Читать книгу Photorefractive Materials for Dynamic Optical Recording - Jaime Frejlich - Страница 4

1 Chapter 1Figure 1.1 Refractive index ellipsoid.Figure 1.2 Refractive indices for a plane wave propagating in an anisotropic m...Figure 1.3 Crystallographic axes of a sillenite and an applied 3D electric fie...Figure 1.4 Structure of an undistorted cubic perovskite structure with general...Figure 1.5 Three‐dimensional sillenite structure: darker spheres represent i...Figure 1.6 Schematic representation of a raw BTO crystal boule with its striat...Figure 1.7 crystal boule as grown along its [001]‐axis.Figure 1.8 Actual undoped sillenite crystals: raw crystal boule grown along ...Figure 1.9 Index‐of‐refraction of BTO that is formulated by [6].Figure 1.10 ‐type cubic crystal and its crystallographic axes , and with...Figure 1.11 Principal coordinate axes system arising by the effect of an ele...Figure 1.12 Sillenite crystal cut along its principal crystallographic axes, w...Figure 1.13 Lithium niobate crystal with an applied electric field along the p...Figure 1.14 Lithium niobate crystal ellipsoid (black) and its modified (gray) ...

2 Chapter 2Figure 2.1 Energy diagram for a typical CdTe crystal doped with vanadium, with...Figure 2.2 Dark conductivity measured at various temperatures for a CdTe:V cry...Figure 2.3 Representation of the sillenite octahedra unit with the lone‐electr...Figure 2.4 Octahedra sharing corners.Figure 2.5 Sillenite structure showing (dashed lines) the empty tetrahedra for...Figure 2.6 Localized states in the Band Gap of nominally undoped crystal, fr...Figure 2.7 Schematic representation of luminescence effect on a sillenite crys...Figure 2.8 Photoluminescence in BTO‐008. The dashed line is the spectrum of th...Figure 2.9 Intrinsic semiconductor: Fermi level for an intrinsic semiconductor...Figure 2.10 Doped semiconductor: Fermi level pinned at the position of the dop...Figure 2.11 Doped semiconductor: Fermi and quasi‐stationary Fermi levels upo...Figure 2.12 Recombination centers.Figure 2.13 Traps.Figure 2.14 Schematic representation of a material with one center (one single...Figure 2.15 Under the action of light (of adequate wavelength) electrons are e...Figure 2.16 In this example, under the action of light, electrons and holes ar...Figure 2.17 Under nonuniform light, negative charges (in this case, we assume ...Figure 2.18 Photochromic effect and the band‐transport model. On the left side...Figure 2.19 Schema for the crystal samples: undoped (labeled BTO‐J40), lead‐...Figure 2.20 Crystal samples.Figure 2.21 (left) and :Fe (right) crystal samples showing the [010] and c‐...Figure 2.22 Average photovoltaic current density measured along axes [010] and...Figure 2.23 Polarization‐dependent photovoltaic photocurrent for both BTeO and...Figure 2.24 Photocurrent ( ) , for undoped as a function of the angle . Th...Figure 2.25 Photovoltaic current versus light intensity (uniform nm laser ...Figure 2.26 Photovoltaic current versus light intensity (uniform nm laser in...Figure 2.27 Photovoltaic current versus light intensity (uniform nm laser in...Figure 2.28 Average photovoltaic current density data, measured along the c‐ax...Figure 2.29 Light‐induced absorption spots produced in the center of an undope...Figure 2.30 Photochromic relaxation time for as a function of inverse absolu...Figure 2.31 Transmitted versus incident power (both measured in the air) for a...Figure 2.32 Light‐induced Schottky barrier at the illuminated transparent cond...Figure 2.33 Schema of a photorefractive BTO crystal plate between two conducti...Figure 2.34 Cross‐section schema of the ITO‐sandwiched BTO plate indicating th...Figure 2.35 ITO sandwiched 0.81 mm thick BTO crystal plate with electrodes wir...Figure 2.36 Measured photocurrent data referred to Fig. 2.35 with , and i...Figure 2.37 Photovoltaic‐based current data ( , and ) computed from curves ...

