Two-dimensional photonic crystal slabs (PCS) offer an appealing alternative to distributed Bragg reflectors or filters for various applications. Indeed, their scattering properties, governed by Fano-resonances, have been used in areas as diverse as optical wavelength and polarization filters, reflectors, semiconductor lasers, photodetectors, bio-sensors, or non-linear optical components. Suspended PCSs also find natural applications in the field of optomechanics, where the mechanical modes of a suspended slab interact via radiation pressure with the optical field of a high finesse cavity. The reflectivity and transmission properties of a defect-free suspended PCS around normal incidence can be used to couple out-of-plane mechanical modes to an optical field by integrating it in a free space cavity. We have demonstrated the successful implementation of a PCS reflector on a high-tensile stress Si3N4 nanomembrane. We could measure the photonic crystal band diagram with a spectrally, angular, and polarization resolved setup. Moreover, a cavity with a finesse as high as 12 000 was formed using the suspended membrane as end-mirror of a Fabry-Perot cavity. These achievements allow us to operate in the resolved sideband regime where the optical storage time exceeds the mechanical period of low-order mechanical drum modes. This condition is a prerequisite to achieve quantum control of the mechanical resonator with light.
We present a vision for the hybrid integration of advanced transceivers at 1.3 μm wavelength, and the progress done towards this vision in the EU-funded RAPIDO project. The final goal of the project is to make five demonstrators that show the feasibility of the proposed concepts to make optical interconnects and packet-switched optical networks that are scalable to Pb/s systems in data centers and high performance computing. Simplest transceivers are to be made by combining directly modulated InP VCSELs with 12 μm SOI multiplexers to launch, for example, 200 Gbps data into a single polymer waveguide with 4 channels to connect processors on a single line card. For more advanced transceivers we develop novel dilute nitride amplifiers and modulators that are expected to be more power-efficient and temperatureinsensitive than InP devices. These edge-emitting III-V chips are flip-chip bonded on 3 μm SOI chips that also have polarization and temperature independent multiplexers and low-loss coupling to the 12 μm SOI interposers, enabling to launch up to 640 Gbps data into a standard single mode (SM) fiber. In this paper we present a number of experimental results, including low-loss multiplexers on SOI, zero-birefringence Si waveguides, micron-scale mirrors and bends with 0.1 dB loss, direct modulation of VCSELs up to 40 Gbps, ±0.25μm length control for dilute nitride SOA, strong band edge shifts in dilute nitride EAMs and SM polymer waveguides with 0.4 dB/cm loss.
Slow light in SOI Slotted Photonic Crystal Waveguides (SPCW) infiltrated by a refractive liquid are investigated. By employing an interferometric technique similar to Optical Coherent Tomography (OCT), we report a group velocity lower than c/20 over a 1 mm-long SPCW. From the OCT measurements, we also infer moderate propagation losses. In the fast light regime (nG <10) propagation loss is about 15 dB.cm-1. Moreover, the coupling to slow modes is efficient. These results show that infiltrated slow light SPCW are a promising route to silicon organic hybrid photonics.
The design, fabrication, and the experimental realization of high-Q slot photonic crystal cavities on SOI infiltrated by a liquid are reported. Loaded Q-factor of 23,000 is measured at telecom wavelengths. The intrinsic quality factor inferred from the transmission spectrum is higher than 200,000 whereas the maximum of intensity of the cavity is as high as 20% of the light transmitted in the waveguide in the bandpass wavelength range. This result makes the demonstrated filled slot photonic crystal cavities very promising for the integration of various active materials for light amplification, nonlinear optics, or sensing.
Proc. SPIE. 8806, Metamaterials: Fundamentals and Applications VI
KEYWORDS: Metamaterials, Crystals, Dielectrics, Photonic crystals, Near field scanning optical microscopy, Line width roughness, Geometrical optics, Light wave propagation, Radio propagation, Near field optics
The transition between the long-wavelength and the short-wavelength regimes of light propagation in all-dielectric
metamaterials is experimentally probed using a hyperspectral near-field scanning microscope technique. Our
measurements lead to an invariant quantity “λ/n” of only 1.78 times the dielectric lattice period as the criterion for the possible application of homogenization theories.
We report slow light measurements in hollow core photonic crystal waveguides. We show that reshaping the slot into a
comb allows increasing the confinement of light and engineering the dispersion of the waveguides. Cut-back
measurements in such waveguides exhibits losses that are comparable to those of standard W1 photonic crystal
waveguides in slow light regime and to those of a refractive slot waveguides in fast light regime, meanwhile the
nonlinear effective area and the modal volume are strongly reduced. Such hollow core waveguides can introduce new
functionalities to silicon and ultra-high nonlinearities when infiltrated by adequate materials.
The dispersive properties of planar photonic crystals (PhCs) have been envisaged for years. In particular, the superprism
effect has been considered to obtain a strong influence of input beam conditions (e.g. wavelength or input angle) on the
light group velocity direction, enabling the design and fabrication of on-chip infra-red spectrometers and integrated
optical demultiplexers. We extend here the properties of PhCs to the study of graded photonic crystals (GPhCs) made of
a two-dimensional chirp of lattice parameters and show that GPhCs enable solving several drawbacks of dispersive PhCs
like the beam divergence issues or the need of long preconditioning regions to precompensate beam diffraction effects.
The proposed approach is applied to a square lattice air-hole PhC with a gradual filling factor that was fabricated using ebeam
lithography and ICP etching techniques. A nearly-constant 0.25μm/nm spatial dispersion is demonstrated for a
60μm square GPhC structure in the 1470-1600nm spectral range without noticeable spatial or spectral spreading.
Moreover, contrary to PhC superprism structures, a linear dispersion is obtained in the considered wavelength range.
We report experimental measurements of slow light in Comb Photonic Crystal Waveguides (CPCW). The tailoring of
the slot into a comb allows performing dispersion engineering in order to achieve slow light regime, and efficient tapers
allow a high coupling efficiency. We also investigate the losses with cut-back measurements and show that losses are
comparable with those of a standard W1 Photonic Crystal Waveguide, whereas the nonlinear effective area is strongly
reduced. This type of waveguide offers opportunities to realize compact devices with an ultra-high light confinement for
achieving optical nonlinearities with a low index material.
We introduce a novel design of wide Slot Photonic Crystal Waveguides (SPCW) by structuring the slot as a comb. This
allows performing dispersion engineering in order to achieve very low group velocities over a few nanometers bandwidth. This kind of SPCW offers opportunities to realize devices requiring strong interactions between light and an optically non-linear low index material by providing an ultra-high optical density while easing the filling of the slot due to its width. We will present dispersion engineering results by Plane Wave Expansion method and Finite Difference Time Domain analysis.
Slowing down the light in Slotted Photonic Crystals Waveguides (SPCW) offers strong opportunities for all-optical
signal processing and non linear optics by dramatically increasing the local electromagnetic energy density in the low
index material. We introduce a novel design of wide SPCW, where the slot is structured as a comb. We show that
structuring the slot in a SPCW allows performing proper dispersion engineering in order to achieve very low group
velocities over a few nanometers. This hybrid structure of SPCW offers possibilities to realize devices requiring strong
interactions between light and an optically non-linear low index material by providing an ultra-high optical density while
easing the filling of the slot due to its large width. We will present the methodology of the dispersion engineering and we
will investigate later the losses and the non linear properties by FDTD analysis and experimental realization.