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In this paper amplitude Fresnel zone plates (ZPs) with silver and chromium relief on silica glass are theoretically and experimentally investigated. Study of the focal spot characteristics versus the height of chromium and silver ring of ZP was carried out. It showed that the height of the relief of 70 nm allows to achieve an optimum ratio of the width and the intensity of the focal spot. Also, the...
Dense WDM in the datacentre will be the next frontier for datacentre interconnects. Current silicon based transceivers are based on a single spatial multiplexed Distributed Feedback laser (DFB) and external silicon modulators providing an effective but limited system. So far, wavelength division multiplexing (WDM) has seen a very slow uptake in data-centre interconnects due to issues in maintaining...
We report a compact uncooled external-cavity mWatt-class laser architecture with a tunable Si Photonic Crystal resonant reflector, suitable for direct Frequency Modulation. Wavelength shifts of the order of GHz for linewidths <10 MHz and SMSRs up to 46 dB were observed.
We designed and experimentally studied all-optical analog to electromagnetically induced transparency (EIT) effect in vertical coupling photonic crystal cavities. By tuning the phase difference between two cavities, EIT-like phenomena for two modes at different wavelengths has been experimentally demonstrated.
Energy efficient Wavelength Division Multiplexing (WDM) is the key to satisfying the future bandwidth requirements of datacentres. As the silicon photonics platform is regarded the only technology able to meet the required power and cost efficiency levels, the development of silicon photonics compatible narrow linewidth lasers is now crucial. We discuss the requirements for such laser systems and...
In this paper, we demonstrate how to efficiently control the quality factor of silicon nitride nanobeam cavities, grown on a silica substrate and embedded in an upper cladding, by engineering the nanobeam cross-section and the shape of the periodic holes. We propose optimized configurations that are able to overcome the decreasing of the Q-factor when the nanobeam is embedded in an asymmetric medium...
Energy efficient Wavelength Division Multiplexing (WDM) is the key to satisfying the future bandwidth requirements of datacentres. As the silicon photonics platform is regarded the only technology able to meet the required power and cost efficiency levels, the development of silicon photonics compatible narrow linewidth lasers is now crucial. We discuss the requirements for such laser systems and...
We report an external-cavity laser comprising a III-V reflective-SOA and a Si Photonic Crystal (PhC) cavity-based resonant reflector. Experimental output powers of mW-level and >25 dB SMSR were observed.
The dynamic frequency shift of the optical pulse can be obtained if the refractive index of the guiding structure is switched while the pulse is inside the structure. We have developed a co-propagating scheme where switching is obtained by a second pulse which generates free carriers into a silicon waveguide and thus shifts refractive index by up to 0.01. The interaction was studied in two systems...
Deep Ultraviolet Lithography is essential for the mass production of silicon devices. To date, restrictions in the process have prevented the realization of high Q factor optical resonators. Here, we demonstrate Q-factor values of approx. 200,000 using an optimized design.
Integration density, channel scalability, low switching energy and low insertion loss are the major prerequisites for on-chip Wavelength Division Multiplexing systems. A number of device geometries have already been demonstrated that fulfil these criteria, at least in part, but combining all of the requirements is still a difficult challenge. Photonic crystal cavities provide the ultimate confinement...
We demonstrate for the first time on-chip dynamic frequency conversion. The signal and the switching pulse both propagate in the silicon photonic crystal waveguide. During dynamic transition switching pulse takes over the signal.
Beam shaping of light on a micron scale is of particular importance when targeting integrated photonic applications. Here, we present a high numerical aperture lens based on high contrast gratings incorporating multiple phase shifts. We show successful fabrication and micron scale focusing which is beneficial to the micro-optics community.
We propose and experimentally demonstrate a novel optical modulator based on a photonic crystal resonator vertically coupled to large mode area bus waveguide.
We demonstrate a silicon chip based all-optical device capable of providing single shot time-domain measurements of picosecond pulses near λ=1550nm. The 96µm long device relies on optical third harmonic generation between two pulses in a slow light photonic crystal waveguide.
We propose and experimentally demonstrate a new approach to the design of Photonic Crystal cavities. Rather than simply maximizing the design Q-factor, we take the effects of disorder into account, and develop a design that provides superior Q factors in the presence of disorder relative to existing designs.
We experimentally demonstrate a new SOI based optical filter design comprising of a photonic crystal cavity and a low index bus waveguide and realise high extinction ratios and low insertion losses.
We present a photonic crystal cavity (PhCC) design methodology that is based on systematically engineering the dispersion curve of a PhC line-defect. Our combined numerical and analytical approach offers the option of using a variety of different defect modifications to create a gentle-confinement cavity with a Gaussian profile. Here, we demonstrate the principle of the method by employing relatively...
We demonstrate a silicon chip-based all-optical device providing single shot time-domain measurements of picosecond pulses near X=1550nm. The auto-correlation visible signal arises from third-harmonic generation in a 96 μm long slow light photonic crystal waveguide.
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