Ultrafast Third-order Nonlinearity Research Articles

Enhancing the Ultrafast Third-Order Nonlinear Optical Response by Charge Transfer in VSe2-Reduced Graphene Oxide Hybrid

Enhancing the Ultrafast Third-Order Nonlinear Optical Response by Charge Transfer in VSe₂-Reduced Graphene Oxide Hybrid

Ultrafast Third-Order Nonlinear Optical Response Excited by fs Laser Pulses at 1550 nm in GaN Crystals.

The ultrafast third-order optical nonlinearity of c-plane GaN crystal, excited by ultrashort (fs) high-repetition-rate laser pulses at 1550 nm, wavelength important for optical communications, is investigated for the first time by optical third-harmonic generation in non-phase-matching conditions. As the thermo-optic effect that can arise in the sample by cumulative thermal effects induced by high-repetition-rate laser pulses cannot be responsible for the third-harmonic generation, the ultrafast nonlinear optical effect of solely electronic origin is the only one involved in this process. The third-order nonlinear optical susceptibility of GaN crystal responsible for the third-harmonic generation process, an important indicative parameter for the potential use of this material in ultrafast photonic functionalities, is determined.

Synthesis, Theoretical Investigation and Ultrafast Third-Order Nonlinear Optical Response of 2-(Pyren-1-yl)-1,8-naphthyridine

Synthesis, Theoretical Investigation and Ultrafast Third-Order Nonlinear Optical Response of 2-(Pyren-1-yl)-1,8-naphthyridine

Synthesis of Two Ferrocene-Based Chalcone Derivatives and Their Ultrafast Third-Order Nonlinear Optical Response

Synthesis of Two Ferrocene-Based Chalcone Derivatives and Their Ultrafast Third-Order Nonlinear Optical Response

Third-order nonlinearity by the inverse Faraday effect in planar magnetoplasmonic structures

We predict a new type of ultrafast third-order nonlinearity of surface plasmon polaritons (SPP) in planar magneto-plasmonic structures caused by the inverse Faraday effect (IFE). Planar SPPs with a significant longitudinal component of the electric field act via the IFE as an effective transverse magnetic field. Its response to the plasmon propagation leads to strong ultrafast self-action which manifests itself through a third-order nonlinearity. We derive a general formula and analytical expressions for the IFE-related nonlinear susceptibility for two specific planar magneto-plasmonic structures from the Lorentz reciprocity theorem. Our estimations predict a very large nonlinear third-order nonlinear susceptibility exceeding those of typical metals such as gold.

Multi-component nanocomposite for all-optical switching applications

We report a multi-component nanocomposite material with large and ultrafast third-order nonlinearity, made of poly(3-hexylthiophene) doped with 1-(3-methoxycarbonyl)propyl-1-phenyl-(6,6)C61 and silver nanoparticles. Large nonlinear refractive index of the order of 10−7 cm2/W is reached by combining surface plasmon resonance enhancing nonlinearity and local-field enhancing nonlinearity. An ultrafast response time of 33.6 ps is achieved due to the enhanced charge transfer and exciton-exciton annihilation associated with surface plasmon resonance. An ultrafast photonic crystal all-optical switching with an ultralow pump intensity of 70 KW/cm2 is also realized.

Ultrafast optical Kerr effect in amorphous chalcogenide films

Amorphous chalcogenide As2S3, As2Se3, GeS2, GeSe2, Ge20As25S55, Ge20As25Se55, Ge10As40S20Se30 films were studied by femtosecond OHD-OKE. Ict was indicated that the third-order nonlinear susceptibility χ(3) was as large as 10-12 esu, and they also exhibited a very fast response time shorter than 200 fs. Their nonlinear refractive indices and absorption were also calculated from the above results. The ultrafast response and large third-order nonlinearity in amorphous chalcogenide films are attributed to the ultrafast distortion of the electron cloud of atoms.

