Design and investigation of surface addressable photonic crystal cavity confined band edge modes for quantum photonic devices.

We propose to use a localized Γ-point slow Bloch mode in a 2D-Photonic Crystal (PC) membrane to realize an efficient surface emitting source. This device can be used as a quantum photonic device, e.g. a single photon source. The physical mechanisms to increase the Q/V factor and to improve the directivity of the PC microcavity rely on a fine tuning of the geometry in the three directions of space. The PC lateral mirrors are first engineered in order to optimize photons confinement. Then, the effect of a Bragg mirror below the 2DPC membrane is investigated in terms of out-of-plane leakages and far field emission pattern. This photonic heterostructure allows for a strong lateral confinement of photons, with a modal volume of a few (λ/n)3 and a Purcell factor up to 80, as calculated by two different numerical methods. We finally discuss the efficiency of the single photon source for different collection set-up.

3D integration of photonic crystal devices: vertical coupling with a silicon waveguide.

Two integrated devices based on the vertical coupling between a photonic crystal microcavity and a silicon (Si) ridge waveguide are presented in this paper. When the resonator is coupled to a single waveguide, light can be spectrally extracted from the waveguide to free space through the far field emission of the resonator. When the resonator is vertically coupled to two waveguides, a vertical add-drop filter can be realized. The dropping efficiency of these devices relies on a careful design of the resonator. In this paper, we use a Fabry-Perot (FP) microcavity composed of two photonic crystal (PhC) slab mirrors. Thanks to the unique dispersion properties of slow Bloch modes (SBM) at the flat extreme of the dispersion curve, it is possible to design a FP cavity exhibiting two quasi-degenerate modes. This specific configuration allows for a coupling efficiency that can theoretically achieve 100%. Using 3D FDTD calculations, we discuss the design of such devices and show that high dropping efficiency can be achieved between the Si waveguides and the PhC microcavity.

Slow Bloch mode confinement in 2D photonic crystals for surface operating devices.

2D photonic crystal (2DPC) structures consisting in 2D silicon nanopillar arrays in silica are investigated. The main motivation of this work lies in that 2D rod arrays should be easily combined with refractive structures (e. g. micro-wire waveguides), unlike 2DPC consisting in hole lattices. Such an association is expected to lead to both new functionalities and larger scale integration. In this paper, we study the loss mechanism for non degenerated Bloch modes located at Gamma-point in a 2DPC slab constituted by a square lattice of silicon rods in silica. For such modes, we show that the quality factor is mainly governed by the lateral losses. To further inhibit the lateral losses, a photonic heterostructure is used. 3D FDTD calculations show that quality factors of 4000 are achieved. To reduce the vertical losses, the 2DPC heterostructure is associated with a vertical Bragg mirror, thus resulting in very high quality factors (>40000).

Fabry-perot multilayers for enhancing the diffraction efficiency of ion-implanted gratings.

Enhancement of the free-space diffraction efficiency of gratings made by titanium-ion implantation is demonstrated both theoretically and experimentally. Indeed, by insertion of a grating into a multilayer dielectric Fabry-Perot cavity, the diffraction efficiency can be increased to as much as 24 times that of a single grating. The sensitivity of the diffraction efficiency to the optogeometrical parameters of the grating or of the Fabry-Perot cavity is discussed. Moreover, a process for performance of a phase grating inside a Fabry-Perot cavity is described, and experimental results concerning efficiency measurements are compared with computed values for various grating periods.