Terahertz spectrum petrochemical sensing: a photonic crystal fiber refractive index hybrid structure approach

Abstract

A photonic crystal fiber (PCF) having hybrid structure cladding with an octagonal core has been introduced for use in liquid (petrochemical) sensing. Mathematical analysis has been done on the sensor performance in the 0.8-3.0 THz frequency range. Kerosene, diesel and purified petrol are pumped inside the core hole. Terahertz (THz) frequencies are used in the analysis as well as changing strut size to investigate the sensor's performance. PCF sensor exhibits a CL of 5.10 × 10-13 dB/m at 2.2 THz and a relative sensitivity of about 95.5%. The PCF also has effective area of 5.27 × 10 −08 m 2 along with very small EML of 0.00920 cm −1 , and size of the spot is 2.563 × 10 −04 μm. Several real-world terahertz usages will be conceivable thanks to the amazing accomplishments achieved with this optical waveguide.

Full text

Vol.:(0123456789)
1 3
J Opt
https://doi.org/10.1007/s12596-023-01553-8
RESEARCH ARTICLE
Terahertz spectrum petrochemical sensing: aphotonic crystal
fiber refractive index hybrid structure approach
A.H.M.IftekharulFerdous1· KhalidSifullaNoor1· KavithaBalamurugan2· GovindarajRamkumar3·
ChandranRameshKumar4· SalemBalamuruganMohan5· BenishaMariaXavier6· Md. ShamimHossain1·
SheikhZannatE.Noor1· BenjirNewazSathi1· AhmedNabihZakiRashed7 · AmzadHossain8
Received: 12 October 2023 / Accepted: 15 November 2023
© The Author(s), under exclusive licence to The Optical Society of India 2023
Abstract A photonic crystal fiber (PCF) having hybrid
structure cladding with an octagonal core has been intro-
duced for use in liquid (petrochemical) sensing. Mathemati-
cal analysis has been done on the sensor performance in
the 0.8–3.0THz frequency range. Kerosene, diesel and
purified petrol are pumped inside the core hole. Terahertz
(THz) frequencies are used in the analysis as well as chang-
ing strut size to investigate the sensor’s performance. PCF
sensor exhibits a CL of 5.10 × 10–13dB/m at 2.2THz and a
relative sensitivity of about 95.5%. The PCF also has effec-
tive area of 5.27 × 10−08 m2 along with very small EML
of 0.00920 cm−1, and size of the spot is 2.563 × 10−04μm.
Several real-world terahertz usages will be conceivable
thanks to the amazing accomplishments achieved with this
optical waveguide.
Keywords Photonic crystal fiber· Sensitivity· Total
loss· Numerical aperture
Introduction
THz irradiation, sometimes identified as "T-rays,"
located within the electromagnetic band microwave and
* Govindaraj Ramkumar
pgrvlsi@gmail.com
* Ahmed Nabih Zaki Rashed
ahmed_733@yahoo.com
* Amzad Hossain
mahossain.eee@gmail.com
A. H. M. Iftekharul Ferdous
digonto_eee3@yahoo.com
Khalid Sifulla Noor
khalidsifullahpusteee180207@gmail.com
Kavitha Balamurugan
kavitha@kcgcollege.com
Chandran Ramesh Kumar
rameshchand2006@gmail.com
Salem Balamurugan Mohan
drsbmohan@gmail.com
Benisha Maria Xavier
benishaxavier@gmail.com
Md. Shamim Hossain
smhossain10ruet@gmail.com
Sheikh Zannat E. Noor
abony227@gmail.com
Benjir Newaz Sathi
sathinewaz069@gmail.com
1 Department ofElectrical andElectronic Engineering,
Pabna University ofScience andTechnology, 6600Pabna,
Bangladesh
2 Department ofECE, KCG College ofTechnology, Chennai,
Tamilnadu, India
3 Department ofECE, Saveetha School ofEngineering,
Chennai, TamilNadu, India
4 Department ofElectronics andCommunication Engineering,
Panimalar Engineering College, Chennai, Tamilnadu, India
5 Department ofECE, S.A. Engineering College, Chennai,
Tamilnadu, India
6 Department ofECE, Jeppiaar Institute ofTechnology,
Kunnam,Chennai, Tamilnadu, India
7 Electronics andElectrical Communications Engineering
Department, Faculty ofElectronic Engineering, Menoufia
University, Menouf32951, Egypt
8 Department ofElectrical andElectronic Engineering,
Jashore University ofScience andTechnology, Jashore7408,
Bangladesh

