System measure for persistence in holographic recording and application to singly-doped and doubly-doped lithium niobate

Abstract

We define a measure for persistence in holographic recording. Using this measure and the known measures for dynamic range and sensitivity, we compare the performance of singly-doped and doublydoped LiNbO 3 crystals. We show that the range of performance that can be obtained using doubly-doped crystals is much larger than that obtained using singly-doped ones.

Properties of Ru-doped near-stoichiometric lithium niobate crystals produced by vapor transport equilibration

“…Higher sensitivity is always better for recording holograms because of the shorter writing time. In the single-hologram recording and erasure experiments, the sensitivity can be calculated by the following formula [25]:…”

Improvement of sensitivity and refractive-index changes in LiNbO3:Ce:Cu crystals with UV light

“…where n o is the average refractive index of LN crystal for ordinary-polarized recording light, 13 is the electro-optic coefficient and E SC is the complex angle of E SC . In this dynamic volume grating system, the self-diffraction behaviour of the grating can be analysed by coupled-wave equations.…”

“…The characteristics of doubly doped LN crystals have since been investigated extensively [3][4][5][6][7][8][9] and the application of such LN crystals to holographic memory has been reported [10]. However, there are a number of crucial practical disadvantages with this technique: insufficient levels of refractive-index change; low sensitivity [5,7,8,11]; the depth of the total grating was greatly reduced as a result of the 180 phase difference between shallow and deep gratings [2,12]; and the extra step of bringing electrons from deep traps to shallow traps and the small absorption cross-section of the shallow traps at large recording wavelength prolong response time [13]. These are intrinsic problems with a UV-sensitized system for use as a recording mechanism, and can only be solved by optimization of material doping, oxidation-reduction processing, and the intensity ratio of red-to-UV [13][14][15].…”

“…However, there are a number of crucial practical disadvantages with this technique: insufficient levels of refractive-index change; low sensitivity [5,7,8,11]; the depth of the total grating was greatly reduced as a result of the 180 phase difference between shallow and deep gratings [2,12]; and the extra step of bringing electrons from deep traps to shallow traps and the small absorption cross-section of the shallow traps at large recording wavelength prolong response time [13]. These are intrinsic problems with a UV-sensitized system for use as a recording mechanism, and can only be solved by optimization of material doping, oxidation-reduction processing, and the intensity ratio of red-to-UV [13][14][15]. In this paper, we proposed a solution to these problems by using modulated UV light to record gratings simultaneously both in shallow and deep traps, and using red light to bleach the grating in the shallow centre to realize persistent photorefractive holographic storage in the doubly doped LN crystals.…”

Advances in photo-thermo-refractive glass composition modifications

“…For instance, selectivity of grating with 500mkm thickness is twice lower than such for 1000mkm one. Due to this fact, such material as a photo-thermo-refractive (PTR) glass, which allows recording of holograms with high efficient thickness, keep getting more and more popular as a material for amplitude-phase hologram and diffraction elements creation [1]. PTR glass is manufactured by several companies: Corning(USA), Optigrate(USA), PD-LD(USA) and University ITMO(Russia).…”