Micro-diffractive nanostructures for cold-atom manipulation (and other interesting stuff) Groupe optique atomique et applications aux nanostructures Université Paul Sabatier—CNRS Toulouse, France FRISNO-8 Ein-Bokek, Israel February 20-25, 2005

The basic idea incoming laser light output optical field structured surface cold atoms

Subwavelength Structures FIB Fabrication

Arrays of Holes in Metal Films Light transmission spectrum Is this evidence of surface plasmons?

Decorated Slits and Holes in Subwavelength Ag Membranes

Light transmission through a slit flanked by periodic grooves detected far-field transmission calculated profile Garcia-Vidal, et al., Appl. Phys. Lett. 83, 4500 (2003)

Measuring the transmission profile– atomic fluorescence mapping of the field intensity

Relation between atomic fluorescence and field intensity excited atoms field intensity

100 nm slit flanked by 10 grooves each side measured calculated

How does the slit/groove structure produce the observed field distributions?

Composite Diffracted Evanescent Wave Lezec and Thio Optics Express, (2004)

Composite Evanescent Wave-I Consider diffraction at a slit of width d. The field along x is given by: Kowarz, Appl. Optics. 34, 3055 (1995) - =

Composite Evanescent Wave-II The phase shift of pi/2 is a signature of the CEW. x/d

CEWs launched on the surface incoming laser light output optical field structured surface

A pi/2 phase shift between the directly transmitted wave and the CEW 100 nm 830 nm 50 nm variable jog incoming light We can “jog” the structures to compensate for the phase shift

Jogged and unjogged slit structures unjogged jogged inward by ¼ period

Distribution and number of grooves controls the output optical field far-field intensity, no phase shift far-field intensity, with phase shift We can produce a “phased array” with constructive interference in the forward direction. The result is a forward “flame”.

Flame divergence vs. grooves—expmt. and model for unjogged grooves 10 grooves 30 grooves calculation

Flame intensity vs. groove number for jogged and unjogged grooves unjogged jogged

Flame angular distributions f CCD microscope objective d

Angular distribution of light vs. groove-slit spacing (in units of period N) for 5 grooves

Intensity angular distribution—jogged grooves output side, 3 selected distances CDEW model measured

Intensity angular distribution—output side, unjogged red, jogged black CDEW model: Phase shift:  CDEW  /2 Index: n CDEW =850/830=1.024 Relative field amplitude  x=2/x

Angular lobe spacing jogged unjogged CDEW modelExperiment

Next step: mirror MOT to get cold atoms close to surface

Next step: mirror MOT with the optical funnel generated by a planar nanostructured phased array Mirror MOT atom trajectories phased array structure optical funnel plane wave excitation

Toward integrated structures: cold atom sources and transport on a chip

Interaction atomes neutres-lumière Champs proches optiques : confinement sub-longueur d’onde de la lumière. nanolithographie optique atomique cohérente : diffraction interaction dipolaire Diffraction and confinement

Coupled resonant rings: symmetric/antisymmetric modes

Funnel effect: optical potential above the rings

Proposé et réalisé : J.V. Hajnal & G.I Opat (1989). Théorie : R. Deutschmann (1993), C. Henkel (1994). Expérience : Villetaneuse (1996), Orsay (1998). * Réseau à onde évanescente stationnaire +1

Réseau à onde évanescente nanostructurée : période orientation motif Diffraction de l’onde évanescente : A. Roberts & J.E. Murphy (1996) Autre approche : potentiel nanostructuré D. van Labeke & D. Barchiesi

Periodicity controllable through angle of optical coupling-1 50 nm above surface250 nm above surface

Periodicity controllable through angle of optical coupling-2 50 nm above surface250 nm above surface

dB =5nm L x =L y =250nm  diff =20mrad e  100nm  =40°  =55° n=2.1 (TiO2) z r =250nm MOT Experimental parameters

Tales from the future—nanophotonics, addressable atom manipulation with optical arrays

E=10V/200nm E= V/m BaTiO 3 : n 0 =2.4 r 42 =1300pm/V  n=0.45 (20%)

SrRu 4 O 3 BaTiO 3 Quartz Electro-Optic Beaming Control with variable index of refraction Ag V Variable Depth Focusing

SrRu 4 O 3 BaTiO 3 Quartz Electro-Optic Beaming Control Ag V Steering Change n from 0.8 to 1.2

Future: arrays of optical traps loaded with one or more atoms 125µm R. Dumke, et al. PRL 89, (2002)

Summary—evolution of conception Yesterday:Today: 10 µm Tomorrow:

The Group Guillaume Gay Renaud Mathevet Bruno Viaris Olivier Alloschery Colm O’Dwyer Gaetan Leveque