Nonlinear Optical Absorption Research Articles

Thermal and optical characterization of a resistance-temperature detector based on platinum thin film: Design and fabrication

In this research, it is presented an easy-to-implement method, utilizing spin coating-sputtering technique, for the production of cost-effective resistance temperature detectors (RTDs) based on platinum (Pt). By employing physical patterning mask techniques such as lithography, the shape of RTDs can be readily customized to meet specific requirements. Furthermore, the developed Pt-based RTDs exhibit a higher sensitivity, with a temperature coefficient of resistance (α) approximately at 3.87 × 10−3 ◦C−1, compared to RTDs based on Au, Ag, and Cu. The sensitivity of these Pt-based RTDs is comparable to that of commercially available Pt-based sensors. Moreover, these RTDs demonstrate exceptional repeatability, maintaining consistent performance within a temperature range of up to 200 ◦C. According to interesting nonlinear optical findings, Pt-based RTD sensor showed the nonlinear optical responses in the 532 nm wavelength because of two photon absorption phenomena in nonlinear absorption coefficient (NLA) and self-focusing effect in addition to their excellent temperature sensing capabilities, the Pt-based RTDs exhibit notable nonlinear optical refractive index (NLR) and nonlinear absorption (NLA) properties. The NLR index of the RTDs is on the order of 10−8 cm2/W, while the NLA index is on the order of 10−3 cm/W. This implies that these RTDs possess significant nonlinear optical response characteristics. Moreover, the Pt-based RTDs demonstrate rapid response times to changes in temperature, making them suitable for applications in nonlinear optical equipment such as optoelectronics and photonics.

Effect of ion intercalation and electrochemisorption on nonlinear optical absorption of MoO3: A comparative study of six different ions

Electrochemical modulation of nonlinear optical (NLO) absorption has recently garnered significant attention. In this work, we demonstrate the effective modulation of the third-order NLO absorption of layered molybdenum trioxide (MoO3) by cation intercalation. Upon application of different negative voltages to samples in different electrolytes, we observe varying degrees of enhancement in MoO3’s nonlinear absorption corresponding to different cations and different electrochemical processes. Cation intercalation of H[Formula: see text], Li[Formula: see text], Na[Formula: see text], K[Formula: see text], and Mg[Formula: see text] is found to be more effective in enhancing the nonlinear absorption of MoO3 than electrochemisorption of Al[Formula: see text] cations. Notably, Li[Formula: see text] intercalation leads to the most significant performance improvement, with an enhancement of 11.6 times and a nonlinear absorption coefficient of [Formula: see text][Formula: see text]cm[Formula: see text]GW[Formula: see text]. This improvement is ascribed to the increasing number of defect states in MoO3 during ion intercalation, which strengthens its saturation absorption behavior. Our work provides valuable insights into the electrically controlled NLO performance of MoO3 and can be applied to other similar materials.

Improved Haacke's quality factor, third order nonlinear susceptibility and specific capacitance realized for PbS thin films through La3+ doping

The present study examines the third order NLO and electrochemical properties of spray deposited lanthanum doped PbS (PbS:La) thin films. FCC crystallization was confirmed by XRD patterns along the plane (2 0 0). PbS crystallites vary in size between 27 and 36 nm with La doping concentration. Surface morphology improved with La doping. La doping increases the band gap from 1.97 to 2.18 eV. Near band edge (NBE) emissions in PL spectra originates from electron-hole recombination. A low resistivity of 0.23 x10−3 Ω-m was realized for PbS film doped with 4 wt% La concentration. Figure of merit of pure PbS improves from 1.32 x 10−3 Ω−1 to 1.607 x 10−2 Ω−1 with La doping. La doping modifies the energy states and band gap of PbS favouring strong nonlinear optical absorption. PbS:La thin films demonstrate self-defocusing due to temperature effects caused by absorption of single photons or free carriers. As a result of the low cationic field strength and high polarizability of La3+ ions, PbS exhibits a higher nonlinear refractive index. The nonlinear susceptibility and refractive index were found to be in the range 3.23–5.33 x 10−6 esu and 2.74 to 3.64 x 10−9 cm2/W, respectively. From the electrochemical studies, increased specific capacitance (256.46 F/g) and decreased charge transfer resistance (12 x 103 Ω) was observed for the 4 wt% La doped film.

