Nonlinear properties of AlGaAs waveguides in continuous wave operation regime

Aluminum Gallium Arsenide (AlGaAs) is an attractive platform for the development of integrated optical circuits for all-optical signal processing thanks to its large nonlinear coefficients in the 1.55-μm telecommunication spectral region. In this paper we discuss the results of the nonlinear continuous-wave optical characterization of AlGaAs waveguides at a wavelength of 1.55 μm. We also report the highest value ever reported in the literature for the real part of the nonlinear coefficient in this material (Re(γ) ≈521 W<sup>−1</sup>m<sup>−1</sup>)

Viscoelasticity measurements by an optofluidic micro-rheometer

During the last decades, microrheology attracted a significant attention thanks to the possibility of investigating the viscoelastic properties of complex systems (e.g. cells and soft materials) at micrometer scale. The inherent low-consumption of sample offered by microrheology makes it the ideal candidate to study the rheological properties of precious/limited materials. In active microrheology, optical or magnetic forces enable trapping and manipulation of micro-probes in the fluid under test. The probe's response to external stimuli is used to derive the rheological properties of the surrounding medium. While this approach has been already reported in the scientific literature mainly using optical tweezers [1], in this document we propose a different system configuration based on a dual beam laser trap, previously exploited to realize a simple viscometer [2,3]. The here proposed device has all the features of a rheometer, also allowing to measure the elastic properties, and has the advantage of requiring a lower beam intensity while being able to apply larger forces with respect to standard optical tweezers. Additionally the system can be easily integrated in a glass substrate, requiring just an external connection to a CW-laser source and a low-magnification objective for sample observation

Integrated optofluidic chip for low-volume fluid viscosity measurement

In the present work, an integrated optofluidic chip for fluid viscosity measurements in the range from 1 mPas to 100 mPas is proposed. The device allows the use of small sample volumes (<1 mu L) and the measurement of viscosity as a function of temperature. Thanks to the precise control of the force exerted on dielectric spheres by optical beams, the viscosity of fluids is assessed by comparing the experimentally observed movement of dielectric beads produced by the optical forces with that expected by numerical calculations. The chip and the developed technique are validated by analyzing several fluids, such as Milli-Q water, ethanol and water-glycerol mixtures. The results show a good agreement between the experimental values and those reported in the literature. The extremely reduced volume of the sample required and the high flexibility of this technique make it a good candidate for measuring a wide range of viscosity values as well as for the analysis of nonlinear viscosity in complex fluids

Fiber optics communications; (230.7405) Wavelength conversion devices; (130.3730) Lithium niobate

Abstract: We present the results of an in-depth experimental investigation about all-optical wavelength conversion of a 100-Gb/s polarization-multiplexed (POLMUX) signal. Each polarization channel is modulated at 25 Gbaud by differential quadrature phase-shift keying (DQPSK). The conversion is realized exploiting the high nonlinear χ ©2009 Optical Society of Americ

Low TPA and free-carrier effects in silicon nanocrystal-based horizontal slot waveguides

This paper was published in OPTICS EXPRESS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OE.20.023838 . Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under lawWe present the characterization of the ultrafast nonlinear dynamics of a CMOS-compatible horizontal-slot waveguide with silicon nanocrystals. Results are compared to strip silicon waveguides, and modeled with nonlinear split-step calculations. The extracted parameters show that the slot waveguide has weaker carrier effects and better nonlinear figure-of-merit than the strip waveguides.We acknowledge EU-project PHOLOGIC (FP6-IST-NMP-017158), Spanish Ministry of Science and Innovation SINADEC (TEC2008-06333) and PROMETEO/2010/087 NANOFOTONICA projects and Universidad Politecnica de Valencia for PAID2011/1914 and J. Matres' doctoral grant.Matres Abril, J.; Lacava, C.; Ballesteros García, G.; Minzioni, P.; Cristiani, I.; Fedeli, JM.; Martí Sendra, J.... (2012). Low TPA and free-carrier effects in silicon nanocrystal-based horizontal slot waveguides. Optics Express. 20(21):23838-23845. https://doi.org/10.1364/OE.20.023838S2383823845202

Highly nonlinear AlGaAs waveguides for broadband signal generation

In the last decade silicon on insulator-based waveguides have progressively attracted the attention of the nonlinear-optics research community. Due to the strong refractive index contrast of such waveguides and thanks to the very high nonlinear refractive index of silicon, strong nonlinear effects can be achieved in SOI structures, even at moderate pump power level (e.g. P &lt; 1 mW) [1]. However, silicon also exhibits a very strong nonlinear absorption coefficient that severely limits the waveguide performance at power level above 1 mW. Very recently nonlinear AlGaAs waveguides were demonstrated, showing both efficient continuous wave and pulsed nonlinearities [2] with no two-photon absorption (TPA) effect, even at high power level