Research Jochen Campo

Abstract

This is a fundamental research project financed by the Research Foundation – Flanders (FWO). The project was subsidized after selection by the FWO-expert panel. The objective of the FWO's Research projects is to advance fundamental scientific research.

Researcher(s)

• Promoter: Wenseleers Wim
• Co-promoter: Campo Jochen

Research team(s)

• Nanostructured and organic optical and electronic materials (NANOrOPT)

Project type(s)

• Research Project

Abstract

Organic molecular materials can exhibit remarkably strong nonlinear optical (NLO) responses which are promising for photonic applications such as ultrafast electro-optic modulators and frequency converters. Most experimental work on their haracterisation and subsequent optimisation is generally limited to one or a few laser wavelengths. Yet, recent measurements on prototypical systems using our unique setup for precise and widely wavelength-tuneable incoherent second-harmonic light scattering (hyper-Rayleigh scattering, HRS) have revealed a far more complex NLO dispersion than generally assumed, implying that the almost universally applied extrapolations to the static limit (for comparison among different compounds or with theory) and to technologically relevant frequency components of the NLO response, are often off by an order of magnitude and more. Based on much more extensive wavelength dependent measurements practical yet accurate models for the NLO dispersion will be developed. To this end, we propose to lift these techniques to a new level and drastically improve the throughput of the setup, by upgrading the laser source to a fully automatically tuneable optical parametric amplifier (OPA), and integrating it with software for automatic calibration and data processing. This will allow for detailed and reliable laser-wavelength dependent NLO characterisation by hyper-Rayleigh as well as hyper-Raman scattering to be performed routinely for a wide range of systems, providing us with a solid basis for the rational design of optimised NLO materials.

Researcher(s)

• Promoter: Wenseleers Wim
• Co-promoter: Campo Jochen

Research team(s)

• Nanostructured and organic optical and electronic materials (NANOrOPT)

Project type(s)

• Research Project

Abstract

This is a groundbreaking fundamental research project financed by the Fund for Scientific Research of Flanders, Belgium (FWO). The project was subsidized after selection by the competent FWO-expert panel.

Researcher(s)

• Promoter: Campo Jochen

Research team(s)

• Nanostructured and organic optical and electronic materials (NANOrOPT)

Project type(s)

• Research Project

Abstract

Organic nonlinear optics (NLO) deals with the nonlinear response of organic molecular materials exposed to intense light beams, with prospective applications in optical telecommunication based on ultrafast switches and modulators, and highly efficient frequency convertors. In this research project, novel approaches will be examined to significantly amplify the molecular NLO response, in particular: (i) doubly (one- and twophoton) resonant enhancement, (ii) coherent addition of contributions from multiple molecular units and (iii) symmetry-breaking in formally centrosymmetric yet bistable molecules. To this aim, the NLO response of different molecular systems will be directly determined through ultrasensitive wavelength-dependent hyper-Rayleigh scattering (HRS) experiments in the appropriate wavelength ranges, using the setup I developed recently and which is unique in terms of both sensitivity and spectral tuneability. Measurements will be performed on well-designed organic molecules, as well as on single-wall carbon nanotubes (SWNTs), both empty and filled with efficient NLO chromophores. For the empty SWNTs, not only the second-order NLO response, but also the third-order response will be characterised by HRS at the tripled frequency. Finally, low-symmetry radial vibrational modes, never observed before but theoretically expected to be highly dependent on tube diameter and environmental interactions (e.g. filling), will be accessible by ultrasensitive (second- and third-order) hyper-Raman experiments.

Researcher(s)

• Promoter: Wenseleers Wim
• Fellow: Campo Jochen

Research team(s)

• Nanostructured and organic optical and electronic materials (NANOrOPT)

Project type(s)

• Research Project

Abstract

The current state-of-the-art setup for hyper-Rayleigh scattering measurements is optimised and automised, through the purchase of a computer-controlled spectrograph which can be combined with the available ultrasensitive camera. In this way, the wavelength-dependent nonlinear optical measurements planned within the framework of my personal FWO postdoctoral project, can be performed efficiently and precisely over a broader wavelength range.

Researcher(s)

• Promoter: Campo Jochen

Research team(s)

• Nanostructured and organic optical and electronic materials (NANOrOPT)

Project type(s)

• Research Project

Abstract

The aim of this research project is to examine the dispersion of the molecular first hyperpolarisability ß, in order to develop a proper ß dispersion model. By performing wavelength-dependent HRS measurements onto a number of well-chosen model systems, the current models can be tested and improved, and if necessary a new approach can be developed.

Researcher(s)

• Promoter: Goovaerts Etienne
• Fellow: Campo Jochen

Research team(s)

• Nanostructured and organic optical and electronic materials (NANOrOPT)

Project type(s)

• Research Project

Abstract

Hyper-Rayleigh scattering measurements are being performed, using a picosecond amplified lasersystem with a new efficient setup with gated parallel detection. With this system it is possible to perform hyper-Rayleigh scattering measurements at a whole range of wavelengths, to determine the dispersion of the first hyperpolarisability of organic molecules. Thanks to the high sensitivity of the setup it is also possible to measure third-order hyper-Rayleigh scattering for the determination of the second hyperpolarisability of organic molecules. In addition, the non-linear optical processes 3-photon absorption and fluorescence (3PF) will be examined. Therefore instrumental developments are necessary, in order to determine the 3PF-efficiencies and their dependence on the excitation wavelength.

Researcher(s)

• Promoter: Goovaerts Etienne
• Fellow: Campo Jochen

Research team(s)

• Nanostructured and organic optical and electronic materials (NANOrOPT)

Project type(s)

• Research Project