Abstract: Dispersion property is an important fact to generate white light. Different structures could change the dispersion properties of fibers. This paper demonstrates how the white light was generated when the ultrashort pulse propagated in a tapered fiber. We simulated how the supercontinuum was generated in a variety of tapered fibers which have different parameters. The supercontinuum range could be reached from 680nm to1750nm. It is shown that the width and the shape of the supercontinuum depend on both the fiber parameters such as the diameter or the length of tapered waist regime and pulse peak power. The paper also discussed the influence of the different dispersion and nonlinear effects in detailed, including GVD (Grouped Velocity Dispersion), SPM (Self Phase Modulation), TOD (Third Order Dispersion), SS (Self Steeping), and SRS (Stimulated Raman Scattering). Through the numerical simulation, it presents when the ultrashort pulse propagates in tapered fibers with anonymous dispersion, the Stimulated Raman Scattering effect plays an important role in the long wave range of the supercontinuum. The influence of the higher order dispersion, especially third order dispersion, on the anti-Stokes part in the supercontinuum process was also discussed. A smoother and broader supercontinuum could be obtained after choosing the suitable parameters of the tapered optical fibers, especially the diameter or the length of tapered waist regime.

Abstract: In order to supply a theoretical guide for chaotic telecommunication, the influences of the chromatic dispersion and nonlinearity in fiber on the chaotic synchronization have been investigated based on the theoretical models used to describe the dynamics of semiconductor laser subjected to the external optical feedback and signal transmission in fiber channel. The numerical simulation results show that, the fiber nonlinear effect is responsible for the phase varying of chaotic signal and do not affect the amplitude of the chaotic signal; due to chromatic dispersion, the amplitude characteristics of chaotic signal are distorted significantly and the system synchronization quality will be impaired; after propagating 200km in dispersion shifted fiber, a desirable system chaotic synchronization with a synchronized coefficient 0.99 can be achieved by adopting a amplifier before the received laser to compensate the fiber loss.

Abstract: Nonlinear optical properties of perylene derivatives were studied by femtosecond Z-scan technique. 3,4,9,10-Perylenetetracarboxylic dianhydride (PTCDA), 3,4,9,10-perylenetetracarboxylic diimide (PTCDI), and perylene-66 (dibenzthiophenoperylene-N,N'-dicyclohexylimide), were studied. Tetrahydrofuran was used as a solvent for perylene- 66. The solubility of PTCDA and PTCDI is very poor. Their colloidal solution was prepared by the irradiation of the third harmonics of a pulsed YAG laser to opaque suspension of PTCDA and PTCDI. Transparent colloidal solution was obtained within 50 minutes of UV irradiation. Colloidal solution of quinacridone was also studied. Two-photon absorption cross sections of these dyes were measured by open aperture Z-scan method using a femtosecond laser. The dependence of two-photon cross section on laser wavelength was measured in the wavelength range of 780-820 nm.

Abstract: In this paper, we proposed a novel variable operation of a DC-OFS based on double SFG+DFG nonlinearity process with double-pass configuration for the first time. In this scheme, the available nonlinear crystal length is used twice: forward for SFG and backward for DFG in each conversion and this device is called double-pass SFG+DFG wavelength converter as the SF wave propagates twice in the waveguide. We used the novel multiple-quasi-phase-matched LiNbO 3 (M-QPM-LN) waveguides having the continuously-phase-modulated domain structure, which can be operated by multiple pump wavelengths with minimum loss of efficiency. The frequency spacing of control signal-a is twice as large as the control signal-b. Conversion bandwidth is the frequency difference of control signal-b and control signal-a. We discussed Double-SFG+DFG-OFS with double-pass configuration theoretically and gave the formula of the input power of input signal, the two controlling light and pump light, which proposed a simple and feasible way to optimize the performance of the device. In this scheme, the advantages of the cascaded SFG+DFG scheme and the DC-OFS scheme are combined to a great extent. We believe this double-pass cascaded SFG+DFG DC-OFS must be better than single-pass cascaded SFG+DFG DC-OFS for constructing future flexible photonic networks.

Abstract: Multi-photon excitation in ZnO material by femtosecond (fs) laser pulses around 800 nm was clearly observed. Under the intense field generated by fs pulses, two-photon absorption process was found very efficient in the excitation of the band edge emission from ZnO material under detuning condition. Nonlinear optical effects, such as Stark effect and Rabi effect, that may emerge under intense field are suggested to be responsible for this efficient excitation via two-photon absorption process. We consider that this NLO route to generate photoluminescence in ZnO material is meaningful in the research of blue-violet semiconductor laser field.

