Search

We report the study of two-dimensional photonic crystals fabricated on silicon-on-insulator substrates. Ge/Si self-assembled islands are embedded as an active internal optical source inside the photonic crystals. We present a detailed analysis of photonic crystal microcavities and waveguides using the room-temperature Ge/Si island photoluminescence. The tunability of the microcavity resonant emission is demonstrated between 1.2 and 1.5 μm. We show that the microcavity photoluminescence is weakly dependent on the temperature. The polarized transmission properties of W1 single-line defect waveguides are investigated using the photoluminescence as an internal source. The transmission spectra are correlated to those given by two-dimensional finite-difference time-domain calculations. [ABSTRACT FROM AUTHOR]

We demonstrate a diamond photonics platform with integrated suspended waveguide-cavity structures and two dimensional photonic crystal (PhC) cavities. PhC cavities with quality factors exceeding 2800 have been fabricated using a top-down approach from thin nanocrystalline diamond films. The developed technological process allows one to access these cavities in a fully planar geometry, including light injection and collection from the outside using lensed-fibers. This diamond platform opens the road to large scale fabrication of photonics devices including optical sensor chips. [ABSTRACT FROM AUTHOR]

The authors show that the use of triangular lattice photonic crystals (PhCs) with wide holes can significantly improve the lasing performances of PhC waveguides in the InP substrate approach. The study is carried out on W2-3 waveguides made in PhCs whose air filling factor is varied from ∼25% to 55%. Intrinsically single-mode laser emissions with reduced threshold (/2) are obtained when the laser mode folds deeply into the gap. Concurrently, the slope of the light-light characteristic is increased by a factor of 14. The laser spectral behavior and threshold evolution are explained from three-dimensional finite difference time domain calculations. [ABSTRACT FROM AUTHOR]

We have investigated the coupling between two-dimensional photonic crystals and a distributed Bragg reflector by fabricating silicon-based photonic crystals on top of a one-dimensional Bragg mirror. The two-dimensional photonic crystals contain Ge/Si self-assembled islands as an internal source covering the 1.1–1.6 μm spectral range. We show that we can control the quality factor of Bloch modes by varying the thickness of the silicon layer on top of the Bragg mirror. Quality factors up to 2200 are obtained for optical radiative modes collected from the surface for a photonic crystal with a square lattice pattern. The variation of the quality factor as a function of the thickness of the upper layer is confirmed by three-dimensional finite-difference time domain calculations of the investigated structures. [ABSTRACT FROM AUTHOR]

Narrow waveguides consisting of a single defect-line (W1) in a square lattice photonic crystal are fabricated on InP using the substrate approach. A single-mode distributed-feedback laser emission is obtained under optical pumping at room temperature. Lasing occurs at the second folding point of the dispersion curve of the fundamental waveguide mode (wave vector k=0). The emitted wavelength ranges from 1420 to 1580 nm for a lattice period varying from 460 to 520 nm and a constant air filling factor of ∼26%. The highly monomode behavior is explained using two-dimensional plane-wave models. Similar experiments conducted on triangular lattice W1 waveguides do not yield a laser emission. Three-dimensional simulations confirm that triangular lattice W1 waveguides suffer higher losses than their square homologues. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated pure germanium two-dimensional photonic crystals. The photonic crystals which exhibit resonances in the near infrared spectral range were fabricated on germanium-on-insulator substrates using standard silicon-based processing. The germanium-on-insulator substrate consists of a thin layer of pure germanium-on-oxide deposited on a silicon substrate. The optical properties are probed by the direct band gap optical recombination of pure germanium at room temperature. Resonant optical modes are evidenced between 1.68 and 1.53μm in different type of hexagonal cavities (H1–H5). The spectral position of the modes is controlled by the lattice periodicity and air filling factor of the photonic crystals. Close to the Ge band edge, the quality factors are limited by the bulk material absorption. [Copyright &y& Elsevier]

Abstract: We report on the integration of Ge/Si self-assembled islands into two-dimensional photonic crystals for silicon-based photonics. The photonic crystals are processed by e-beam lithography on silicon-on-insulator substrates. The room temperature photoluminescence of the Ge islands is used to probe the photonic structures, especially those with defect-microcavities intentionally processed in the photonic crystals. We show that for H2 microcavities, the modes preferentially coupled out of the crystal plane are non-degenerate. We also show that the evolution of the microcavity photoluminescence with pump power depends on the air filling factor of the photonic crystals. A superlinear dependence is obtained for a large hole radius to period ratio. [Copyright &y& Elsevier]