Asymmetric directional coupler having a reduced drive voltage
US7522784B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 9, 2007 |
| Grant date | Apr 21, 2009 |
| Priority date | — |
| Expiry date | Feb 9, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F2203/48
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention relates to an electro-optic directional coupler suitable for use as a variable optical attenuator at reduced voltages compared to those known in the prior art. The present invention has found that by careful selection of an asymmetric directional coupler geometry, the transfer function of the device can be shifted so that it has an operating point between maximum and minimum transmission. Signal electrodes driven in push pull configuration advantageously use this operating point to achieve significant reduction in operating voltages for switching to maximum or minimum transmission. Asymmetry is created in the directional coupler by forming the waveguides to have different propagation constants by a difference in waveguide width, depth, index of refraction or index profile. Asymmetry can alternatively be created by causing mechanical stress in the waveguides through the placement, number, or dimensions of the electrodes, or through asymmetric dielectric structures between the waveguides and the electrodes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.