Proton exchanged depth determination in LiNbO3 from laser induced pyroelectric voltage measurements
TL;DR: In this article, a non-destructive technique for the determination of depth of proton exchanged (PE) layers in LiNbO3 was proposed, based on the difference in the magnitudes of measured pyroelectric voltages induced by an intensity modulated laser beam on the exchanged and unexchanged regions.
Abstract: We report a new nondestructive technique for the determination of depth of proton exchanged (PE) layers in LiNbO3. Relying on the difference in the magnitudes of measured pyroelectric voltages, induced by an intensity modulated laser beam, on the exchanged and unexchanged regions, the depth of the PE layer has been measured and corroborated by a conventional optical characterization method.
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TL;DR: In this paper, a noncontact, non-destructive technique for the depth profiling of micromachined structures is presented based on the mirage or optical-beam deflection method of photothermal spectroscopy, an experimental measurement of a 8 μm step in silicon is given by way of illustration.
Abstract: A non-contact, non-destructive technique for the depth profiling of micromachined structures is presented. Based on the mirage or optical-beam deflection method of photothermal spectroscopy, an experimental measurement of a 8 μm step in silicon is given by way of illustration.
6 citations
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31 Dec 1959
TL;DR: In this paper, a classic account describes the known exact solutions of problems of heat flow, with detailed discussion of all the most important boundary value problems, including boundary value maximization.
Abstract: This classic account describes the known exact solutions of problems of heat flow, with detailed discussion of all the most important boundary value problems.
21,807 citations
TL;DR: In this article, the fabrication and characterization of optical waveguides formed in LiNbO3 by proton exchange in benzoic acid melts at 200-250°C is described.
Abstract: We describe the fabrication and characterization of optical waveguides formed in LiNbO3 by proton exchange in benzoic acid melts at 200–250 °C. Proton exchange, in LiNbO3 the replacement of lithium ions with protons, takes place when the substrate is immersed in the molten acid. We observe a surface increase in the refractive index of 0.12, for the extraordinary polarization only, with a step function index profile. This is the highest index increase obtainable to date for LiNbO3. Measured diffusion rates for x‐cut crystals are 1.37 μm2/h at T = 249 °C and 0.37 μm2/h at T = 217 °C, so that very deep guides can be formed in short times. Diffusion is somewhat slower in the z direction. The process as described is not useful for y‐cut crystals, since it damgaes this surface. Losses, measured on x‐cut samples, were <0.5 dB/cm. All measurements were made at 0.633 μm.
693 citations
TL;DR: The WKB approximation is used to derive simple equations that predict the shape of the index profile from measured mode indices of a planar optical waveguide and results are compared with mathematical solutions for exponential, Fermi, and step distributions.
Abstract: The WKB approximation is used to derive simple equations that predict the shape of the index profile from measured mode indices of a planar optical waveguide. This nondestructive test is a useful tool in the study of diffused guides. The index profile is assumed either to decrease monotonically from the surface or to be symmetrical in the case of a buried guide. The approximation uses straight line segments to connect the measured points. Results are compared with mathematical solutions for exponential, Fermi, and step distributions and with other independent experimental observations of the profile in a nickel-diffused LiNbO(3) guide.
566 citations
TL;DR: In this paper, the results of structural analysis of proton exchanged lithium niobate optical waveguides fabricated in Z, X, and Y cut substrates immersed in pure benzoic acid Rutherford backscattering spectrometry, nuclear reactions, secondary ion mass spectrometer, scanning electron microscopy, and x-ray diffraction were used to measure atomic composition profiles.
Abstract: This paper reports the results of structural analysis of proton‐exchanged lithium niobate optical waveguides fabricated in Z‐, X‐, and Y‐cut substrates immersed in pure benzoic acid Rutherford backscattering spectrometry, nuclear reactions, secondary ion mass spectrometry, scanning electron microscopy, and x‐ray diffraction were used to measure atomic composition profiles and the marked lattice distortion induced by the proton exchange process in the waveguiding layer H and Li concentration measurements indicate an exchange of about 70% of the Li atoms are present in the virgin LiNbO3 crystal
94 citations
TL;DR: It is shown that by use of the presented method, the elastic stiffness constants and propagation properties of any nonpiezoelectric isotropic, cubic, or even trigonal layer can be determined.
Abstract: A method is demonstrated for determination of elastic constants of anisotropic layers on arbitrarily anisotropic and piezoelectric substrates only using the easily measured velocity of surface acoustic waves. By means of a detailed theoretical analysis it is shown that by use of the presented method, the elastic stiffness constants and propagation properties of any nonpiezoelectric isotropic, cubic, or even trigonal layer can be determined. The method is applied to proton-exchanged lithium niobate (PE:LiNbO/sub 3/). Complete measurements of dispersion characteristics of Rayleigh waves on Y-cut PE:LiNbO/sub 3/ and calculated values of all elastic stiffness constants of the proton-exchanged film are reported. >
18 citations