Allard Mosk

Universiteit Twente

Scattering Lens

Allard Mosk (APM) Complex Photonic Systems

MESA+, Universiteit Twente, The Netherlands

Why you can see sharper through a dirty window.

Transmission Coefficients

Eq. (1) of M.Sc. thesis APM (1994)

APM, Nieuwenhuizen & Barnes, PRB (1996)

Soukoulis & Economou Conductance Formula

Coworkers Elbert van Putten

Duygu Akbulut

Hasan Yilmaz

Thomas Huisman

Willem Vos

Jacopo Bertolotti -U. Florence & COPS

Ad Lagendijk - AMOLF & COPS

Jochen Aulbach - AMOLF & ESPCI Paris

Bergin Gjonaj - AMOLF

Kobus Kuipers - AMOLF

Patrick Johnson - AMOLF

Ivo Vellekoop - Recently @ CalTech

Frerik van Beijnum - Now at U. Leiden

Multiple Scattering Elastic scattering: random unitary transformation.

S Diffuse speckle through a 10 μm layer of TiO2 pigment.

Opaque Lens

S

Vellekoop & APM, Opt. Lett. 32, 2309 (2007)

measured transmission normalized by average diffuse intensity

How to generate complex field patterns

Spatial amplitude and phase modulation using commercial TN LCDs van Putten, Vellekoop & APM, Appl. Opt. 47, 2076 (2008).

Spatial light modulator (SLM)

Millions of pixels

Group into 1000’s of segments

Intensity and/or phase modulation

with single SLM.

Experimental setup

LCD

Sample: 10 µm layer of TiO2 pigment. Light source: 633 nm HeNe laser. Detection : 1 pixel of CCD camera.

Feedback Optimization

before after

Re E

Im E

Vellekoop & APM Opt. Comm. 281, 3071 (2008)

Experimental results

Always a tight, diffraction-limited spot

Vellekoop, Lagendijk & APM, Nat. Photon. 4, 320 (2010)

Application: Hi-Res scattering lens • Gallium Phosphide (GaP)

- High index of refraction: n=3.4

- Transparent large part visible spectrum

- Can be made extremely scattering*

1 cm

GaP

n = 3.4

* Schuurmans, Vanmaekelbergh, van de Lagemaat & Lagendijk, Science (1999)

Scan the focus Use angular correlations in scattered light

(Memory effect)

Feng et al., Phys. Rev. Lett. (1988) Freund et al., Phys. Rev. Lett. (1988)

Vellekoop & Aegerter, Opt. Lett. (2010)

Setup Microscope

objective

λ = 561 nm

SLM (800 x 600) - Reference image

- Light collection

Does Not Work

Experiment

Theory

Multiple Internal Reflections

Anti-internal reflection layer 200 nm a-Si

Does Work

Reference image High quality optics (NA = 1.49)

Reference image of gold

nano particles

High resolution imaging High quality optics (NA = 1.49) GaP scattering lens

Reference image of gold

nano particles

High resolution image

High resolution imaging

van Putten, Akbulut, Bertolotti, Vos, Lagendijk & APM, PRL (2011)

Conclusion • High Index Resolution Enhancement by Scattering

– First lens with sub-100 nm resolution using visible light.

– Basis for new high-resolution imaging methods

• To do

– Extend to fluorescence and STED imaging

– Use plasmonic structures to improve focal width

– Improve imaging using “4 Pi” microscopy

– Create superoscillating beams

New Postdoc/PhD vacancies

cops.tnw.utwente.nl for all our papers and recent M.Sc/ Ph.D. theses