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In this work the analysis, fabrication and optical characterization of a circular two-dimensional photonic crystal (2D-CPC) nano-resonator based on a air/GaAs/air slab waveguide are presented. Four InAs/InGaAs quantum dots (QDs) stacked layers emitting around 1300 nm were embedded in a GaAs waveguide layer grown on an Al0.7Ga0.3As sacrificial layer. The nano-resonator was realized by drilling 2D-PC air holes arranged in a circular lattice configuration through electron beam lithography (EBL), inductively coupled plasma (ICP) etching and wet selective etching of the Al0.7Ga0.3As sacrificial layer in order to release the membrane. The spectral response of the active circular nano-cavity has been simulated by using a three dimensional finite-difference time-domain method (3D-FDTD) as a function of both the inner and outer holes radius/period ratios of the photonic crystal structure. Good agreement between the calculated resonance and the experimental results, recorded from the nano-cavity by a mu PL setup, has been achieved. (c) 2007 Elsevier B.V. All rights reserved.

Inthiswork,theanalysis,fabricationandopticalcharacterizationofatwo-dimensionalcircularphotoniccrystal(2D-CPC)nano-resonatorbasedonanair/GaAs/airslabwaveguidearepresented.FourInAs/InGaAsquantumdots(QDs)stackedlayersemittingaround1300nmatroomtemperaturewereembeddedinaGaAswaveguide layer grown on an Al 0.7 Ga 0.3 As layer and GaAs substrate. The patterning of the structure andthe membrane release were achieved by using electron beam lithography, ICP plasma etching and selectivewetetchingoftheAlGaAssacrificiallayer.Themicro-luminescencespectrumrecordedfromthefabricatednano-cavityshowsanarrowopticaltransitionattheresonancewavelengthofabout1282nmwithaFWHMand Q-factor of 6.2 A and more than 2000, respectively.˚c 2007 Elsevier Ltd. All rights reserved. Keywords: Nano-cavity; Quantum dot; Photonic crystal 1. IntroductionElectromagnetic resonant cavities, which trap light within a finite volume, are essentialcomponents for the fabrication of high efficiency photonic devices such as ultra small opticalfilters, single-photon sources [1,2] and low-threshold lasers [3]. In a micro-cavity and in weakcoupling regimes, according to the Purcell factor relationship [4], an increase in the Q-factorand a reduction of the modal volume V

In this paper, we study an unconventional kind of quasi-three-dimensional (3-D) photonic crystal (PhC) with circular lattice pattern: it consists of air holes in a GaAs material (n = 3.408) along circular concentric lines. This particular PhC geometry has peculiar behavior if compared with the traditional square and triangular lattices, but it is difficult to model by using conventional numerical approaches such as wave expansion method. The resonance and the radiation aspects are analyzed by the 3-D finite-element method (FEM). The model, based on a scattering matrix approach, considers the cavity resonance frequency and evaluates the input-output relationship by enclosing the photonic crystal slab (PhCS) in a black box in order to define the responses at different input-output ports. The scattering matrix method gives important information about the frequency responses of the passive 3-D crystal in the 3-D spatial domain. A high sensitivity of the scattering parameters to the variation of the geometrical imperfection is also observed. The model is completed by the quality factor (Q-factor) estimation. We fabricated the designed circular photonic crystal over a slab membrane waveguide embedding InAs/GaAs quantum dots emitting around 1.28 mu m. Good agreement between numerical and experimental results was found, thus validating the 3-D FEM full-wave investigation.

This work presents a detailed numerical Finite Element Method FEM modeling for passive optical components such as photonic crystals (PhCs). The accurate modeling characterizes the PhCs structures by considering the field resonance and the radiation behavior of the periodic pattern. The frequency responses at each side of the photonic crystal are evaluated by considering the 3D periodic structure enclosed in a black box with six input/output ports. This scattering matrix approach (SMA) is useful in order to evaluate in plane and vertical PhCs the resonance of the photonic crystal. Through the analysis of all the frequency responses we characterize the passband regions and the stopband regions of the PhC slab.