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Controlling the interaction between light and matter

confined in nanoscale

Leonardo de S. MenezesDepartamento de Física

Universidade Federal de Pernambuco50670-901 Recife-PE, Brasil

lmenezes@df.ufpe.brwww.df.ufpe.br/~lmenezes

Limits and Interfaces in Sciences / Kumboldt-KollegSão Paulo-SP, 28th - 30th October 2009

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1. Introduction2. Scanning near-field optical microscope (SNOM)

probe for controlling Raman microlaser action3. SNOM probe as a tool for controlling the

interaction of a nanoscopic light emitter with confined electromagnetic field

Outline of the talk

Motivation Using scanning probe tech-niques (SNOM) for controlling and manipulating confined light in microresonators, as well as to control the interaction of single nanoparticles with it.

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1. Introduction

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St. Paul´s cathedral, LondonLord Rayleigh, 1878

33 m

60 µm15 µm

· Easily produced by melting an optical fiber with a CO2 laser.

· Diameters from 20 m to 200 m.· Q factors up to 1010.· May store photons for some s.· Comparison: tuning fork 550 Hz,

same Q: oscillates for 4 days!!!· Modal volume V~3003

· Evanescent field allows the external coupling.

Braginsky et al., Phys. Lett. A 137, 393 (1989); L. Collot et al., Eur. Phys. Lett. 23, 327 (1993).

· Light is trapped in a whispering gallery mode by successive total internal reflections, travel-ling in a great circle along the cavity's perimeter.

Microspheres as optical cavities

100 m

Represent optical resonatorswith ultra-high Q-factors and small mode volumes.

~33 m

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Experimental setupSpectroscopy of the microspheres´ eigenmodes

Typical spectrum measured byabsorption and scattering

DiodeLase r

Pho

todi

ode

Pho

todi

ode

DiodeLase r

F iber toP

MT

F iber toP

MT

3D3D3D3D

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Experimental setup…

Constant distance (~10 nm) between the microsphere sur-face and the SNOM tip via a shear force control loop.

Tip-limited (~50 nm) optical resolution.

Allows getting a topogra-phical image.

Scanning Near-field Optical Microscopy

20mm

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2. Scanning optical near-field probe for controlling Raman

microlaser action

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For Q = 109, Pthreshold = 4.3 W world record!

=70mQ=3108

=795nm

4 mm

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Near-field probe

1D scan + laser scanned

Pump mode (@ 795 nm) Laser mode (@ 814 nm)

Tip reduces the Q-factor of the WGM laser threshold increases

A. Mazzei et al., Appl. Phys. Lett. 89, 101105 (2006).

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3. Controlled and efficient photon transfer betweentwo single nanoemitters

mediated by WGMs

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Controlled coupling with a single dye-doped bead

PMTSpectrometerCCD

532 nmPump laser

N an o partic le

N ea r-fie ld p robe

Fluorescence microscope images of a single 200 nm dye-doped bead attached to a SNOM tip

Without notch filter

Withnotch filter

606 608 610200

400

600

Inte

nsity

[a.u

.]Wavelength [nm ]

FSR

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PM T

75 80 85 90 95 100 105 110 6

8

10

12

14

16

18

20

22

24

Inte

nsity

(a. u

.)

Angle (degrees)

0 4 8 12 16 20 24 28 D istance [µm ]

200 nm

=85 µm

0

1

3

shea

rfor

cear

ea

2

4

shea

rfor

cear

ea

D is tance from bead to sphere surface [µm ] 0.0 0.2 0.4 0.6 0.8 1.0

Inte

nsity

[a.u

.]

PM T

200 nm in diameter dye-doped bead

S. Götzinger et al., Nano Lett. 6, 1151 (2006).

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Pho

todi

ode

D iode Laser

3D

Fiber t oP

MT

3D

CC

D

3D

APD

F ilte r

F ibe r co up ledC o llim a to r

Spec

trom

eter

PM

T

O bje c tive

Galvo-drives

F ilte r

via scope

via prism

S. Götzinger et al., J. Opt. B: Quantum Semiclass. Opt. 6, 154 (2004).

Coupling of single semiconductor quantum dots:

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Heart of the experimental setupMultimode fiber connected to PMT Prism Collimating lens

Monomode fiber socket

Rotation stage

Monomode fiber with collimating and focus-sing lenses

Goniometer

Confocal microscope obejctive

Temperature stabilized Cu block

Stabilized 3D piezo stack

Cu tube with microsphere

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Cavity-mediated photon transfer

620 640 660 680

-30

0

30

60

90

120

150

Inten

sity [

a.u.]

Wavelength [nm]

In

tens

ity

(arb

. un

its)

Wavelength (nm)

620 640 660 680

0

50

100

150

200

250

Inte

nsity

[a.u

.]

Wavelength [nm]

I

nten

sity

(arb

. uni

ts)

Wavelength (nm)

Efficient photon transfer between two single nanoemitters

S. Götzinger et al., Nano Lett. 6, 1151 (2006).

Our calculations show that the transfer efficiency is 106 times larger that in free space!

WGM

Obj

ectiv

e

Spectrometer

exc=532nm

=35 m

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By using our setup, we have obtained cavity-mediated enhanced pho-ton transfer between two single nanoparticles.

We have used silica microspheres to observe an ultralow threshold Raman microlaser action and used a SNOM probe to control it.

We have shown how to fabricate microresonators presenting resonan-ces with ultrahigh quality factors, i.e., ultralong photon storage times.

Thank you for your attention!!!

And pretty close to our labs...

Baía dos Porcos, Fernando de Noronha-PE

A single nanoparticle was attached to the end of a near-field probe. The coupling to a high-Q WGM was obtained in a very controlled way.