Graphene Field-Effect Transistors Employing Different Thin Oxide Films: A Comparative Study.

In this work, we report on a comparison among graphene field-effect transistors (GFETs) employing different dielectrics as gate layers to evaluate their microwave response. In particular, aluminum oxide (AlO), titanium oxide (TiO), and hafnium oxide (HfO) have been tested. GFETs have been fabricated on a single chip and a statistical analysis has been performed on a set of 24 devices for each type of oxide.

Backward frequency doubling of near infrared picosecond pulses.

We report on backward second-harmonic generation using ps laser pulses in congruent lithium niobate with 3.2 µm periodic poling. Three resonant peaks were measured between 1530 and 1730 nm, corresponding to 16th, 17th and 18th quasi-phase-matching orders in the backward configuration, with a conversion efficiency of 4.

Features of randomized electric-field assisted domain inversion in lithium tantalate.

We report on bulk and guided-wave second-harmonic generation via random Quasi-Phase-Matching in Lithium Tantalate. By acquiring the far-field profiles at several wavelengths, we extract statistical information on the distribution of the quadratic nonlinearity as well as its average period, both at the surface and in the bulk of the sample. By investigating the distribution in the two regions we demonstrate a non-invasive approach to the study of poling dynamics.

Soft proton exchanged channel waveguides in congruent lithium tantalate for frequency doubling.

We report on stable optical waveguides fabricated by soft-proton exchange in periodically-poled congruent lithium tantalate in the α-phase. The channel waveguides are characterized in the telecom wavelength range in terms of both linear properties and frequency doubling. The measurements yield a nonlinear coefficient of about 9.

Integrated Optic Surface Plasmon Resonance Measurements in a Borosilicate Glass Substrate.

The surface plasmon resonance (SPR) technique is a well-known optical method that can be used to measure the refractive index of organic nano-layers adsorbed on a thin metal film. Although there are many configurations for measuring biomolecular interactions, SPR-based techniques play a central role in many current biosensing experiments, since they are the most suited for sensitive and quantitative kinetic measurements. Here we give some results from the analysis and numerical elaboration of SPR data from integrated optics experiments in a particular borosilicate glass, chosen for its composition offering the rather low refractive index of 1.

Nonstoichiometric silica mask for fabricating reverse proton-exchanged waveguides in lithium niobate crystals.

Producing channel waveguides requires a photolithographic mask, but the standard technique of using thermally evaporated metal films for proton exchange has proved to be unsuitable for withstanding the rather aggressive process of reverse proton exchange. We report the fabrication of a nonstoichiometric silica mask by ion-plating plasma-assisted deposition. This mask is strong enough to resist both direct and reverse proton exchange and is also compatible with anisotropic dry etching for patterning the mask and with electric field poling.