J Opt
1 3
infrared radiation. It has wavelengths that range from around
30µm–3mm and has frequency that lies around 0.1 to 10
terahertz. Due to its special characteristics, THz radiation
can be used in many different scientific, commercial, and
medical fields [1]. When using photonic crystal fiber (PCF)
for communication, information is transmitted through the
fiber’s core as pulses of light. The THz regime is significant
in optics and various scientific and technological applica-
tions due to its unique properties, including its ability to
interact with matter in distinctive ways, its non-destructive
nature, and its potential for imaging, communication, and
materials analysis. Researchers continue to explore and
develop new applications for terahertz radiation across mul-
tiple fields. PCF has unique varieties of optical fiber that
have an ordered network of air holes running along their
length. This arrangement results in a photonic bandgap that
alters the behavior of light inside the fiber. High data speeds,
low loss, and flexibility in guiding light are just a few of the
special qualities PCF provides that make them suited for a
range of communication applications [2]. In order to detect
different physical, chemical, or environmental properties,
optical fiber sensing includes taking advantage of the fiber’
capacity to transmit light and interact with outside forces.
Remote sensing, tolerance to electromagnetic interference,
and compatibility for severe situations are some of the ben-
efits that fiberoptic detectors can provide [3]. Petroleum-
based chemicals (such as diesel or petrol) are being used
more frequently as a result of the growth of the transporta-
tion sector. As an outcome, the lifespan of every transport
depends on the condition of the oil used in it. The surround-
ings will be greatly endangered by a low-quality (degraded)
oil, which will also adversely affect the efficiency of the
transport[4, 5]. When contaminated oil is used in vehicles,
a significant how much CO2 is released entering an envi-
ronment, polluting the ecosystem and significantly raising
global temperatures [6]. As a residential energy sources,
kerosene is much less expensive than diesel as well as pet-
rol. Since kerosene dissolves easily with diesel and petrol,
some corrupt firms purposefully do so in order to make more
money. Automobile cars who utilize this contaminated oil
produce large amounts of CO2 ejection, which pollute the
soil, air, and water [7, 8]. Therefore, researchers must cre-
ate a reliable system for detecting clean petroleum-based
chemicals. At the time, a number of methods to perform
petrochemical detection were published. Between these,
several procedures involve examining various petrochemi-
cal qualities, such as viscidity, thickness, toneand smell.
Other techniques (such as titration, ultrasonic, chromatog-
raphytechniques, and so on) are also available [5, 9]. How-
ever, the methods are time-consuming, costly, and insuffi-
ciently precise.
For liquid/chemical sensing throughout the past twenty
years, academics and scientists have proposed photonic
crystal fiber(PCF)-based sensors. PCF offers more adjust-
able optical qualities than conventional optical fibers. In
(2004) A. Márquez Lucero examined bend-based optics
petroleum analyzers with consistent laser spectrum reflec-
tometry [10]. In (2005) chemical sensing of optical fiber is
observed by Pickrell Gary [11]. M. Douseri AL Fatemah
performed THz wave sensing for use in the energy sector
in the year (2006) [12]. In (2007) Sun Jian proposed high-
resolution pharmacological detector using refractive bands
wire [13]. For low concentration biomolecular detection,
in (2008) Shi Zhang ChaoYi used a LCPCF Sers detector
[14]. In (2009) G. Maglio did optical sensing with hybrid
polymer-porous silicon photonic crystals [15]. L.Thévenaz
proposed gas–light interaction under optimal conditions
in photonic crystal fibers year (2010) [16]. In (2014) Tang
Dong-Lin developed hollow-core photonic bandgap fiber for
H2S detection in natural gas [17]. H Ademgil improved RS,
increased birefringence, and reduced CL PCF-based sen-
sor regarding fluid sample detection with sensitivity about
23.75% in the year (2015) [18]. Biddut MJH year (2017)
proposed a novel PCFdesign that has excellent RS, strong
nonlinearity, great birefringence, and minimal CLin fluid
sample measurements of sensitivity about 53.95% [19].
Terahertz determination of alcohol utilizing a PCF sensor
with 68.9% sensitivity is described in (2018) by J. Sultana
[20]. In (2018) B.K Paul proposed architecture and research
for a spectroscopic chemical analyzer dependent upon a
Quasi-PCF working in the THzregion with sensitivity about
78.80% [20]. F. Ahmed and others in (2019) suggest sens-
ing of blood components using a THz-range optical index
about 80.9% sensitivity [21]. In (2020) S.R. Tahhan study,
"Detecting of BannedDrugs via Applying PCFwithin the
THzDomain with 82% Sensitivity" was proposed [22]. A
novel approach for spectroscopic chemical identification in
the THzband with 85.7% accuracy utilizing PCF was pro-
posed by D. Abbott at (2018) [23]. Year (2018) K. Ahmed
published Sensing of Toxic Chemicals Using Polarized Pho-
tonic Crystal Fiber in the Terahertz Regime with sensitivity
85.8% about [24]. In (2020) Podder proposed "Identification
of Cyanide within Hollow Core Photonics Crystal Fiber"
with sensitivity about 88.5% [25]. Alcohol classification and
detection utilizing PCF-based sensors developed in (2020)
with 91.5% sensitivity achieved was examined by Iqbal [26].
MA Habib and others at (2021) develop hollow-core pho-
tonic crystal fiber sensor in an efficient manner with 82.52%
sensitivity [27]. In (2021) Nishat Farha Islam Nira designed
and observed numerical analysis of PCF-based toxic chemi-
cal detection in the THz regime of sensitivity 92.7% [28].
AA Bulbul and his colleagues in the year (2020) proposed
detection of harmful compounds using photonic crystal fiber
in the THz regime of sensitivity about 94.4% [29]. Recently,
PCF sensor is used to sense petrochemical to detect their
purity. Because impure petrochemical fuel is harmful for

