IEEE Photonics Journal All-Optical Microwave Photonic Downconverter
All-Optical Microwave Photonic
Downconverter With Tunable
Phase Shift
Yunxin Wang,
1,2
Jingnan Li ,
1,2
Tao Zhou,
3
Dayong Wang,
1,2
Jiahao Xu,
1,2
Xin Zhong,
3
Dengcai Yang,
1,2
and Lu Rong
1,2
1
College of Applied Sciences, Beijing University of Technology, Beijing 100124, China
2
Beijing Engineering Research Center of Precision Measurement Technology and
Instruments, Beijing University of Technology, Beijing 100124, China
3
Science and Technology on Electronic Information Control Laboratory,
Chengdu 610036, China
DOI:10.1109/JPHOT.2017.2763942
1943-0655
C
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Manuscript received June 19, 2017; revised October 11, 2017; accepted October 12, 2017. Date
of publication October 20, 2017; date of current version November 13, 2017. This work was sup-
ported in part by the National Natural Science Foundation of China under Grant 61372061, Grant
61771438, and Grant 51477028 and in part by the Importation and Development of High-Caliber
Talents Project of Beijing Municipal Institutions under Grant CIT&TCD201504020. Corresponding
authors: Tao Zhou and Dayong Wang (e-mail: zhj_zht@163.com; wdyong@bjut.edu.cn).
Abstract: An all-optical microwave photonic frequency downconverter with tunable full
range continuous phase shift is presented. In the proposed system, the radio frequency
(RF) and local oscillator (LO) signals modulate two sub Mach–Zehnder modulators (MZMs)
in an integrated dual-parallel MZM (DPMZM), respectively. The two sub-MZMs are both
biased at the minimum transmission point to implement the carrier-suppressed double-
sideband modulation. An optical bandpass filter is then used to retain the +1st order RF
and LO sidebands. When the two sidebands are send to a photodetector, an intermediate
frequency (IF) signal is produced, and the phase of the converted IF signal is linearly
changed by adjusting the bias voltage of the parent MZM in the DPMZM. An experiment
is carried out. An RF signal can be downconverted to a phase-tunable IF signal, and the
measured spurious-free dynamic range reaches 100.2 dB·Hz
2/3
. The phase deviation and
power ripple of the IF signal are less than 2° and 0.26 dB, respectively. The all-optical design
makes the system bandwidth unlimited by electrical components. Meanwhile, since the
proposed microwave photonic link can simultaneously implement frequency downconversion
and full range phase shift of the converted IF signal, it provides a compact alternative for
the applications including radio-over-fiber system and phased-array beamforming.
Index Terms: Fiber optics links and subsystems, radio frequency photonics, analog optical
signal processing.
1. Introduction
Microwave photonics (MWP), as a new interdisciplinary subject, combines microwave and fiber
optics to create a new communication system [1]. Owing to the advantages of wide bandwidth,
low loss, and immunity to electromagnetic interference (EMI) in comparison to the conventional
electrical devices, microwave photonic links based frequency downconverter, phase shifter and
filter have become more and more appealing and been applied i n radio-over-fiber (RoF) system,
phased-array beamforming and high-speed signal processing, etc [1]–[5].
Vol. 9, No. 6, December 2017 5503408
