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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Towards Optimized Photon-Pair Sources for Two-Photon Transitions
摘要： Two-photon absorption (TPA) is a nonlinear optical process with wide applications in ?uorescence microscopy and spectroscopy of organic molecules and compounds, as it enables atoms or molecules to transition into states that may otherwise be inaccessible by a single photon, either because of selection rules or energy conservation. Despite its common use, TPA is a rather inef?cient process, often requiring very large photon numbers to produce significant results. It has been demonstrated and analytically described [1,2], that using frequency entangled pairs of photons can in some cases enhance the ef?ciency of TPA. For this to occur, the joint spectral amplitude (JSA) of the photon-pair state, which describes the spectral entanglement between the pair, must be engineered according to the spectral properties of the TPA response-function of the speci?c system in question. In this work, we consider different cases for the spectral functionality of TPA and propose that the control of the group indices of the modes involved in the pair-generation process is a key property in the design of photon-pair sources for optimized TPA.
关键词： joint spectral amplitude,spectral entanglement,group indices,Two-photon absorption,photon-pair sources
更新于2025-09-11 14:15:04
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Application of Two-Photon-Absorption Pulsed Laser for Single-Event-Effects Sensitivity Mapping Technology
摘要： Single-event effects (SEEs) in integrated circuits and devices can be studied by utilizing ultra-fast pulsed laser system through Two Photon Absorption process. This paper presents technical ways to characterize key factors for laser based SEEs mapping testing system: output power from laser source, spot size focused by objective lens, opening window of Pockels cell, and calibration of injected laser energy. The laser based SEEs mapping testing system can work in a stable and controllable status by applying these methods. Furthermore, a sensitivity map of a Static Random Access Memory (SRAM) cell with a 65 nm technique node was created through the established laser system. The sensitivity map of the SRAM cell was compared to a map generated by a commercial simulation tool (TFIT), and the two matched well. In addition, experiments in this paper also provided energy distribution pro?le along Z axis that is the direction of the pulsed laser injection and threshold energy for different SRAM structures.
关键词： pulsed laser,SRAM,single event effect,sensitive mapping,two photon absorption
更新于2025-09-11 14:15:04
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Slipped Structure of Covalent Organic Framework Facilitates Two‐Photon Adsorption for Improving Near‐Infrared Excited Fluorescence Imaging
摘要： Fluorescent materials exhibiting the characteristics of strong two-photon absorption (TPA) are extensively used for nonlinear optics, bio-imaging and phototherapy. One practical approach to obtain fluorescent materials with high TPA performance is to polymerize molecular chromophores to form π-conjugated structure. This leads to the increase in TPA cross-section per chromophore, however, efforts to towards this direction was capped by the lack of long-range ordering in the structure and the strong π-π stacking between the chromophores. Here, we reported the rational design of benzothiadiazole-based covalent organic framework (COF) for promoting TPA performance and obtaining the efficient two-photon excited fluorescence. Structure characterizations and spectroscopic studies revealed that the enhancement in TPA performance was attributed to the donor-π-acceptor-π-donor (D-π-A-π-D) configuration of the chromophore, long-range order, and large π-conjugation domain of COF crystals. The structural slipping in TPA-COF not only attenuates the π-π stacking interaction between the layers, but more importantly, overcomes the aggregation-caused emission quenching of the chromophores for improving near-infrared two-photon excited fluorescence imaging.
关键词： covalent organic framework,long-range order,two-photon absorption,slipped structure,fluorescence imaging
更新于2025-09-11 14:15:04
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Slipped Structure of Covalent Organic Framework Facilitates Two-Photon Adsorption for Improving Near-Infrared Excited Fluorescence Imaging
摘要： Fluorescent materials exhibiting the characteristics of strong two-photon absorption (TPA) are extensively used for nonlinear optics, bio-imaging and phototherapy. One practical approach to obtain fluorescent materials with high TPA performance is to polymerize molecular chromophores to form π-conjugated structure. This leads to the increase in TPA cross-section per chromophore, however, efforts to towards this direction was capped by the lack of long-range ordering in the structure and the strong π-π stacking between the chromophores. Here, we reported the rational design of benzothiadiazole-based covalent organic framework (COF) for promoting TPA performance and obtaining the efficient two-photon excited fluorescence. Structure characterizations and spectroscopic studies revealed that the enhancement in TPA performance was attributed to the donor-π-acceptor-π-donor (D-π-A-π-D) configuration of the chromophore, long-range order, and large π-conjugation domain of COF crystals. The structural slipping in TPA-COF not only attenuates the π-π stacking interaction between the layers, but more importantly, overcomes the aggregation-caused emission quenching of the chromophores for improving near-infrared two-photon excited fluorescence imaging.