Spectroscopic Identification of the Charge Transfer State in Thiophene/Fullerene Heterojunctions: Electroabsorption Spectroscopy from GW/BSE Calculations.

Creation of charge transfer (CT) states in bulk heterojunction systems such as C60/polymer blends is an important intermediate step in the creation of carriers in organic photovoltaic systems. CT states generally have small oscillator strengths in linear optical absorption spectroscopy owing to limited spatial overlap of electron and hole wave functions in the CT excited state. Electroabsorption spectroscopy (EA) exploits changes in wave function character of CT states in response to static electric fields to enhance detection of CT states via nonlinear optical absorption spectroscopies. A 4 × 4 model Hamiltonian is used to derive splittings of even and odd Frenkel (FR) excited states and changes in wave function character of CT excited states in an external electric field. These are used to explain why FR and CT states yield EA lineshapes which are first and second derivatives of the linear optical absorption spectrum. The model is applied to ammonia-borane molecules and pairs of molecules with large and small B-N separations and CT or FR excited states. EA spectra are obtained from differences in linear optical absorption spectra in the presence or absence of a static electric field and from perturbative sum over states (SOS) configuration interaction singles χ(2) and χ(3) nonlinear susceptibility calculations. Good agreement is found between finite field (FF) and SOS methods at field strengths similar to those used in EA experiments. EA spectra of three C60/oligothiophene complexes are calculated using the SOS method combined with GW/BSE methods. For these C60/oligothiophene complexes, we find several CT states in a narrow energy range in which charge transfer from the thiophene HOMO level to several closely spaced C60 acceptor levels yields an EA signal around 10% of the signal from oligothiophene.

Nonlinear optical absorption and optical limiting of magnetic iron oxide nanomaterials

Integration of nanoparticles into polymeric materials enhances the optical properties and stability of the formed nano-composite materials. In this work, magnetic iron oxide nanoparticles Fe3O4NPs were prepared via chemical coprecipitation. In addition, it is polymerized in a host of polyvinylpyrrolidone PVP. The prepared iron oxide nano-size was about 14.0 nm as confirmed by Transmission Electron Microscopy, A vibrating sample magnetometer VSM studies showed Fe3O4NPs possess superparamagnetic behavior. Energy-dispersive X-ray spectroscopy, and X-ray diffraction confirmed the structure and composition of Fe3O4NPs. Open aperture Z-scan and optical limiting experiments were carried out at nanosecond pulses of wavelength 532 nm. The nonlinear absorption coefficients were calculated for the colloidal and polymeric iron oxide. Fe3O4NPs polymeric film exhibits enhanced nonlinear optical properties NLO, and superior optical limiting properties compared to Fe3O4NPs colloidal solution. That makes Fe3O4 nanocomposites a promising candidate for optical limiting applications.

High-damage-threshold mid-infrared saturable absorber enabled by tantalum carbide nanoparticles.

A stable mid-infrared saturable absorber with a high damage threshold is urgently required for high-performance optical modulation in the mid-infrared regime. Here, we demonstrate stable mid-infrared erbium-doped fiber laser generation modulated by tantalum carbide nanoparticles (TaC NPs) experimentally. The TaC NPs show high physicochemical stability, obvious nonlinear optical absorption, and a high damage threshold. By introducing the TaC-based saturable absorber into an erbium-doped fiber laser, stable nanosecond pulses can be successfully delivered with a minimum pulse duration of 575 ns and signal-to-noise ratio of over 40 dB. The experimental results show that TaC NPs can act as a stable mid-infrared pulse modulator, and may make inroads for developing highly stable broadband optoelectronic devices.

Magnetic field effect on the linear and nonlinear refractive index and optical absorption of a donor in a GaAs quantum ring

The effects of the magnetic field (γ), the radial position of impurity and the degree of confinement on the oscillator strength (OS), refractive index and optical absorption (α) of an impurity inside a GaAs quantum ring (QR) are explored using the effective mass approximation and variational method. It is shown that the peak position of the optical absorption and the refractive index decrease and move toward the lower incident photon energy as the strength of the γ increases. In addition, it is found that the strongest α relates to the case when the impurity is positioned at the right side of QR in the presence of the magnetic field. Our examinations also show that the oscillator strength decreases as the γ increases especially for an on-center donor impurity.

