Engineering the light matter interaction with ultra-small open
access microcavities Jason M. Smith Department of Materials,
University of Oxford, Parks Road, Oxford OX1 3PH, UK Slide 2
Photonics in Oxford Engineering Science Liquid crystals Optical
wireless CMOS imagers/ detectors Microscopy Fibre/waveguide theory
Metamaterials Acousto-optics Physics Quantum optics and control
Quantum optics,fundamentals and processing Metrology Biophysics
measurement CMOS imagers Telescope instrumentation Spectroscopy X
ray generation Optical techniques in nano-technology Biophysics
Photovoltaics Chemistry Cavity ringdown Spectroscopy Absorption
spectroscopy Novel spectroscopic techniques Ultrafast spectroscopy
Fluorescence imaging Molecular materials Synthetic organic
chemistry Molecular electronics Organic chemistry Soft condensed
matter Surface analysis Materials Nanocrystal quantum dots
synthesis, characterisation and modeling Biochemistry and Life
sciences Advanced microscopy- Micron imaging centre Biochemistry
Microscopy for single molecule Biochemistry Bionanotech,
Biochemistry Correlative microscopy Wellcome trust centre for human
genetics Cell imaging X-ray crystallography Diamond Imaging.
Weatherall Inst. for Molecular Medicine. Radiation Oncology
(Imaging) High speed imaging Processing of visual information. Exp.
Psychology Cavity QED Photovoltaics silicon and 3 rd Gen materials
Carbon nano- materials synthesis, characterisation and modeling
Diamond photonics Slide 3 The Photonic Nanomaterials Group,
Department of Materials Jason Smith Characterisation of single
colour centres in diamond Optically Detected Magnetic Resonance of
single spins (300K) Microwave frequency (GHz)
http://www-png.materials.ox.ac.uk Engineering interfaces in quantum
photonics / electronics / spintronics Novel optical microcavity
arrays for enhanced light-matter interactions Engineering excitonic
states in semiconductor nanocrystal quantum dots Photonics of
diamond and its defects Modified emission spectra and transition
rates Sub-femtolitre tunable microcavity arrays Nanocrystal
synthesis, characterisation and modeling Slide 4 Outline Optical
microcavities why small is beautiful Fabrication and
characterisation of novel femtoliter open-access cavities
Preliminary studies of light-matter coupling at room temperature
Slide 5 Introduction to optical microcavities Strong coupling: is
the field per photon is the coupling strength Energy output time
Slide 6 Fermis Golden Rule: Energy output time Can either a)work
out new matrix element with cavity vacuum field and count photon
states or b)use free space matrix element and work out change in
the optical DoS (Purcell approach) Weak coupling: Slide 7 From J P
Reithmayer, Wurzburg. From K Vahala, Caltech From E. L. Hu, (then)
UCSB Popular microcavity designs Slide 8 Planar-concave
half-symmetric cavities Stability criterion High quality dielectric
mirrors Fully tunable Efficient coupling Access to field maximum
Trupke et al APL 2005, PRL 2007 Steinmetz et al APL 2006 Muller et
al APL 2009 Cui et al Optics Express 2006 Slide 9 P R Dolan et al,
Femtoliter tunable optical cavity arrays, Optics Letters 35, p.3556
(2010). High Q open access microcavities with femtoliter mode
volumes Sub nm surface roughness for high reflectivity mirrors SEM
of arrayed concave surfaces by ion beam milling Slide 10 White
light transmission spectra Slide 11 Hermite-Gauss mode structure
TEM x,y 0,00,1 1,0 0,2 1,1 2,0 0,3 1,2 2,1 3,0 0123 Slide 12 Laser
Transmission Imaging of mode structure Slide 13 Quality factors Q =
5 x10 4 achieved Q ~ 10 6 anticipated Slide 14 Photoluminescence
measurements of solutions of intra-cavity quantum dots Z. Di, H. V.
Jones, P. R. Dolan, S. M. Fairclough, M. B. Wincott, J. Fill, G. M.
Hughes and J. M. Smith, Controlling the emission from semiconductor
quantum dots using ultra-small tunable optical microcavities, New
J. Phys. 14 103048 (2012). Slide 15 http://users.ox.ac.uk/~png
Fluorescence from CdSe/ZnS colloidal quantum dots coupled to cavity
modes Slide 16 Purcell effect at room temperature Bad emitter
regime Best aligned quantum dots Worst aligned quantum dots Slide
17 F = F P +1 FDTD calculations (assumes free space emission is
unperturbed by cavity) Slide 18 Suppression of leaky modes Purcell
factor of resonant mode Slide 19 Emission from a single quantum dot
into a cavity Count rate ~ 100,000 s -1 into NA = 0.4. Compare
~50,000 s -1 with NA = 1.25 and no cavity. Slide 20 Apparatus for
cryogenic operation awaiting first low T results! Nitrogen-vacancy
centres in diamond N V Wavelength /nm Slide 21 Mode volume ~ 3
Mirrors: silica/titania (n=2.5) terminated with /4 titania. Above:
planar mirror, 8 pairs Below: curved mirror, 10 pairs, = 3 m Mirror
spacing = /2 (222 nm), n=1.44 Emitter = 640 8nm, dipole //x NB this
is about as good as an L3 photonic crystal cavity (Chalcraft APL
90, 241117 2007) How small can open access cavities be made (with
decent Q)? Slide 22 CurrentPossible Mirror
reflectivity99.9%>99.995% Q factor5 x 10 4 >10 6 Mode
volume0.5 m 3 0.1 m 3 Field per photon~1.8 kV cm -1 ~6 kV cm -1
Purcell factor *~70~10000 Leakage rate ~60 GHz< 5 GHz Summary of
cavity specifications Applications Cavity QED/ quantum information
science Sensing & spectroscopy Tunable lasers Slide 23
Acknowledgments Phil DolanZiyun Di Helene Jones Gareth Hughes
Postdoc position available soon Aurlien Trichet Slide 24 Funding
and support EPSRC The Leverhulme Trust The Royal Society Oxford
Martin School The KC Wong Foundation Hewlett Packard Ltd
