Citation: Sun, Y.; Wu, H.; Yu, L.; Sun,
H.; Zhang, P.; Zhang, X.; Dai, B.;
Wang, Y. Utilizing the Transverse
Thermoelectric Effect of Thin Films
for Pulse Laser Detection. Sensors
2022, 22, 4867. https://doi.org/
10.3390/s22134867
Academic Editor: Chelakara S.
Subramanian
Received: 6 May 2022
Accepted: 24 June 2022
Published: 28 June 2022
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Communication
Utilizing the Transverse Thermoelectric Effect of Thin Films for
Pulse Laser Detection
Yanju Sun
1
, Haorong Wu
2
, Lan Yu
2
, Hui Sun
1
, Peng Zhang
1
, Xiaowei Zhang
3
, Bo Dai
3
and Yong Wang
1,
*
1
School of Space Science and Physics, Shandong University, Weihai 264209, China;
201900830051@mail.sdu.edu.cn (Y.S.); huisun@sdu.edu.cn (H.S.); zhangpeng@sdu.edu.cn (P.Z.)
2
Faculty of Materials Science and Engineering, Kunming University of Science and Technology,
Kunming 650093, China; wuhaorong@stu.kust.edu.cn (H.W.); 11302084@kust.edu.cn (L.Y.)
3
State Key Laboratory for Environmental-Friendly Energy Materials, Southwest University of Science and
Technology, Mianyang 621010, China; xiaoweizhang@swust.edu.cn (X.Z.); daibo@swust.edu.cn (B.D.)
* Correspondence: wang.yong06@sdu.edu.cn
Abstract:
In this work, pulse laser detectors based on the transverse thermoelectric effect of YBa
2
Cu
3
O
7-δ
thin films on vicinal cut LaAlO
3
(001) substrates have been fabricated. The anisotropic Seebeck coeffi-
cients between ab-plane (S
ab
) and c-axis (S
c
) of thin films are utilized to generate the output voltage
signal in such kind of detectors. Fast response has been determined in these sensors, including
both the rise time and the decay time. Under the irradiation of pulse laser with the pulse duration
of 5–7 ns, the output voltage of these detectors shows the rise time and the decay time of 6 and
42 ns, respectively, which are much smaller than those from other materials. The small rise time
in YBa
2
Cu
3
O
7-δ
-based detectors may be due to its low resistivity. While the high thermal conduc-
tivity and the large contribution of electronic thermal conductivity to the thermal conductivity of
YBa
2
Cu
3
O
7-δ
are thought to be responsible for the small decay time. In addition, these detectors
show good response under the irradiation of pulse lasers with a repetition rate of 4 kHz, including
the precise determinations of amplitude and time. These results may pave a simple and convenient
approach to manufacture the pulse laser detectors with a fast response.
Keywords:
transverse thermoelectric effect; anisotropic seebeck coefficients; pulse laser detectors;
thin films; fast response
1. Introduction
Laser-irradiation sensors are of great value in detecting the laser parameters, such as
power/energy, pulse duration, pulse frequency and shape. These measurements may be
required as closed loop control arrangement or simple record-keeping. Nowadays, the
commonly used laser-irradiation sensors are represented by three types according to their
physical principles, such as photodiodes, pyroelectric and thermoelectric sensors [1].
The photodiode-based sensors detect lasers by converting photon energy into electron–
hole pairs in p-n junctions, giving rise to the fast response time of sub-nanoseconds. In
addition, the sensitivity of this type of sensors is much higher, which allows the detectabil-
ity of low power continuous wave (CW) and pulse lasers [
1
–
3
]. However, such a high
sensitivity is usually companied with a relatively low power saturation threshold, which is
not suitable for the detection of high power lasers. In addition, these photodiode-based
sensors suffer from the limited spectral response, which is determined by the band gap
of the semiconductors. For instance, sensors based on silicon possess a spectral response
range between 0.2 and 2 µm [4].
Pyroelectric sensors transduce a temperature change into an electric signal via the
spontaneous polarization. Benefiting from their thermal nature, pyroelectric sensors have
the broad spectral response (i.e., from UV to THz). High sensitivity for pulse lasers can
also be achieved in such pyroelectric sensors. Unfortunately, due to the transient response
Sensors 2022, 22, 4867. https://doi.org/10.3390/s22134867 https://www.mdpi.com/journal/sensors