Investigation of band parameters and electrochemical analysis of multi core-shell CdSe/CdS/ZnS quantum dots

Highly emissive core−multi-shell (CdSe/CdS/ZnS) quantum dots (QDs) within size range of ∼ 2 nm–5 nm were prepared via hot injection method. Capping agent (polymers) were used to increase the lifetime of QDs, without a protective atmosphere. Red shift was observed in an absorption spectrum of QDs peaks at 362 nm, 365 nm, 558 nm, and 556 nm for CdSe/CdS and CdSe/CdS/ZnS with respect to CdSe core. Voltammetry measurements (Eg ∼ 2. 09 eV) for band gaps were in good agreement with the UV–visible spectroscopic data (Eg ∼ 2.65 eV). QDs exhibited three distinguished peaks comparing to (111), (220), and (311) planes of cubic structures of CdSe, CdSe/CdS and CdSe/CdS/ZnS within crystallite size of 20–27 nm as observed by XRD spectra. A larger active surface area 0.06 cm−2, computed by CV increased the catalytic activity of sensors by exposing the electroactive sites. Linear, nonlinear optical susceptibility and absorption coefficients were computed by an effective mass model. Quantum confinement was confirmed by taking electron probability density as function of radial distance of quantum dots.

Plasmon enhancement of third-order nonlinear optical absorption of gold nanoparticles dispersed in planar oriented nematic liquid crystals

We report structural and nonlinear optical properties of 20 nm gold (Au) nanoparticles (NPs) that are dispersed in planar degenerate (non-oriented) and planar oriented nematic liquid crystals (LCs) (4′-Pentyl-4-biphenylcarbonitrile-5CB). Taking advantage of elastic forces in the planar oriented nematic LC, we aligned AuNPs parallel to the 5CB director axis. In the case of planar degenerate, 5CB is not aligned and has no preferred orientation, forcing the AuNPs to disperse randomly. Results show that the linear optical absorption coefficient for the planar oriented 5CB/AuNPs mixture is larger than the corresponding planar degenerate sample. The nonlinear absorption coefficients are greatly enhanced in planar oriented samples at relatively high concentrations which can be attributed to plasmon coupling between the aligned AuNPs. This study demonstrates the utility of LCs for developing the assembly of NPs with enhanced optical properties which may offer important insight and technological advancement for novel applications, including photonic nanomaterials and optoelectronic devices.

Nonlinear refractive index enhancement of Nd3+ ions loaded borate glasses in the near–infrared region by silver nanoparticles

The study presents an evaluation and in–depth discussion of the efficacy of silver (Ag) nanoparticles (NPs) concentration on the third–order nonlinear optical (NLO) proeprties of borate glasses. The optical absorption data revealed Nd3+ ions and Ag NPs to be present in the studied glasses. Measurements carried out on the tested glass through transmission electron microscopy revealed spherical–shaped NPs with a median size of ∼16.53 nm (analyzed using the ImageJ software). Open and closed aperture Z–scan configurations were employed to ascertain the attributes of NLO absorption and refraction, respectively. Open–aperture Z–scan data revelaed two–photon absorption nonlinearity in the studied glasses, while the closed aperture Z–scan data revealed self–focusing nonlinear refraction. With the increase in silver NPs concentration, the nonlinear refraction coefficient was significantly increased compared to the nonlinear absorption parameter. The results instantiate large concentrations of Ag NPs embedded in borate glasses bearing Nd3+ ions are suitable for all–optical switching applications that excel in their functioning in near–infrared spectral range.

Tunable, efficient, ultrafast broadband nonlinear optical properties of TiO2–loaded complex phosphate glasses

On account of their excellent optical transparency from ultraviolet to far infrared spectral regions, phosphate glasses have become interesting nonlinear optical (NLO) materials for photonic nonlinear devices. However, small NLO coefficients tend to limit the usage of phosphate–based glasses in nonlinear photonic devices. Herein, we explored the NLO tunability in multicomponent phosphate glasses by increasing the coordination of orthophosphate (PO4)3– structural units with a great number of AlO4 groups through the addition of titanium dioxide (TiO2) in the composition. The NLO absorption and refraction characteristics were ascertained using open and closed–aperture Z–scan configurations respectively in a broadband spectral region ranging from 400 nm to 1200 nm under an ultrafast regime. The Z–scan results illustrate the increase of nonlinear susceptibility of glasses with titanium dioxide content in the composition due to the formation of non–π–conjugated orthophosphate groups which are in connection with AlO4 units. Typically, at 400 nm excitation, the NLO susceptibility improved by 119.91% upon addtion of 5 mol% of TiO2. The outcomes of the study acknowledge a new approach for conceiving highly NLO active phosphate glasses while maintaining deep–ultraviolet transparency through the polymerization of (PO4)3−groups. Consequently, the strategy explored in this work might pave the way for achieving the high NLO features of phosphate–based glasses to excel in their usage in data storage, signal transmission, optical limiting, and harmonic generation functionalities.

