Improved 60 degrees bend transmission of submicron-width waveguides defined in two-dimensional photonic crystals

We compare quantitatively the transmission properties of various 60degrees bends carved into a photonic crystal based on a two-dimensional triangular lattice of holes perforating a GaAs-based heterostructure. The bends are inserted into channel waveguides defined by three missing rows in the photonic crystal. Their design is inspired by some ideas from classical integrated optics. We show experimentally that in some cases the transmission of the bent waveguide is fairly high, up to 70%, within a bandwidth of 3%, e.g., 30 nm at 1 mum, sufficient to contemplate wavelength-division-multiplexing applications. The observed performance opens the opportunity to implement a variety of optical functions in view of future photonic crystal integrated circuits for which low-loss bends constitute an essential building block.</p

Two-mode fringes in planar photonic crystal waveguides with constrictions: a probe that is sensitive to propagation losses

We analyze the transmission of planar photonic crystal channel waveguides, each of which consists of three missing rows in a triangular lattice of air holes and modified at both ends by constrictions. The structures are fabricated into a GaAs/AlGaAs heterostructure in which an internal source consisting of three layers of quantum dots is embedded. The constrictions induce peculiar spectral features that are used to improve the sensitivity of transmission measurements to propagation losses. Two effects are pointed out: (i) The constrictions act as mirrors, inducing Fabry-Perot fringes on the transmitted spectra, (ii) and the constrictions also induce a mode-mixing process, mostly between the fundamental and the third transverse modes of the waveguides. Using the visibility of the resultant two-mode fringes observed on the transmitted spectra, we extract a quantitative value for propagation losses at lambda = 1 mum: alpha(1) = 25 cm(-1) (1 dB/100 mum) for the fundamental mode. (C) 2002 Optical Society of America.</p

Toward Ultrahigh-Efficiency aluminium oxide microcavity light-emitting diodes: Guided mode extraction by photonic crystals

In this paper, we present an improved version of microcavity light-emitting diodes, relying on the use of a low-index material, aluminum oxide. Our work addresses in particular the injection scheme required by the insulating nature of this oxide. The device we fabricated demonstrated efficiencies up to 28% in air, using only planar technology. In these structures, most of the emission is guided. We further propose to include photonic crystals to extract this guided light. The design of the photonic crystals are discussed and substantiated by photoluminescence-based experiments.</p

Two-mode fringes in planar photonic crystal waveguides with constrictions: a probe that is sensitive to propagation losses

We analyze the transmission of planar photonic crystal channel waveguides, each of which consists of three missing rows in a triangular lattice of air holes and modified at both ends by constrictions. The structures are fabricated into a GaAs/AlGaAs heterostructure in which an internal source consisting of three layers of quantum dots is embedded. The constrictions induce peculiar spectral features that are used to improve the sensitivity of transmission measurements to propagation losses. Two effects are pointed out: (i) The constrictions act as mirrors, inducing Fabry-Perot fringes on the transmitted spectra, (ii) and the constrictions also induce a mode-mixing process, mostly between the fundamental and the third transverse modes of the waveguides. Using the visibility of the resultant two-mode fringes observed on the transmitted spectra, we extract a quantitative value for propagation losses at lambda = 1 mum: alpha(1) = 25 cm(-1) (1 dB/100 mum) for the fundamental mode. (C) 2002 Optical Society of America.</p

Toward Ultrahigh-Efficiency aluminium oxide microcavity light-emitting diodes: Guided mode extraction by photonic crystals

In this paper, we present an improved version of microcavity light-emitting diodes, relying on the use of a low-index material, aluminum oxide. Our work addresses in particular the injection scheme required by the insulating nature of this oxide. The device we fabricated demonstrated efficiencies up to 28% in air, using only planar technology. In these structures, most of the emission is guided. We further propose to include photonic crystals to extract this guided light. The design of the photonic crystals are discussed and substantiated by photoluminescence-based experiments.</p