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Microwave and millimeter-wave measurements using photonics

Authors:
Xihua Zou at Southwest Jiaotong University, China / University of Duisbure-Essen, Germany
Xihua Zou
  • Southwest Jiaotong University, China / University of Duisbure-Essen, Germany
Jianping Yao at University of Ottawa
Jianping Yao
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10.1117/2.1201505.005976
Microwave and millimeter-wave
measurements using photonics
Xihua Zou and Jianping Yao
Photonic approaches enable measurements with wide frequency cover-
age and large instantaneous bandwidth.
Measuring micro- and millimeter waves with large instanta-
neous bandwidth and wide frequency coverage (e.g., from
several MHz to a hundred GHz or wider) is necessary for ap-
plications including medicine, wireless communications, radar,
and electronic warfare. (Electronic warfare includes control-
ling the electromagnetic spectrum by communications jamming,
measures to protect against guided missiles, or interception of
enemy signals.) However, the so-called electronic bottleneck—
the inability of electronic circuits to process data at sufficiently
high speeds—hinders purely electronic measurements to meet
these stringent requirements.
Fortunately, photonics offer an intrinsic large instantaneous
bandwidth that enables nearly real-time operation over a large
frequency range for wideband microwave and millimeter-wave
measurements.1In addition, photonic methods also have ad-
vantages such as immunity to electromagnetic interference, low
loss, and compact size. Consequently, we have proposed several
photonic approaches for microwave and millimeter-wave mea-
surements of frequency, angle-of-arrival (AOA), and Doppler
frequency shift (DFS).2–4
For instantaneous frequency measurement, we have proposed
a photonic approach using a complementary optical filter pair.2
As shown in Figure 1, a microwave/millimeter-wave signal is
applied to an electro-optic modulator (EOM, a key device for
transferring electrical signals to optical waves). The EOM is
biased at the minimum transmission point to suppress the opti-
cal carrier, and the carrier-suppressed optical signal is then sent
to the complementary optical filter pair with two complemen-
tary transmission responses. The microwave frequency is sub-
sequently measured by monitoring the filtered optical powers
with two optical power meters. Measurement errors are less than
˙0:2GHz across the entire measurement range from 1 to 26GHz.
For AOA measurement, we have proposed a photonic ap-
proach using two EOMs, both of which are biased at the
Figure 1. Photonic approach to instantaneous frequency measurement.
A, B: Filters. LD: Laser diode. EOM: Electro-optic modulator.
Figure 2. Photonic approach to angle-of-arrival (AOA) measurement.
: Phase shift induced by the AOA.
minimum transmission point to suppress the optical carrier.3As
shown in Figure 2, two optical components at the carrier wave-
length are generated at the output of the second EOM. Their total
power is a function of the phase shift induced by the AOA. We
simply measure the optical power to obtain the phase shift and
hence calculate the AOA (i.e., ). In the experiment, the phase
shift of 160◦to 40◦was measured for a microwave signal at
18GHz with measurement errors less than ˙2:5◦.
For DFS measurement, we developed a photonic approach
able to provide fine resolution and wide frequency coverage.4
As shown in Figure 3, the DFS (i.e., fD) between the transmit-
ted signal and the received echo signal is mapped into a doubled
Continued on next page
10.1117/2.1201505.005976 Page 2/3
spacing between two generated optical sidebands. Subsequently,
fDis extracted by analyzing the spectrum of a low-frequency
electrical signal generated from the frequency beating between
the two optical sidebands. The measurement errors in fDare less
than ˙51010Hz between 9and 9kHz for a millimeter sig-
nal at 30GHz. Correspondingly, the estimated fDcorresponds
to a measured radial velocity of 0–450m/s with a resolution
of 51012m/s. This photonic approach is totally indepen-
dent of the carrier frequency, allowing a wide-frequency-range
operation from the L to W bands (i.e., 1–110GHz, according to
Figure 3. (a) Schematic diagram and (b) experimental setup for mea-
suring fD, the Doppler frequency shift (DFS). EDFA: Erbium-doped
fiber amplifier. ESA: Electrical spectrum analyzer. GPIB: General-
purpose interface bus. HER-Pol: High-extinction-ratio polarizer.
MSG: Microwave signal generator. PC: Polarization controller.
PD: Photodetector. PM: Phase modulator. PolM: Polarization modu-
lator.)
the IEEE standard). This frequency range covers most applica-
tions, including wireless Internet, radio-frequency identification,
cell phones, the global positioning system, satellite television
and communications, military/civil radar, and radio astronomy.
In summary, we have proposed and demonstrated pho-
tonic approaches to measurements of frequency, AOA, and
DFS for micro- and millimeter waves. These approaches can
find versatile applications in civil and defense systems using
high-frequency radiation, wide frequency coverage, and large
instantaneous bandwidth, such as 5G wireless communications,
radar, and electronic warfare. In future work, we will develop
photonic integrated chips and multiple-dimension detection
for micro- and millimeter-wave measurements, in terms of high
stability and diverse functionality.
This work was supported in part by the National High Technology
Research and Development Program of China (SS2015AA012303),
the National Basic Research Program of China (2012CB315704), the
Program for New Century Excellent Talents in University of China
(NCET-12-0940), and the Sichuan Youth Science and Technology
Foundation of China (2015JQ0032). X. Zou was also supported by a
fellowship from the Alexander von Humboldt Foundation, Germany.
Author Information
Xihua Zou
Southwest Jiaotong University
Chengdu, China
and
University of Duisburg-Essen
Duisburg, Germany
Xihua Zou is a professor at Southwest Jiaotong University,
China, and a Humboldt Research Fellow at the University of
Duisburg-Essen, Germany. His research interests include mi-
crowave photonic and fiber-wireless converged communica-
tions.
Jianping Yao
School of Electrical Engineering and Computer Science
University of Ottawa
Ottawa, Canada
Jianping Yao is a professor and holds the University Research
Chair in Microwave Photonics. His research interests include mi-
crowave photonics and silicon photonics.
Continued on next page
10.1117/2.1201505.005976 Page 3/3
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2015 SPIE
... The low-loss and large available time-bandwidth product capability of fiber optic systems makes them attractive, not only for transmission of signals, but also for processing of high-speed signals [1][2][3][4][5][6]. The inter-disciplinary field of microwave photonics, which combines microwave engineering and optoelectronics, has rapidly expanded due to the microwave photonics offers, including immunity to electromagnetic interference, the ability to realize true-time delay lines [7,8], the ability to tune the filter center frequency over a wide range with shape invariance [9], the ability to control both phase and amplitude independently [10], and a fully programmable capability [11,12]. ...
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