J Opt
1 3
our environment as they produce the basic harmful gases
and thus pollute out atmosphere as well as drinking water,
earth soil also partially gets polluted [30–38].
In our design, we construct a hybrid cladding with octag-
onal core photonic crystal fiber sensor where we get about
95.5% sensitivity in sensing petrochemicals such as petrol,
diesel, and kerosene. In petrochemical industries, the use
of PCF sensors contributes to safety, environmental protec-
tion, and process optimization. They enable early detection
of leaks, emissions, and deviations from normal operations,
helping to prevent accidents, minimize environmental
impact, and ensure the efficient production of petrochemi-
cal product.
This type of sensor can save us from those corrupted busi-
ness man or business farm who mixed high-grade petro-
chemical with low-grade petrochemical for achieving more
profit. This sensing system can play important role in reduc-
ing the harmful gas emission. Hybrid photonic crystal fiber
structures offer customizable dispersion control, enhanced
nonlinear effects, and mode manipulation for various opti-
cal applications. The utilization of PCF in petrochemical
detection could lead to a number of intriguing new research
and development directions in future. Because PCF are spe-
cial optical fibers with a great deal of design freedom, they
are excellent for sensing applications like petrochemical
detection.
Methodology
The proposed structure includes a hollow octagonal corethat
is filled with petrochemicals (e.g., petrol, kerosene, and die-
sel with corresponding RI = 1.418,1.44,1.46). The main rea-
son for selecting octagonal hybrid core is that it gives better
light confinement as well as higher sensitivity. The design
is started with an octagonal hollow core which is made by
using rectangles and their rotation of π/4. Then union is
taken between all the rectangles. From the union we shall
get our desire octagonal core. The cladding layer is a hybrid
structure which is made by using several numbers of circular
airholes with their specified arrangement on the cladding
layer to form the hybrid structure. Here the RI = 1 for all this
circle made in the cladding layer. The PML layer is also cir-
cular shape. The Zeonex is the material with RI = 1.53 that
uses the PML as well as the cladding layer for the extreme
RS and low CL of this sensor. The purpose of using Zeonex
as background material is because Zenox, a type of borosili-
cate glass, is used in photonic crystal fibers due to its low
optical loss, high thermal stability, and compatibility with
a wide range of wavelengths, making it suitable for various
photonic applications. In Fig.1a, P represents the pitch of
this sensor, C represents the octagonal core of this sensor
which is full of petrochemicals for their detection, and the
term A represents the air holes which jointly form the hybrid
structure on the cladding.
Figure1b represents the triangular mesh is considered
to encompass the model’s entire layout. A mesh structure
is crucial in photonic crystal fiber (PCF) design because
it creates periodic air-hole patterns in the cladding, allow-
ing precise control over the fiber’s optical properties, such
as dispersion, confinement of light, and guiding of specific
modes, enabling customization for various optical applica-
tions. Here, the number of vertex elements is 440, the low-
est element excellence is 0.4514, the number of boundary
elements is 4358, and the number of elements is 47984.
Figure2 depicts the positioning of the power petrochemical
Fig. 1 a A rendering of the intended hexagonal core PCF viewed
cross-sectionally. b Hexagonal core PCF mesh visualization

J Opt
1 3
regarding atthe x-polarizations at the ideal in the range
of 2.2 terahertz. The unfilled core of the drawing makes it
very evident a tight enclosure of the light, which creates an
intriguing the transmitted field’s and the identified object’s
relations. This would lead to a clear indication of relative
sensitivity. Figure2 demonstrates the electric power arrange-
ment under a specific set of factor permutations. We have
inserted zoomed core picture and titled it Fig.2a–c with the
proper dimension so that the octagonal core shape can easy
to detect.
A PML borders constraint has been incorporated through-
out our model. Aeolotropic permittivity values and values
for permeability were used to classify PML considered
an element. PML is applied to the external boundary of
the model to absorb every shock that comes in. The PML
and exterior ring of this detector’s waveguide are made of
zeonex’s. It offers many advantages, including a constant
RI, low EML, and high temperature rudeness. The PML’s
thickness is 20% of the planned PCF’s diameter. Air filling
fraction in PCF sensors is crucial for customizing optical
properties and sensing capabilities, enabling tailored appli-
cations in environmental monitoring, biology, and telecom-
munications. We have considered aff = 0.956 because the
relative sensitivity increases with increase in aff. But if the
aff is greater than 0.965, the air holes will overlap.
Results andanalyses
The computational investigation had been carried out uti-
lizing FEA, a tool that solves Maxwell’s theorem. By
Fig. 2 Petrochemical distribution of electrical power utilizing x-polarization at f = 2.2THz: a petrol b kerosene, c diesel