Abstract: Sol-gel-processed TiO 2 /SiO 2 films doped with organic azo dye have been investigated. The film was spin-coated on the ITO coated glass substrate and rapidly condensed by evaporation of the solvent from the liquid film. The thickness of the hybrid films can be varied from 0.2 to 0.6 micron. When the prehydrolyzed tetraethoxysilane (TEOS) sol and titania precursor(titanium butoxide) are mixed together with various molar ratios, the refractive index of the film may vary from 1.49 to 1.81 at 1300nm. The film is aged at 80°C for 2 h and then corona poled at 120°C for 1 h so that the dye molecules are dispersed in numerous pores of the oxide matrix. The absorbance spectra of the film measured by a UV-visible spectrophotometer show that the process of aging and poling in the sample preparation causes the pores in the oxide matrix to shrink and nonlinear molecules are aligned in the direction of the poling field and are trapped in the pores. The electro-optic coefficient r 33 is 42 pm/V at a fundamental wavelength of 1300nm. The nonlinearity is stable at 80°C for 2500h at least. The excellent thermal stability of the hybrid organic/inorganic film is an advantage for optical applications.

Abstract: In this paper, we performed experimental and quantum-chemical studies on a series of symmetrically substituted phenylenevinylene chromophores with different lengths of conjugated chains and different electro negativity of substitution groups to provide an insight into the nature of the two-photon absorption (TPA) processes and to reveal structure-property relations. TPA spectra were obtained at the wavelengths ranging from 600 to 1000 nm with 6ns laser pulses of 10Hz repetition rate. The TPA spectra show that absorption band is mainly related to the transition of electrons btween the orbital localized at phenyl rings of the conjugated chains. Quantum-chemical calculations were performed with MOLCAO (Molecular Orbital as a Linear Combination of Atomic Orbitals) method to calculate the positions of the electronic levels and the shapes of the molecular orbitals. Considering all of the series of symmetrically substituted phenylenevinylene chromophores, the planar structure and the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is influenced significantly by the length of conjugated chains and the electro negativity of substitution groups. Structure-property relations revealed that the TPA cross section tends to be enhanced by an increase in the electro negativity of the substitution groups and tends to be reduced by an interruption of the conjugated chain.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Abstract: A basic scheme of the polarization insensitive four-wave-mixing all-optical wavelength conversion with a copolarization dual-pump configuration in a highly nonlinear photonic crystal fiber (PCF) is demonstrated. With two fiber Bragg Gratings and a Faraday rotator mirror, both the pumps and the signal make a dual pass through a highly nonlinear PCF. The rotation of the signal polarization by the Faraday rotator mirror guarantees that both orthogonal polarization components of the signal will efficiently mix with the two pumps to produce a polarization-insensitive multi-wavelength conversion. The design and simulation of the bismuth oxide-based PCF indicate that the desired dispersion properties can be tailored by the geometrical parameters of PCF microstructure. The propagation loss at 1550nm is about 0.8dB/m. The nonlinear coefficient is expected to be 1100W -1 km -1 by using bismuth oxide-based glass and reducing the effective core area. The mode-field diameter of PCF is estimated to be 1.98μm and the predicted effective core area is 3.3μm 2 . The polarization insensitive four-wave-mixing wavelength converter with copolarization dual-pump configuration shows the small polarization sensitivity, the high conversion efficiency and the simultaneous multi-wavelength conversion.

Abstract: In this paper, we proposed a novel numerical algorithm for nth-order cascaded Raman fiber lasers (CRFLs) with the combination of genetic algorithm (GA) and shooting method. Although shooting method possesses fast speed in solving nonlinear two-point boundary-value ordinary differential equations, calculating process may diverge if it is directly applied in the coupled equations of CRFLs when arbitrarily guessed initial values are out of the domain of convergence. To overcome the problem, genetic algorithm which has rather strong searching ability in global space is firstly employed to search for the initial value in convergent domain for each Stokes power; and then, the task of finding the more accurate initial values is finished by shooting method instead of GA whose searching ability is weak in local region. As an example, a sixth-order Ge-doped CRFL has been simulated by the novel algorithm. Calculated results show that the new method can effectively and quickly solve the coupled equations of the CRFL without the problem of divergence.

Abstract: The ultra-short pulse optical parametric amplification based on continuous wave pump and pulse signal model is investigated by solving three nonlinear Schrodinger equations numerically. The effect of the order of soliton is presented by comparing the evolution process of signal pulse and the changing of root mean square width of signal. The phenomenon of signal pulse splitting and the broadening of the pulse will appear in the amplification process. Larger order of the soliton makes the pulse split at first, then begin to broaden. Smaller order of the soliton leads to the broadening of pulse firstly, then the pulse begin to split after propagating in a section of fiber.

