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G. A. Torchia

Publications and source records attributed to G. A. Torchia.

3 recordsLinked to original sources

Small MMI with simplified coherent coupling branches used to develop a lower footprint power splitter on SOI platform

In this paper, we introduce a new approach to fabricate under the Silicon on Insulator (SOI) platform a 1x2 power splitter and scale it to 1xN system device from the proposed model. The current strategy of design is based on the well-known simplified coherent coupling (SCC) which allows the construction of very sharp bends. To split the incoming light, we add at the entrance of the splitter a small Multi Mode Interferometer (MMI). The sensibility of the design parameters is analyzed and discussed in the paper. In addition, we fabricated and evaluated the new splitter architecture on 1x2 and 1x4 versions and then compared our devices with those splitters based on standard multimode interferometer (MMI) also performed in the same SOI photonic chip. The new splitter scheme shows a similar performance to standard MMI, however, a slight spectral flat response was observed in new devices. By the novel approach, highly compact devices can be designed so this strategy can also open new avenues to improve and enhance the performance of integrated devices developed under the SOI scheme.

physics.optics

Phenomenological studies of femtosecond laser ablation on optical thin films for integrated photonics

In this work, for the first time of our knowledge, we present a well-supported procedure to fabricate ridge optical waveguides onto thin films of PLZT by femtosecond laser ablation. In order to achieve smooth guiding structures to guarantee good optical performance, we have studied the ablation threshold characteristics for different kinematic conditions of fs laser machining and also we have explored the different ablation regimens for several fluencies reached. Besides, we characterize the morphology and roughness of ridge waveguides through a modal and scattering loss analysis, for waveguides made with single and multiple scan. An innovative phenomenological model that relates the sidewall roughness to process parameters is proposed in this paper. Conducting this approach it is possible to extend the fabrication method of smooth guiding structures by fs micromachining to many optical thin films in order to develop integrated photonics devices addressed to different technological applications.

physics.app-ph

High-order harmonic generation driven by inhomogeneous plasmonics fields spatially bounded: influence on the cut-off law

We study high-order harmonic generation (HHG) in model atoms driven by plasmonic-enhanced fields. These fields result from the illumination of plasmonic nanostructures by few-cycle laser pulses. We demonstrate that the spatial inhomogeneous character of the laser electric field, in a form of Gaussian-shaped functions, leads to an unexpected relationship between the HHG cutoff and the laser wavelength. Precise description of the spatial form of the plasmonic-enhanced field allows us to predict this relationship. We combine the numerical solutions of the time-dependent Schrödinger equation (TDSE) with the plasmonic-enhanced electric fields obtained from 3D finite element simulations. We additionally employ classical simulations to supplement the TDSE outcomes and characterize the extended HHG spectra by means of their associated electron trajectories. A proper definition of the spatially inhomogeneous laser electric field is instrumental to accurately describe the underlying physics of HHG driven by plasmonic-enhanced fields. This characterization opens new perspectives for HHG control with various experimental nano-setups

physics.atom-ph