Liu Si-Min

Photorefractive Spatial Dark-Soliton Stripes in LiNbO3:Fe Crystal and Their Application

We observed the photorefractive spatial dark-soliton stripes in LiNbO3:Fe crystal, and demonstrate the planar waveguide property of refractive index profile induced by these spatial dark-soliton stripes. We suggest a new mothed to form the planar waveguide utilizing the grating fixing technique.

Light-climbing effect in LiNbO(3):Fe crystal.

The light-climbing effect in a LiNbO(3):Fe crystal sheet was experimentally studied, and the mechanism for light climbing proposed was proved to be correct. The relevant optical properties were investigated.

Saturable Nonlinearity in Photovoltaic-Photorefractive Crystals Under Open-circuit Condition

We show that the refractive index change induced by a focused incident beam with an additional incoherent uniform illumination in photovoltaic-photorefractive crystals under open-circuit condition has a saturable nonlinearity form. The incoherent uniform background illumination can be used to increase the effective dark irradiance. The formation time of the photovoltaic soliton can be decreased by keeping the intensity of the soliton at a higher value without over-saturation by use of the background illumination.

Waveguides Written and Stored by Photovoltaic Dark Spatial Solitons in LiNbO3:Fe Crystals

To our knowledge, we have demonstrated for the first time that (2+1)-dimension photorefractive waveguides can be written and stored by light using the (2+1)-dimension photovoltaic dark spatial solitons in LiNbO3:Fe crystals. It can guide a probe beam of the same wavelength as that of the writing beam.

Lens-Like Effect in LiNbO3: Fe Photorefractive Crystal

The lens-like effects, both photorefractive effect and thermo-optical effect, were studied in the LiNbO3: Fe sheet. The threshold light intensity above which the photorefractive effect was overwhelmed by the thermal effect was determined and the thermo-optical coefficient dn/dT is evaluated by the Z-scanning method. The limiting characteristics of LiNbO3: Fe sheet is examined.

White-Light Nonlinear Photonic Lattices in Self-Defocusing Media

Using fully incoherent white light emitted from an incandescent lamp and amplitude mask, we experimentally investigate the influence of several factors on the fabrication of the lattice in photovoltaic self-defocusing LiNbO3:Fe crystal, the factors include the orientation of the crystalline c axis relative to the principal axis of the photonic lattice and the filament, the diameter of input dark spot and the separation of the adjacent input dark spots. Experimental results reveal that the best fabricating condition of photonic lattices is that the principal axis of lattice is tilted for 45° relative to the crystalline c axis which is parallel to the filament of the lamp. In addition, it is necessary that the diameter of the input dark spot is larger than the half of their separation.

Photorefractive Self-Bending and High-Performance KNSBN:Cu Crystal Self-Pumped Phase-Conjugator

The mechanism for the high-performance KNSBN:Cu crystal self-pumped phase-conjugator is first put forward in this letter as no-loop photorefractive self-bending succesive four-wave mixing interaction. And the photorefractive backscattering amplification was found to play a very important role in it.

White Light Photorefractive Phase Zone Plates

Incoherent white light from an incandescent source is employed to fabricate volume phase zone plates in LiNbO3: Fe, for the first time to our knowledge, which can guide and modulate the input white light or laser light. The diffractive efficiency of the white light volume phase zone plates fabricated can reach as high as 12%. In addition, we test the volume phase zone plates by a probe beam and find that the volume phase zone plate is present in the direction perpendicular to the c-axis and absent in the direction parallel to the c-axis. This directly proves the existence of photovoltaic photorefractive anisotropy of white light.

Pump Intensity Dependence of Two-Beam Coupling in Doped Lithium Niobate Crystals

We demonstrated experimentally the dependence of two-beam coupling on the incident pump intensity in our samples of doped LiNbO3 crystals. Our results show that there is an optimum pump intensity for the signal beam amplification, which can be easily controlled by doping the LiNbO3 crystal with suitable concentrations of Fe and damage-resistant dopants such as Mg, In, and Zn.

Reduction of the Resolution Losses in Dual-Wavelength Storage

The dual-wavelength storage for multi-page storage with the nondestructive readout is investigated in the double-doped lithium niobate crystals. The image field losses are minimized by adjusting the readout wave vectors, and the resolution is improved by optimizing the storage setup.