3 Chapter 3Figure 3.1 Photoactive centers inside the Band Gap. There are filled traps (...Figure 3.2 Under the action of light the electrons are excited from the traps ...Figure 3.3 The charge distribution produces a space‐charge electric field modu...Figure 3.4 The electric field modulation may produce deformations in the cryst...Figure 3.5 If the photoconductive material is also electro‐optic, that is to s...Figure 3.6 Holographic setup: A laser beam is divided by the beamsplitter BS, ...Figure 3.7 Generation of an interference pattern of fringes.Figure 3.8Figure 3.8 Light excitation of electrons to the CB in the crystal.Figure 3.9Figure 3.9 Generation of an electric charge spatial modulation in th...Figure 3.10Figure 3.10 Generation of a space‐charge electric field modulation.Figure 3.11Figure 3.11 The electric field modulation produces a index‐of‐refra...Figure 3.12Figure 3.12 The recorded grating can be read using one of the recor...Figure 3.13Figure 3.13 The grating is erased during reading.Figure 3.14 Until all recording is erased.Figure 3.15 Space‐charge electric field grating being recorded by the ‐shifte...Figure 3.16 Space‐charge electric field without an externally applied field fo...Figure 3.17 Simulated recording (from 0 to 20 au) and erasure (from 20 to 50 a...Figure 3.18 Index‐of‐refraction modulation arising in the crystal volume. The ...Figure 3.19 Schematic description of running hologram generation in photorefra...Figure 3.20 Plot of for the assumed parameters: m, m, , rad/s, and Figure 3.21 Plot of from Eq. 3.85 for the same parameters referred to in Fig...Figure 3.22 Plotting of Q as a function of ( ‐axis) and ( ‐axis) for V/m...Figure 3.23 Plotting of Q as a function of K, from Eq. 3.91, for typical value...Figure 3.24 Plotting of (continuous curve), (long dashing curve) and (sh...Figure 3.25 One‐species/two‐valence/two‐charge carrier model contributing to c...Figure 3.26 Two‐species/two‐valence/two‐charge carrier model contributing to c...Figure 3.27 Hole‐electron competition on different photoactive centers under t...Figure 3.28 Short circuit schema using conductive silver glue to electrically ...

4 Chapter 4Figure 4.1 Reading the recorded hologram with one of the recording beams.Figure 4.2 Recording a fixed volume index‐of‐refraction hologram that is phase...Figure 4.3 Bragg condition where and are the incident beam and the diffrac...Figure 4.4 Amplitude coupling in two‐wave mixing: in this example, the weaker...Figure 4.5 Phase coupling in two‐wave mixing: the pattern of fringes and assoc...Figure 4.6 Numerical plotting of versus the normalized time , from Eq. 4.80...Figure 4.7 Numerical plotting of versus the normalized time , from Eq. 4.80...Figure 4.8 Numerical plotting of versus the normalized time , from Eq. 4.80...Figure 4.9 Numerical plotting of versus the normalized time , from Eq. 4.80...Figure 4.10 Transient effect of a perturbation, in the form of a ramp voltage ...Figure 4.11 Computed running hologram as a function of (rad/s) for and d...Figure 4.12 Computed running hologram as a function of (rad/s) for and d...Figure 4.13 Computed running hologram as a function of (rad/s) for and d...Figure 4.14 Computed running hologram as a function of (rad/s) for and d...Figure 4.15 versus (rad/s), computed for and different material paramete...Figure 4.16 versus (rad/s), computed for and different material paramete...Figure 4.17 versus (rad/s), computed for and different material paramete...Figure 4.18 versus (rad/s), computed for and different material paramete...Figure 4.19 Phase modulation setup: BS: beamsplitter, PZT piezoelectric‐suppor...Figure 4.20 Wave‐mixing schema showing the hologram phase shift and the phas...Figure 4.21 Degenerate four‐wave mixing showing the signal S and reference R b...

