Confined photon modes with triangular symmetry in hexagonal microcavities in 2D photonic Crystals

We present theoretical and experimental studies of the size and thickness dependencies of the optical emission spectra from microcavities with hexagonal shape in films of two-dimensional photonic crystal. A semiclassical plane-wave model, which takes into account the electrodynamic properties of quasi-2D planar photonic microcavity, is developed to predict the eigenfrequencies of the confined photon modes as a function of both the hexagon-cavity size and the film thickness. Modes with two different symmetries, triangular and hexagonal, are critically analyzed. It is shown that the model of confined photon modes with triangular symmetry gives a better agreement between the predicted eigenmodes and the observed resonances.Comment: 14 pages, 6 figure

High-speed 1.55 μm operation of low-temperature-grown GaAs-based resonant-cavity-enhanced p–i–n photodiodes

We report the design, growth, fabrication, and characterization of GaAs-based high-speed p–i–n photodiodes operating at 1.55 μm. A low-temperature-grown GaAs (LT-GaAs) layer was used as the absorption layer and the photoresponse was selectively enhanced at 1.55 μm using a resonant-cavity-detector structure. The bottom mirror of the resonant cavity was formed by a highly reflecting 15-pair GaAs/AlAs Bragg mirror. Molecular-beam epitaxy was used for wafer growth, where the active LT-GaAs layer was grown at a substrate temperature of 200 °C. The fabricated devices exhibited a resonance around 1548 nm. When compared to the efficiency of a conventional single-pass detector, an enhancement factor of 7.5 was achieved. Temporal pulse-response measurements were carried out at 1.55 μm. Fast pulse responses with 30 ps pulse-width and a corresponding 3 dB bandwidth of 11.2 GHz was measured.This work was supported by NATO Grant No. SfP971970, Turkish Department of Defense Grant No.KOBRA-001, Thales JP8.04, CAM 07N/0059/2002 and ‘‘NANOSELF’’ TIC2002-04096-C03-03. E.O. acknowledges partial support received from Turkish Academy of Sciences.Peer reviewe

Tuning of spontaneous emission of two-dimensional photonic crystal microcavities by accurate control of slab thickness

We have found a blueshift in the cavity modes confined in two-dimensional photonic crystal microcavities when the thickness of the slab was varied uniformly by accurate dry etching. The shifts in the wavelength of the cavity modes were around 2 nm towards shorter wavelengths per nanometer reduced in the thickness of the slab. Three-dimensional plane wave expansion calculations showed that the observed shifts are inside the calculated photonic band gap of the structures. The variation in the energy position of the peaks with the thickness has been analyzed by three-dimensional finite difference time domain calculations for a one missing hole microcavity. This tuning of the emission wavelength with the change in the thickness slab shows the important effect of the third dimension in photonic crystals made out of semiconductor slabs and it can be of interest for its application in the final processed photonic devices like photonic crystal lasers.A. R. Alija thanks an FPU fellowship AP2002-0474 and L. J. Martínez an I3P fellowship. P. A. Postigo and A. García-Martín would like to thank “Ramón y Cajal” contracts and projects CAM 07N/0059/02, CICYT TIC2002-C03-03, DPI2001-0024-C03-01.Peer reviewe

New Technological Approaches for the Fabrication of Planar Photonic Crystals on III-V Compounds

1 página, 1 figura.-- Póster presentado al ICTON 2006 celebrado en Nottingham (UK) del 18 al 22 de Junio de 2006.Peer reviewe

Theoretical and experimental study of the Suzuki-phase photonic crystal lattice by angle-resolved photoluminescence spectroscopy

A complete theoretical and experimental analysis of the photonic band structure for the Suzuki-phase lattice is presented. The band diagrams were calculated by two-dimensional plane wave expansion and three-dimensional guided-mode expansion methods. Angle resolved photoluminescence spectroscopy has been used to measure the emission of the photonic crystal structure realized in active InAsP/InP slabs. Photonic bands with a very low group velocity along an entire direction of the reciprocal lattice have been measured, which may have important applications on future photonic devices. The experimentally determined dispersion is in very good agreement with the calculated photonic bands. The presence of defect modes produced by microcavities in the Suzuki-phase lattice has also been established

Optical emission of InAs/GaAs quantum rings coupled to a two-dimensional photonic crystal microcavity

4 páginas, 4 figuras.-- PACS: 78.67.Hc; 42.70.Qs; 73.63.Kv.Microphotoluminescence measurements on InAs/GaAs quantum rings embedded in a bi-dimensional photonic crystal cavity display enhanced emission intensity of single rings depending on the coupling strength to the cavity modes. The cavity is formed by three holes missing at the center of the photonic crystal structure (a linear 3 defect, L3). Light emission by the quantum rings show sharp lines at low excitation power. They undergo different enhancement factors by the separate effects of the photonic crystal and by coupling to the resonant modes, which show full linear polarization. Upon changing temperature, the uncoupled emission of single quantum rings and the resonant modes undergo different frequency shifts. This allows for an external control of the coupling.L.J. Martinez thanks an I3P-CSIC fellowship, I. Prieto an FPI-MEC fellowship. The authors gratefully acknowledge financial support by the Spanish MEC and CAM through Projects NANOSELFII TEC-2005-05781-C03-01, MEC MAT2005-01388, NAN2004-09109-C04, NAN2004- 08843-C05-04, Consolider-CSD 2006-19 and CAM S- 0505-/ESP-0200, the European Commission through SANDIE NMP4-CT-2004-500101 and PHOREMOST IST-2-511616-NOE Networks of Excellence.Peer reviewe

Laser nanosources based on planar photonic crystals as new platforms for nanophotonic devices

Two-dimensional photonic crystal lasers have been fabricated on III–V semiconductor slabs. Tuning of the spontaneous emission in micro and nanocavities has been achieved by accurate control of the slab thickness. Different structures, some of them of new application to photonic crystal lasers, have been fabricated like the Suzuki-phase or the coupled-cavity ring-like resonators. Laser emission has been obtained by pulsed optical pumping. Optical characterization of the lasing modes have been performed showing one or more laser peaks centred around 1.55 ?m. Far field characterization of the emission pattern has been realized showing different patterns depending on the geometrical shape of the structures. These kinds of devices may be used as efficient nanolaser sources for optical communications or optical sensor