We report on the recording of stabilized running holograms in photorefractive materials with arbitrarily selected phase shift φ between the transmitted and difracted beams propagating along the same direction behind the photorefractive crystal. The dependence of the diffraction efficiency and of the hologram speed on φ , in such stabilized holograms, can be easily measured and used for material...

Neuromorphic models are proving capable of performing complex machine learning tasks, overcoming the structural limitations imposed by software algorithms and electronic architectures. Recently, both supervised unsupervised learnings were obtained in photonic neurons means spatial-soliton-waveguide X-junctions. This paper investigates behavior networks based on these solitonic neurons, which ta...

Photorefractive crystals exhibit large optical nonlinearities1 and have great potential in optical data processing.2 The extrinsic photorefractive effect in these electro-optic and photoconductive materials is rather well understood. The band-transport model' has been successfully employed to describe photorefraction in crystals such as the sillenite compounds, Bi12SiO2 0 and Bi12GeO 2 0 (BGO)....

We investigated 2k-grating-assisted self-pumped phase conjugation in photorefractive Ce:BaTiO3 crystals. The phase-conjugation process involves a combination of four-wave mixing and stimulated photorefractive backscattering. An approximation involving separate interaction regions is used to theoretically calculate the reflectivity of phase conjugation as a function of the coupling strength of f...

PURPOSE To evaluate the quality of life, vision and stress before and after refractive surgery. METHODS This is a longitudinal, observational study, where 100 patients were evaluated; 54 espectacles wearers, 21 contact lens users before surgery and 25 controls wearers spectacles or contact lenses, who did not want to undergo refractive surgery during one year despite refractive error. The app...

PURPOSE A seventh annual survey was carried out by mail in February 1999 to investigate the current trends in cataract and refractive surgery in Japan. METHODS Questionnaires were sent to 925 ophthalmologist members of the Japanese Society of Cataract and Refractive Surgery. Data received from 411 (44.4%) of the recipients were cross-analyzed and compared with those from the previous surveys....

Journal of Refractive Surgery Volume 17 May/June 2001 ABSTRACT PURPOSE: To review the etiology, prevention, and management of laser in situ keratomileusis (LASIK) complications. METHODS: Review of literature and the experience of the authors. RESULTS: Careful preoperative screening is critical to prevention of many potential complications of LASIK. Flap complications that occur during surgery a...

The demand for holographic recording materials has been ever increasing for the past few decades. Photorefractive materials have been studied extensively as candidate recording media. They offer high index modulation with reversible recording that make them very attractive for applications such as threedimensional holographic displays, adaptive optics, optical data storage and medical optics. R...

PURPOSE The analgesic efficacy and safety of topical ketorolac tromethamine 0.5% ophthalmic solution (Acular) in photorefractive keratectomy was compared to its vehicle. METHODS Double-masked, multicenter, study of 200 patients dosed with 1 drop of study medication (ketorolac or vehicle) in the operated eye immediately after surgery (eye patched), with four-times daily dosing for the next 3 d...

We describe a method for increasing the diffraction efficiency of multiply exposed photorefractive holograms by periodic copying. The method is experimentally demonstrated with photorefractive and thermoplastic recording media.