5 Chapter 5Figure 5.1 Input and output light polarization.Figure 5.2 Input and output polarization referred to actual principal axes coo...Figure 5.3 General illustration of the polarization direction of the transmitt...Figure 5.4 Transmitted and diffracted beams orthogonally polarized at the outp...Figure 5.5 Transmitted and diffracted beams parallel‐polarized at the output t...

6 Chapter 6Figure 6.1 Scanning electronic microscopy image of a 1D hollow sleeve structur...Figure 6.2 Scanning electronic microscopy image of a 2D‐array holographically ...Figure 6.3 Scanning electronic microscopy image of a blazed grating made by th...Figure 6.4 Block‐diagram of a self‐stabilized setup: D photodetector, LA‐...Figure 6.5 Schematic description of the actual self‐stabilized holographic rec...Figure 6.6 Schematic description of the effect of noise on the two‐wave mixing...Figure 6.7 Block‐diagram of fringe‐locked running hologram setup: same as for ...Figure 6.8 Schematic actual setup for self‐stabilized running hologram recordi...Figure 6.9 Fringe‐locked running hologram speed: Kv (rad/s) versus feedback am...Figure 6.10 Schema of the self‐stabilized setup in Fig. 6.8 modified to operat...Figure 6.11 Transverse optical configuration for holographic recording on BTO:...Figure 6.12 Self‐stabilized recording in a crystal: The upper figure shows t...Figure 6.13 Second harmonic evolution during holographic recording in a nomina...Figure 6.14 Experimental setup: BS beamsplitter, C: :Fe crystal, M mirror, PZ...Figure 6.15 Computed as a function of 2 from Eq. 6.53 for nonstabilized rec...Figure 6.16 Computed as a function of 2 and , for .Figure 6.17 Computed as a function of 2 and , for . The plane superimpo...Figure 6.18 Computed (in arbitrary units), with (that is, , ) as a functi...Figure 6.19 Computed evolution of ( ), ( ) in arbitrary units and ( ) as...Figure 6.20 Computed evolution of ( ), ( ) in arbitrary units, and ( ) a...Figure 6.21 Self‐stabilized recording in the less‐oxidized crystal (sample LNB...Figure 6.22 Self‐stabilized recording in an oxidized crystal (sample LNB1) wit...Figure 6.23 Self‐stabilized recording in an oxidized crystal (sample LNB1) wit...Figure 6.24 Overall beam produced by the interference of the recording beams...Figure 6.25 Measurement of the running hologram speed for the sample LNB1, , Figure 6.26 Self‐stabilized recording on the same :Fe sample (LNB3) with ordi...Figure 6.27 Recording setup stabilized on a nearby placed glassplate G, all ot...Figure 6.28 Glassplate‐stabilized experimental data for the recording on an ox...Figure 6.29 Mathematical simulation of non self‐stabilized recording with . T...Figure 6.30 Evolution of and scattering PSL during stabilized holographic re...

