Moore's Law has set great expectations that the performance/price ratio of commercially available semiconductor devices will continue to improve exponentially at least until the end of the next decade. Although the physics of nanoscale silicon transistors alone would allow these expectations to be met, the physics of the metal wires that connect these transistors will soon place stringent limits on the performance of integrated circuits. We will describe a Si-compatible global interconnect architecture - based on chip-scale optical wavelength division multiplexing - that could precipitate an "optical Moore's Law" and allow exponential performance gains until the transistors themselves become the bottleneck. Based on similar fabrication techniques and technologies, we will also present an approach to an optically-coupled quantum information processor for computation beyond Moore's Law, encouraging the development of practical applications of quantum information technology for commercial utilization. We present recent results demonstrating coherent population trapping in single N-V diamond color centers as an important first step in this direction.

One of the remaining challenges to solve the interconnection bottlenecks at the Printed Circuit Board (PCB) and Multi-Chip-Module (MCM) level, is to adequately replace the galvanic interconnects with high-performance, low-cost, compact and reliable micro-photonic alternatives. At our labs of the Vrije Universiteit Brussel we are therefore optimizing and deploying a rapid micro-optical prototyping technology for micro-optical interconnect modules, which we call Deep Proton Writing (DPW). An advantage of the DPW process is that it can create steep micro-optical surfaces, micro-holes, micro-lenses and alignment features in one irradation step. Hence, relative accuracies are very well controlled. In this report, we will address more specifically the following components, made each with the DPW technology: 1) out-of-plane couplers for optical wave-guides embedded in PCB, 2) peripheral fiber ribbons and two dimensional single- and multimode fiber connectors for high-speed parallel optical connections, and 3) intra-MCM level optical interconnections via free-space optical modules. We will give special attention to the optical tolerancing and the opto-mechanical integration of components in their packages. We use both a sensitivity analysis to misalignment errors and Monte-Carlo simulations. It is our aim to investigate the whole component integration chain from the optoelectronic device packaging to the micro-opto-mechanical assembly of the interconnect module.

In this paper we review basic properties of nanopillar coupled periodic waveguides. A nanopillar coupled periodic waveguide consists of several rows of periodically placed dielectric cylinders. In such a waveguide, light confinement is due to the total internal reflection, while guided modes dispersion is strongly affected by waveguide periodicity. We present a systematic analysis of the dispersion and transmission efficiency of nanopillar coupled periodic waveguides and discusses their possible applications for integrated optics.

The coupled-mode equations are derived to describe the dynamics of coupling between the pump mode and Stokes mode for stimulated Raman scattering in designed high-Q/V_m silicon photonic band gap nanocavities. The interplay of other Χ⁽³⁾ effects such as two-photon absorption and optical Kerr, related free-carrier dynamics, thermal effects, as well as linear losses such as cavity radiation and linear material absorption are also included. The numerical results demonstrate both the lasing thresholds and the pulsed Raman frequency conversion in monolithic silicon high-Q/V_m photonic band gap nanocavity lasers.

We present a fabrication method to realize three dimensional (3D) isotropic homogeneous negative index material (3DNIMs) using a low cost and massively parallel manufacturable and self-assembly technique. The construction of self-assembled 3D-NIM array was realized through two dimensional (2-D) planar microfabrication techniques exploiting the as-deposited residual stress imbalance between a bi-layer consisting of e-beam evaporated metal (chromium) and a structural layer of low stress silicon nitride deposited by LPCVD on a p-doped silicon substrate. A periodic continuation of a single rectangular unit cell consisting of split-ring resonators (SRR) and wires were fabricated to generate a 3D assembly by orienting them along all three Cartesian axes. The thin chromium and silicon nitride bi-layer is formed as hinges. The strain mismatch between the two layers at the hinge curls the structural layer containing the SRR upwards. The self-assembled out-of-plane angular position depends on the thickness and material composing the bi-layer. This built-in stress-actuated assembly method is suitable for applications requiring a thin dielectric layer for the SRR and/or active devices.

Semiconductor quantum dots have unique characteristics which advantage especially for saturable absorbers. We characterized nonlinear optical absorption of highly-stacked InAs quantum dot layers on an InP (311)B substrate in 1.5-μm band. High-density (5 x 10¹² cm^-2) quantum dots by stacked more than 150 layers were recently fabricated with a strain-controlled technique for 1.5-μm communication devices. The transmission increase for the vertical incidence was observed as much as 1%, and transmittance decreased at higher intensity of incident pulse. The temporal behavior of the transmission increase showed two decay components of a few picoseconds and several hundred picoseconds decay. The nonlinear absorption was explained by the saturable absorption of the quantum dots layer and the two photon absorption of the InP substrate. The features of the saturable absorber are suitable for application to a mode-locker for generating short optical pulses in the 1.5-μm band. Analysis showed that we can tune the saturable absorption characteristics by adjusting the numbers of quantum dot layers, thickness of residual InP substrate and antireflection coating on the surfaces. We obtained planar type saturable absorbers at a typical saturation intensity of 35MW/cm² with 3.5% transmittance change for a traveling type and 8% change for reflective type, respectively.

