Different from the cases discussed preciously, nonlinear changes of refractive index in the photorefractive materials are influenced by both the linear and quadratic electro-optic effect simultaneously now. Here we pr...Different from the cases discussed preciously, nonlinear changes of refractive index in the photorefractive materials are influenced by both the linear and quadratic electro-optic effect simultaneously now. Here we present the evolution equations of one-dimension incoherently coupled spatial soliton families due to two-photon effect in biased photorefractive crystals with both the linear and quadratic electro-optic effect and discuss their existence conditions and properties in detail. Our analysis indicates that these soliton families can exist in all three possible realizations： dark-dark, bright-bright and dark-bright provided that the incident beams have the same polarization, wavelength and are mutually incoherent. Finally, the stabilities of these soliton families have been discussed by means of beam propagation methods.展开更多
In a biased photorefractive crystal, the process of two one-dimensional waves mixing, i.e., the dynamical evolution of both pump beam and signal beam, is traced by numerically solving the coupled-wave equation. Direct...In a biased photorefractive crystal, the process of two one-dimensional waves mixing, i.e., the dynamical evolution of both pump beam and signal beam, is traced by numerically solving the coupled-wave equation. Direct simulations show that the propagation and stability of the two beams are completely determined by the system parameters, such as the external bias field, the intensity and the beam waist of the pump beam. By adjusting these parameters, one can control the state of two Gaussian waves mixing. The numerical results are helpful for performing a two-wave mixing experiment.展开更多
Bi 12 TiO 20 (BTO)crystals have same structure as that of the Bi 12 SiO 20 (BSO)which is one of the most popular photorefractive materials.And both of them belong to cubic non centrosymmetric nonferroelectric material...Bi 12 TiO 20 (BTO)crystals have same structure as that of the Bi 12 SiO 20 (BSO)which is one of the most popular photorefractive materials.And both of them belong to cubic non centrosymmetric nonferroelectric materials.The cubic nonferroelectric oxides exhibit a number of advantages such as higher sensitivity and faster respond for applications in photorefractive.Compared to BSO,BTO have the largest electro optical coefficient and lower optical activity,especially it exhibits much high photosensitivity in the red light region that permits to use a cheap He Ne laser.It is,therefore,of high potential for applications in optical devices.展开更多
Waveguides were fabricated in lithium niobate crystals solely by light irradiation using binary optical masks and SLM-prepared optical masks. Arrayed-waveguides were also obtained by once or twice irradiations of an i...Waveguides were fabricated in lithium niobate crystals solely by light irradiation using binary optical masks and SLM-prepared optical masks. Arrayed-waveguides were also obtained by once or twice irradiations of an interferogram of two plane waves.展开更多
A new scheme for recording a dynamic phase grating with an asymmetric profile in C60-doped homeotropically aligned nematic liquid crystal（NLC） was presented.An oblique incidence beam was used to record the thin asym...A new scheme for recording a dynamic phase grating with an asymmetric profile in C60-doped homeotropically aligned nematic liquid crystal（NLC） was presented.An oblique incidence beam was used to record the thin asymmetric dynamic phase holographic grating.The diffraction efficiency we achieved is more than 40%,exceeding the theoretical limit for symmetric profile gratings.Both facts can be explained by assuming that a grating with an asymmetric saw-tooth profile is formed in the NLC.Finally,physical mechanism and mathematical model for characterizing the asymmetric phase holographic grating were presented,based on the photo-refractive-like（PR-like） effect.展开更多
We investigate theoretically the temperature effects on the evolutions of both bright and dark screening spatial solitons in biased two-photon photorefractive crystals.For a stable bright or dark two-photon screening ...We investigate theoretically the temperature effects on the evolutions of both bright and dark screening spatial solitons in biased two-photon photorefractive crystals.For a stable bright or dark two-photon screening spatial soliton originally formed in a crystal at a given temperature,when the crystal temperature changes,it will evolve into another stable screening soliton if the temperature change is quite small,while it will become unstable or break down if the temperature change is large enough.The spatial shape of a stable two-photon screening spatial soliton can be changed by appropriately adjusting the crystal temperature.展开更多
文摘Different from the cases discussed preciously, nonlinear changes of refractive index in the photorefractive materials are influenced by both the linear and quadratic electro-optic effect simultaneously now. Here we present the evolution equations of one-dimension incoherently coupled spatial soliton families due to two-photon effect in biased photorefractive crystals with both the linear and quadratic electro-optic effect and discuss their existence conditions and properties in detail. Our analysis indicates that these soliton families can exist in all three possible realizations： dark-dark, bright-bright and dark-bright provided that the incident beams have the same polarization, wavelength and are mutually incoherent. Finally, the stabilities of these soliton families have been discussed by means of beam propagation methods.
基金supported by the National Natural Science Foundations of China(Grant Nos 10174025 and 10574051)
文摘In a biased photorefractive crystal, the process of two one-dimensional waves mixing, i.e., the dynamical evolution of both pump beam and signal beam, is traced by numerically solving the coupled-wave equation. Direct simulations show that the propagation and stability of the two beams are completely determined by the system parameters, such as the external bias field, the intensity and the beam waist of the pump beam. By adjusting these parameters, one can control the state of two Gaussian waves mixing. The numerical results are helpful for performing a two-wave mixing experiment.
文摘Bi 12 TiO 20 (BTO)crystals have same structure as that of the Bi 12 SiO 20 (BSO)which is one of the most popular photorefractive materials.And both of them belong to cubic non centrosymmetric nonferroelectric materials.The cubic nonferroelectric oxides exhibit a number of advantages such as higher sensitivity and faster respond for applications in photorefractive.Compared to BSO,BTO have the largest electro optical coefficient and lower optical activity,especially it exhibits much high photosensitivity in the red light region that permits to use a cheap He Ne laser.It is,therefore,of high potential for applications in optical devices.
文摘Waveguides were fabricated in lithium niobate crystals solely by light irradiation using binary optical masks and SLM-prepared optical masks. Arrayed-waveguides were also obtained by once or twice irradiations of an interferogram of two plane waves.
基金Project supported by the Science and Technology Programs of the Educational Committee of Heilongjiang Province,China(Grant No.12541730)the National Natural Science Foundation of China(Grant No.61405057)
文摘A new scheme for recording a dynamic phase grating with an asymmetric profile in C60-doped homeotropically aligned nematic liquid crystal（NLC） was presented.An oblique incidence beam was used to record the thin asymmetric dynamic phase holographic grating.The diffraction efficiency we achieved is more than 40%,exceeding the theoretical limit for symmetric profile gratings.Both facts can be explained by assuming that a grating with an asymmetric saw-tooth profile is formed in the NLC.Finally,physical mechanism and mathematical model for characterizing the asymmetric phase holographic grating were presented,based on the photo-refractive-like（PR-like） effect.
基金supported by the Science and Technology Development Foundation of Higher Education of Shanxi Province,China (No.200611042)
文摘We investigate theoretically the temperature effects on the evolutions of both bright and dark screening spatial solitons in biased two-photon photorefractive crystals.For a stable bright or dark two-photon screening spatial soliton originally formed in a crystal at a given temperature,when the crystal temperature changes,it will evolve into another stable screening soliton if the temperature change is quite small,while it will become unstable or break down if the temperature change is large enough.The spatial shape of a stable two-photon screening spatial soliton can be changed by appropriately adjusting the crystal temperature.