7 Chapter 7Figure 7.1 Schema of the experimental setup for electro‐optic coefficient meas...Figure 7.2 Evolution of the absorption coefficient in an undoped crystal (la...Figure 7.3 Light‐induced absorption: transmitted versus incident irradianc...Figure 7.4 Light‐induced absorption of undoped (sample labeled BTO‐013) at Figure 7.5 Absorption coefficient‐thickness measured for three different BTO...Figure 7.6 Arrhenius curve dark conductivity for BTO:V. Data fitting to Eq. 7....Figure 7.7 Frequency‐dependence of the absolute value in Eq. 7.12 for differ...Figure 7.8 Schematic setup for the electric measurement of photoconductivity. ...Figure 7.9 Typical crystal schema, in the so‐called “Transverse Configuration”...Figure 7.10 Photocurrent (in pA) as a function of the incident irradiance on t...Figure 7.11 (Left) Photograph of the wavelength‐resolved photoconductivity exp...Figure 7.12 Transverse configuration: coefficient σ on a logarithmic scal...Figure 7.13 Detailed view of Fig. 7.12 showing a strong increase in σ for...Figure 7.14 σ (s m/ ) for thermally relaxed BTO:V ( ) and pre‐exposed to Figure 7.15 Longitudinal configuration schema showing an externally polarized Figure 7.16 Lateral view of the sandwiched BTO crystal plate showing the light...Figure 7.17 Plotting of with positive polarization (ranging from 0 to 500 V)...Figure 7.18 Light‐induced photoelectric conversion efficiency measured ( ) o...Figure 7.19 Comparative longitudinal (without external applied field) ( ) an...Figure 7.20 and measured on an ITO‐sandwiched BTO with mm and mm under...Figure 7.21 Modulated photocurrent data of an undoped crystal, with monochro...Figure 7.22 Plot of the Airy function (left), the equivalent Gaussian function...Figure 7.23 Plotting of in the plane, for (left) and (right).Figure 7.24 Schematic representation of an ac photocurrent produced by a sinus...Figure 7.25Figure 7.25 Stationary space‐charge field arising from a speckle pa...Figure 7.26 Plotting of in the plane for a speckle pattern of light vibrat...Figure 7.27 Simulation of the first harmonic photocurrent coefficient (in ar...Figure 7.28 Simulation of the first harmonic photocurrent coefficient as a f...Figure 7.29 Schematic representation of the experimental setup. A laser beam i...Figure 7.30 Optical sensor in metallic housing (from Fig. 7.29) showing the se...Figure 7.31Figure 7.31 Expanded front view of the photorefractive sensor housi...Figure 7.32 First harmonic photocurrent as function of reduced vibration ampli...Figure 7.33 Experimental first harmonic photocurrent measured on a CdTe:V ph...

8 Chapter 8Figure 8.1 Holographic setup: a laser beam is divided by the beamsplitter BS, ...Figure 8.2 Energy transfer between interfering = 633 nm beams in the two‐wav...Figure 8.3 Exponential gain coefficient as a function of the external incide...Figure 8.4 White light hologram erasure in :Fe: The erasure data ( ), measure...Figure 8.5 The graph shows the erasure of holograms in undoped BTO under 10–15...Figure 8.6 Hologram diffraction efficiency (arbitrary units) decay during nm...Figure 8.7 Diffraction efficiency ( in arbitrary units) during erasure of a h...Figure 8.8 Erasure of holograms in Pb‐doped BTO (same sample as in Fig. 8.6) r...Figure 8.9 Diffraction efficiency (recorded and measured using nm laser beam...Figure 8.10 Diffraction efficiency (au) as a function of time (seconds, in log...Figure 8.11 Hologram relaxation in the dark: exponential time as a function of...Figure 8.12 Photorefractive sensitivity S data ( ) as a function of the extern...Figure 8.13 Second harmonic evolution for KNSBN:Ti for the same sample and exp...Figure 8.14 Evolution of the accounting on self‐diffraction effects as de...Figure 8.15 Two‐wave mixing experiment in a photorefractive GaAs intrinsic cry...Figure 8.16 Second harmonic response curves for an undoped semi‐insulating GaA...Figure 8.17 Two‐wave mixing experiment in a photorefractive GaAs intrinsic cry...Figure 8.18 Two‐wave mixing experiment in a photorefractive GaAs intrinsic cry...Figure 8.19 Plot of the first (Eq. 8.76) and second (Eq. 8.78) harmonic te...Figure 8.20 Experimental setup for the generation and measurement of running h...Figure 8.21 Diffraction efficiency (left) and (right) as a function of Kv co...Figure 8.22 Diffraction efficiency (left) and (right) as a function of Kv co...Figure 8.23 Diffraction efficiency experimental data (spots) as a function o...Figure 8.24 experimental data (spots) as a function of for the same condit...Figure 8.25 Holographic photoelectromotive force current setup schema: a laser...Figure 8.26 (in arbitrary units) as a function of the vibration amplitude ...Figure 8.27 Computed (in arbitrary units) as a function of in rad for a fi...Figure 8.28 First harmonic component of the holographic current data (spots)...Figure 8.29 First harmonic component of the holographic current data (spots)...Figure 8.30 data (spots) plotted as a function of , for rad: Ce‐doped BTO...

