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Project: Multiple modes resonant waveguide grating enabled by LOPA direct laser writing (MUMORES)


In this project, we study theoretically and experimentally the realization of resonant waveguide grating (RWG) structures by using the low one-photon absorption based direct laser writing method and by using a newly elaborated polymeric porous material. The project will be realized in a close collaboration between the LUMIN and PPSM laboratories. The first step is to study the optical properties of polymer-based RWG by using FDTD simulation method. The polymeric porous material will be then performed and optimized to obtain an optimum effective refractive index. The desired RWG structures will be fabricated by using a well-known direct laser writing. Finally, the fabricated structure will be used to enhance the second-harmonic generation of nonlinear nanoparticles, as a first demonstration of this polymeric porous material-based RWG structure.


Resonant waveguide grating (RWG) is a typical dielectric structure, which contains single or multi-layer layer of planar waveguide and its top surface textured with one-dimensional or two-dimensional subwavelength grating. Guided mode resonance (GMR) is an important optical property of RWG, which occurs when the incident light diffracted by the grating is coupled to a waveguide mode of the waveguide layer. When a GMR condition is fulfilled, a sharp reflection and near-zero transmission anomaly is formed at a specific wavelength and incident angle. This allows many applications in different domains, such as multiple bandpass filters, tuneable laser, bio/chemical sensors, etc.

In this project, we propose to realize all polymer-based RWG structures, which have different advantages, such as rapid fabrication, simple and low cost, easy to be functionalized and optically integrated, etc. However, in order to localize the light field strongly on the free surface of the RWGs, which is practically important for applications, it requires that the refractive index of the lower layer of the RWG has lower refractive index. We therefore propose to elaborate a new porous polymer material with a controllable refractive index, lower than 1.55.  Besides, in order to obtain multiple periodicities in the same RWG structure, we propose to use the one-photon absorption (LOPA) based direct laser writing (DLW). The multiple resonant RWG enables new applications such as multiple modes laser, multiple wavelengths sensors and bandpass filters, based on simple all-polymer-based RWGs.

In order to realize this project, different tasks are proposed and will be realized in collaboration between LUMIN and PPSM laboratories, with possible interactions with Chinese and Taiwanese partners.

(a) Modèle de RWG à base de matériau polymère poreux. (b) Résultat préliminaire de simulation de l’indice de réfraction optimal du matériau polymère poreux

(a) Model of a RWG based on porous polymer material. (b) Preliminary simulation result of optimum refractive index of porous material.