Microwave and Optical Technology Letters,
Год журнала:
2025,
Номер
67(5)
Опубликована: Апрель 27, 2025
ABSTRACT
Accurate
monitoring
of
atmospheric
δ
13
C
isotope
is
critical
for
quantifying
anthropogenic
carbon
emissions
and
ecosystem
responses
within
global
cycle
research.
This
study
used
off‐axis
integrated
cavity
output
spectroscopy
(OA‐ICOS)
combined
with
distributed
feedback
(DFB)
laser
achieved
an
effective
absorption
path
length
approximately
22
km,
the
simultaneous
detection
dioxide
its
(δ
C)
under
background
conditions.
Laboratory
validation
demonstrated
limits
104.5
ppb,
3.3
0.72‰
12
CO
2
,
C,
respectively,
a
2000
s
integration
time,
alongside
linear
calibration
R
>
0.999.
While
Kalman
filtering
reduced
concentration
variability
by
73.5%–74.7%
improved
precision
4.6
times.
The
sensor's
capability
to
quantify
isotopic
ratios
molecular
concentrations
in
real‐time
addresses
gaps
monitoring,
offering
robust
tool
climate
research
source–sink
analysis,
expanding
applicability
environmental
sensing.
Applied Physics Reviews,
Год журнала:
2024,
Номер
11(4)
Опубликована: Окт. 23, 2024
A
novel
tapered
quartz
tuning
fork
(QTF)
was
designed
to
enhance
its
stress
magnitude
and
charge
distribution
in
QTF-based
laser
spectroscopy,
which
had
a
low
resonant
frequency
of
7.83
kHz
wide
gap
for
long
energy
accumulation
time
easy
optical
alignment.
Compared
the
reported
rectangular
QTF,
this
QTF
transfers
maximum
position
from
root
middle
improve
sensing
performance.
Furthermore,
unique
design
eliminates
90°
right
angles
typically
found
standard
QTFs,
often
lead
undesired
“webs”
“facets”
during
etching
process.
This
minimizes
performance
degradation
by
reducing
presence
residual
unexpected
materials.
spectroscopy
quartz-enhanced
photoacoustic
(QEPAS)
light-induced
thermoelastic
(LITES)
were
adopted
verify
with
widely
used
total
surface
improved
5.08
times
5.69
QEPAS
LITES
simulations,
respectively.
Experiments
revealed
that
sensor
3.02
improvement
signal-to-noise-ratio
(SNR)
compared
system.
Adding
an
acoustic
micro-resonator
signal
level
97.20
times.
The
minimum
detection
limit
(MDL)
acetylene
(C2H2)
determined
be
16.45
ppbv.
In
technique,
3.60
SNR.
MDL
C2H2
146.39
Photoacoustics,
Год журнала:
2025,
Номер
42, С. 100683 - 100683
Опубликована: Янв. 6, 2025
A
high
sensitive
methane
(CH4)
sensor
based
on
quartz-enhanced
photoacoustic
spectroscopy
(QEPAS)
using
self-designed
trapezoidal-head
quartz
tuning
fork
(QTF)
and
power
diode
laser
is
reported
for
the
first
time
in
this
paper.
The
QTF
with
low
resonant
frequency
(f
0
)
of
∼
9
kHz,
serves
as
detection
element,
enabling
longer
energy
accumulation
times.
an
output
10
mW
utilized
excitation
source.
Raman
fiber
amplifier
(RFA)
employed
to
boost
300
increase
intensity.
Acoustic
micro-resonators
(AmRs)
are
designed
placed
both
sides
form
acoustic
standing
wave
cavity,
which
increases
intensity
enhances
vibration
amplitude
QTF.
Additionally,
long-term
stability
analyzed
by
Allan
deviation
analysis.
When
average
system
increased
150
s,
minimum
limit
(MDL)
CH4-QEPAS
can
be
improved
15.5
ppb.
Photoacoustics,
Год журнала:
2025,
Номер
42, С. 100699 - 100699
Опубликована: Фев. 11, 2025
This
paper
presented
a
highly
sensitive
light-induced
thermoelastic
spectroscopy
(LITES)
sensor
for
detecting
hydrogen
sulfide
(H₂S)
gas.
Optical
path
multiplexing
(OPM)
technology
was
implemented
within
the
fiber-coupled
multi-pass
cell
(MPC)
to
realize
∼
80
m
gas
absorption
optical
length
(OPL),
compensating
weak
coefficient
of
H2S
in
near-infrared
band.
A
circle-head
quartz
tuning
fork
(QTF)
with
resonant
frequency
9.5
kHz
adopted
H₂S-LITES
enhance
energy
accumulation
time
and
detection
ability.
Compared
commercial
QTF,
signal-to-noise
ratio
(SNR)
based
on
QTF
improved
by
factor
3.36
times.