9 Chapter 9Figure 9.1 Typical time evolution of the and signals (dots) at the initial...Figure 9.2 Computed initial versus applied electric field data (spots) in ....Figure 9.3 Output phase‐shift versus applied electric field ( ) data (circle...Figure 9.4 Fringe‐locked running hologram speed versus applied electric field ...Figure 9.5 Fringe‐locked running hologram experiment: frequency detuning (me...Figure 9.6 Fringe‐locked running hologram experiment on undoped crystal usin...Figure 9.7 and experimentally measured as function of on an undoped cr...Figure 9.8 3D plotting of experimentally measured and as function of fro...Figure 9.9 3D surface plotting of and as function of from Eq. 9.19 with ...Figure 9.10 Characterization of reduced :Fe (labeled LNB3): self‐stabilized h...Figure 9.11Figure 9.11 Characterization of reduced :Fe (labeled LNB5): self‐s...Figure 9.12 Characterization of oxidized :Fe (labeled LNB1): self‐stabilized ...

10 Chapter 10Figure 10.1 Schematic diagram of the experimental holographic setup: PBS: pola...Figure 10.2Figure 10.2 (a) Lateral view of the holographic setup: CCD camera (...Figure 10.3 Simplified schema showing the distribution of incident light ( ) b...Figure 10.4 Optimization of the target illumination: , diffracted reference b...Figure 10.5 Loudspeaker membrane (left) driven at 3.0 kHz and analyzed by the ...Figure 10.6 Amplitude of vibration at a point of local maximum in the membrane...Figure 10.7 Amplitude of vibration at two different points of local maximum in...Figure 10.8 Time‐average holographic interferometry pattern of a thin phosphor...Figure 10.9Figure 10.9 Time‐average holographic interferometry pattern of a th...Figure 10.10 Time‐average holographic interferometry pattern of a thin phospho...Figure 10.11 Double exposure holographic interferometry of a tilted rigid plat...Figure 10.12 Double exposure holographic interferometry of a rigid plate that ...Figure 10.13 Double exposure holographic interferometry of a rigid plate that ...

11 Chapter 11Figure 11.1 Experimental setup: S: massive copper cylinder with temperature‐co...Figure 11.2 Evolution of and during high temperature self‐stabilized holog...Figure 11.3 Diffraction efficiency of the overall grating during white‐light d...

12 1Figure 1 Naturally birefringent uniaxial lithium niobate crystal view under co...

13 2Figure B.1 Diffraction efficiency as a function of out‐of‐Bragg angle in mra...Figure B.2 , computed from Eq. B.15, as a function of for in‐Bragg conditio...Figure B.3 Measurement of diffraction efficiency: The recording beams are not ...

14 3Figure C.1 Effective field coefficient: the figure shows a Gaussian cross‐sect...

15 4Figure D.1 Volume with fixed ions of volume density of characteristic coll...

16 5Figure E.1 np‐junction showing the depletion layer and a diagram of the Schott...Figure E.2 np‐junction showing the depletion layer including the intrinsic lay...Figure E.3Figure E.3 pn‐junction showing the depletion layer including the int...Figure E.4 Photovoltaic mode operation for photodiodes. A shows its operation ...Figure E.5 Photoconductive mode operation for photodiodes. A reverse bias volt...Figure E.6 Operational amplifier operated photodiode in the short‐circuit phot...