Tunable optical nonlinearities and surface plasmon resonance in Fe3O4 nanoparticles-decorated Ti3C2 MXene composite for ultrafast fiber lasers

In this work, the Ti3C2 MXene was modified with Fe3O4 nanoparticles to obtain a composite with in-plane optical anisotropy and surface plasmon properties. Based on a side-polished D-shaped fiber (DSF), this Fe3O4/Ti3C2 MXene (F/M) composite exhibits a tunable nonlinear optical (NLO) absorption response under 1.5 μm laser excitation with different polarization states. The modulation depths can be obtained from 0.9% to 12.1%. As an application, the ultrafast erbium-doped fiber laser (EDFL) with multiple pulsed laser operations was demonstrated using the F/M-DSF device as a saturable absorber (SA). Both stable Q-switching and mode-locking operations were demonstrated in the same all-fiber laser cavity, which generated pulsed laser with microsecond and sub-picosecond durations respectively. In addition, the bound state (BS) of solitons in harmonic mode-locked lasers with the pulse time interval of 3 ps and the highest order of 30th was also realized. This versatile and simple-structured all-fiber laser has great potential in various applications, such as optical communication. With the numerical simulations, the dynamic of F/M composite-based soliton mode-locking was also explored, illustrating the mechanism of soliton formation and propagation. This work not only expands the advanced applications of F/M composite in ultrafast photonics but also provides a new perspective for designing and optimizing its ultrafast modulating performance.

Toward strong nonlinear optical absorption properties of perovskite films via porphyrin axial passivation

Defects within perovskite layers are considered to be a primary factor that inhibits nonlinear optical (NLO) performance, and mitigating or eliminating them is indispensable for the implementation of high-performance perovskite-based photonic and energy devices. Herein, we propose a novel defect modulation strategy through binding the functional groups at the axial positions of porphyrins with the defects of perovskites. Two axially-coordinated porphyrin molecules (TiOPr and SnOHPr) were utilized as effective functional additives to passivate the defects and control perovskite crystallization, while the role of axial functional groups of porphyrins has been systematically studied. Z-scan measurement results demonstrate that porphyrin-treated perovskite films exhibit prominently enhanced optical absorption nonlinearities under ultrafast femtosecond (fs) laser excitation at 800 nm in comparison to the MAPbI3 perovskite film, the NLO absorption coefficient (β) values for the modified films are approximately one or two orders of magnitudes superior to that of the pristine film. This significant improvement in NLO performance likely stems from the increased photoinduced ground-state dipole moment of the perovskite film treated by porphyrin during the process of two-photon absorption (TPA), and their photoinduced charge/energy transfer between perovskite and porphyrin. Particularly, the MAPbI3/SnOHPr film displays the largest β values (636.92–6621.42 cm GW−1) among all measured samples at different irradiation energies and a low optical limiting threshold of 5 mJ cm−2, which may profit from the dual-functional passivation effect of SnOHPr onto perovskite, suggesting its great potential as optical limiters. These observations strongly indicate that porphyrin-axial passivated perovskite films are outstanding material candidates for optical limiting applications towards ultrafast fs laser pulses in the near-infrared region. Our work affords a feasible paradigm for constructing high-performance NLO perovskite materials through porphyrin-axial passivation of defects.

