Study of nonlinear elliptical polarization rotation: refractive nonlinearity origin influence

• Grant number: 13/11514-5
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date until: October 01, 2013
• End date until: September 30, 2017
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Lino Misoguti
• Grantee: Maria Luiza Miguez
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

The materials third-order nonlinearities can arise from different physical mechanisms, which have different characteristics such as magnitude, response time, signal, etc. Effects from thermal origin, for instance, usually are strong, but very slow for photonics device applications. On other hand, nonresonant electronic effects are ultrafast but are much weaker than thermal effects. In the field of new photonic materials characterization, it is very important to discover not only the magnitude(s), but also the origin(s) of the nonlinearity(ies). Therefore, new experimental techniques for more complete nonlinear optical properties study are welcome. In this project we propose to study the third-order nonlinear refractivity using the traditional Z-scan technique and a new method for nonlinear elliptical polarization rotation determination. As we will go to see, each technique allows obtaining one particularity of the nonlinear effect, which all results together, allows determining the magnitude and the origin of the nonlinearity with more precision. In this project, we present some proposals for studying refractive nonlinearities in isotropic materials by two effects which they can stimulate, one is the effect of induced lens due to spatial gaussian beam shape and the other is the nonlinear rotation of elliptical polarization. The first effect will be explored by the Z-scan technique and the second one by a new technique that we are presenting in this project. Each of techniques allows obtaining a particular characteristic of nonlinear refraction. The traditional Z-scan technique is already well established as a standard method for materials nonlinearity determination, but, it still present some limitation such as, in many cases, no capacity to distinguish the origin of the nonlinear signal, for example, slow and fast effect can concomitant contribute on the Z-scan signal. As we known, the Z-scan technique is frequently used to investigate abortive and refractive nonlinearities in different type of materials because of its simplicity and precision, but there are other important experimental techniques which can supply additional information. Different changes and improvements on the Z-scan were introduced to improve the sensitivity and precision on the nonlinearity determination. On other hand, the polarization rotation still not well explored and can help to determine the magnitude and the origin of the nonlinearity. Furthermore, preliminary studies showed that it is possible to obtain the nonlinear elliptical rotation with very high precision using a dual phase lock-in, allowing a significant improvement in the nonlinearity determination. In this study, it will be used commercial lasers, which produce picosecond (ps) and femtosecond (fs) pulses, for studying several nonlinear processes. Furthermore, an optical parametric amplifier, which generates tunable fs pulses at broad wavelength range, will be used to study the spectral dependence of nonlinear processes. Different materials such as glasses, organic solvent, organic polymer, etc., will be studied with purpose to develop and to establish a new precise technique for measuring the nonlinear polarization rotation. The Z-scan technique will be used for comparison purpose since it is a well known and precise technique. Different nonlinear effect with different origin and time response will also be explored. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

MIGUEZ, M. L.; BARBANO, E. C.; COURA, J. A.; ZILIO, S. C.; MISOGUTI, L.. Nonlinear ellipse rotation measurements in optical thick samples. APPLIED PHYSICS B-LASERS AND OPTICS, v. 120, n. 4, p. 653-658, SEP 2015. (13/11514-5)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

MIGUEZ, Maria Luiza. Nonlinear rotation of elliptical polarization: new proposals on the study of refractive non-linearities. 2017. Doctoral Thesis - Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT) São Carlos.