Open AccessMicrowave photonic frequency up-converter with LO doubling based on carrier suppression single-sideband modulation
Author(s) -
Jiahao Xu,
Yunxin Wang,
Dayong Wang,
Tao Zhou,
Feng Yang,
Xin Zhong,
Hongbiao Zhang,
DerChing Yang
Publication year - 2019
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.68.20190266
Subject(s) - sideband , compatible sideband transmission , optical carrier transmission rates , signal (programming language) , physics , modulation (music) , radio transmitter design , frequency multiplier , frequency modulation , local oscillator , amplitude modulation , intermediate frequency , radio frequency , optics , microwave , optoelectronics , telecommunications , transmitter , radio over fiber , optical fiber , phase noise , computer science , acoustics , quantum mechanics , programming language , channel (broadcasting) , cmos
Frequency up-converter as an essential component of the transmitter, which is used to implement the frequency up-conversion by mixing a low-frequency intermediate frequency (IF) signal with a local oscillator (LO) signal. However, only the 1st-order sideband of the LO signal and the IF signal are used in the tradtioanal microwave photonic up-converser, thus the frequency of the up-conversion signal is ω LO + ω IF . In this case, an LO with a higher frequency is needed for generating a high-frequency up-converted signal. In order to reduce the frequency requirement of the LO signal, the high-order LO singals or secondary modulation can be used to achieve high-frequency up-conversion. A microwave photonic up-converter with LO doubling based on carrier suppressing single-sideband modulation is proposed based on the cascaded structure of a Mach-Zehnder modulator (MZM) and a dual-parallel Mach-Zehnder modulator (DPMZM). The MZM is driven by an LO signal biased at the minimum transmission point for carrier suppressing double-sideband (CS-DSB) modulation. A fiber Bragg grating (FBG) is used to separate the +1st-order from 1st-order of the LO signal. The 1st-order of LO signal is then sent to a DPMZM for the secondary modulation, and the carrier suppressing single-sideband (CS-SSB) modulation is realized in order to generate the 1st-order of the IF signal by using an electrical 90° hybrid coupler. The modulated IF signal is then combined with the +1st-order LO signal reflected by the FBG and sent into the photodetector (PD) to implement the photoelectric detection. The upconverted signal with a frequency of 2 ω LO + ω IF can be detected by a PD. The experimental results show that the spur suppression ratio of the optical spectrum and the up-converter signal reach 22.5 dB and 23.6 dB, respectively. The spurious-free dynamic range of the system is 96.1 dB·Hz 2/3 . The proposed system can effectively reduce the frequency requirement of LO signal, and the purity of the electrical spectrum is largely improved which benefits from the CS-SSB modulation. The proposed microwave photonic up-converter provides an effective way for high-frequency emissions in systems such as radio-over-fiber and optically controlled phased array radar.