Article comprising an epitaxial multilayer mirror
US5244749A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 3, 1992 |
| Grant date | Sep 14, 1993 |
| Priority date | — |
| Expiry date | Aug 3, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/12674
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
We have found a way to, e.g., substantially increase the number of layers in a pseudomorphic strained layer semiconductor mirror over the number obtainable in an analogous conventional mirror, making it possible to obtain pseudomorphic strained layer mirrors of increased reflectance. Such a pseudomorphic mirror consists of alternating layers of a first and a second semiconductor material (e.g., Ge.sub.x Si.sub.1-x /Si), of thickness t.sub.1 and t.sub.2, and refractive index n.sub.1 and n.sub.2, respectively, with the number of layer pairs chosen such that the mirror thickness is less than or equal to the "critical thickness" L.sub.c. For thicknesses >L.sub.c the mirror will contain dislocations. An article according to the invention comprises a mirror whose layer thicknesses are chosen such that n.sub.1 t.sub.1 .noteq.n.sub.2 t.sub.2, with n.sub.1 t.sub.1 +n.sub.2 t.sub.2 =p.lambda./2, (p being an odd integer, typically 1). In other words, the optical thickness of the layers is not the conventional p.lambda./4. The thicknesses are also chosen such that the average lattice mismatch between substrate and mirror is reduced, compared to the analogous conventional (.lambda./4) mirror. M…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.