We present the result of our investigations on electrical fixing in Sr<sub>0.60</sub>Ba<sub>0.40</sub>Nb<sub>2</sub>O<sub>6</sub> (SEN:60). Two electrical fixing techniques which result in very high diffraction efficiencies are discussed and compared to previous publications on electrical fixing. Constant and varying depoling voltages around the coercive field are applied along the <i>c</i>-axis during and after holographic recording in the crystal. The holographic grating is written with two mutually coherent, ordinarily polarized Argon beams at 514 nm. The diffraction efficiency is monitored with an extraordinarily polarized, low power He-Ne beam. The writing beams are expanded to fill the crystal to improve the stability of the reversed domains. The diffraction efficiency in the recording stage is more than an order of magnitude higher than that of a grating written without an external field. We achieve diffraction efficiencies as high as 95% with a gradually increasing negative voltage, while a positive voltage produces a revealed grating with a diffraction efficiency of up to 15%.
© 2001 Optical Society of AmericaPDF Article