Researches in the field of optical sensors benefit from the works developed in integrated optics, either concerning technological developments or models. The main line of this thematic is characterized by a important activity of technology transfer (4 patent deposits since 2004) and is linked to two main projects.
The first project, supported by the DGA (French Military Programs Management and Procurement Agency ) concerns the development of electric-field vectorial measurement systems (measure of both magnitude and phase of the 3 components) over an ultra wide band (quasi DC - 20 GHz) and using pigtailed electro-optic probes as non invasive ultra compact electric-field sensors.
Based on the electric-field induced variation of the polarization state of a laser beam probing an electro-optic crystal constituting the active part of the sensor, the system allow a simultaneous measurement of the probe temperature with a accuracy of 40 mK. Thanks to this simultaneous measurement of electric-field and temperature, the system presents a fully temperature-independent response. The creation of a laboratory spin-off is on the way.
The second project is named SWIFTS for Stationary Wavelength Inverse Fourier Transform Spectrometer. It consists in a integrated spectrometer based on the measurement of the interference between two counter-propagative waves propagating in the same optical guide. The two counter-propagative waves are obtained by division of the incident wave thanks to a Y junction.
Some nanodetectors deposited on the top surface of the waveguide act as diffraction elements that take a small fraction of the light. The light spectrum is simply obtained by taking the Fourier transform of the interference figure diffracted by the nanodetectors. The proof of concept of this innovative Fourier transform integrated spectrometer has been recently demonstrated via the realization in integrated optics on glass of the smallest spectrometer ever fabricated (dimensions of 512 µm by 22 µm for the measurement of wavelengths close to 1550 nm - Nature Photonics 1, 473-478 (2007)).