Integrated LiNbO3 photonic crystals

We present easy-to-implement technologies to produce LiNbO3 PhCs in confined optical waveguides. Ti-indiffusion or Annealed Proton Exchange (APE) are combined with optical grade dicing to fabricate ridge waveguides with propagation losses that can be lower than 0.2 dB/cm. Firstly we show how a PhC inscribed in a confined ridge waveguide can be exploited as a temperature sensor with an unexpectedly high 8 nm/°C temperature sensitivity. LiNbO3 PhCs with high aspect ratio are also demonstrated. The performance is achieved by properly tilting the ridge before patterning its walls by Focused Ion Beam (FIB). A eight micrometer long 1D-PhC on a Ti:LiNbO3 ridge waveguide has been fabricated and its reflectivity has been evaluated using an optical coherence tomography (OCT) system: it is measured to be 53 % for the TM wave and 47 % for the TE wave. The period can be optimized in order to increase the reflection of the 1D-PhC up to 80 %. These developments open the way to the dense integration of compact dynamic devices such as modulators, spectral filters or electric field sensors.