J Opt
1 3
dissecting the problem into its separate elements, this
approach resolves the effects associated with every finite
aspect. The COMSOL Multiphysics program has been
employed to mimic the suggested approach in order to
clarify the sensing characteristics like as sensitivity, EML,
confinement loss, numerical aperture, and effective area. In
this paper, the detecting analyte is one of three oils (such as
pure gasoline, kerosene, or diesel). After that, modeling is
run at various operation phases, namely 0.8–3.0THz. To test
several sensing characteristics, for example sensitivity, spot
size, effective area, EML, confinement loss, etc., we first run
pure petrolthrough the PCF sensor. After that, in the same
way we run kerosene and diesel correspondingly through
the fiber sensor. It is essential to understand the PCF’s char-
acteristics before determining the RSreaction. A PCF’s RS
reaction demonstrated the indicated PCF’sdetecting ability.
The RS of a photonic crystal refers to how well its optical
characteristics can adjust to environmental changes such
variations in temperature or pressure. The composition of
fiber, the range of light, and the features of surroundings
are a few factors that affect a PCF’s sensitivities in contrast
to other components. Compared to typical optical fibers,
PCF frequently has superior relative sensitivity because of
its wide surface area and small core size. Beer–Lambert’s
law states, differences in the RS are caused by variations in
the connection between radiation and matter. The following
equation was used to find any sensor’s relative position [30].
Whereas RI in directed action (
neff
) is known as the
strength of the fraction, p is the true component of the
detecting sample’s RI, and the following calculation can be
used to determine both [30]
where magnetic domain field is in the x-axis represented
with Hx and element of the electric field is in x-axis with
Ex. Power distribution for petrochemicals (petrol, kerosene,
and diesel) is the same for both x-polarizations. The fre-
quency variation-affected RS graph is displayed in Fig.3a.
A terahertz mathematical domain study (0.8–3.0) has been
performed on the proposed RI detector inspired by PCF. In
this paper, we have consider only the x-polarization modes
because as we have used an octagonal shape core in the sen-
sor, it provides similar results in both x- and y-polarization
modes.
At its ideal pitch, the sensor’s sensitivity achieved 95.5%.
The plot depicts the frequency-dependent rise of interaction
of optical strength with the sample or photo concentration,
(1)
r
=
n
r
n
eff
×p
%
(2)
p
=
∫
sample
Re
(
ExHy−EyHx
)
dxdy
∫
tot al
R
e(
E
x
H
y
−E
y
H
x)
dxd
y
which reaches its maximum at 2.2THz. The RS graph by
pitch change is given in Fig.3b. This sensor’s sensitivity is
95.5% at its best frequency. The volume of the material that
is filled with air or spaces is measured by the Aff. Air filling
fraction in PCF sensors is crucial for customizing optical
properties and sensing capabilities, enabling tailored appli-
cations in environmental monitoring, biology, and telecom-
munications. The value of Aff is measured by:
By increasing the value of Aff, the RS of the suggested
detector can be increased consistently but there arises a
problem that excessive increase in Aff causes fabrication
difficulties which means that it will increase the chance of
overlapping of the air holes that’s why the optimum AFF
is 0.965. The recommended sensor mentions two signifi-
cant types of losses: EML and CL. These losses occur in all
types of optic’s waveguides. Important aspect of THz wave-
guide guidance is massive digestion damage, also referred
by EML. The EML shows how the core substance took in
the energy of light.
Two noteworthy types of losses have been recognized
for the proposed sensor: effective material loss (EML) and
confinement loss. The aforementioned losses occur in all
optical waveguide types. EML, often referred to as bulk
absorption loss, is an especially important aspect of a THz
waveguide. The EML shows how much light energy the core
material has taken in overall. EML stands for optical power
loss within the fiber’s core and cladding as light travels
through it. It is not ok of having large EML because EML
can impact the sensor’s performance by reducing its sensi-
tivity and signal-to-noise ratio. Minimizing effective mate-
rial loss is essential to enhance the sensor’s efficiency and
accuracy. EML is a symptom of reduced strength caused by
the robust design of the PCF. The EML expression is given
by the subsequent equation [31].
where αmat describes loss coefficient of the background
element’s reduced power caused by the strong and E is the
modal electrical field. Figure4a, b, respectively, exhibits
the fluctuation of EML for different architectural and func-
tional conditions for different THz pitches and frequencies.
This graph shows the diminishing characteristics of the
loss for longer cores. Zeonex`s lengthier core’s ability to
absorb power decreases as more light may pass through it
with less resistance. As previously shown, through the core,
greater-frequency radiation is consistently severely limited.
Thus, we observed with frequency increases and EMLof
(3)
Af f =
V
air
V
tot al
×
100
(4)
𝛼
eff =
(𝜀0
𝜇0
)
1
2∫Amax
n𝛼mat |E|2
dA
2∫
ALL
S
z
dA

