 레이저 가공의 역사

투명• 재료 내 광자 흡수의 원리

극초단• 레이저 투명 취성 재료 가공 기술Stealth• dicing of sapphire

Glass cutting•

Glass welding via heat accumulation•

Hybrid process•

Laser assisted selective etching•

Microfluidics•

Micro• -moulding

Laser• -assisted morphing

Page 3: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

What is an “ultrashort” pulse?

3

time

Δx = 3μm10 fs light pulse:

1fs = 10-15sec

time

ns pulsefs pulse

Wavelength

fs pulsens pulse

Femtosecond laser pulses are usually Fourier transform-limited pulses

Dw·Dt ≈ 2p Dw ≈ 2p/Dt Large spectral bandwidth for short pulses

Page 4: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Why ultrashort pulse?

4

Femtosecond pulse (τ = 10-15 s)

nanosecond pulse (τ = 10-9 s)

Continuous Wave

Inte

nsi

ty (

W/c

m2)

Time (sec)

Page 5: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

• 10mJ pulse with 10fs pulse width = 1TW

• Intensity at tightly focused beam spot (10µm)

= 1018 W/cm2

Power of an ultrashort laser pulse

1018 W/cm2

= Earth’s solar flux

on a pinhead

5

Page 6: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Ultrashort pulse regime for micromachining

The evolution of pulse duration

Milestones in the evolution of pulse duration

Era of ultrashort pulsed lasers (USPLs)

Era of ultrashort pulsed laser micromachining

Commercialization of

USPL machining platforms

Commercialization of

high power USPLs 6

Page 7: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Copyrightⓒ Jiyeon Choi, Do not copy or distribute

Milestones in the ultrashort pulse laser micromachining

Chirped Pulse Amplification

1985• : D. Strickland & G. Mourou, Chirped pulse amplification

7

Page 8: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Milestones in the ultrashort pulse laser micromachining

Late 80s :

first comparative study & empirical understanding

Küper, S and Stuke, M., Appl. Phys. B, 44, pp. 199-204 (1987). 8

Page 9: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Milestones in the ultrashort pulsed laser micromachining

9

90s : quantitative investigation

80fs, 5J, 20mm/s

200ps, 20J, 15mm/s

200ps, 150J, 20mm/s

80fs, 5J, 8mm/s

deterministic

statistic

B. C. Stuart et al., Phys. Rev. Lett., vol. 74, pp. 2248-2251, 1995.

X. Liu et al., Quant. Electron., IEEE Journal of, vol. 33, pp. 1706-1716, 1997.

Damage threshold vs. pulse width

For short pulse (< 10ps)Obeys different interaction -

mechanism

Deterministic feature of USPL

Page 10: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Theoretical understanding

Photo-ionization vs avalanche ionization

B. C. Stuart et al., Phys. Rev. Lett., vol. 74, pp. 2248-2251, 1995 10

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THG readout

Milestones in the ultrashort pulsed laser micromachining

11

2000 - : efforts on industrialization

MicromachiningDrilling-Cutting-Welding-LASE-

3D photonic structuresWaveguides-Couplers-Gratings -DOEs-Optical storages-

R. Gattass and E. Mazur, Nature Photonics (2008)

J. Choi et al., Opt. Lett 37(16) 3375 (2012)

R. Berlich, J. Choi et al., Opt Lett 37 (14) 3003 (2012)

L. Canioni et al., Opt Lett 33 (4) 360 (2008)

Page 12: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Milestones in the ultrashort pulse laser micromachining

12

2010- : Successful Industrialization and more

Biomedical

Page 13: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

13

Laser dicing of sapphire

Saw dicing vs. laser dicing

http://www.disco.co.jp/eg/solution/library/stealth.html

Page 14: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Chemically strengthened glass for display

14

Immersed in KNO3 solution for 8 Hr@ 410 C̊

~ 30 µm

Compressive stress > 650 MPa

www.corning.com

How to cut/machine the sophisticated glass flawlessly ?

http://informationdisplay.org/

Page 15: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Glass goes thinner

15

Glass for wearable devices

Garner, S., et al. "Ultra-slim flexible glass for electronic application." Proceedings of the MRS Fall Meeting. 2012.

Toerker, M., et al. "Transparent OLEDs for signage and decorative lighting applications." LOPE-C, June (2012): 19-21.

www.corning.com

http://www.wirelessefficiency.com/?p=2755

Page 16: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Glass goes into body

16

Glass for implantable devices

15 mm x 3.2 mm x 2 mm

Fused silica

16 mm x 4 mm x 0.5 mm

Quartz

10 mm x 1.1 mmSilicon

Page 17: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Various strategies for laser cutting of glass

CO2 based thermal cleaving

NL absorption

Full body cleaving

Ablation

Thin glass?