Gold Nanomaterial‐Based Optical Modulators for Wideband Pulse Laser Generation

Pulsed lasers have wide applications in several fields, such as basic research, telecommunications, and industrial materials processing. A saturable absorber (SA) is a key component for pulse laser generation. However, the current SAs exhibit certain limitations. Hence, developing new nonlinear optical materials as SAs for pulse lasers generation is significantly important in ultrafast photonics and related applications. Metallic nanomaterials have attracted considerable attention because of their higher nonlinearity coefficients and wideband nonlinear response, which are induced by the surface plasmon resonance (SPR) effect. The SPR effect depends on the size and morphology of materials. Thus, the nonlinear optical absorption effect of gold nanomaterials for pulse laser generation must be explored. In this review, the optical properties of gold nanomaterials are introduced, including SPR absorption, photoluminescence properties, and surface‐enhanced Raman scattering effect. Then, the synthesis and characterization of different gold nanomaterials are reviewed. Subsequently, the nonlinear optical characteristics and devices based on gold nanomaterials are also introduced. Furthermore, the generation of different types of lasers using gold nanomaterial‐based devices is also reviewed. A comparison between gold nanomaterials and other SA materials is presented. Finally, the conclusion and outlook on gold nanomaterial‐based nonlinear optical devices are presented.

Nonlinear optical properties in organic fish gelatin, potassium dichromate, and organic–inorganic mix

The nonlinear optical properties of fish gelatin, potassium dichromate, and a mix of both are presented. The z-scan experimental technique and the photo-induced thermal lens formation model are used to determine nonlinear optical parameters such as the non-linear refractive index and the nonlinear optical absorption coefficient. The spatial self-phase modulation in the mixture is analyzed with an Ar continuous wave (cw) laser at 477 nm at different light powers. Furthermore, we theoretically studied the electrostatic interaction between potassium dichromate and fish collagen based on the Density Functional Theory. The experimental and theoretical results show that the nonlinear optical properties of the mixture are improved due to better thermal conductivity and stability, indicating a high potential for optical applications such as nonlinear gratings and holography.

Nonlinear Optical Response of Dispersed Medium Based on Conjugates Single-Walled Carbon Nanotubes with Phthalocyanines

Nanosecond lasers have recently been widely involved in human activity. However, high-intensity laser radiation can cause severe damage to organs of vision and expensive photonic devices. Radiation in the near UV range is especially dangerous for human eyes, since it is strongly absorbed by biological media and is also invisible, i.e., the reaction time of the eye to such radiation is much lower than that of visible light. Passive limiters have high transmission (>70%) at a low light intensity and begin to “darken” only when the threshold value of the laser radiation intensity is reached. In this work, we studied liquid nanodispersed nonlinear optical limiters based on hybrids of single-walled carbon nanotubes (SWCNTs) with metal-free tetra(hydroxy)phthalocyanine (OH)4PcHH). The value of the hydrodynamic radius of separate particles after (OH)4PcHH binding increased from 288 ± 55 nm to 350 ± 60 nm, which confirms the attachment of phthalocyanine complexes to nanotubes. The third harmonic of a Nd:YAG nanosecond laser (355 nm, 20 ns) was used to study the nonlinear optical response. Based on a Z-scan with open-aperture and input-output dependence curves, third-order nonlinear optical absorption coefficients of 149, 236, and 229 cm/GW were obtained for dispersions of composites of SWCNTs and (OH)4PcHH in water, dimethylformamide (DMF), and dimethylsulfoxide (DMSO), respectively. Threshold values did not exceed 100 mJ/cm2. The Z-scan showed a gradual decrease in the duration of the laser pulse by 53%; however, near the focus, there was a sharp increase in the duration of the transmitted pulse, reaching a value of 29 ns in z = 0. This phenomenon confirms the occurrence of reverse saturable absorption in the investigated media and can be used in photonic devices to control the temporal characteristics of the signal. Thus, the possibility of protection of sensitive photonic devices and human eyes from nanosecond laser pulses in the near UV range by nanodispersed liquid media based on composites of SWCNTs with (OH)4PcHH has been discussed in this paper.

A Cut-to-Link Strategy for Cubane-Based Heterometallic Sulfide Clusters with Giant Third-Order Nonlinear Optical Response

Although the synthesis of low-dimensional metal sulfides by assembling cluster-based units is expected to promote the development of optical materials and models of enzyme active centers such as dinitrogenase, it is faced with limited assembly methodology. Herein we present a cut-to-link strategy to generate high-nuclearity assemblies, inspired by the formation of a Z-type dimer of the W-S-Cu analogues of PN cluster through in situ release of active linkers. Four new compounds with structures based on the same {Tp*WS3Cu3} incomplete cubane-like units were obtained using varied combinations of mild reagents. Open-aperture Z-scan measurements demonstrated the highest-nuclearity complex has the largest nonlinear optical absorption coefficient among discrete cluster-based materials reported to date. This approach enables building high-nuclearity metal sulfide clusters through cluster-based building blocks and opens a way to the design and exploration of materials based on well-identified building blocks.

