Accurate Power-Efficient Format-Scalable Multi-Parallel Optical Digital-to-Analogue Conversion
In optical transmitters generating multi-level constellations, optical modulators are preceded by Electronic Digital-to-Analog-Converters (eDAC). It is advantageous to use eDAC-free Optical Analog to Digital Converters (oDAC) to directly convert digital bitstreams into multilevel PAM/QAM optical sig...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-02-01
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| Series: | Photonics |
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| Online Access: | https://www.mdpi.com/2304-6732/8/2/38 |
| _version_ | 1797415184405364736 |
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| author | Moshe Nazarathy Ioannis Tomkos |
| author_facet | Moshe Nazarathy Ioannis Tomkos |
| author_sort | Moshe Nazarathy |
| collection | DOAJ |
| description | In optical transmitters generating multi-level constellations, optical modulators are preceded by Electronic Digital-to-Analog-Converters (eDAC). It is advantageous to use eDAC-free Optical Analog to Digital Converters (oDAC) to directly convert digital bitstreams into multilevel PAM/QAM optical signals. State-of-the-art oDACs are based on Segmented Mach-Zehnder-Modulators (SEMZM) using multiple modulation segments strung along the MZM waveguides to serially accumulate binary-modulated optical phases. Here we aim to assess performance limits of the Serial oDACs (SEMZM) and introduce an alternative improved Multi-Parallel oDAC (MPoDAC) architecture, in particular based on arraying multiple binary-driven MZMs in parallel: Multi-parallel MZM (MPMZM) oDAC. We develop generic methodologies of oDAC specification and optimization encompassing both SEMZM and MPMZM options in Direct-Detection (DD) and Coherent-Detection (COH) implementations. We quantify and compare intrinsic performance limits of the various serial/parallel DD/COH subclasses for general constellation orders, comparing with the scant prior-work on the multi-parallel option. A key finding: COH-MPMZM is the only class synthesizing ‘perfect’ (equi-spaced max-full-scale) constellations while maximizing energy-efficiency-SEMZM/MPMZM for DD are less accurate when maximal energy-efficiency is required. In particular, we introduce multiple variants of PAM4|8 DD and QAM16|64 COH MPMZMs, working out their accuracy vs. energy-efficiency-and-complexity tradeoffs, establishing their format-reconfigurability (format-flexible switching of constellation order and/or DD/COH). |
| first_indexed | 2024-03-09T05:45:07Z |
| format | Article |
| id | doaj.art-7247f015e0444e03a59d8130da692c09 |
| institution | Directory Open Access Journal |
| issn | 2304-6732 |
| language | English |
| last_indexed | 2024-03-09T05:45:07Z |
| publishDate | 2021-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Photonics |
| spelling | doaj.art-7247f015e0444e03a59d8130da692c092023-12-03T12:22:10ZengMDPI AGPhotonics2304-67322021-02-01823810.3390/photonics8020038Accurate Power-Efficient Format-Scalable Multi-Parallel Optical Digital-to-Analogue ConversionMoshe Nazarathy0Ioannis Tomkos1Faculty of Electrical Engineering, Technion, Israel Institute of Technology, Haifa 32000, IsraelElectrical & Computer Engineering Department, University of Patras, 265 04 Patras, GreeceIn optical transmitters generating multi-level constellations, optical modulators are preceded by Electronic Digital-to-Analog-Converters (eDAC). It is advantageous to use eDAC-free Optical Analog to Digital Converters (oDAC) to directly convert digital bitstreams into multilevel PAM/QAM optical signals. State-of-the-art oDACs are based on Segmented Mach-Zehnder-Modulators (SEMZM) using multiple modulation segments strung along the MZM waveguides to serially accumulate binary-modulated optical phases. Here we aim to assess performance limits of the Serial oDACs (SEMZM) and introduce an alternative improved Multi-Parallel oDAC (MPoDAC) architecture, in particular based on arraying multiple binary-driven MZMs in parallel: Multi-parallel MZM (MPMZM) oDAC. We develop generic methodologies of oDAC specification and optimization encompassing both SEMZM and MPMZM options in Direct-Detection (DD) and Coherent-Detection (COH) implementations. We quantify and compare intrinsic performance limits of the various serial/parallel DD/COH subclasses for general constellation orders, comparing with the scant prior-work on the multi-parallel option. A key finding: COH-MPMZM is the only class synthesizing ‘perfect’ (equi-spaced max-full-scale) constellations while maximizing energy-efficiency-SEMZM/MPMZM for DD are less accurate when maximal energy-efficiency is required. In particular, we introduce multiple variants of PAM4|8 DD and QAM16|64 COH MPMZMs, working out their accuracy vs. energy-efficiency-and-complexity tradeoffs, establishing their format-reconfigurability (format-flexible switching of constellation order and/or DD/COH).https://www.mdpi.com/2304-6732/8/2/38optical modulationoptical DACSegmented MZMMulti-Parallel MZM |
| spellingShingle | Moshe Nazarathy Ioannis Tomkos Accurate Power-Efficient Format-Scalable Multi-Parallel Optical Digital-to-Analogue Conversion Photonics optical modulation optical DAC Segmented MZM Multi-Parallel MZM |
| title | Accurate Power-Efficient Format-Scalable Multi-Parallel Optical Digital-to-Analogue Conversion |
| title_full | Accurate Power-Efficient Format-Scalable Multi-Parallel Optical Digital-to-Analogue Conversion |
| title_fullStr | Accurate Power-Efficient Format-Scalable Multi-Parallel Optical Digital-to-Analogue Conversion |
| title_full_unstemmed | Accurate Power-Efficient Format-Scalable Multi-Parallel Optical Digital-to-Analogue Conversion |
| title_short | Accurate Power-Efficient Format-Scalable Multi-Parallel Optical Digital-to-Analogue Conversion |
| title_sort | accurate power efficient format scalable multi parallel optical digital to analogue conversion |
| topic | optical modulation optical DAC Segmented MZM Multi-Parallel MZM |
| url | https://www.mdpi.com/2304-6732/8/2/38 |
| work_keys_str_mv | AT moshenazarathy accuratepowerefficientformatscalablemultiparallelopticaldigitaltoanalogueconversion AT ioannistomkos accuratepowerefficientformatscalablemultiparallelopticaldigitaltoanalogueconversion |