关键词： covalent organic framework,long-range order,two-photon absorption,slipped structure,fluorescence imaging
更新于2025-09-11 14:15:04
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Isomerism and coordination mode effects on two-photon absorption of tris(picolyl)amine-based fluorescent probes for zinc ions
摘要： One-photon absorption and two-photon absorption (TPA) properties of three tris(picolyl)amine-based zinc ion sensors are investigated by employing the density functional response theory in combination with the polarizable continuum model. The different isomer and coordination geometry of each probe are taken into account. Special emphasis is placed on the effects of isomerism and the coordination mode on the optical properties. The intra-molecular charge transfer (ICT) properties are specified by natural bond orbital charge analysis. It is shown that the isomerism has non-negligible effects on TPA properties of free ligands. It is found that both the TPA wavelength and the cross section are highly dependent on the coordination mode. When the zinc ion connects with the picolyl unit in the middle of a ligand, the zinc complex has a large TPA intensity in a long wavelength range due to the increased ICT mechanism.
关键词： isomerism,zinc ion,coordination mode,two-photon absorption
更新于2025-09-09 09:28:46
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[Polymers and Polymeric Composites: A Reference Series] Functional Polymers || Photo-polymerization
摘要： The synthesis of functional polymers by photopolymerization thrives on the rich tradition of industrial photochemistry. Photo-induced polymerization can be broadly divided based on the initiation mechanism as radical, cationic, and anionic photopolymerization. A wide variety of initiators, photosensitizers, and polymerizable materials have been studied for various applications. This chapter is intended to be a primer to major concepts of photopolymerization. In the beginning of the chapter, physical aspects of light matter interactions are presented followed by photochemical pathways leading to reactions. In the subsequent sections radical polymerization is discussed by introducing different types of initiating systems and polymerizable materials. Within the section on radical polymerization, visible light polymerization and thio-ene photochemistry are also discussed. The section on thiol-ene looks at the fundamentals of thiol-ene reactions, their initiation, reactivity, and advantages over other radical driven polymerizations. Cationic polymerization is covered based on the material science of ionic and nonionic photoacid generators (PAGs). This section also discusses spectral broadening of reactivity in PAGs to visible wavelengths through electron transfer sensitization and free radical promoted cationic polymerization (FRPCP). Unlike radical and cationic polymerization there are little or no reports of commercial application of anionic polymerization. However, due to typical monomers employed in anionic polymerization and the control over the extent of polymerization afforded by this techniques makes it very attractive for functional applications. The section on anionic polymerization summarizes recent developments in this field. Finally in the section about two-photon initiated polymerization, we discuss the scope of nonlinear optical phenomena in photopolymerization.
关键词： anionic polymerization,radical polymerization,two-photon absorption,photopolymerization,photoinitiators,photosensitizers,cationic polymerization
更新于2025-09-09 09:28:46
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A series of two-photon absorption organotin (IV) cyano carboxylate derivatives for targeting nuclear and visualization of anticancer activities
摘要： Compared to organotin (IV) compounds with biochemical activity, two-photon absorption (2PA) organotin (IV) complexes for targeting nuclear with anticancer activities are rarely reported. Here, two novel 2PA organotin (IV) cyano carboxylate complexes (C1Sn-1, C1Sn-2) are synthesized and characterized. The two-photon absorption cross section values (δ) in the near-infrared region are significantly enhanced for C1Sn-2 compared to C1Sn-1, thus developing for targeting nuclear by two-photon fluorescence microscopy (2PFM). C1Sn-2 could specifically target nuclear DNA in vitro. The mechanism demonstrated that there are abundant hydrogen bond interactions between hydroxy group of C1Sn-2 and DNA. The animal mode studies are first proposed that C1Sn-2 displayed a certain anti-cancer efficiency with non-significant toxicity.
