Various latest experiments have proven the theoretical prediction that domain walls in planar magnetic structures can channel spin waves as outstanding magnonic waveguides, establishing a superb platform for building ...
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Nanoparticle chain waveguide based on negative-epsilon material is investigated through a generic 3D finite-element Bloch-mode solver which derives complex propagation constant (k). Our study starts from waveguides ma...
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In this work, a comparative study of the susceptibility chart in a partially dielectric-loaded rectangular wave-guide and in its equivalent partially dielectric-loaded parallel-plate wave-guide with the same height is...
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We study dc and ac transport along armchair graphene nanoribbons using the k · p spectrum and eigenfunctions and general linear-response expressions for the conductivities. Then we contrast the results with those...
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We provide an efficient method for the calculation of high-gain, twin-beam generation in waveguides. Equations of motion are derived that naturally accommodate photon generation via spontaneous parametric down-convers...
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III-nitride waveguides featuring AlInN claddings and GaN/AlGaN quantum wells (QWs) offer promising perspectives for applications in many fields of short-wavelength photonics. Thanks to their nearly lattice-matched nat...
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III-nitride waveguides featuring AlInN claddings and GaN/AlGaN quantum wells (QWs) offer promising perspectives for applications in many fields of short-wavelength photonics. Thanks to their nearly lattice-matched nature, these structures exhibit an excellent material quality, leading, e. g., to strong light-matter interaction in such QWs, and several promising phenom- ena. In the low carrier density regime, the strong coupling between QW excitons and waveguide photons results in propagating hybrid light-matter particles, called (exciton-)polaritons, which combine photon-like propagation and exciton-like interactions. These interactions lead to a strong optical nonlinearity, which could be useful for integrated all-optical devices. Due to their strong exciton binding energy ( ∼ 40 meV in the present structures), III-nitride devices have the potential to maintain these nonlinearities up to room temperature. In the high carrier density regime, a GaN/AlGaN QW electron-hole plasma can provide gain to an optical field in the UV, which can be useful for realizing near-UV laser diodes and semicon- ductor optical amplifiers. The performance of current UV devices featuring AlGaN claddings is limited by poor material quality. The improved structural quality of waveguides with lattice- matched AlInN claddings could therefore circumvent these issues. This study aims at an in-depth investigation of the optical properties of III-nitride waveguides with AlInN claddings and GaN/AlGaN QWs grown on freestanding GaN substrates. In a sample with an active region that was optimized forstrong exciton-photon coupling, we observe propa- gating polaritons in the low-density regime. A sample with an active region that was optimized for homogeneous near-resonant excitation with a 355 nm laser shows elevated optical gain in the high-density regime. The nearly lattice-matched nature of the entire structure leads to a high structural and optical quality. We found inhomogeneous broadening values
Direct Laser Writing (DLW) has been an exponentially growing research field during the last two decades, by providing an efficient and robust way to directly fabricate three dimensional (3D) structures in transparent ...
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Direct Laser Writing (DLW) has been an exponentially growing research field during the last two decades, by providing an efficient and robust way to directly fabricate three dimensional (3D) structures in transparent materials such as glasses using femtosecond laser pulses. It exhibits many advantages over the lithography technique, which is mostly limited to two dimensional (2D) structuring and involves many fabrication steps. This competitive aspect makes the DLW technique suitable for future technological transfer to advanced industrial manufacturing. Generally, DLW in glasses induces physical changes such as permanent local refractive index modifications that have been classified under three distinct types: (Type I, Type II & Type III). In silver containing glasses with embedded silver ions Ag+, DLW induces the creation of fluorescent silver clusters Agmx+ at the vicinity of the interaction voxel. In this work, we present a new type of refractive index change, called type A occurring in the low pulse energy regime that is based on the creation of the photo-induced silver clusters allowing the creation of new linear and nonlinear optical waveguides in silver containing glasses. Various waveguides, a 50- 50 Y beam splitter, as well as optical couplers, were written based on type A modification inside bulk glasses and further characterized. In addition, a comparitive study between type A and type I waveguides is presented, showing that finely tuning the laser parameters allows the creation of either type A or type I modifications inside silver containing glasses. Finally, based on type A near-surface waveguides, a highly sensitive refractive index sensor is created in a 1 cm glass chip, which could exhibit a pioneer demonstration of double sensing refractive ranges. The waveguiding properties observed and reported in the bulk of such silver containing glasses were transposed to ribbon shaped fibers of the same material. Those results pave the way towards the fabric
We present a method to achieve polarization rotation in asymmetric silicon waveguides using Berry's phase. By exploiting periodic in-plane and out-of-plane sections, we achieve 90° polarization rotation in th...
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We present a new procedure for direct laser writing of high performance waveguides in chalcogenide glass. The propagation losses are measured to be lower than 0.2 dB/cm both in the near- (λ = 1:55 μm) and in the mid...
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We report the transmission of a 10 Gbps telecommunication signal at 2 μm in waveguides made of three different materials: Si, SiGe and TiO2. Bit error rates below 10-9 can be achieved after transmission in the device...
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