Sub-nanosecond-speed frequency-reconfigurable
photonic radio frequency switch using a silicon
modulator
YIWEI XIE,
1
LEIMENG ZHUANG,
4
PENGCHENG JIAO,
2,3,
* AND DAOXIN DAI
1
1
Centre for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang Provincial Key Laboratory
for Sensing Technologies, Zhejiang University, Hangzhou 310058, China
2
Institute of Port, Coastal and Offshore Engineering, Ocean College, Zhejiang University, Zhoushan 316021, China
3
Engineering Research Center of Oceanic Sensing Technology and Equipment, Ministry of Education, Zhejiang University, Hangzhou 310000, China
4
e-mail: leimeng.zhuang@ieee.org
*Corresponding author: pjiao@zju.edu.cn
Received 8 January 2020; revised 9 March 2020; accepted 22 March 2020; posted 24 March 2020 (Doc. ID 387480); published 7 May 2020
Radio frequency (RF) switches are essential for implementing routing of RF signals. However, the increasing demand
for RF signal frequency and bandwidth is posing a challenge of switching speed to the conventional solutions, i.e., the
capability of operating at a sub-nanosecond speed or faster. In addition, signal frequency reconfigurability is also a
desirable feature to facilitate new innovations of flexible system functions. Utilizing microwave photonics as an alter-
native path, we present here a photonic implementation of an RF switch providing not only the capability of switching
at a sub-nanosecond speed but also options of frequency doubling of the input RF signals, allowing for flexible output
waveforms.Thecoredeviceisatraveling-wavesiliconmodulatorwithadevicesizeof0.2mm× 1.8mmand a modu-
lation bandwidth of 10 GHz. Using microwave frequencies, i.e., 15 GHz and 20 GHz, as two simultaneous RF input
signals, we experimentally demonstrated their amplitude and frequency switching as well as that of the doubled
frequencies, i.e., 30 GHz and 40 GHz, at a switching frequency of 5 GHz. The results of this work point to a solution
for creating high-speed RF switches with high compactness and flexibility.
© 2020 Chinese Laser Press
https://doi.org/10.1364/PRJ.387480
1. INTRODUCTION
Radio frequency (RF) switches are essential for implementing
routing of RF signals and are widely applied in modern com-
munication and radar systems [1–3]. The conventional solu-
tions with practical compact forms are generally based on
micro-electromechanics or employing solid-state PIN-diode
or active-device switches [4–6]. Although allowing for various
designs, these solutions are faced with an important challenge
raised by the ever-increasing demand for RF signal frequency
and bandwidth, i.e., sub-nanosecond or faster switching speeds.
The difficulty of implementation stems from the limitations of
material properties or the lack of tunability of the electrical cir-
cuits [6]. Alternatively, microwave photonics provides a prom-
ising path to overcome the bottleneck, where the inherent
advantages of photonics such as wide bandwidth, easy tuning
mechanism, a diversity of light wave interaction properties for
signal carrying and processing, and low electromagnetic inter-
ference can be utilized for RF engineering to enable new break-
throughs in performance and features [7–10]. Regarding
photonic implementations of RF switches, several previous pro-
posals using discrete components have demonstrated the func-
tions of amplitude and frequency switching at speeds down to
tens of picoseconds [11,12]. In general, these methods use
electro-optical phase modulators incorporated in an optical
fiber-based interferometer, which features flexible system com-
position and allows for the use of various tuning mechanisms,
e.g., in the frequency domain or polarization domain. These
works manifest the value and potential of microwave photonics.
From a practical point of view, commercial adoption of pho-
tonic RF solutions also requires the motivations of easy imple-
mentation, high robustness, low power consumption, as well as
fabrication cost. In addition, functional reconfigurability is also
a desirable feature to facilitate new innovations of flexible sys-
tems. In this context, silicon photonics is a promising technol-
ogy platform. The recent development has demonstrated
remarkable capabilities such as compact passive devices with
bend radii in the order of a few micrometers (μm) [13–16],
high-efficiency modulators and photodiodes with bandwidth
of tens of gigahertz (GHz) [17,18], and potential for hybrid
electronics-photonics integration [19,20].
Here we propose and verify a photonic implementation of
an RF switch. It is not only able to perform switching at a sub-
nanosecond speed but can also provide options of frequency
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Vol. 8, No. 6 / June 2020 / Photonics Research
Research Article
2327-9125/20/060852-06 Journal © 2020 Chinese Laser Press