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Double polarization electro-optic beam combiners based on a Ti:diffusion lithium niobate waveguide have been developed for mid-infrared applications. A monochromatic rejection ratio of up to 33 dB at λ=3.39 μm was obtained, as well as wideband fringes showing low dispersion. In a first part, studying the fringe contrast as a function of waveguide width, we found a compromise among transmission, signal-to-noise ratio, and fringe contrast, depending on the single-mode behavior of the waveguides. We will show that both polarizations are guided, and at least 70% and 90% contrast is achieved, respectively, in TE and TM with a 400 nm wideband light centered at 3.39 μm. After choosing the optimal combiner and designing the electrodes, we studied the electro-optic response of the device, using a monochromatic source and scanning the fringe, by external as well as internal modulation, in order to determine the rejection ratio and the voltage needed to cover half a fringe (V(π)) voltage for both TE and TM polarizations.

We propose a new optical architecture for the laser optical feedback imaging (LOFI) technique which makes it possible to avoid the adverse effect of the optical parasitic backscattering introduced by all the optical interfaces located between the laser source and the studied object. This proposed setup needs no specific or complex alignment, which is why we can consider the proposed setup to be self-aligned. We describe the principle used to avoid the parasitic backscattering contributions that dramatically deteriorate amplitude and phase information contained in the LOFI images. Finally, we give a successful demonstration of amplitude and phase images obtained with this self-aligned setup in the presence of a parasitic reflection.