关键词： anticancer,organotin,two-photon absorption
更新于2025-09-09 09:28:46
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Temporally Resolving Synchronous Degenerate and Nondegenerate Two-Photon Absorption in 2D Semiconducting Monolayers
摘要： Degenerate and nondegenerate two-photon absorption (TPA) in WS2 and MoSe2 monolayers are synchronously induced and temporally resolved by femtosecond laser pump-probe. Di?erential transmission signals in the ?rst 500 fs consist of negative and positive components, that originate from direct probe depletion via nondegenerate TPA and carrier accumulation via degenerate TPA, respectively. Temporal cross-correlation of pump and probe pulses allows us to fully decouple the ultrafast nondegenerate and degenerate TPA signals. Subsequently, degenerate and nondegenerate TPA coe?cients are calculated as a function of pump irradiance. Under nonresonant pumping, 100 ± 10 and 250 ± 25 cm GW?1 are obtained for degenerate and nondegenerate TPA coe?cients of monolayer WS2, respectively, which both present linearly decreasing trends as increasing pump irradiances. However, under resonant pumping of 2 p excitonic states in monolayer MoSe2, degenerate TPA coe?cients exponentially decrease from 800 to 80 cm GW?1 as increasing pump irradiances, due to the interplay between band-renormalization and band-?lling e?ects, while nondegenerate TPA coe?cient is about 650 ± 50 cm GW?1. For comparison, a trilayer MoSe2 is also investigated. These results set a foundation for precisely measuring TPA coe?cients and actively controlling nonlinear excitonic dynamics via TPA in 2D semiconducting monolayers.
关键词： 2D monolayer,transition metal dichalcogenide,femtosecond laser pump-probe,nondegenerate two-photon absorption,degenerate two-photon absorption
更新于2025-09-04 15:30:14
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All-Optical Poling and Two-Photon Absorption in Heterocyclic Azo Dyes with Different Side Groups
摘要： We investigated the optical properties of heterocyclic azo dyes with different side groups prepared: as powders, in PMMA matrix and side-chain polymers. We characterized the nonlinear optical effects of these compounds by Z-scan and all-optical poling techniques and supported these experiments with theoretical modeling. It was also found that these materials show strong two-photon absorption cross-sections exceeding 20 GM, which is one order of magnitude stronger than that of similar materials (azobenzene and p-aminoazobenzene). Our study reveals the dominant role of the side-chain system over the guest-host one and stress out the importance of the substituent in the efficiency of the poling process.
关键词： All-Optical Poling,Hybrid Materials,Heterocyclic Azo Dyes,Two-Photon Absorption,Plasmonics,Optical,Magnetic
更新于2025-09-04 15:30:14
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Synthesis, Photophysical Properties and Two Photon Absorption Study of Tetraazachrysene‐based N‐heteroacenes
摘要： Three novel N-heteroacene molecules (SDNU-1, SDNU-2 and SDNU-3) based on tetraazachrysene units as cores have been designed, synthesized and fully characterized. Their photophysical, electrochemical and fluorescence properties were investigated, and they exhibited blue to green emission in solid state. Interestingly, SDNU-2 exhibited high solid photoluminescence quantum efficiencies (75.3%), which is the highest value of N-heteroacenes derivatives to date. Two-photon absorption studies have been conducted by using open and close aperture Z-scan technique. SDNU-3 showed a significant enhancement in the two-photon absorption cross-section with magnitudes as high as ～700 GM (1 GM = 1 × 10–50 cm4 s/photon) when excited with 800 nm light, which is the largest value based on heteroacene system measured by Z-scan experiment so far. We attribute the outcome to sufficient electronic coupling between the strong charge transfer of quadrupolar substituents and the tetraazachrysene core. Our result would provide a new guideline to design novel efficient two-photon materials based on N-heteroacene cores.
关键词： Synthesis,Fluorescence quantum yields,Azaacenes,Two Photon Absorption
更新于2025-09-04 15:30:14