SbS 3 enhanced ultrafast third-order optical nonlinearities of Ge–S chalcogenide glasses at 820 nm

GeS 2 based multi-component chalcogenide glasses, Ge–S–Sb(Cd), were prepared in series. With femtosecond time-resolved optical Kerr gate technique, we investigate their ultrafast third-order nonlinear optical (NLO) properties. The strongest NLO response comes from 0.70GeS 2–0.30Sb 2S 3. Its χ (3), 1.8 × 10 −12 esu, is more than three times to GeS 2 glass. Their instant NLO responses are within 120 fs pulse duration. We suggest that lone-pair electrons from highly polarizable Sb atom in [SbS 3] structure unit play an important role for the enhanced NLO response. This enhancement is much stronger to the contribution from S–S covalent bond.

Ultrafast third-order nonlinearity of silver nanospheres and nanodiscs

We have measured and compared the absolute values of nonlinear susceptibility of colloidalsolutions containing silver nanospheres and nanodiscs at their respective plasmon peaks using afemtosecond laser. The nonlinear process responsible for the laser-induced grating formation inthe sample is determined to be of third order. The ratio between the third-order susceptibility(|χ(3)|) and the linearabsorption coefficient (α) of the nanodiscs at 590 nm is three times than that of the similar ratio for nanospheres at398 nm. Using a randomly oriented ellipsoidal model, we have shown that the increase in|χ(3)|/α for a nanodisc at 590 nm can be attributed to the change in the field enhancement factorwith shape.

Structure dependence of ultrafast third-order optical nonlinearity for GeS 2–In 2S 3–CsI chalcohalide glasses

Ultrafast third-order nonlinear optical responses of GeS 2–In 2S 3–CsI chalcohalide glasses have been measured by using the femtosecond time-resolved optical Kerr effect (OKE) technique at a wavelength of 820 nm. The third-order nonlinear susceptibility was estimated to be as large as 5.12×10 −13 esu. The full width at half maximum of the Kerr signal was 120 fs and its response was dominantly assigned to the ultrafast distortion of the electron cloud. The relationship between the structural units and the third-order nonlinear optical responses was analysed by Raman spectra. It is suggested that the covalent bonds of S–Ge or S–In constituting the tetrahedral units [GeS 4/2] or [InS 4− x I x ], respectively, play an important role in the ultrafast third-order nonlinear optical responses of these chalcohalide glasses.

Ultrafast all-optical chalcogenide glass photonic circuits

<p> <a href="http://oe.osa.org/virtual_issue.cfm?vid=36">Focus Serial: Frontiers of Nonlinear Optics</a> </p>Chalcogenide glasses offer large ultrafast third-order nonlinearities, low two-photon absorption and the absence of free carrier absorption in a photosensitive medium. This unique combination of properties is nearly ideal for all-optical signal processing devices. In this paper we review the key properties of these materials, outline progress in the field and focus on several recent highlights: high quality gratings, signal regeneration, pulse compression and wavelength conversion.

Bisdioxaborine Polymethines with Large Third-Order Nonlinearities for All-Optical Signal Processing

Organic materials with large third-order nonlinearities in the near-infrared spectral regime are critical in the development of photonic devices to be utilized in all-optical signal processing. We have developed polymethine materials, specifically bisdioxaborine-terminated polymethine dyes, which possess large ultrafast third-order nonlinearities and low nonlinear loss all in the near-infrared spectral regime. An extended bisdioxaborine polymethine anion exhibited the largest value of gamma (third-order microscopic nonlinearity) at 1.3 mum (|gamma| = 5.7 x 10-32 esu) and showed no characteristics of symmetry breaking, unlike other polymethines of similar lengths. A neat film of this molecule maintained relatively low linear loss in the near-infrared and showed a large third-order macroscopic nonlinearity at 1.3 mum (|chi(3)| = 3.6 x 10-10 esu), with a temporal response of less than 8 ps. Furthermore, the real part of chi(3) was nearly an order-of-magnitude larger than the imaginary component. Consequently, this material exhibited good figures of merit for all-optical signal processing throughout the entire telecommunications band.