Ultrafast optical nonlinearity in natural van der Waals heterostructure nanosheets of franckeite

Franckeite, a natural van der Waals heterostructure with excellent physicochemical characteristics, has shown great potential for high-performance optoelectronic device. Here, the few-layer franckeite nanosheets have been prepared by liquid phase-exfoliation method successfully, and the nonlinear optical absorption and carrier dynamics behaviors of the nanosheets have been studied experimentally. The franckeite nanosheets show wavelength- and intensity-dependent nonlinear absorption characteristics, and exhibit ultrafast carrier dynamic process. The ultrafast optical nonlinearity in franckeite nanosheets has been further validated via an Er3+-doped fiber laser to deliver stable femtosecond pulse. The experimental results reveal that franckeite heterostructure nanosheets can be an ideal candidate in the design and manufacture of ultrafast nonlinear optoelectronic devices.

Enhanced Optical Nonlinearity in Bi3+-Doped CePO4 Nanostructures for Optical Limiting Applications

Pure and Bi3+-doped CePO4 were synthesized by the simple co-precipitation method. Successful dopant incorporation into the host lattice of orthophosphate without altering the crystalline structure was confirmed by structure analysis, X-ray diffraction, and Raman characterization. Morphological investigation was done using HR-SEM which portrays the co-existence of nanospheres and nanorods in doped CePO4 and only nanospheres in pure CePO4. X-ray photoelectron spectroscopy studies confirm the +3 oxidation state of Ce3+ and Bi3+ with the presence of a trace amount of Ce4+ in the as-prepared nanoparticles. Vibration sample magnetometer studies show weak ferromagnetic behavior of the nanostructures at room temperature. The absorption band in the wavelength range 200–300 nm accounts for 4f–5d electronic transition, and a red shift in the band edge is due to the increase in the band gap with the addition of the dopant. Photoluminescence emission spectra show broad blue-green emission owing to transition of Ce3+ from the excited state to the ground state and also due to oxygen vacancy. The nonlinear optical absorption and optical limiting (OL) behaviors of Bi3+-doped cerium orthophosphate (CePO4) were investigated using an open-aperture (OA) Z-scan technique under an excitation source of 532 nm nanopulsed lasers. The recorded OA transmittance curve reveals a transition from saturable absorption to reverse saturable absorption in pure CePO4 at 2.46 GW/m2, whereas all the doped samples exhibit RSA attributed to 2PA. The increase in the nonlinear absorption (NLA) coefficient with on-axis intensity and the availability of the near resonant energy state due to the Bi3+ dopant ensure the sequential 2PA (1PA + ESA) phenomenon. Compared to pure CePO4, doped nanostructures show improved NLA coefficients due to the availability of the defect state and oxygen vacancies in Bi3+-doped CePO4. Interestingly, a lower OL threshold (OLT) of 0.14 × 10–13 W/m2 is observed in 0.3% Bi3+-doped CePO4. The lower OLT value of Bi3+-doped CePO4 ensures its potential candidature for OL applications in protecting optical sensors and human eyes.

Physical Mechanism of Nonlinear Spectra in Triangene.

In this work, we theoretically investigate the linear and nonlinear optical absorption properties of open triangulene spin chains and cyclic triangulene spin chains in relation to their lengths and shapes. The physical mechanism of local excitation within the triangular alkene unit and the weak charge transfer between the units are discussed. The uniformly distributed electrostatic potential allows the system to have a small permanent dipole moment that blocks the electronic transition in the light excitation such that the electronic transition can only be carried out between adjacent carbon atoms. The one-photon absorption (OPA) spectra and two-photon absorption (TPA) spectra are red-shifted with the addition of triangulene units compared to N = 3TSCs (triangulene spin chains, TSCs). Here, TPA is mainly caused by the first step of the transition. The length of the spin chain has a significant adjustment effect on the photon cross-section. TSCs of different lengths and shapes can control chirality by adjusting the distribution of the electric dipole moment and transition magnetic dipole moment. These analyses reveal the photophysical properties of triangulene and provide a theoretical basis for studying the photophysical properties of triangulene and its derivatives.