Prism-coupling systems and methods for characterizing ion-exchanged waveguides with large depth-of-layer
First Claim
1. A method of characterizing a double ion-exchanged (DIOX) waveguide formed in a substrate, comprising:
- performing a first ion-exchange in the glass substrate to form the waveguide, the waveguide having a deep ion-exchange region with a first profile and a depth-of-layer (DOL);
capturing a first mode spectrum of the waveguide and determining the DOL from the first mode spectrum;
performing a second ion-exchange in the glass substrate to alter the first profile and to define a shallow ion-exchange region with a steep profile;
capturing a second mode spectrum of the waveguide by partially blocking a portion of the mode spectrum associated with the deep ion-exchange region to improve the contrast of a portion of the mode spectrum associated with the shallow ion-exchange region; and
determining from the improved-contrast second mode spectrum at least one of a compressive stress, a tensile strength, and a surface stress of the waveguide for the shallow ion-exchange region.
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Abstract
Prism-coupling systems and methods for characterizing large depth-of-layer waveguides formed in glass substrates are disclosed. One method includes making a first measurement after a first ion-exchange process that forms a deep region and then performing a second measurement after a second ion-exchange process that forms a shallow region. Light-blocking features are arranged relative to the prism to produce a mode spectrum where the contrast of the mode lines for the strongly coupled low-order modes is improved at the expense of loss of resolution for measuring characteristics of the shallow region. Standard techniques for determining the compressive stress, the depth of layer or the tensile strength of the shallow region are then employed. A second measurement can be made using a near-IR wavelength to measure characteristics of the deeper, first ion-exchange process. Systems and methods of measuring ion-exchanged samples using shape control are also disclosed.
30 Citations
20 Claims
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1. A method of characterizing a double ion-exchanged (DIOX) waveguide formed in a substrate, comprising:
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performing a first ion-exchange in the glass substrate to form the waveguide, the waveguide having a deep ion-exchange region with a first profile and a depth-of-layer (DOL); capturing a first mode spectrum of the waveguide and determining the DOL from the first mode spectrum; performing a second ion-exchange in the glass substrate to alter the first profile and to define a shallow ion-exchange region with a steep profile; capturing a second mode spectrum of the waveguide by partially blocking a portion of the mode spectrum associated with the deep ion-exchange region to improve the contrast of a portion of the mode spectrum associated with the shallow ion-exchange region; and determining from the improved-contrast second mode spectrum at least one of a compressive stress, a tensile strength, and a surface stress of the waveguide for the shallow ion-exchange region. - View Dependent Claims (2, 3, 4)
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5. A method of characterizing a double ion-exchanged (DIOX) waveguide formed in a substrate, comprising:
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performing a first ion-exchange in the glass substrate to define deep ion-exchange region with a shallow profile and a depth-of-layer (DOL) greater than 100 μ
m;capturing with a prism-coupling system operating at an IR wavelength a first mode spectrum of the waveguide and determining the DOL from the first mode spectrum; performing a second ion-exchange in the glass substrate to define a shallow ion-exchange region with a steep profile; capturing a second mode spectrum of the waveguide by partially blocking a portion of the mode spectrum associated with the deep ion-exchange region to improve the contrast of a portion of the mode spectrum associated with the shallow ion-exchange region while reducing the contrast of the portion of the mode spectrum associated with the deep ion-exchange region; and determining from a low-order-mode portion of the improved-contrast second mode spectrum at least one of a compressive stress, a tensile strength and a surface stress of the waveguide for the shallow ion-exchange region. - View Dependent Claims (6, 7, 8, 9)
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10. A measurement system for measuring at least one characteristic of a double ion-exchange (DIOX) waveguide formed in a substrate to include a deep region and a shallow region, wherein the waveguide includes lower-order and higher-order modes that define a mode spectrum, the system comprising:
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a coupling prism having an input surface, an output surface and a coupling surface, and wherein the coupling surface interfaces with the waveguide at a substrate upper surface, thereby defining a substrate-prism interface; a light source system that emits light that illuminates the substrate-prism interface through the input surface of the prism, thereby forming reflected light that includes mode lines of the mode spectrum, wherein the reflected light exits the output surface of the coupling prism; at least one light-blocking feature arranged relative to the coupling prism and configured to limit the amount of light from the light source that couples into higher-order modes of the waveguide; a photodetector system having a detector and arranged to receive the reflected light from the coupling prism and detect a mode spectrum on the detector, wherein the mode spectrum has a higher resolution for the lower-order modes as compared to if the at least one light-blocking feature was absent; and a controller configured to process the detected a mode spectrum to determine the at least one characteristic of the waveguide, wherein the at least one characteristic includes a surface stress, a compressive stress and a tensile strength of the shallow region. - View Dependent Claims (11, 12, 13)
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14. A measurement system for measuring at least one characteristic of a double ion-exchange (DIOX) waveguide formed in a substrate to include a deep region and a shallow region, wherein the waveguide includes lower-order and higher-order modes that define a mode spectrum, the system comprising:
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a coupling prism having an input surface, an output surface and a coupling surface, and wherein the coupling surface interfaces with the waveguide at a substrate upper surface, thereby defining a substrate-prism interface; a chuck assembly that operably supports the substrate and defines a shape for the substrate; a light source system that emits light that illuminates the substrate-prism interface through the input surface of the prism, thereby forming reflected light that includes mode lines of the mode spectrum, wherein the reflected light exits the output surface of the coupling prism; a photodetector system having a detector and arranged to receive the reflected light from the coupling prism and detect the a mode spectrum on the detector; and a controller configured to process the detected a mode spectrum to determine the at least one characteristic of the waveguide, wherein the at least one characteristic includes a surface stress, a compressive stress and a tensile strength. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A method of performing prism coupling of a substrate having a waveguide having an upper surface and a coupling surface of a prism, comprising:
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providing a vacuum via through channels that are open at the coupling surface; and bring the waveguide upper surface into contact with the prism coupling surface such that the vacuum causes the waveguide upper surface to be pressed against and substantially conform to the coupling surface of the prism.
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Specification