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Nonlinear interactions in nanowaveguides

Nanowaveguides have recently had a huge impact on the field of nonlinear optics. The strong light-matter interactions that arises from the high-confinement of light in nanowaveguides on chip allows for ultra-low threshold nonlinear interactions. At Bright, we focus on the integration of highly nonlinear materials (III/V’s, 2D materials,…) conventional silicon or silicon nitride platforms to make scalable platforms for nonlinear optical interactions. In particular, we demonstrated modulation instability low-power supercontinuum generation, soliton fission, analogs of event, frequency converters and frequency comb generation. Picture: Scanning electron microscope image of a  gallium phosphide-on-insulator ring resonator.

Integrated quantum optics

The activity on integrated quantum optics focuses on actively multiplexing of heralded single photon sources[1], on single photon detectors detectors, on the manipulation of two-photon states[2], and the frequency conversion of single photons [3]. Currently, we rely mostly on SiN photonics ICs that we complement with other functional elements such as nonlinear materials[4] or semiconductors. Picture : The process of four-wave mixing is used to create pairs of correlated photons [5] or change their wavelength [3] (A). It benefits strongly from the filed enhancements in microcavities (B) and it can induce strong coupling between single photons inside a cavity (C)

Microscopy and spectroscopy

For decades, optical microscopy has played an important role in the observation of cell biology. In microscopy, as for all imaging optical system, the spatial resolution is limited. Recently, several new approaches have been developed to overcome this limit, particularly in fluorescence microscopy. We investigate the use of saturation of the two-photon absorption fluorescence excitation for improving the spatial resolution. We are also investigating the use of quantum optics technologies for high and low frequency Raman spectroscopy.

Picture: Plasmonic Raman sensor with free space resonant excitation and waveguide harvesting of Raman signal.

Picture:  3D imaging of fluorescent microspheres embedded in HeLa cells by multiphoton microscopy with resolution enhancement by fluorescence saturation

Pattern formation in optical resonators

Patter formation is ubiquitous in nature. Examples include the stripes on a zebras skin and the ripples in wind-blown dunes. Through the interaction between microscopic elements of the system, a macroscopic order may spontaneously emerge when a system is brought outside of equilibrium. In optics, the interaction of a focusing nonlinearity with a diffusion -like process such as diffraction of dispersion leads to the formation of stable modulated patterns. We investigate, both experimentally and theoretically the dynamics of temporal dissipative structures in nonlinear optical resonators. Picture : ULB stored as cavity solitons in a fiber resonator