Nonlinear self-channeling of a laser beam at the surface of a photorefractive fiber

Abstract

We experimentally observed the self-channeling of the light beam in photorefractive Bi12TiO20 fiberlike sample owing to the strong fanning effect. It results in significant speed up of the photorefractive response time in waveguides and in anomalous dependence of the response time on the applied ac electric field amplitude: the higher electric field, the faster response.

Fast mutually pumped phase conjugation using transient photorefractive coupling

“…2͑a͒ is applied to the crystal, the transient beam coupling results in appearance of unusual nonstationary distribution of the fanning light: at the beginning of fanning formation process strong scattering occurs at small angles in respect to the transmitted pump beam, but then the scattering maximum proceeds further to the larger angles. 13. Because of the transient nature of the beam fanning process described above, the evolution of light intensity scattered at the small angle has a pulse shape as shown in Fig.…”

“…3͑a͒, that the higher electric field is applied to the crystal the faster the MPPC-response time is observed. 13,15 These waves appear in the crystal with the strong fanning effect because of internal reflections of fanned beams on the crystal side surface and from the photorefractive gratings recorded near that surface. Similar character of the fanning response was reported recently for fiberlike BTO crystals.…”

Acceleration of a photorefractive response in Bi 12 TiO 20 crystals

“…'4 Immediately after that they were experimentally demonstrated with bulk BaTiO3 crystals by Cronin-Golomb'5 and with fiber-like 3i12Ti020 crystals by Kamshilin et.al. 4 Both works consider the cycle of deflection into the crystal edge, total internal reflection, and deflection back into the crystal edge as a basic mechanism for the generation of photorefractive surface wave. It was mentioned above and shown in Fig.5 that the peak intensity of a surface wave may exceed the incident one.…”

Дифференциальные Характеристики Спектров Оптического Пропускания Кристаллов Класса Силленитов

“…Кристаллы класса силленитов Bi 12 MO 20 (M=Si, Ge, Ti), обладающие фотопроводящими, фоторефрактивными и фотохромными свойствами, являются привлекательными материалами для исследования эффектов взаимодействия и самовоздействия световых пучков и реализации устройств фоторефрактивной нелинейной оптики и динамической голографии [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Эти фоточувствительные свойства связываются с дефектными центрами, энергетические уровни которых расположены в запрещенной зоне.…”