An investigation of the specially doped cerium:iron:lithium niobate photorefractive crystals: Optical properties and applications | Posted on:1996-02-27 | Degree:Ph.D | Type:Dissertation | University:The Pennsylvania State University | Candidate:Zhao, Feng | Full Text:PDF | GTID:1460390014987419 | Subject:Engineering | Abstract/Summary: | | The first half of this dissertation presents investigations of the material aspects of photorefractive properties of LiNbO{dollar}sb3{dollar} doped with cerium (Ce) and iron (Fe). A two-wave coupling approach is utilized to measure the photorefractive sensitivity, response time, and material dynamic range. The wavelength-sensitivity range of the crystal is determined by using the optical absorption method. The absorption spectra show that the Ce:Fe:LiNbO{dollar}sb3{dollar} crystal has a higher photorefractive sensitivity in the red light region than singly doped and undoped LiNbO{dollar}sb3{dollar} crystals. These characterization measurements show that the Ce:Fe:LiNbO{dollar}sb3{dollar} crystal has the overall best photorefractive properties which make it very suitable for practical applications for photonic technologies. Both theoretical and experimental results show strong temperature dependence of the light-induced scattering noise due to thermally activated ionic charges. Based on this result, a method for signal-to-noise ratio (SNR) enhancement is proposed. It is shown that the scattering noise can be effective reduced if the crystal is operated at an elevated temperature.; The remaining of this dissertation is concerned with the applications of the Ce:Fe:LiNbO{dollar}sb3{dollar} photorefractive crystal. First, an optical phase-conjugator using nondegenerate four-wave mixing is studied, in which a strong steady-state frequency-varied phase-conjugate wave is obtained by operating the crystal at an elevated temperature. Second, wavelength-multiplexed crystal fiber holograms are investigated. The minimum channel separation is proposed to achieve maximum storage capacity. The cross-talk-limited storage capacity is evaluated. The requirement of the laser linewidth for wavelength-multiplexing applications is studied. | Keywords/Search Tags: | Photorefractive, Crystal, Doped, Applications, Linbo{dollar}sb3{dollar}, Optical | | Related items |
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