Enhancement Of Diffraction Efficiency Research Articles

Optical nonlinearity enhancement due to induced self-diffraction in GaAs

Picosecond time-resolved four-wave mixing at 1.06 μm in GaAs was performed. A diffraction efficiency enhancement due to the induced self-diffraction was observed and discussed.

Moving grating for enhanced holographic recording in cerium-doped Sr_06Ba_04Nb_2O_6

We demonstrate that holographic recording in photorefractive materials can be improved by using a moving grating to reduce energy coupling. In cerium-doped Sr(0.6)Ba(0.4)Nb(2)O(6) under an applied dc electric field, experimental and theoretical results show that the proper grating velocity can maximize the modulus and the real part of the spacecharge field while reducing the imaginary component of the space-charge field (and energy coupling) to zero. Avoiding energy transfer between the recording beams allows us to maintain maximum contrast throughout the crystal, producing a uniform, high-index-modulation grating with enhanced diffraction efficiency and superposition properties.

Spatial light modulation via enhanced diffraction efficiency of photochromic gratings in photorefractive BSO

We report a novel scheme for spatial light modulation in which the diffraction efficiency of a permanent photochromic hologram stored in photorefractive BSO is spatially enhanced by illumination with a laser beam at the strongly absorbed blue wavelength, λ=488 nm. Experimental results and characteristics of this enhancement process are presented, and possible causes discussed.

Field and time thresholds for the electrical fixation of holograms recorded in (Sr0.75Ba0.25)Nb2O6 crystals

We demonstrate that the electrical fixation of holograms recorded in (Sr0.75Ba0.25)Nb2O6 involves local polarization switching; the fixing threshold is found to be nearly the average coercive field Ec = 970 V/cm, and the minimum fixing time is the polarization switching time. The diffraction efficiency enhancement of fixed holograms is attributed to the photoinduced space charge field's overcancellation by ionic displacements associated with the polarization switching.