J Opt
1 3
Fig. 3 Sensitivity of envisaged sensing reagent expressed as a function of a signal bandwidth at a constant pitch 240µm and b pitch at
f = 2.2THz and c Aff at constant pitch 240 µm and frequency f = 2.2THz

J Opt
1 3
recommended detector lowers in Fig.4a at 2.2THz, the sen-
sor fiber exhibits a 0.00920 cm−1 EML, which is extremely
low. Effective material loss can impact the sensor’s perfor-
mance by reducing its sensitivity and signal-to-noise ratio.
Minimizing effective material loss is essential to enhance
the sensor’s efficiency and accuracy, and hence, large EML
should be avoided.
When light propagates through a wire but is not com-
pletely held within the fiber’s core, it loses its optical
strength. This is referred to as CL. CL in PCF sensor stems
from imperfection, bending, or interaction with external
materials that adversely impacts sensor performance. Con-
finement loss (CL) must also be taken into account while
evaluating the sensor’s accuracy. The loss is brought about
by leakage in the system and moreover due to incorrect
breath vent positioning or design. In a circuit, the dielectric
material is the air holes. Its negative association with both
the real and fictitious halves for EML and CL may be cal-
culated with high accuracy by modifying the characteristics
of the structure. The next expression results in CL as [27]:
Here the imaginary portion of EMI is denoted as imag
neff
in this example, and the operational wavelength is defined as
lamda. The link between CL and THz frequency is plotted in
Fig.5a. According to Fig.5b, for different pitches, as pitch
in m increases, the value of CL is progressively decreas-
ing. It indicates that as frequency and pitch increase, the
CLvalue is declining. Thus, cl is 5.10 × 10–13dB/m of the
detecting fiber at its best.
(5)
L
c=40𝜋
𝑙𝑛(
10
)𝜆
img
(
neff
)
×10
6dB
m
Fig. 4 EML of the chosen
sensing reagent as a function of
a signal frequency at a preset
pitch 240µm and b pitch at
f = 2.2THz

J Opt
1 3
NA refers a fundamental detector’s driving factor deter-
mining maximum acceptance angle for an optical fiber for
incident light. The NA is a number without units that has
a range of 0.1–0.5. A PCF’s NA is impacted by the differ-
ences in RIamong cladding and core components as well
as the arrangement of the air slots or any other defects in
the PCI. Having a larger NA than regular fibers, PCFs are
frequently the best choice for applications including light
transportation, curved optics, and detecting. Higher NA
is advantageous because it captures lights from a wider
range of angle. The formula eq. (6) can be computed to
determine this optical sensor’s NA [30]:
where the NA of the detecting substants is given as
Aeff
and the definition of the adaptable wave is Fig.6a and the
responses of NA to changes in pitch and frequency are
shown in Fig.6b. The findings clearly demonstrate that in
both cases, the numerical aperture decreases as pitch and
frequency increase. The detecting analyte’s NA is 0.317
under ideal building circumstances.
(6)
NA = 1
√
1+𝜋Aeff f2
c
2
≈
1
√
1+𝜋Aeff
𝜆
2
Fig. 5 Expression of CL of the
envisioned sensing analyte as an
indicator of a signal frequency
at fixed pitch 240µm and b
pitch at f = 2.2THz

J Opt
1 3
Additionally, the region that receives the mode’s optical
power is known as the effective area. Aeff of this detector fiber
is investigated for different functioning. The Aeff is used like
barometer to measure the area covered by the complete laser
indication traverses. Thus, Aeff is the area in the transverse
plane of the fiberwhere light energy is dispersed. Because
of their unique microstructure, PCFs can focus light via both
photonic bandgap effects and total internal reflection. PCFs
have an Aeff which are significantly lower compared with tradi-
tional fiber because of their configuration, which makes them
appealing for a range of applications. The expression below
helps to determine the Aeff [30]:
(7)
A
eff =[∫I(r)rd r]
2
[
∫
I2(r)rdr]2
where I(r) =|E|2 represents dispersion for sensing ana-
lyte’s fields of electricity. The effective area for this PCF in
Fig.7 displays several functioning frequencies. This image
demonstrates that only the core can receive the more pow-
erful pulse and the effective region shrinks increasing fre-
quency of operation. The effective area of the sensor fiber at
2.2THz at optimal pitch is
5.27 ×10−08
m2.
The "spot size" in PCF is the size of optic beam that is
traveling through the tube. In PCF, the claddings within air
vents are spaced apart from the occurrence of a band gap in
photons that limits the travel of particular wave. This fiber
design and the lights influence the spot size in PCF, among
other factors such as the operating mode and wavelength.
Size of spot in PCF is frequently smaller as compared to
standard fiber optics because the areas of the core and clad-
ding have markedly different index values. Spot size in
PCF sensor is critical for optimal interaction with sensing
Fig. 6 a Signal frequency at
a preset pitch 240µm and b
pitch at f = 2.2THz; NA of the
advocated sensing analyte is
presented