We present a fabrication technique for creating high-quality structures of antimonide-based quantum dots (Sb-based QDs), which show long-wavelength emissions for fiber-optic communications. By using the Sb-based QDs as the active medium, we successfully demonstrated optical-emissions in the 1.3- and 1.5-μm wavebands from a long-wavelength vertical-cavity surface emitting laser (VCSEL) structure fabricated on a GaAs substrate. Additionally, we describe a growth technique for Sb-based QDs on a silicon wafer, which may become novel-materials for silicon photonics technology.

In this paper, we will first compare different synthesis methods of semiconductor nanowires (PVD, CVD, VLS, lithography, electrodeposition, etc.) by analyzing their advantages and inconveniences, then present our own work on the electrodeposited CdSe luminescent nanowires. Using a low cost and low temperature approach by electrochemistry, CdSe nanowires were successfully grown using polycarbonate template. Depending on the host pore dimension of the substrate, wire diameter can be varied from 400 nm down to 30 nm and wire length from a few microns to tens microns. The as-deposited nanowires exhibit predominantly metastable zinc blende (ZB) structure but after the heat treatment they become wurtzite (W) structure. A combination of different characterization techniques, such as X-ray diffraction, SEM, TEM-HRTEM and EDXS, was used to investigate the growth morphology, crystalline structure and defects in the nanowires. The luminescent properties of CdSe nanowires have also been studied by means of photoluminescence.

We review our research work on the development of photonic devices and systems embedded with nanocyrstals for new functionality within EU Phoremost Network of Excellence on nanophotonics. Here we report on CdSe/ZnS nanocrystal-based hybrid optoelectronic devices and systems used for scintillation to enhance optical detection and imaging in the ultraviolet range and for optical modulation via electric field dependent optical absorption and photoluminescence in the visible. In our collaboration with DYO, we also present photocatalytic TiO₂ nanoparticles incorporated in solgel matrix that are optically activated in the ultraviolet for the purpose of self-cleaning.

The nonlinear refractive index (n₂) and two-photon absorption coefficient (β₂), was determined for PbSe nanocrystals (NCs) suspended in trichloroethylene (TCE) using a standard Z-scan technique with femtosecond pulses over a range of wavelengths in the near-IR. For comparison, the n₂ of PbS NCs in chloroform was also measured. The exciton peaks of the NCs were tuned to telecommunications wavelengths. The concentration of the solutions ranged from 4.5 mg/mL to 18.8 mg/mL.

A new optical pump-probe technique is implemented for the investigation of acoustic phonon dynamics in the GHz to THz frequency range which is based on two asynchronously linked femtosecond lasers. Asynchronous optical sampling (ASOPS) provides the performance of on all-optical oscilloscope and allows us to record optically induced lattice dynamics over nanosecond times with 200 femtoseconds resolution at scan rates of 10 kHz. The generation of coherent acoustic phonons and their propagation and decay dynamics are investigated in semiconductor heterostructures, layered nanoscale materials of relevance for microelectronics, and X-ray mirrors. Changes of the optical properties of tailored semiconductor heterostructures associated with coherent phonon dynamics open the pathway for the modulation of optical signals at up to THz frequencies.

We present the design and fabrication of an all-optical bistable device in AlGaAs. The material is known to have a nonlinear figure-of-merit that is in larger silicon and thus well suited to nonlinear experiments. We employ theoretical analysis consisting of both analytical models and finite-difference time-domain (FDTD) methods to ensure robust design and to estimate the power threshold of the proposed device. The proposed nanocavity experiment suggests low powers (~10² μW) and ultra fast switching (~ps) on chip limited only by photon lifetime. This is an improvement over silicon based experiments, which have demonstrated ~ 100 nanosecond responses but intrinsically bounded by free-carrier dynamics [12]. In this manuscript, we will elaborate on theoretical and experimental considerations required to implement a low power, ultrafast bistable device that forms a fundamental building block in all-optical logic operations.

Photonic crystal superprism structures exhibit a rapid change in the group propagation direction with wavelength. For a fixed wavelength, a small change of the refractive index in a superprism structure also results in a rapid change of the group propagation direction. We present a theoretical investigation of switching in active one-dimensional photonic nanostructures with coupled defects (cavities). This switch can be realized as a multilayer thin-film stack or alternatively in a planar waveguide geometry. The device will allow the switching of an incident laser beam to one of N output positions using either electro-optical or all-optical effects. We consider organic optically nonlinear layers, since organic materials show large nonlinear effects and fast switching times. The proper design of the layer structure is a key component for optimizing the performance of the device. We investigate the most effective position for the integrated nonlinear layers. The active layers can be placed inside the cavities or they can serve as coupling layers between cavities. Both approaches are evaluated with respect to performance parameters such as switching energy and necessary number of layers.

Two concepts of performing All-Optical Wavelength conversion are presented and discussed. The novelty of this manuscript is in presenting a configuration providing increased extinction ratio of conversion. Both concepts are based on the photorefractive effect in crystals. By generating diffractive photo refractive pattern we improve the conversion extinction ratio. In the first concept two beam pairs are used to create two index gratings in the medium and by that receive wavelength conversion. In the second concept, the fanning effect in the photorefractive medium is used to perform wavelength conversion using only one beam pair. Proof-of-Principle experiments results are presented.