DSP-free coherent receiver
US11218224B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 15, 2018 |
| Grant date | Jan 4, 2022 |
| Priority date | — |
| Expiry date | May 15, 2038 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0069
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Disclosed are systems, methods, and structures for DSP-free coherent receiver architectures applicable for short-reach optical links. Operationally, a received optical signal is down-converted by mixing it with a local oscillator (LO) laser signal using a 90-degree hybrid followed by balanced photodiodes. Other receiver functions are performed using analog signal processing thereby avoiding power-hungry, high-speed analog-to-digital converters and high-speed digital signal processing. Carrier phase recovery is performed by an electrical phase-locked loop employing a multiplier-free phase estimator stage that—while designed for quaternary phase-shift keying signals—may be employed in designs exhibiting higher modulation formats. Since carrier phase recovery is performed in the electrical domain, LO laser frequency modulation or LO laser integration is not employed. Polarization demultiplexing—if employed—may be performed by the addition of an optical polarization controller prior to the hybrid and may advantageously be realized by cascading multiple phase shifters driven by low-speed circuitry.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.