J Opt
1 3
element directly impacting sensor sensitivity and perfor-
mance. Lastly, we investigate size of spot for this detector, a
key parameter in detecting applications. For detecting uses,
a large size of spot is required, which is determined by the
below calculation [30]:
where the adjusted frequency level V and the circum-
ference of the hexagonal core R are both used. Figure8a
depicts the size of spot for detecting reaction of optic to fre-
quency, and the sensor’s field of view definitely gets smaller
as frequency rises. Figure8b shows that as the pitch param-
eter increases, so does the sensor’s spot size. Size of average
spot is 2.563 × 10−04μm at the best pitch and frequency.
By providing specified parameters, a list is shown that
provides a difference between detecting optics and con-
ventional optics. The contrast among the outcomes char-
acteristics of this proposed detector creation and that of
conventional detectors is made clear in Table1. With the
introduction of greater technological innovation, such as the
extruding method, the three-dimensional printing device,
and the interpretation of a sol–gel, current production pro-
cedures may readily manufacture the advised analyte design.
Any type of complex preform can be produced by a 3-D
(8)
Weff
=R×
(
.65 ×1.619 ×V
−1.5
+2.789 ×V
−6)
printer, and it can then be ejected using an extrusion tech-
nique [31, 32]. An author suggested a hybrid model on fuel
adulteration with 102% of relative sensitivity which is an
unrealistic value for sensing fuel [35] and also faced prob-
lems in fabrication. We have revised the single constant as
"P", and all the parameters depend on "P". Although nearly
any kind of framework may be created using the extrusive
fabrication approach or the sol–gel technology, this allows
for greater design flexibility since the air holes can be
changed in size, shape, and spacing, which lets the manu-
facturer produce this type of sensor in large quantities. We
have thoroughly searched for existing PCF-based sensors
that meet the criteria to detect petrochemical. However, we
could not find additional references that specifically match
these criteria.
Conclusion
In this paper, a hybrid shape octagonal RI sensor with a
core allows the identification for petrochemical which is
developed and simulated using COMSOL Multiphysics. A
PML has been utilized in order to capture the electromag-
netic energy from the PCF. No terahertz waveguide or the
first documented THz-type detectorfor chemicals for usage,
Fig. 7 Effective area of intended sensing chemical articulated as an indication of signal frequency at a preset pitch of 240µm

J Opt
1 3
as far as we know. In this paper, we recommended a novel
PCF-based petrochemical sensor because it has a unique
octagonal core and five layers of air holes in cladding which
forms a new type hybrid structure. A brief overview of this
section offers the discussion of THztechniqueand numer-
ous THztraveling wave. The detecting and driving char-
acteristics for various THz detectors have mathematically
explained and architecturally presented the readers’ conveni-
ence. The results show that 95.5% sensitivity is the highest
in the 2.2THz range and 240µm pitch utilizing a minimal
EML about 0.0092 cm−1, a CL about 5.10
×
10–13dB/m,
and a large NA of 0.317. Nowadays, PCF with SPR modes
becomes very popular and hot topic in optical fiber sensing
[33, 34]. There are actions that can be performed to mitigate
the loss of custody. As a result, in determining the petro-
chemical degree, the recommended detector would be quite
helpful.
Fig. 8 Spot size of the envis-
aged sensing component
responding to a signal fre-
quency at a preset pitch 240µm
and b pitch at f = 2.2THz

