Method for characterization of optical waveguide devices using partial coherence interferometry
US5341205A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 15, 1991 |
| Grant date | Aug 23, 1994 |
| Priority date | — |
| Expiry date | Jan 15, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/0675
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical system and method include a short coherence length edge, emitt LED, a fiber optic coupler probe, and a Michelson interferometer to measure the parameter of thickness of optical devices, such as thin silicon substrate samples and to characterize other parameters of optical waveguide devices such as absolute attenuation, effective refractive index, and changes in these parameters with the application of a modulation voltage or an external disturbance. The measurable thickness range from a few to hundreds of microns with a thickness precision exceeding 0.1 micron for a 10 micron sample. In situ localized measurements of samples in an etching chamber are obtainable to control processing and provide for thickness uniformity. Attenuation measurements for optical waveguides compare the values of interferogram maxima at the values of the reference arm path length to changes corresponding to one and two times the optical path length of the sample. Effective refractive index is determined by counting the number of fringes in the recorded interferogram between successive maxima. Changes in these parameters due to an external disturbance are measured by comparing the interferograms …
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