Progress and perspectives of LiNbO₃ wideband Bragg cells

Anisotropic LiNbO₃ Bragg cells have been optimized for acoustooptic spectrum analyzer (AOSA) implementation in the fields of electronic warfare, and radioastronomy. Aperture time limited performances due to acoustic propagation losses are analyzed and BT optimization versus bandwidth is discussed for different optical wavelengths versus the electrode parameters. 1000 resolution points have been achieved for 1-GHz bandwidth Bragg cells operating at 830 nm in AOSA systems (radioastronomy spectrometers). In the near future 1500 points are expected with a resolution of 0.5 MHz. The diffraction efficiency is 35%/W_rf with 5-MHz resolution and 4%/W_rf with 1-MHz resolution. In addition, at 532 nm, a 2.5-GHz bandwidth has been achieved with a resolution of 3 MHz (BT=750) and an effective diffraction efficiency of 5%/W_rf. AOSA dynamic range measurements are analyzed including IM3 intermodulation product investigations with the self-heterodyning technique