Surface addressable photonic crystal resonators: General design rules and applications

Abstract

It is emphasized that two dimensional Photonic Crystals (2D PC) have not only a great potential for integrated Nanophotonics in the waveguided configuration, but that they may also open the way to other brilliant developments, with an extension to out of plane operation.In the latter case, the basic building block is a 1D or 2D Photonic Crystal Membrane (PCM) where only the Bloch modes above the light line are considered. Conceptual approaches used to analyse optical properties of surface addressable Photonic Crystal Membrane (PCM) resonators will be presented from which design rules will be deduced and illustrated on some photonic devices. INTRODUCTIONDuring the last decades, Photonic Crystals have played a fast growing role in nanophotonics. This success relies in their ability to harness the light at the wavelength scale leading to a spatial and spectral control of photons. In practice the fabrication of 3D PhCs is very difficult, and most of the developments have concerned the production of 1D and 2D PhCs formed in wave-guiding dielectric slabs as they can be fabricated using conventional planar technological approaches. The resulting structures are called Photonic Crystal Membrane (PCM) where the light can be "index guided" in the vertical direction. The spectro-spatial trajectory of this guided modes are then controlled through a high contrast 1D or 2D periodic modulation of the optical index. In most of the reported works, the PCM is meant to operate in this waveguiding regime, which gave rise to numerous demonstrations like strongly confining resonators (high Q/V), slow light and superprism phenomena…In this paper, we will concentrate on most recent developments where PCM are used to control photons not only in the waveguiding configuration but also in the free space regime. In this case, the PCM can be view as a high index contrast grating (HCG) which enables the coupling between in plane waveguided and out of plane free space modes, leading to an efficient 3D harnessing of light. In 1902, Wood has reported on the observation of strong intensity variations (Wood anomalies) in the spectrum of an optical beam diffracted by a diffraction grating [1]. This has been interpreted by Rayleigh in 1907 as resulting to the conversion of a propagating diffraction order into an evanescent diffraction order and vice versa [2]. In 1965, Hessel et al., using rigorous diffraction theory, introduced the concept of resonance anomalies due to the coupling between a propagating mode with a surface or guided wave [3]. The first experimental demonstration of guided mode resonances in dielectric gratings was reported by Mashev and Popov [4] and their first practical applications have been proposed by Magnusson et al. [5,6]. The observation of guided mode resonances in 1D and 2D PCM have been reported [7] and the specific properties of these high index contrast gratings have been analysed in [8].In this article, it will be emphasized that PCMs (i.e. planar gratings with a strong periodic index distribution), exhibits two main a...

Confinement of photons and control of their emission using surface addressable photonic crystal membrane

“…Thanks to the high index contrast patterning, this mode exhibits a low group velocity 4 and, therefore, a flat dispersion curve. This property results in mirrors with a large angular acceptance 19 . This approach can be applied to 2D and 3D resonators 25 which can be fabricated either by conventional "top-down" technologies or by a controlled mechanical relaxation of pre-stressed planar microstructures 26 .…”

“…The effect of the vertical symmetry has been less studied but is also significant. As an illustration, we have recently emphasized the fact that the strong dependence of the Q factor with the PCM thickness can be understood by symmetry considerations 19 . More specifically, the" guided mode" approach can be analysed using the model developed by Kazarinov and Henry for shallow gratings 20,21 where the coupling between guided and free space modes, for a vertically symmetric grating, is shown to be proportional to:…”

Photonic crystal mirror based optical microsources for silicon photonics

“…The effect of the vertical symmetry has been less studied but is also significant. As an illustration, we have recently emphasized the fact that the strong dependence of the Q factor with the PCM thickness can be understood by symmetry considerations 13 . This approach leads to an analytical formulation which allows for the simple design of PCMs with controllable bandwidth.…”