Optical code generation and detection
US6628864B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 8, 2001 |
| Grant date | Sep 30, 2003 |
| Priority date | — |
| Expiry date | Mar 8, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F1/3519
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Optical code division multiple access (OCDMA) coder:decoder gratings have been fabricated. The modulated refractive index profile that makes up the OCDMA coder:decoder grating incorporates changes in polarity between OCDMA chips by discrete phase shifts, thereby to provide bipolar coding through phase modulation. (In another embodiment quadrupolar coding is achieved). For NRZ modulation, each grating section is either in phase with, or has a predetermined phase shift relative to, the preceding grating section, depending on whether the OCDMA signature has a change in polarity between chips. RZ modulation is also possible. Results are presented from specific examples of bipolar OCDMA with NRZ modulation, which show higher data rates (10 Gbit/s), shorter chip-lengths (6.4 ps) and far longer code sequences (63 bits) than previously demonstrated. Other embodiments relate to optical packet switching, for example using the Internet Protocol (IP) or Asynchronous Transfer Mode (ATM).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.