Structure dependence of ultrafast third-order optical nonlinearity for Ge–Ga–Cd sulfide glasses

Ultrafast third-order nonlinear optical responses of GeS2?Ga2S3?CdS glasses have been measured by using femtosecond time-resolved optical Kerr effect (OKE) technique at the wavelengths of 820nm and 640nm respectively. The experimental results show that GeS2?Ga2S3?CdS glasses have large femtosecond third-order optical nonlinear responses and their OKE signals vary considerably with the composition. The relationship of structure-property is discussed by means of Raman spectroscopy analysis, suggesting that the tetrahedron unit [GeS4] or [GaS4] plays an important role in the ultrafast third-order nonlinear optical response. In addition, the experimental results also reveal that the ultrafast third-order optical nonlinearity of these glasses does not obey the Miller rule.

Optical resonant absorption and third-order nonlinearity of (Au,Ag)–TiO2 granular composite films

The nanosized (Au,Ag)–Ti three-component granular composite films on glass substrates were prepared using an rf co-sputtering method, and the deposited films were annealed in air. The optical absorption and the ultrafast third-order nonlinearity of the (Au,Ag)–TiO2 films annealed at different temperatures were investigated. The composite film annealed at 600°C exhibits strong resonant absorption at wavelengths of 400 and 670 nm. The ultrafast third-order nonlinear optical susceptibility at 820 nm of the phase separated (Au,Ag)–TiO2 composite film is measured to be 7.4 × 10−9 esu. This is about 70% larger than that of the Au–TiO2 composite film.

Ultrafast optical Kerr effect measurements of third-order nonlinearities in cross-conjugated iso-polydiacetylene oligomers

We present a study on the ultrafast third-order nonlinearities of a novel series of iso-polydiacetylene oligomers (iso-PDAs). Unlike polydiacetylenes that contain a linearly-conjugated backbone, iso-PDAs have a backbone that is cross-conjugated. A new Kerr-gate technique, differential optical Kerr effect (DOKE) detection, is used to measure third-order nonlinear susceptibilities, χ(3), and second hyperpolarizabilities, γ, of monomer, dimer, trimer, pentamer, and heptamer samples in tetrahydrofuran (THF) solutions. A linear increase in γ as a function of the number of repeat units is observed for all samples except the monomer, suggesting that the fixed-length linearly conjugated segments dominate the electronic polarizability. An added increase to the oligomer nonlinearities due to communication along the cross-conjugated path is not observed. The largest nonlinearity was observed in the heptamer sample, displaying a second hyperpolarizability relative to the THF solvent of γheptamer/γTHF=181±9. In addition, an interesting feature arising out of the signal decay tail is present in the samples but absent in our THF solvent reference.

Ultrafast two-photon nonlinearities in CdSe near 1.5 μm studied by interferometric autocorrelation

We have used interferometric autocorrelation measurements to study the femtosecond nonlinear optical properties of bulk CdSe crystals in the wavelength region just above the half gap wavelength of 1.42 /spl mu/m. Between 1.42 and 1.55 /spl mu/m, we measured an ultrafast third-order nonlinearity with nonlinear refractive index n/sub 2/=1.3/spl times/10/sup -13/ cm/sup 2//W/sup -1/. Detailed modeling of the autocorrelations revealed the influence of higher order effects due to free carriers generated by nonlinear absorption. We find that CdSe is an interesting alternative material to AlGaAs for applications in this technologically important wavelength region.

Two-photon resonance enhanced nonlinear optical response in C 60-copolymer charge transfer complex

Ultrafast third-order nonlinearity of C 60-poly tetrahydrofurfuryl methacrylate charge transfer complex was measured using femtosecond optical Kerr gate at both 640 nm and 820 nm wavelength. In the material's two-photon absorption region, extra large third-order nonlinear optical response was observed.