A flat waveguide for the middle infrared was made by co-extrusion of two silver halide crystals of different chemical compositions. The transmission of the waveguide and its modal behavior was studied using a Fourier Transform Spectrometer and a dedicated optical bench. Analyzing this spectrum, we were able to obtain the cut-off wavelength of the waveguide. We observed a single mode behavior for wavelengths longer than 8.83mum, in good agreement with the theoretically expected values. This novel procedure is ideal for tailoring the properties of the waveguide for specific applications, in particular the spectral range where it exhibits a single-mode behavior. It can thus be applied to achieve modal filtering for mid-IR astronomical interferometers (e.g. beam combiners, nullers, etc.).

Space applications are challenging infrared (IR) technologies, demanding the best system performance achievable. This requires covering the entire IR spectrum from short-wavelength infrared (SWIR) to very long-wavelength infrared (VLWIR) for various pixel sizes, which is possible thanks to a wellmastered mercury cadmium telluride technology. Because of its adjustable gap, it can be operated in all the IR bands. Nevertheless, technology optimization requires deep understanding of physical mechanisms. This paper presents computations by finite-element modeling of two aspects of electrooptical performance: spectral response and modulation transfer function (MTF). Computations and characterizations for all IR bands demonstrate the accuracy of our simulations and the state-of-the-art nature of our technology, which performs according to theory. This paper also highlights the capability to measure MTF at very small pitch (10 lm) by a nondestructive method.

This paper reports the characterization of hollow metallic waveguides (HMW) to be used as single-mode wavefront filters for nulling interferometry in the 6-20µm range. The measurements presented here were performed using both single-mode and multimode conductive waveguides at 10.6µm. We found propagation losses of about 16dB/mm, which are mainly due to the theoretical skin effect absorption in addition to the roughness of the waveguide's metallic walls. The input and output coupling efficiency of our samples has been improved by adding tapers to minimize the impedance mismatch. A proper distinction between propagation losses and coupling losses is presented. Despite their elevate propagation losses, HMW show excellent spatial filtering capabilities in a spectral range where photonics technologies are only emerging. 1601-1610 (2000). 15. L. Labadie, E. Le Coarer, R. Maurand, P. Labeye, P. Kern, B. Arezki, and J.-E. Broquin, "Mid-infrared laser light nulling experiment using single-mode conductive waveguides," A&A 471, 355-360 (2007).

SOFRADIR is widely present on the IR detector market for high-performance space, military and security applications thanks to a well mastered Mercury Cadmium Telluride (MCT) technology, and to the recent acquisition of the III-V InSb, InGaAs, and QWIP technologies. As a result, strong and continuous development efforts are deployed to deliver cutting edge products with improved performances in terms of sensitivity, spatial and thermal resolution. The actual trend in quantum IR detector development is the design of very small pixel, with high operating temperature. The selfconfinement of neighboring diodes may not be efficient enough to maintain optimal modulation transfert function (MTF). This paper presents the recent developments achieved in Sofradir in terms of MTF measurements protocol challenged by the pitch reduction. An overview of state of the art MTF results with optimized measurement technic will be shown, from SWIR to VLWIR MCT focal plane. In order to optimize device performances and reduce development cycle time, this experimental approach has been coupled with finite elements modelisation (FEM). Optimized MTF results for 10µm pitch and HOT MCT technology will be exposed.

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