3D polymer based air-bridge waveguides for on chip applications

In this paper we proposed new concept for fabrication of 3D polymer waveguides with surface Bragg grating (SBG). For the structures fabrication we used 3D laser lithography based on direct laser writing process with nonlinear two-photon absorption in photosensitive material. High-resolution negative IP-Dip photoresist for the structure fabrication was used. The 3D photonic structure consists of supporting structure and waveguide with SBG. To improve the light guiding properties, waveguide part was isolated from the supporting structure by thin polymer pillars. The SBG parameters were numerically proposed by transfer matrix method to reflect narrow spectral band at 1.55 mu m wavelength. Design of the proposed structure is suitable as a sensor for on-chip application for measurement of temperature or refractive index. Reflection characteristics of the SBG waveguide were measured with direct edge optical fiber coupling by optical spectrum analyzer. Quality of prepared structure was investigated by scanning electron microscope.