Littrow gratings as alignment structures for the wafer level testing of optical and optoelectronic chips
First Claim
1. An apparatus comprising:
- an integrated substrate,an optical probe with an optical port above the substrate,a Littrow grating disposed on the integrated substrate, anda plurality of optical structures disposed on the substrate,where a light beam is directed down from the optical port of the optical probe to the Littrow grating,the light beam is retro-reflected up by the Littrow grating to the optical port of the optical probe, andthere is a plurality of positional relationships comprised of a positional relationship between the Littrow grating and each of the plurality of optical structures.
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Abstract
This application describes, among others, wafer designs, testing systems and techniques for wafer-level optical and optoelectronic testing by coupling probe light to/from the top of the wafer. In the described exemplary implementations, wafers are designed with one or more optical alignment features or structures. The alignment structures are alongside the devices to be tested, but are easier to find or locate by optical means, than the devices to be tested. An optical diffraction grating structure such as a Littrow grating may be used as reflective alignment structures. (FIG. 6B and paragraph 56.) A Littrow grating as an alignment structure produces a retro-reflection. A Littrow grating is a one-port optical device, with input and output beams going along the same path. Various exemplary implementations are shown in FIGS. 3C, 5, 6A, 6B, 7A and 7B and described in paragraphs 18–21, 39–40 and 53–64.
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Citations
22 Claims
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1. An apparatus comprising:
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an integrated substrate, an optical probe with an optical port above the substrate, a Littrow grating disposed on the integrated substrate, and a plurality of optical structures disposed on the substrate, where a light beam is directed down from the optical port of the optical probe to the Littrow grating, the light beam is retro-reflected up by the Littrow grating to the optical port of the optical probe, and there is a plurality of positional relationships comprised of a positional relationship between the Littrow grating and each of the plurality of optical structures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification