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Comments on Zihang Zhu, Shanghong Zhao, Xuan Li, and Kun Qu, Tao Lin, 'Photonic generation of frequency-octupled microwave signal with reduced electrical local oscillator power and improved spectrum purity' Opt. Quant. Electron (2017)
- Source :
- Optical and Quantum Electronics. 51
- Publication Year :
- 2019
- Publisher :
- Springer Science and Business Media LLC, 2019.
-
Abstract
- In the title paper, Zhu et al. presented a technique for generating filter less frequency octo-tupling signal based on a cascade of two dual-polarization modulators. Firstly, the harmonics of order 4 $$l$$ ( $$l$$ in an integer) are generated in the $$x$$ -polarization by driving the x-modulators with an RF signal with a 90° phase difference between the two stages. Then the carrier is suppressed using unmodulated $$y$$ -polarization by means of polarization multiplexing. Accordingly, the demerit of their design is the requirement to reset a precise polarizer angle to suppress the optical carrier every time there is a change in the RF drive amplitude or the modulation index. Nevertheless, the authors claim superior performance to a similar architecture in which the y-branch is modulated with the proper RF drive phases to suppress the carrier for all drive levels with no need to adjust a splitting ratio. The aim of this comment is to show that by modulating the $$y$$ -polarization with adjusted RF drive phases, same architecture can be used to perform frequency octo-tupling whose performance is neither limited by precise settings of the polarizer angle nor by the proper settings of the modulation index. The carrier is suppressed for a unique value of the polarizer angle for all modulation index. If the modulation index is adjusted to suppress the $$4{\text{th}}$$ harmonics, same circuit can be used to perform frequency 24-tupling generation.
- Subjects :
- Physics
business.industry
Local oscillator
Modulation index
02 engineering and technology
Polarizer
021001 nanoscience & nanotechnology
Polarization (waves)
01 natural sciences
Atomic and Molecular Physics, and Optics
Electronic, Optical and Magnetic Materials
law.invention
010309 optics
Optics
Optical Carrier transmission rates
law
Harmonics
0103 physical sciences
Radio frequency
Electrical and Electronic Engineering
Photonics
0210 nano-technology
business
Subjects
Details
- ISSN :
- 1572817X and 03068919
- Volume :
- 51
- Database :
- OpenAIRE
- Journal :
- Optical and Quantum Electronics
- Accession number :
- edsair.doi...........d558a21244ba5ac26010822794763054