In this letter, we report the fabrication of deep x-cut periodically poled lithium niobate (PPLN) crystal. The technique relies on ridges performed by wet etching to improve poling field penetration into the substrate and, hence, to provide more depth to inverted domains. Based on this approach, domain inversions as deep as 6.5μm were achieved. As an application, reverse proton exchanged waveguides were fabricated on top of the PPLN to demonstrate efficient second harmonic generation in the near infrared. A conversion efficiency as high as 46%W−1cm−2 was measured near 1.5μm.

The Broadband Radiometer (BBR) is an instrument being developed for the ESA EarthCARE satellite. The BBR instrument objective is to provide top-of-atmosphere (TOA) radiance measurements in two spectral channels, and over three along-track directions. The instrument has three fixed telescopes (one for each view) each containing a broadband detector. Each detector consists of an uncooled 30-pixel linear focal plane array (FPA) coated with gold black in order to ensure uniform spectral responsivity from 0.2 µm to 50 µm. The FPA is hybridized with a readout integrated circuit (ROIC) and a proximity electronics circuit-card assembly (CCA) packaged in an aluminum base plate with cover. This paper provides a technical description of the detector design and operation. Performance data at the FPA pixel level as well as unit-level test results on early prototypes of the detectors are also presented.

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We report a new method of tuning the second-harmonic signal generated in a periodically poled lithium niobate (PPLN) waveguide. This technique relies on the recent progress in the fabrication of PPLNs on x-cut substrates along with periodical coplanar electrodes to reduce the tuning voltage while preserving the conversion efficiency. Our scheme exploits a type I interaction implemented in a titanium waveguide to impede cancellation of the electro-optical coefficients and to minimize the group-velocity mismatch between the first- and second-harmonic modes. The tuning range covers 58 nm with an applied voltage of +/-150 V.