Cavity quantum electrodynamics with three-dimensional photonic bandgap crystals

This paper gives an overview of recent work on three-dimensional (3D) photonic crystals with a "full and complete" 3D photonic band gap. We review five main aspects: 1) spontaneous emission inhibition, 2) spatial localization of light within a tiny nanoscale volume (aka "a nanobox for light"), 3) the introduction of a gain medium leading to thresholdless lasers, 4) breaking of the weak-coupling approximation of cavity QED, both in the frequency and in the time-domain, 5) decoherence, in particular the shielding of vacuum fluctuations by a 3D photonic bandgap. In addition, we list and evaluate all known photonic crystal structures with a demonstrated 3D band gap.Comment: 21 pages, 6 figures, 2 tables, Chapter 8 in "Light Localisation and Lasing: Random and Pseudorandom Photonic Structures", Eds. M. Ghulinyan and L. Pavesi (Cambridge University Press, Cambridge, 2015, ISBN 978-1-107-03877-6

Simulating three dimensional self-assembly of shape modified particles using magnetic dipolar forces

The feasibility of 3D self-assembly of milli-magnetic particles that interact via magnetic dipolar forces is investigated. Typically magnetic particles, such as isotropic spheres, self-organize in stable 2D configurations. By modifying the shape of the particles, 3D self-assembly may be enabled. The design of the particles and the experimental setup are presented. The magnetic configurations of simple particle arrangements are obtained via energy minimization in simulations. The simulations show that a 3D configuration can become energetically favourable over 2D configurations, if the shape of the particle is modified

Design of a 3D photonic band gap cavity in a diamond-like inverse woodpile photonic crystal

We theoretically investigate the design of cavities in a three-dimensional (3D) inverse woodpile photonic crystal. This class of cubic diamond-like crystals has a very broad photonic band gap and consists of two perpendicular arrays of pores with a rectangular structure. The point defect that acts as a cavity is centred on the intersection of two intersecting perpendicular pores with a radius that differs from the ones in the bulk of the crystal. We have performed supercell bandstructure calculations with up to $5 \times 5 \times 5$ unit cells. We find that up to five isolated and dispersionless bands appear within the 3D photonic band gap. For each isolated band, the electric-field energy is localized in a volume centred on the point defect, hence the point defect acts as a 3D photonic band gap cavity. The mode volume of the cavities resonances is as small as 0.8 $\lambda^{3}$ (resonance wavelength cubed), indicating a strong confinement of the light. By varying the radius of the defect pores we found that only donor-like resonances appear for smaller defect radius, whereas no acceptor-like resonances appear for greater defect radius. From a 3D plot of the distribution of the electric-field energy density we conclude that peaks of energy found in sharp edges situated at the point defect, similar to how electrons collect at such features. This is different from what is observed for cavities in non-inverted woodpile structures. Since inverse woodpile crystals can be fabricated from silicon by CMOS-compatible means, we project that single cavities and even cavity arrays can be realized, for wavelength ranges compatible with telecommunication windows in the near infrared.Comment: 11 figure

Method to make a single-step etch mask for 3D monolithic nanostructures

Current nanostructure fabrication by etching is usually limited to planar structures as they are defined by a planar mask. The realisation of three-dimensional (3D) nanostructures by etching requires technologies beyond planar masks. We present a method to fabricate a 3D mask that allows to etch three-dimensional monolithic nanostructures by using only CMOS-compatible processes. The mask is written in a hard-mask layer that is deposited on two adjacent inclined surfaces of a Si wafer. By projecting in single step two different 2D patterns within one 3D mask on the two inclined surfaces, the mutual alignment between the patterns is ensured. Thereby after the mask pattern is defined, the etching of deep pores in two oblique directions yields a three-dimensional structure in Si. As a proof of concept we demonstrate 3D mask fabrication for three-dimensional diamond-like photonic band gap crystals in silicon. The fabricated crystals reveal a broad stop gap in optical reflectivity measurements. We propose how 3D nanostructures with five different Bravais lattices can be realised, namely cubic, tetragonal, orthorhombic, monoclinic, and hexagonal, and demonstrate a mask for a 3D hexagonal crystal. We also demonstrate the mask for a diamond-structure crystal with a 3D array of cavities. In general, the 2D patterns for the different surfaces can be completely independent and still be in perfect mutual alignment. Indeed, we observe an alignment accuracy of better than 3.0 nm between the 2D mask patterns on the inclined surfaces, which permits one to etch well-defined monolithic 3D nanostructures.Comment: 18 pages, 10 figure

Signature of a three-dimensional photonic band gap observed on silicon inverse woodpile photonic crystals

We have studied the reflectivity of CMOS-compatible three-dimensional silicon inverse woodpile photonic crystals at near-infrared frequencies. Polarization-resolved reflectivity spectra were obtained from two orthogonal crystal surfaces corresponding to 1.88 pi sr solid angle. The spectra reveal broad peaks with high reflectivity up to 67 % that are independent of the spatial position on the crystals. The spectrally overlapping reflectivity peaks for all directions and polarizations form the signature of a broad photonic band gap with a relative bandwidth up to 16 %. This signature is supported with stopgaps in plane wave bandstructure calculations and with the frequency region of the expected band gap.Comment: 9 pages, 5 figure

A Musical instrument in MEMS

In this work we describe a MEMS instrument that resonates at audible frequencies, and with which music can be made. The sounds are generated by mechanical resonators and capacitive displacement sensors. Damping by air scales unfavourably for generating audible frequencies with small devices. Therefore a vacuum of 1.5 mbar is used to increase the quality factor and consequently the duration of the sounds to around 0.25 s. The instrument will be demonstrated during the MME 2010 conference opening, in a musical composition especially made for the occasion