Search results for "Waveguide"
showing 10 items of 311 documents
Design of a 1 kW output power Folded Waveguide TWT operating in ka-band
2019
A Ka-band Serpentine Folded Waveguide Travelling Wave Tube (TWT) has been designed. The imposed design parameters values in terms of high power, high load, wide bandwidth, low weight, along with a structure manufactured with planar technique or by means of a micro milling process, have been obtained. Small signal simulations have been carried out with an in-house software for interaction impedance evaluation. The commercial electromagnetic simulation code CST Suite has been used for dispersion diagram prediction. An optimization of the one-dimensional software, normally used for large-signal simulation in coupled cavity TWTs (“Computer Program for Analysis of Coupled-cavity Travelling-wave-…
Plasmonic Waveguides Co-Integrated with Si3N4 Waveguide Platform for Integrated Biosensors
2019
Integration of plasmonic waveguides with low-loss photonic platforms have attracted research efforts as the means to benefit from the extra-ordinary features of plasmonics while enhancing the functional portfolio of Photonic Integrated Circuits (PICs). In this work, we review a technology platform that integrates water cladded plasmonic waveguides integrated in a low-loss Si 3 N 4 photonic platform, targeting biosensing applications. Results obtained experimentally and numerically will be presented with respect to propagation losses, interface coupling loss and accumulated phase change per unit length, showing how Surface Plasmon Polariton (SPP) waveguides can be effectively combined with p…
Self-assembled three-dimensional inverted photonic crystals on a photonic chip
2017
Three dimensional photonic crystals (PhCs) exhibiting a full photonic band gap have high potential in optical signal processing and detector applications. However, the challenges in the integration of the 3D PhCs into photonic circuits have so far hindered their exploitation in real devices. This article demonstrates the fabrication of 3D PhCs exploiting the capillary directed self-assembly (CDSA) of monodisperse colloidal silica spheres, their inversion to silicon shells, and integration with silicon waveguides. The measured transmission characteristics agree with numerical predictions and provide strong indication of a full photonic band gap in the inverted 3D photonic crystals at wavelen…
Z+/Z− lithium niobate optical waveguide sensitivity related to pyroelectric effect
2020
Lithium niobate crystal is widely used for the design and fabrication of integrated electro-optic modulators. As a ferroelectric material, one sees its spontaneous polarization change with temperature variations. This phenomenon, known as the pyroelectric effect, induces strong waveguide transmission variations for waveguides realized on Z -cut wafers. Waveguides made by titanium in-diffusion either on the Z + or Z − side of the crystal show a significant difference in temperature behavior. Experimental data, enlightened by numerical simulations, help to show why Z − waveguides are more immune to temperature changes than Z + ones.
Subwavelength imaging of field confinement in a waveguide-integrated photonic crystal cavity
2005
A photonic crystal microcavity is designed to obtain an original field distribution inside the cavity and the structure is etched inside a silicon-on-insulator waveguide. Spectral location of the photonic band gap and cavity resonance are identified by using transmittance measurements and by analyzing the light collected by a scanning near-field optical microscope probe exactly positioned on the center of the cavity. The results obtained with the two techniques are in very good agreement. Then the near-field distribution above the device is mapped and light confinement inside the cavity is evidenced. Moreover, this confined light presents some remarkable patterns which clearly correspond to…
Lithium niobate step-index waveguides for broadband second harmonic generation
2006
We investigate modal phase matching in lithium niobate step-index waveguides for second harmonic generation. We predict doubling bandwidths as large as 110 nm and show that temperature tuning can compensate for any deviation from the designed film thickness. © World Scientific Publishing Company.
Two-wave mixing at 854 nm in BaTiO3:Rh planar waveguide implanted with He+
2001
Abstract Guided waves at 854 nm are observed in a BaTiO 3 :Rh waveguide fabricated by the technique of ion-beam implantation. The photorefractive interaction between two guided modes is demonstrated and characterized. The experiments reveal that the gain direction is reversed in the guiding layer in comparison with that in the bulk. A maximum gain of 24 cm −1 is achieved.
Dispersion-optimized multicladding silicon nitride waveguides for nonlinear frequency generation from ultraviolet to mid-infrared
2016
Nonlinear frequency conversion spanning from the ultraviolet to the mid-infrared (beyond 2.4 μm) is experimentally demonstrated in multicladding silicon nitride (𝑆𝑖𝑋𝑁𝑌) waveguides. By adjusting the waveguide cross-section the chromatic dispersion is flattened, which enhances both the efficiency and the bandwidth of the nonlinear conversion. How accurately the dispersion is tailored is assessed through chromatic dispersion measurements and an experiment/simulation comparison of the dispersive waves' wavelength locations. Undesirable fluctuations of both the refractive index and the dimensions of the waveguide during the fabrication process result in a dispersion unpredictability of at l…
Volume integrated phase modulator based on funnel waveguides for reconfigurable miniaturized optical circuits.
2015
We demonstrate the integration of a miniaturized 30(x) μm × 30(y) μm × 2.7(z) mm electro-optic phase modulator operating in the near-IR (λ = 980 nm) based on the electro-activation of a funnel waveguide inside a paraelectric sample of photorefractive potassium lithium tantalate niobate. The modulator forms a basic tassel in the realization of miniaturized reconfigurable optical circuits embedded in a single solid-state three-dimensional chip.
Near-field scanning optical microscopy to study nanometric structural details of LiNbO3 Zn-diffused channel waveguides
2008
A near-field scanning optical microscope (NSOM) is used to perform structural and optical characterization of the surface layer after Zn diffusion in a channel waveguide fabricated on lithium niobate. A theoretical approach has been developed in order to extract refractive index contrast from NSOM optical transmission measurements (illumination configuration). As a result, different solid phases present on the sample surface can be identified, such as ZnO and ZnNb2O6. They appear like submicrometric crystallites aligned along the domain wall direction, whose origin can be ascribed to some strain relaxation mechanism during the annealing process after Zn diffusion. Jose.Canet-Ferrer@uv.es