Minimum
limit
(MDL)
measured
be
238.8
ppb.
When
integration
system
increased
250
s,
MDL
could
19.8
Analytical Chemistry,
Год журнала:
2025,
Номер
unknown
Опубликована: Фев. 27, 2025
In
this
paper,
an
acetylene–carbon
dioxide
dual-component
gas
sensor
based
on
light-induced
thermoelastic
spectroscopy
and
deep
learning
is
reported
for
the
first
time.
Two
lasers
with
wavelengths
of
1530
1577
nm
were
coupled
by
a
wavelength
division
multiplexer
to
excite
two
molecules.
The
combined
four
algorithms,
namely,
sparrow
search
algorithm
(SSA),
convolutional
neural
network
(CNN),
bidirectional
gated
recurrent
unit
(BiGRU),
attention
mechanism
(Attention),
achieve
two-component
concentration
inversion
in
three
cases,
which
overlap
spectral
lines
different.
advantage
combination
SSA-CNN-BiGRU-Attention
model
that
weight
can
be
assigned
according
characteristics
second
harmonic
(2f)
signal
itself,
optimal
parameters
automatically
found.
effectively
improved
accuracy
significantly
reduced
mean
relative
error
(MRE).
experimental
results
show
R-square
values
test
set
are
all
greater
than
0.99,
MRE
less
1.2%,
showing
high
accuracy.
This
work
provides
instructions
absorption
line
detection
expected
applied
study
more
components
future.
Analytical Chemistry,
Год журнала:
2025,
Номер
unknown
Опубликована: Март 20, 2025
In
the
paper,
quartz-enhanced
photoacoustic
spectroscopy
(QEPAS)
and
heterodyne
(H-QEPAS)-based
ppb-level
methane
(CH4)
detection
using
a
self-designed
low-frequency
round-head
quartz
tuning
fork
(QTF)
power-amplified
diode
laser
is
reported
for
first
time.
Compared
to
standard
32.768
kHz
QTF,
novel
with
resonance
frequency
(f0)
of
9.7
kHz,
utilized
as
acoustic
wave
transducer,
benefiting
from
longer
energy
accumulation
time
reduced
optical
noise.
A
Raman
fiber
amplifier
(RFA)
adopted
amplify
power
continuous
wavelength
distributed
feedback
(CW-DFB)
300
mW.
Acoustic
microresonators
(AmRs)
at
specific
sizes
are
on
both
sides
QTF
enhancement
waves.
It
observed
that,
after
installation
AmRs,
signal
level
enhanced
by
factor
107.029
compared
bare
QTF.
Both
CH4-QEPAS
CH4-H-QEPAS
sensors
show
excellent
linearity
in
response
CH4
concentration,
R-squared
values
exceeding
0.99
each.
The
minimum
limit
(MDL)
determined
be
1.321
2.126
ppb
CH4-H-QEPAS,
respectively,
when
integration
sensor
systems
extended
1000
s.
50
s
measurement
period
sensor,
can
identify
f0
finish
3
s,
demonstrating
its
rapid
capability.
Furthermore,
H-QEPAS
technology
allows
acquisition
without
interrupting
measurement,
enabling
real-time
calibration
f0.
Finally,
monitoring
concentrations
air
human-exhaled
gases,
practical
capabilities.
Analytical Chemistry,
Год журнала:
2025,
Номер
unknown
Опубликована: Янв. 27, 2025
A
highly
sensitive
trace
gas
sensing
system
based
on
carbon
black
absorption
enhanced
photoacoustic
(PA)
spectroscopy
(PAS)
is
reported.
sheet
and
a
fiber-optic
cantilever
microphone
(FOCM)
are
integrated
to
form
spectrophone
(FOCS).
The
concentration
obtained
by
measuring
the
acoustic
wave
amplitude
generated
sheet,
which
absorbs
laser
passing
through
interest
gas.
Due
higher
rate
of
than
that
flake
graphite,
excited
solid-state
PA
pressure
enhanced.
ability
FOCS
detect
weak
sound
waves
related
power
length.
Therefore,
an
Erbium-doped
optical
fiber
amplifier
multipass
cell
also
used
increase
tested
gas,
combines
with
FOCM
achieve
multimechanism
enhancement
performance.
Different
from
traditional
PAS
detection
systems,
this
noncontact
measurement
solution,
not
only
effectively
avoids
flow
noise
but
makes
element
immune
damage
corrosive
gases.
experimental
results
show
sensitivity
about
four
times
using
graphite
as
light-absorbing
element.
When
average
time
100
s,
minimum
limit
acetylene
0.31
ppb.
normalized
equivalent
coefficient
designed
achieved
be
7.1
×
10-10
cm-1·W·Hz-1/2.