J Opt
1 3
Author contributions Authors contributed equally in this work.
Funding Not applicable.
Availability of data and material COMSOL software.
Code availability Not applicable.
Declarations
Conflict of interest No competing interests.
Ethics approval Not applicable.
Consent to participate Not applicable.
Consent for publication Not applicable.
References
1. Xu. Jiaxuan, Hu. Yue, X. Ruan, X. Wang, T. Feng, H. Bao, Non-
equilibrium phonon transport induced by finite sizes: Effect of
phonon-phonon coupling. Phys. Rev. B 104(10), 1–13 (2021)
2. T.G. Giallorenzi etal., Optical Fiber Sensor Technology. IEEE
Trans. Microw. Theory Tech. 30(4), 472–511 (1982)
3. D.H. Auston, K.P. Cheung, Coherent time-domain far-infrared
spectroscopy. J. Opt. Soc. Am. B 2(4), 606–614 (1985)
4. P.C. Chiang, Y.C. Chiang, E.E. Chang, S.C. Chang, Characteri-
zations of hazardous air pollutants emitted from motor vehicles.
Toxicol. Environ. Chem. 56(4), 85–104 (1996)
5. M. Shahru Bahari, W.J. Criddie, J.D.R. Thomas, Determination
of the adulteration of petrol with kerosine using a rapid phase-
titration procedure. Analyst 115(4), 417–419 (1990)
6. V. Sorathiya, S. Lavadiya, A. AlGhamdi, O.S. Faragallah, H.S.
El-sayed, M.M.A. Eid, A.N.Z. Rashed, A comparative study of
broadband solar absorbers with different gold metasurfaces and
MgF2 on tungsten substrates. J. Comput. Electron. 20(3), 1840–
1850 (2021)
7. S. Urooj, N.M. Alwadai, A. Ibrahim, A.N.Z. Rashed, Simulative
study of raised cosine impulse function with Hamming grating
profile based Chirp Bragg grating fiber. J. Opt. Commun. 42(1),
350–365 (2021)
8. A. Sadat, Determining the adulteration of diesel by an optical
method. Int. J. Comput. Appl. 100(13), 34–36 (2014)
9. Y.-L. Cheng etal., We are intechopen, the world ’ s leading pub-
lisher of open access books built by scientists, for scientists TOP
1 %. INTECH 11(1), 13–20 (2016)
10. R.M. López etal., Coherent optical frequency domain reflectom-
etry for interrogation of bend-based fiber optic hydrocarbon sen-
sors. Opt. Fiber Technol. 10(1), 79–90 (2004)
11. G. Pickrell, W. Peng, B. Alfeeli, A. Wang, Fiber optic chemical
sensing. Sensors Harsh Environ. 5998(2), 45–55 (2005)
12. F.M. Al-Douseri, Y. Chen, X.C. Zhang, THz wave sensing for
petroleum industrial applications. Int. J. Infrared Millimeter
Waves 27(4), 481–503 (2006)
13. J. Sun, C.-C. Chan, X.-Y. Dong, P. Shum, High-resolution pho-
tonic bandgap fiber-based biochemical sensor. J. Biomed. Opt.
12(4), 044022–044032 (2007)
14. C. Shi, Y. Zhang, C. Gu, L. Seballos, J.Z. Zhang, Low concen-
tration biomolecular detection using liquid core photonic crystal
fiber (LCPCF) SERS sensor. Opt. Fibers Sensors Med. Diagnos-
tics Treat. Appl. 6852(3), 685204–685212 (2008)
15. L. De Stefano etal., Hybrid polymer-porous silicon photonic crys-
tals for optical sensing. J. Appl. Phys. 106(2), 45–55 (2009)
16. I. Dicaire, J.-C. Beugnot, L. Thévenaz, Optimized conditions for
gas light interaction in photonic crystal fibres. Fourth Eur. Work.
Opt. Fibre Sensors 7653(5), 76530–76545 (2010)
17. D.L. Tang, S. He, B. Dai, X.H. Tang, Detection H2S mixed with
natural gas using hollow-core photonic bandgap fiber. Opt. J.
125(11), 2547–2549 (2014)
18. H. Ademgil, S. Haxha, PCF based sensor with high sensitivity,
high birefringence and low confinement losses for liquid ana-
lyte sensing applications. Sens. Jpurnal 15(12), 31833–31842
(2015)
Table 1 The recommended sensor design’s performance features compared with those of earlier released sensors
References Shape of the PCF Frequency (THz) Sensitivity (%) CL (dB/m) EML(cm-1) NA
PCF [24] Kagome structured with rectan-
gular structured air holes
f = 1.6THz 85.7 1.7
×
10–9 – –
PCF [25] Symmetrical and asymmetri-
cal core structures inside a
suspension-type cladding
f = 2.0THz 85.8 1.62
×
10–9 0.00859 –
PCF [26] Rectangular-based air holes
structured with rectangular core
f = 1.3THz 88.5 1.20
×
10–11 0.0051 –
PCF [27] Heptagonal-based structured
circular air holes with circular
core
f = 2.0THz 91.5 1.51
×
10–12 0.0072 –
PCF [29] Cladding of different rectangles
with square hollow core
f = 1.9THz 92.7 3.78
×
10–12 0.0064 0.219
PCF [30] Hexagonal-based structured
circular air holes with circular
core
f = 1.8THz 94.4 1.71
×
10–14 – –
This PCF Hybrid structure cladding with
octagonal hollow core
f = 2.2THz 93.3(petrol) 94.4
(kerosene) 95.5
(diesel)
1.20
×
10–12 5.59
×
10–13 5.10
×
10–13
0.0121 0.0105 0.0092 0.344
0.335
0.317

