Daphné Duval

All-optical phase modulation for integrated interferometric biosensors

We present the theoretical and the experimental implementation of an all-optical phase modulation system in integrated Mach-Zehnder Interferometers to solve the drawbacks related to the periodic nature of the interferometric signal. Sensor phase is tuned by modulating the emission wavelength of low-cost commercial laser diodes by changing their output power. FFT deconvolution of the signal allows for direct phase readout, immune to sensitivity variations and to light intensity fluctuations. This simple phase modulation scheme increases the signal-to-noise ratio of the measurements in one order of magnitude, rendering in a sensor with a detection limit of 1.9·10⁻⁷ RIU. The viability of the all-optical modulation approach is demonstrated with an immunoassay detection as a biosensing proof of concept.

Grating couplers integrated on Mach-Zehnder interferometric biosensors operating in the visible range

We present the design, fabrication, and characterization of submicronic grating couplers integrated on Si3N4 rib waveguide Mach-Zehnder interferometers (MZIs) for biosensing applications working in the visible spectral range for both TE and TM polarizations. Depending on the waveguide structure, a maximum of 11.5% of coupling efficiency has been experimentally obtained at 658 nm, while a limit of detection of 1.6 × 10-7 in refractive index unit is achieved for the biosensor. These results represent an important milestone toward the achievement of a truly portable and multiplexed point-of-care platform using the integrated MZI sensor.

Breakthroughs in Photonics 2012: 2012 Breakthroughs in Lab-on-a-Chip and Optical Biosensors

We review the most important achievements published in 2012 in the field of lab-on-a-chip (LOC) and optical biosensors. We will specially focus on optical label-free biosensors and their implementation into lab-on-a-chip platforms, with an emphasis on manuscripts demonstrating bioanalytical applications.

Light propagation in single mode polymer nanotubes integrated on photonic circuits

We report the theoretical and experimental study of photonic propagation in organic dielectric nanotubes elaborated by a wetting template method and showing off an aspect ratio as high as 200. Single mode behaviour is theoretically demonstrated without any cut-off conditions. Efficient evanescent coupling between polymer microstructures and nanotubes dispersed on a photonic chip as well as the high confinement and propagation in a single nanotube have been demonstrated. These results show the potential of well-defined one-dimensional nanostructures as building blocks for integrated organic photonic devices. Applications such as sensing and high speed communication are envisaged.

Interferometric waveguide biosensors based on Si-technology for point-of-care diagnostic

Silicon photonic biosensors based on evanescent wave detection have revealed themselves as the most promising candidates for achieving truly point-of-care devices as they can overcome the limitations of current analytical techniques. Advantages such as miniaturization, extreme sensitivity, robustness, reliability, potential for multiplexing and mass production at low cost can be offered. Among the existing integrated optical sensors, the interferometric ones are the most attractive due to their extreme sensitivity for label-free and real-time evaluations with detection limits close to 10-7- 10-8 in bulk refractive index. In this article we will review the recent progress in the most common interferometric waveguide biosensors (Mach-Zehnder interferometers, Young interferometers, Hartman interferometers, dual polarization interferometers and bimodal optical waveguides). In particular, we will focus on the description of their optical structures and their applicability for bioanalytical detection.

Investigation of fabrication and resonant optical coupling in various 2D micro-resonator structures in a UV210 polymer

In this paper, we report on the design and the overall realization of micro-resonators based on the development of adequate processes on a UV210 polymer. These micro-optical structures are developed by deep ultraviolet lithography allowing fabrication of nano-structured devices by means of low cost and reproducible processes. Two families of resonant micro-structures shaped on disk and stadium with various sizes are investigated. Structural and optical imaging characterizations have been carried out to ensure their ability to act as resonant integrated micro-structures. At first, scanning electron microscopy and Nomarsky microscopy studies confirm the UV-light process resolution down to 450 nm developed on a UV210 polymer. Then, optical characterizations have been performed as regards intensity and spectral properties of such micro-resonators. Field intensity measurements in visible and infrared ranges have been realized and validate light propagation by evanescent coupling between waveguides and micro-resonators. Finally, spectral analyses on TE modes demonstrate the presence of optical resonances with 1.45 nm and 2.19 nm free spectral range values for respectively disk and stadium micro-structures. The UV210 polymer appears appropriate for the realization of micro-structures requiring a few hundred nanometers gap-scale while maintaining adequate spectral properties for versatile applications in telecommunication and metrology.

Towards a complete lab-on-chip system using integrated Mach-Zehnder interferometers

Most clinical tests are time-consuming, expensive and have to be performed by specialized technicians in laboratory environments. Indeed this kind of tests require sampling and labelling with fluorescent or radioactive tags. There is an urgent and compelling need of methods which can allow the identification of any disease at the earliest stage possible in a fast, direct, simple and cost-effective way. To fulfill these requirements, integrated optical biosensors and, in particular, those based on evanescent field sensing, are very attractive, especially because they allow for compactness, sensitive, real-time and label-free on-site measurements [1], [2]. They also offer the possibility to perform different measurements in parallel or to integrate several analytical steps, from sample preparation to detection, into a single miniaturized device (the so-called “Lab-Ona-Chip” platform).

Silicon photonic biosensors for high innovative point-of-care diagnostic platforms

The application of portable, easy-to-use and highly sensitive biosensor devices for real-time diagnosis could offer significant advantages over current analytical methods. We will describe our last developments in silicon photonic biosensors based on evanescent wave detection, mainly related to the development of portable and highly sensitive integrated photonic sensing platforms.

Multiplexed Integrated Interferometers for Advanced Lab-on-a-Chip Biosensors

We present our last achievements towards the assembly of lab-on-a-chip platforms based on ultrasensitive Mach-Zehnder interferometers. In particular, we will focus on the development of a label-free and real-time multiplexed detection scheme.

Investigation on 2D disks and stadiums micro-resonators structures based on UV210 polymer

In this paper, we report on the design and the overall realization of micro-resonators based on the development of adequate processes on UV210 polymer. These micro-optical structures are developed by deep ultraviolet lithography allowing fabrication of nano-structured devices by mean of low cost and reproducible processes. Resonant microstructures of disk and stadium shapes with various sizes were investigated. Structural and optical characterizations have been carried out to ensure their ability as integrated resonant micro-structures. At first, scanning electron microscopy studies confirm the UV-light process resolution down to 450 nm developed on UV210 polymer. Then, optical characterizations have been performed as regards spectral properties of such micro-resonators. Field intensity measurements in visible and infrared range have been realized and validate the aptitude of the micro-structures to propagate and to allow an evanescent photonic coupling between waveguides and micro-resonators. Finally, spectral analyses on TE modes demonstrate the presence of optical resonances associated to whispering gallery modes for disk structures and chaotic modes for stadium shapes. The UV210 polymer appears appropriate for the realization of microstructures requiring a few hundred nanometers gap-scale while maintaining adequate spectral properties for versatile applications in telecommunication and metrology.