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.
Photoacoustics,
Год журнала:
2025,
Номер
42, С. 100692 - 100692
Опубликована: Фев. 1, 2025
An
innovative
and
miniature
photoacoustic
spectroscopy
(PAS)
gas
sensor
based
on
a
multivariate-coupled
amplification
cell
(MVCA-PAC)
with
total
length
of
100
mm
was
developed
to
achieve
ultra-sensitive
trace
CH4
detection.
Acoustic
pressure
distribution
simulations
reveal
that
at
the
first-order
resonance
frequency,
MVCA-PAC
achieves
maximum
acoustic
approximately
3.9
times
higher
than
conventional
cell.
The
absorption
optical
path
reached
2068
through
22
reflections,
resulting
in
2-fold
increase
amplitude
signals
compared
traditional
an
equivalent
path.
Furthermore,
single-pass
cell,
2-f
signal
intensity
increased
by
factor
4.5.
Allan
variance
analysis
indicated
detection
limit
0.572
ppm
for
averaging
time
300
s.
To
further
improve
measurement
precision
designed
sensor,
Chebyshev
rational
fractional-order
filtering
(CRFOF)
algorithm
introduced
PAS
processing
first
time.
Post-processing
results
demonstrated
15.4-fold
improvement
precision,
achieving
0.578
ppm.
Finally,
continuous
monitoring
atmospheric
over
48-hour
period
validated
reliability
feasibility
sensor.
Laser & Photonics Review,
Год журнала:
2025,
Номер
unknown
Опубликована: Май 9, 2025
Abstract
In
this
paper,
an
ultrahigh
sensitive
light‐induced
thermoelastic
spectroscopy
(LITES)
sensor
based
on
a
trilayer
ultrathin
perfect
absorber
coated
T‐head
quartz
tuning
fork
(QTF)
is
reported
for
the
first
time.
The
designed
according
to
streamlined
theoretical
framework
admittance
matching
principles.
incorporation
of
Cr
as
primary
and
dual‐layer
anti‐reflection
coating
SiO
2
Si
in
tri‐layer
(Si‐SiO
‐Cr)
ultra‐thin
enables
high
absorption
across
wide
spectral
range.
It
results
93%
absorbance
1530
nm
laser
by
QTF.
This
feature
enhances
QTF's
photothermal‐elastic‐electric
conversion
efficiency
detection
sensitivity.
self‐designed
QTF
with
low
resonant
frequency
8.78
kHz
beneficial
increase
energy
accumulation
signal‐to‐noise
ratio
increases
3.35‐fold
after
absorber,
it
6.90
times
greater
than
that
standard
To
achieve
ultra‐high
acetylene
(C
H
)
detection,
40
m
fiber‐coupled
multi‐pass
cell
erbium‐doped
fiber
amplifier
are
integrated
into
sensing
system
augment
target
gas's
boost
power.
Finally,
minimum
detecting
limit
(MDL)
209.59
ppt
obtained,
indicating
sensitivity
best
MDL
among
all
C
‐LITES
sensors.
work
paves
effective
new
way
enhance
LITES
sensor,
can
provide
broader
enhancement
detect
additional
gases
optimized
architecture.
Analytical Chemistry,
Год журнала:
2024,
Номер
96(46), С. 18528 - 18536
Опубликована: Ноя. 7, 2024
In
photoacoustic
spectroscopy
based
multicomponent
gas
analysis,
the
overlap
of
absorption
spectra
among
different
gases
can
affect
measurement
accuracy
concentrations.
We
report
a
analysis
method
on
empirical
modal
decomposition
(EMD),
convolutional
neural
networks
(CNN),
and
long
short-term
memory
(LSTM)
that
extract
exact
concentrations
mixed
from
overlapping
wavelength-modulated
with
second
harmonic
(WMS-2f)
detection.
The
WMS-2f
signals
25
concentration
combinations
acetylene-ammonia
mixtures
are
detected
using
single
distributed
feedback
laser
(DFB)
at
1531.5
nm.
acetylene
range
2.5
to
7.5
ppm
ammonia
12.5
37.5
ppm.
data
set
is
enhanced
by
cyclic
shifting
adding
Gaussian
noise.
classification
test
reaches
99.89%
after
tuning.
mean
absolute
errors
five
additional
sets
measured
under
conditions
0.092
for
1.902
ammonia,
within
above
ranges.
Microwave and Optical Technology Letters,
Год журнала:
2025,
Номер
67(1)
Опубликована: Янв. 1, 2025
ABSTRACT
To
achieve
low‐concentration
measurement
using
near‐infrared
dual‐comb
spectroscopy
(DCS),
this
study
presents
a
trace
C
2
H
detection
DCS.
A
multi‐pass
gas
cell
is
employed
to
extend
the
optical
path
length,
improving
sensor's
sensitivity.
Signal
post‐processing
via
interpolation
method
applied
reduce
noise
and
flatter
dual‐comb.
The
sensitivity
transient
characteristics
are
evaluated
by
selecting
absorption
lines
at
6526.53,
6529.17,
6531.78
cm
−1
,
with
experimental
profile
being
well‐fitted
Voigt
function.
stability
of
system
confirmed
concentration
200
ppm
over
2.5
h
observation
period,
showing
better
than
2.305
×
10
−2
.
Allan
variance
analysis
indicates
an
optimal
integration
time
597
s,
yielding
minimum
limit
6.15
−4
for
absorbance
350
ppb
concentration.
Additionally,
nine
demonstrates
multi‐peak
capability,
deviations
ranging
from
0.059%
12.496%.
Analytical Chemistry,
Год журнала:
2025,
Номер
unknown
Опубликована: Янв. 15, 2025
The
photoacoustic
spectroscopy
(PAS)
system
commonly
enhances
the
efficiency
of
optical-acoustic-electrical
energy
conversion
by
increasing
laser
power,
optimizing
resonance
characteristics
cell
(PAC),
and
improving
sensitivity
acoustic
sensors.
However,
conventional
systems
using
a
single-microphone
or
dual-microphone
differential
setup
for
point
sampling
signal
fail
to
account
its
spatial
distribution,
leading
loss
gain.
Drawing
on
microphone
array
theory
derived
from
sonar
technology,
this
study,
first
time,
presents
PAS
sensing
based
four-microphone
array,
which
is
applied
detect
chloroform
gas.
microphones
are
positioned
at
90°
intervals
around
PAC
chamber
wall,
enhancing
rate
signals.
A
digital
phase-locked
algorithm
demodulates
combined
signals
four
into
concentration
data.
Experimental
results
show
that,
compared
system,
increases
factor
4,
doubles
signal-to-noise
ratio,
achieves
minimum
detection
limit
69
ppb,
demonstrating
significant
improvement
in
capturing
distribution
PA
