We demonstrate that symmetry breaking opens a new degree of freedom to tailor energy-momentum dispersion in photonic crystals. Using a general theoretical framework in two illustrative practical ...structures, we show that breaking symmetry enables an on-demand tuning of the local density of states of the same photonic band from zero (Dirac cone dispersion) to infinity (flatband dispersion), as well as any constant density over an adjustable spectral range. As a proof of concept, we demonstrate experimentally the transformation of the very same photonic band from a conventional quadratic shape to a Dirac dispersion, a flatband dispersion, and a multivalley one. This transition is achieved by finely tuning the vertical symmetry breaking of the photonic structures. Our results provide an unprecedented degree of freedom for optical dispersion engineering in planar integrated photonic devices.
Two-dimensional (2-D) compact photonic crystal reflectors on suspended InP membranes were studied under normal incidence. We report the first experimental demonstration of 2-D broadband reflectors ...(experimental stopband superior to 200 nm, theoretical stopband of 350 nm). They are based on the coupling of free space waves with two slow Bloch modes of the crystal. Moreover, they present a very strong sensitivity of the polarization dependence, when modifying their geometry. A compact (50×50 μm 2 ) demonstrator was realized and characterized, behaving either as a broadband reflector or as a broadband transmitter, depending on the polarization of the incident wave. Experimental results are in good agreement with numerical simulations.
Vertical Fabry Perot cavities (VFPC) have been extensively studied, especially for the realization of vertical-cavity surface emitting lasers (VCSELs). They are traditionally composed of two ...Distributed Bragg Reflectors (DBR) which reflectivity has to be sufficient in order to obtain highly resonant cavity, which is particularly necessary for laser emission in VCSELs. As a consequence, DBRs consist generally in very thick layer stacks. In this paper, we demonstrate the smallest conceivable high Q vertical Fabry-Perot cavity, using ultra-thin and highly-efficient photonic crystal slab mirrors instead of conventional DBRs, which enable moreover a control of the polarization.
III-V/Si photonics by die-to-wafer bonding Roelkens, G.; Van Campenhout, J.; Brouckaert, J. ...
Materials today (Kidlington, England),
07/2007, Volume:
10, Issue:
7-8
Journal Article
Peer reviewed
Open access
Photonic integrated circuits offer the potential of realizing low-cost, compact optical functions. Silicon-on-insulator (SOI) is a promising material platform for this photonic integration, as one ...can rely on the massive electronics processing infrastructure to process the optical components. However, the integration of a Si laser is hampered by its indirect bandgap. Here, we present the integration of a direct bandgap III-V epitaxial layer on top of the SOI waveguide layer by means of a die-to-wafer bonding process in order to realize near-infrared laser emission on and coupled to SOI.
We present a passive novel optical add-drop filter incorporating microdisk resonators, in complementary metal-oxide-semiconductor compatible silicon-on-insulator technology, which enables a simple ...layout of complex optical networks-on-chip. The measured properties of the fabricated devices are in agreement with theory, established using the time-domain coupled mode theory and finite-difference time-domain simulations.
We propose to use a localized Γ-point slow Bloch mode in a 2D-Photonic Crystal (PC) membrane to realize an efficient surface emitting source. This device can be used as a quantum photonic device, ...e.g. a single photon source. The physical mechanisms to increase the Q/V factor and to improve the directivity of the PC microcavity rely on a fine tuning of the geometry in the three directions of space. The PC lateral mirrors are first engineered in order to optimize photons confinement. Then, the effect of a Bragg mirror below the 2DPC membrane is investigated in terms of out-of-plane leakages and far field emission pattern. This photonic heterostructure allows for a strong lateral confinement of photons, with a modal volume of a few (λ/n)3 and a Purcell factor up to 80, as calculated by two different numerical methods. We finally discuss the efficiency of the single photon source for different collection set-up.
The authors report a compact and highly selective tunable filter using a Fabry-Perot resonator combining a bottom micromachined 3-pair-InP/air-gap Bragg reflector with a top photonic crystal slab ...mirror. It is based on the coupling between radiated vertical cavity modes and waveguided modes of the photonic crystal. The full-width at half maximum (FWHM) of the resonance, as measured by microreflectivity experiments, is close to 1.5nm (around 1.55 microm). The presence of the photonic crystal slab mirror results in a very compact resonator, with a limited number of layers. The demonstrator was tuned over a 20nm range for a 4V tuning voltage, the FWHM being kept below 2.5nm. Bending of membranes is a critical issue, and better results (FWHM=0.5nm) should be obtained on the same structure if this technological point is fixed.
A new approach is proposed to realize an optical link for intrachip optical interconnects. This link includes III-V compound-based laser sources and photodetectors, and silicon-on-insulator-based ...strip waveguides. The heterogeneous integration of an InP-based microdisk laser with a silicon waveguide using SiO/sub 2/-SiO/sub 2/ molecular bonding and nanofabrication procedures is emphasized. The technological procedure is described and first experimental results show that, with an adequate configuration, 35% of light could be coupled from the optically pumped microlaser to the waveguide, as a result of the vertical evanescent coupling.
A new approach for an electrically driven microlaser based on a microdisk transferred onto Silicon is proposed. The structure is based on a quaternary InGaAsP p-i-n junction including three InAsP ...quantum wells, on a thin membrane transferred onto silicon by molecular bonding. A p++/n++ tunnel junction is used as the p-type contact. The technological procedure is described and first experimental results show a laser emission in pulsed regime at room temperature, with a threshold current near 1.5 mA.
We report the direct, room-temperature, near-field mapping and spectroscopy of the optical modes of a photonic-crystal microcavity containing quantum wells. We use a near-field optical probe to ...reveal the imprint of the cavity mode structure on the quantum-well emission. Furthermore, near-field spectroscopy allows us to demonstrate the strong spatial and spectral dependence of the coupling between the sources and the microcavity. This knowledge will be essential in devising future nanophotonic devices.
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