Dynamic Y-branched structures in quadratic nonlinear media

A selfsplitting of the beams entering a waveguide made of a quadratic nonlinear material is observed numerically. Relative π phase differences between harmonics as positively contributing to linear diffraction are shown to trigger the effect. Formation of solitons out of this energy so that a Y-branched structure is nonlinearly induced, is shown to be dependent on input and material parameters. Simple setups should provide the means for experimental observation of the predicted phenomena.Peer Reviewe

Conmutacion totalmente optica de ondas guiadas en medios virefring.

A new kind of tunable all-optical guided-wave thresholding device using waveguides consisting of both birefringent linear media and isotropic nonlinear media is discussed. The behavior of the lower threshold with a suitable orientation of the crystal optical axis of the birefringent substrate, relative to the direction of propagation, is analyzed for TE-dominant guided wavesPeer ReviewedPostprint (published version

Figure of merit for multiband antennas

This communication defines a figure of merit for multiband antennas that gives an objective quantification of the similarities between radiation patterns at the different antenna operating bands.Peer Reviewe

Square root module to combat dispersion-induced nonlinear distortion in Radio-over-Fiber Systems

Reduced dispersion-induced harmonics levels are reported for analogue radio-over-fiber systems by using a linearized receiver incorporating a memoryless electronic circuit with square root (SQRT)-like transfer function, and performing amplitude modulation (AM) at the transmitter. A practical implementation demonstrates the effectiveness of the AM-SQRT approach in linearizing the optical transmission system with respect to the conventional intensity modulation and direct detection system.Peer Reviewe

Spatial walking solitons in quadratic nonlinear crystals

We investigate the properties of the families of spatial walking solitons propagating in planar waveguides made of quadratic nonlinear media under conditions for second-harmonic generation in the presence of Poynting vector walk-off. We study in detail the shape and various features of the solitons, their stability on propagation, and their excitation.Peer Reviewe

New modulation zero-shift method to characterize fast group delay ripple of dispersion-compensating fiber Bragg gratings

An upgrade to standard modulation phase-shift method is shown to improve accuracy through electrical scan of the optical spectrum. Experiments have allowed the capture of fast group delay ripple of a dispersion-compensating fiber Bragg grating with only a small modification to the standard setup.Peer Reviewe

A 3D printed lens antenna for 5G applications

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.A switchable multi-antenna architecture for lens-assisted beamsteering in the Ka-band region allocated for 5G communications (24-30 GHz) is proposed. The radiating elements are bow-tie antennas mounted with a 3D printed high-permittivity dielectric lens (e r = 10). A 5-element array is simulated showing switchable 30° beam steering over a 120° sector with 19 dB maximum gain. Single antenna measurements of a scaled prototype with a Polylactic Acid (PLA) lens (e r = 2.7) show gains around 11 dB, in agreement with projected performances.Peer ReviewedPostprint (author's final draft

General Equations for the Induced Phase Shift in Resonant Electro-Optic Modulators

We derive general equations to calculate the electrooptically induced optical phase shift in resonantly enhanced modulators. The equations are useful in designing modulator electrodes with optimal length and optimal mismatch between electrical and optical velocities. We demonstrate the existence of an optimal velocity mismatch depending on the resonant mode used.Peer Reviewe

Performance Projection of Electro-Optical Modulators for Radio-Over-Fiber in 2 GHz Cryogenic Front-End Receivers

We present the design of a Y-Ba-Cu-O on LiNbO/sub 3/ cryogenic electro-optical modulator for analog 2 GHz applications. A resonant configuration of coplanar electrodes is considered, showing improvements with respect to both resonant Au electrodes and to traveling-wave electrodes, even beyond the traveling-wave theoretical maximum performance limit. The optimized layout is presented featuring a reduced length of 8.26 mm.Peer Reviewe

Bandgap widening in macroporous silicon photonic crystals by multiperiodic structures

Large bandgaps with low transmission in 3D macroporous silicon photonic crystals have been proved as an interesting technology for the development of optical filters and spectroscopic MIR gas sensors. The aim of this study is the investigation of different bandgap widening methods based on multiperiodic structures for 3D macroporous silicon photonic crystals. To do so, chirped modulations and structures with different periodicity groups have been modelled and theoretically analysed by means of 3D FDTD simulations. They have revealed that by using different decreasing periodicity groups, bandgaps with null transmission and widths as high as 1800 nm, 4 times the original single periodicity photonic crystal bandgap, can be obtained. Furthermore, it has been shown that a resonant cavity with a 20% transmission can be placed in a 1 µm wide bandgap. The results open a way to use this type of structures not only for gas sensing but also for other purposes such as wide stop-band filters, selective filters or broadband mirrors.Peer ReviewedPostprint (published version