J Opt
1 3
19. M.F.H. Arif, M.J.H. Biddut, A new structure of photonic crystal
fiber with high sensitivity, high nonlinearity, high birefringence
and low confinement loss for liquid analyte sensing applications.
Sens. Bio-Sens. Res. 12(1), 8–14 (2017)
20. J. Sultana, M.S. Islam, K. Ahmed, A. Dinovitser, B.W.-H. Ng, D.
Abbott, Terahertz detection of alcohol using a photonic crystal
fiber sensor. Appl. Opt. 57(10), 2426–2435 (2018)
21. B.K. Paul, K. Ahmed, D. Vigneswaran, F. Ahmed, S. Roy, D.
Abbott, Quasi-photonic crystal fiber-based spectroscopic chemical
sensor in the terahertz spectrum: Design and analysis. IEEE Sens.
J. 18(24), 9948–9954 (2018)
22. K. Ahmed etal., Refractive index-based blood components sens-
ing in terahertz spectrum. IEEE Sens. J. 19(9), 3368–3375 (2019)
23. S.R. Tahhan, H.K. Aljobouri, Sensing of illegal drugs by using
photonic crystal fiber in terahertz regime. J. Opt. Commun. 41(2),
45–55 (2020)
24. M.S. Islam etal., A novel approach for spectroscopic chemical
identification using photonic crystal fiber in the terahertz regime.
IEEE Sens. J. 18(2), 575–582 (2018)
25. M.S. Islam, J. Sultana, A. Dinovitser, K. Ahmed, B.W.H. Ng, D.
Abbott, Sensing of toxic chemicals using polarized photonic crys-
tal fiber in the terahertz regime. Opt. Commun. 426(4), 341–347
(2018)
26. M. Sagar Bhattarai, G.F. Khalid Hossain, I. Toki, R. Pandey, D.P.
Jaya Madan, S.E. Samajdar, L.B. Farhat, M.Z. Ansari, S.H. Aham-
mad, A.N.Z. Rashed, Efficiency enhancement of perovskite solar
cell devices utilizing MXene and TiO2 as an electron transport
layer. New J. Chem. 47(10), 17908–17922 (2023)
27. F. Iqbal etal., Alcohol sensing and classification using PCF-based
sensor. Sens. Bio-Sensing Res. 30(1), 100384–100400 (2020)
28. M.A. Habib, M.S. Anower, A. AlGhamdi, O.S. Faragallah,
M.M.A. Eid, A.N.Z. Rashed, Efficient way for detection of alco-
hols using hollow core photonic crystal fiber sensor. Opt. Rev.
28(4), 383–392 (2021)
29. R.H. Jibon, S. Biswas, S. Biswas, N.F.I. Nira, Poisonous chemical
detection in the THz regime using PCF: Design and numerical
investigation. J. Opt. 50(4), 671–680 (2021)
30. M.B. Hossain, E. Podder, A.A.M. Bulbul, H.S. Mondal, Bane
chemicals detection through photonic crystal fiber in THz regime.
Opt. Fiber Technol. 54(5), 102102–102112 (2020)
31. M.A. Habib, E. Reyes-Vera, J. Villegas-Aristizabal, M.S. Anower,
Numerical modeling of a rectangular hollow-core waveguide for
the detection of fuel adulteration in terahertz region. Fibers 8(10),
1–17 (2020)
32. H. Ebendorff-heidepriem, J. Schuppich, A. Dowler, L. Lima-
marques, T.M. Monro, 3D-printed extrusion dies : A versatile
approach to optical material processing. Opt. Mater. Express 4(8),
15086–15092 (2014)
33. M.G. Daher, S.A. Taya, S.K. Patel, O. Ramahi, SPR base biosens.
Detect. water born bact. 55(2), 99–110 (2022)
34. Ajay Kumar Singh, Asita Kulshreshtha, Anirudh Banerjee. Design
of corrosion sensors by using 1D quaternary photonic crystal with
defect layer. 32(4), 1123–1134, (2023)
35. A.H.M. Iftekharul Ferdous, Md. Shamim Anower , Ahmmad
Musha , Md. Ahasan Habib, Md. Asaduzzaman Shobug. A hep-
tagonal PCF-based oil sensor to detect fuel adulteration using
terahertz spectrum, 56(2), 675–684 (2022)
36. K. Saikumar, S.H. Ahammad, K. Suvarna Vani, T.M.K. Anwer,
M. Hadjouni, L.J. Menzli, A.N.Z. Rashed, Md. Amzad Hossain,
Improvising and enhancing the patterned surface performance of
mimo antenna parameters and emphasizing the efficiency using
tampered miniature sizes and layers. Plasmonics J. 18(5), 1771–
1786 (2023)
37. A.H.M. Iftekharul Ferdous, Md. Pretom Sarker, Md. Galib Hasan,
A. Islam, A. Musha, T.M.K. Anwer, S.H. Ahammad, A.N.Z.
Rashed, M.M.A. Eid, Md. Amzad Hossain, Design of a terahertz
regime-based surface plasmon hybrid photonic crystal fiber edible
oil biosensor. Plasmonics J. 18(5), 1923–1932 (2023)
38. D. Kayam Saikumar, R. Arulanantham, R.T. Rajalakshmi, P.S.
Prabu, K.S. Kumar, S.H. Vani, M.M.A. Ahammad, A.N. Eid, Md.
Zaki Rashed, A. Hossain, A. Pal, design and development of sur-
face plasmon polariton resonance four-element triple-band multi-
input multioutput systems for LTE/5G applications. Plasmonics J.
18(5), 1949–1958 (2023)
Publisher’s Note Springer Nature remains neutral with regard to
jurisdictional claims in published maps and institutional affiliations.
Springer Nature or its licensor (e.g. a society or other partner) holds
exclusive rights to this article under a publishing agreement with the
author(s) or other rightsholder(s); author self-archiving of the accepted
manuscript version of this article is solely governed by the terms of
such publishing agreement and applicable law.