Curvy Line?

Size effect?

Proper Laser?

Microcrack?

Chipping?

NLO Control?

Speed?

Urs Eppelt et al., Proc. ICALEO 2012, #M504

Proc. of SPIE 688007-1 (2008)US PTO 5,609,284

J. Choi et al., ICALEO (2013)

17

Page 18: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

New breakthrough

Full body cleavage using ultrafast lasers

Proc. of SPIE 688007-1 (2008)

~99% Abs. < 5 µm

Proper laserCO2 laser

(10.6 µm)

YAG laser

(1.06 µm)

Excessive

absorption

Proper

absorption

No

absorption

Glass substrate

Linear absorption by doping

No active triggeringNonlinear absorption

triggered by laser intensity

18

𝛼 = 𝛼𝑜 + 𝛽𝐼 + ⋯

Page 19: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Microscopic investigation

Laser-cut surface of Gorilla glass

1

2

21

Page 20: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Considerations

20

Nonlinear-optical effect

@ Ep = 6μJ (P.P 20 MW)

~35μm𝑃𝑐𝑟 =

𝜋0.612𝜆2

8𝑛𝑜𝑛2

Critical power•

for fused silica, ~ 2.2 MW requiredto initiate self-focusing

Self• -focusing distance

0.3

0.5

0.7

1

3

5

10

Laser incidence

ps

~56μm

~152μm

11 μJ (37 MW)

R. Boyd, Nonlinear optics, 3rd ed. Academic press

Page 21: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Elongation of laser focus

21/43J. Lopez et al., SPIE LASE 2016

Page 22: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Various techniques in spatial & temporal beam shaping

axicon

DOE

Spatio-temporal beam shaping

Airy beam

F. Courvoisier et al., Appl.phys. A 112:pp29 (2013)

www.holoor.il

Mindaugas Gecevičius et al., Opt. Lett 39(24) (2014)

Page 23: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Conventional vs. USPL Glass welding

http://spie.org/x8508.xml

microcracks

Glass frit sealing No adhesives•

No • microcracksDirect bonding of glass •

Page 24: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Direct glass welding

24

I. Miyamoto, “Welding of glass by ultrafast laser pulses”, 3rd UKP workshop

Page 25: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Heat accumulation at high rep. rate

Page 26: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Heat accumulation

S. M. Eaton et al., Opt. Express 16(13) 9443 (2008)

Page 27: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Hybrid process

27

FLDW + LASE (laser assisted selective etching)

Optofluidics

Koji Sugioka and Ya Cheng Lab Chip, 2012,12, 3576-3589Koji Sugioka and Ya Cheng Light: Science & Applications (2014) 3, e149; doi:10.1038/lsa.2014.30

Page 28: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Hybrid process

28Y. Bellourd, JLMN 7(1), pp1-10, 2012

FLDW + LASE (laser assisted selective etching) 3D microstructures

• Applications: Micro-optics, MEMS, biomedical, active platforms…

Page 30: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Various applications of LASE

30

Micro-moulding

Micro-flexure

MEMS

Passive alignment system

Micro gear (watch component)

Page 31: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Laser assisted morphing

31J. Drs et al., Opt. Express 23 (13) 17355 (2015)

Page 32: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Ultrafast laser processing of glass•Full body cutting with mirror– -like cut surface

Direct – glass welding for hermetic sealing

LASE for MEMS device fabrication–

Conclusion

32

Syringe Pump

Flow : 500 nL / min

Experiment setup (Laminar flow)

outlet

YellowBlue

Redwelding Non welding

Page 33: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

33

Questions?

Page 34: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

LASE process to fabricate a microfluidic device

34

Fused silica (base)

Laser direct writing (fs)

Fluidic channel Inlet & outlet

Laser drilling

Interface Laser welding (ps) without direct bonding

Pristine fused silica(cover)

Total fabrication time within two hours !

HF(hydrofluoric acid) etching

Sonication bath

Page 35: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Laminar flow test w/ microfluidics via LASE

35

Syringe Pump

Flow : 500 nL / min

Experiment setup (Laminar flow)

outlet

YellowBlue

Redwelding Non welding

75mm x 25mm

Ferrules

Non welding area Interference pattern

Flow result

100 μm

Injection (red)

Glass to glass bonding

Page 36: Microscopic investigation on the ultrafast laser cutting of …osk.or.kr › UploadData › Editor › Conference › 201706 › 8192284E92... · 2017-06-04 · Full body cleavage

Various microchannels via LASE

3 trench structure

Stereoscopic microscope image Multi channel fabrication

Transparency as a key of femtosecond laser direct writing (High aspect ratio channel)

Number of Passes 10 + HF Etching(30min)Width= 79 μm depth= 377 μm

Aspect ratio 4.77