Construction of refractive-index profiles of planar dielectric waveguides from the distribution of effective indexes

Chiang, Kin Seng

doi:10.1109/jlt.1985.1074194

Cited by 323 publications

(112 citation statements)

References 8 publications

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“…These include ellipsometry using multiple angle data [1], mode measurements mediated with a prism coupler (for both guided and leaky modes) [2][3][4], reflectance analysis [5,6] and numerous interferometric methods [7][8][9][10][11][12][13]. Each method has advantages and disadvantages.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, some a priori knowledge of the index profile is required. If the sample is known to support only guided modes, then a smooth monotonically decreasing index profile can be deduced without further assumptions [4]. Reflectance measurements are not limited to planar index profiles but require careful sample preparation and are sensitive only to large index differences [5,6].…”

Section: Introductionmentioning

confidence: 99%

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Measurement of planar refractive index profiles with rapid variations in glass using interferometry and total variation regularized differentiation

Oven

2015

Journal of Modern Optics

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Planar refractive index profiles with rapid variations, formed in glass, are measured with interferometry. This involves forming a bevel in the glass and orientating the fringe pattern to be normal to the bevel edge. The index profile is determined by differentiation of the phase function of the fringe pattern. The differentiation has been performed using the total variation regularization method in order to preserve rapid changes in the derivative. This new approach avoids the necessity of filtering, in order to reduce noise, in the direction perpendicular to the bevel, which would otherwise smooth out the rapid index changes. The method is assessed using a model refractive index profile that contains an index gradient of 0.24 μm −1 and is then applied practically to measure the refractive index profile of electrically poled BK7 glass. The new approach allows the sharp transition in the index between poled and unpoled glass to be observed as well as the accumulation of potassium ions beyond the poled glass region.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Measurement of planar refractive index profiles with rapid variations in glass using interferometry and total variation regularized differentiation

Oven

2015

Journal of Modern Optics

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“…Optical characterizations with a prism coupler (Metricon, 2010/M) were employed to quantify the depth of the PE region. 21 Prior to photodeposition, the samples were cleaned using sonication for 20 min each in acetone, isopropanol, and Milli-Q water (18.2 MX/cm), respectively. The silver deposition was carried out in 70 ll of a 0.01 M AgNO 3 solution (Sigma Aldrich) during illumination with a UV pen lamp of 254 nm wavelength and nominal 1400 lW/cm 2 power output (Spectroline) for 5 min at a fixed distance of 2 cm.…”

mentioning

confidence: 99%

Direct shape control of photoreduced nanostructures on proton exchanged ferroelectric templates

Balobaid

Carville

Manzo

et al. 2013

Applied Physics Letters

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Photoreduction on a periodically proton exchanged ferroelectric crystal leads to the formation of periodic metallic nanostructures on the surface. By varying the depth of the proton exchange (PE) from 0.59 to 3.10 μm in congruent lithium niobate crystals, the width of the lateral diffusion region formed by protons diffusing under the mask layer can be controlled. The resulting deposition occurs in the PE region with the shallowest PE depth and preferentially in the lateral diffusion region for greater PE depths. PE depth-control provides a route for the fabrication of complex metallic nanostructures with controlled dimensions on chemically patterned ferroelectric templates.

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“…18,31 The maximum depth of these PE channels into the Mg:LN substrate is 5.87 lm as measured with an optical prism coupling technique. 32 Apart from the periodic PE channels, proton exchange also took place at isolated locations within the alternating LN stripes due to fine openings in the mask that allowed for shallow localized PE islands, which are visible in light microscope images (Figure 1(a)). Chemo-mechanical wedge polishing (angle %14…”

Section: Methodsmentioning

confidence: 99%

Interface and thickness dependent domain switching and stability in Mg doped lithium niobate

Neumayer

Ivanov

Manzo

et al. 2015

Journal of Applied Physics

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Controlling ferroelectric switching in Mg doped lithium niobate (Mg:LN) is of fundamental importance for optical device and domain wall electronics applications that require precise domain patterns. Stable ferroelectric switching has been previously observed in undoped LN layers above proton exchanged (PE) phases that exhibit reduced polarization, whereas PE layers have been found to inhibit lateral domain growth. Here, Mg doping, which is known to significantly alter ferroelectric switching properties including coercive field and switching currents, is shown to inhibit domain nucleation and stability in Mg:LN above buried PE phases that allow for precise ferroelectric patterning via domain growth control. Furthermore, piezoresponse force microscopy (PFM) and switching spectroscopy PFM reveal that the voltage at which polarization switches from the "up" to the "down" state increases with increasing thickness in pure Mg:LN, whereas the voltage required for stable back switching to the original "up" state does not exhibit this thickness dependence. This behavior is consistent with the presence of an internal frozen defect field. The inhibition of domain nucleation above PE interfaces, observed in this study, is a phenomenon that occurs in Mg:LN but not in undoped samples and is mainly ascribed to a remaining frozen polarization in the PE phase that opposes polarization reversal. This reduced frozen depolarization field in the PE phase also influences the depolarization field of the Mg:LN layer above due to the presence of uncompensated polarization charge at the PE-Mg:LN boundary. These alterations in internal electric fields within the sample cause long-range lattice distortions in Mg:LN via electromechanical coupling, which were corroborated with complimentary Raman measurements. V C 2015 AIP Publishing LLC. [http://dx

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Construction of refractive-index profiles of planar dielectric waveguides from the distribution of effective indexes

Cited by 323 publications

References 8 publications

Measurement of planar refractive index profiles with rapid variations in glass using interferometry and total variation regularized differentiation

Measurement of planar refractive index profiles with rapid variations in glass using interferometry and total variation regularized differentiation

Direct shape control of photoreduced nanostructures on proton exchanged ferroelectric templates

Interface and thickness dependent domain switching and stability in Mg doped lithium niobate

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