Abstract: In this paper, after taking into account two situations that the polarization of the injection light is parallel or orthogonal with the solitary vertical-cavity surface-emitting laser (VCSEL) output light, the nonlinear dynamic characteristics of an optical injection VCSEL are investigated numerically. The simulated results show that VCSEL can exhibit periodic oscillations, deterministic chaos and other complex instabilities under optical injection. For parallel or orthogonal optical injection, the same injection coefficients have different effects on the output of VCSEL. By properly adjusting the injection strength or detuning frequency, the dynamical state of the laser output can be controlled to a fixed state, and the polarization of the VCSEL output light can also be controlled.

Abstract: In this paper, all-optical wavelength conversion based on FWM in ROF system is theoretically analyzed. It can be used to generate the optical millimeter wave signals and to implement the all-optical frequency up/down conversion in ROF systems. Due to the ultrafast nonlinear response of the HNL-DSF, it is possible to realize terahertz waveform all-optical mixing or up-conversion. All-optical frequency up-conversions of an optical IF signal to the upper frequency band using FWM without serious crosstalk were demonstrated. Based on analysis of the all-optical wavelength conversion in high-nonlinear fiber, main factors related to the conversion efficiency are presented. Methods to increase the conversion efficiency have been discussed. With the longer high-nonlinear fiber, the higher nonlinear coefficient, the appropriate power of the pump, the appropriate polarization between the signal and the bump, and high efficiency to implement the wavelength conversion can be achieved. The theoretical analysis is verified by the simulation results.

Abstract: A simple and low-cost all-optical equivalent-time sampling system is present. The optical sampling was realized by XGM in SOA and pulse-broadening in low-bandwidth PIN. A system model is funded based on noisy SOA dynamic function and a simplified equivalent electric circuit model about PIN. The sampling-recovery process had been simulated to validate the measuring capability of the sampler. Sampling error caused by ASE noise of SOA, thermal noise of PIN and time-domain jitter of control pulse is discussed too. Simulation results show that SOA XGM sampler can efficiently sample low repetition rate optical short pulse or short pulse with poor stability.

Abstract: In this paper, we design a new nonlinear fiber by filling a highly nonlinear liquid into hollow-core photonic crystal fibers. The liquid-core photonic crystal fiber with carbon disulfide exhibits an extremely high nonlinear parameter γ which can be more than 20 times larger than that of a conventional PCF, which is desired for FOPA. By using Full Vector Finite Element Method (FEM) with hybrid edge/nodal elements and anisotropic perfectly matched layers we simulate the transverse intensity distribution, the nonlinear parameter γ, and the GVD of the fiber mode. Simulation shows such a PCF' structure has near-zero flattened dispersion and dispersion slope at the pump wavelength, which meet another crucial requirement for FOPA.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Abstract: Nonlinear dynamics of a laser-generated single cavitation bubble near an elastic boundary is investigated by a fiber-optic diagnostic technique based on optical beam deflection (OBD). The maximum bubble radii and the bubble life-time for each oscillation cycle are determined according to the characteristic signals. It is shown that with the increase of the number of oscillating cycles, the maximum radii and the life-time of the bubble are decreased sharply. Furthermore, the effect of material elasticity on nonlinear dynamics of cavitation bubble has also been investigated in some detail. The maximum bubble size and thus the bubble life time decreases with an increase in elastic modulus. In addition, increasing elastic modulus leads to a significant decrease of the collapse amplitude and the bubble energy. These results are valuable in the fields of cavitation erosion, collateral damage in laser surgery, and cavitation-mediated enhancement of pulsed laser ablation of tissue.

Abstract: A novel configuration of ring cavity-coupled Michelson interferometer is proposed to create sharp asymmetric multiple-resonance line shape, in which a ring cavity is side-coupled to one arm and a phase shifter is introduced into the other arm for static phase compensation. Such asymmetric line shape allows the tuning of the system between zero and complete transmission, with a phase offset much narrower than the full width of the cavity resonance itself. As tuning between resonance peak and notch of such asymmetric profile, optical transmission becomes much more sensitive to the round-trip phase shift of ring cavity than that in the case of symmetric Lorentzian line shape. By cooperating Kerr nonlinearity and cavity feedback, novel hysteresis loops and intrinsic bistability are achievable by adjusting incident power. The shapes of hysteresis curves associated with asymmetric resonance line shape are different from those arising from symmetric line shape. By adjusting the static phase compensation of phase shifter, tunable hysteresis loop and asymmetric multiple-resonance transmission can be easy performed. The simply constructed device is a good reference for sensitive optical switch, filter and sensor.

Abstract: The phase conjugation properties of self-pumped phase conjugation (SPPC), mutually pumped phase conjugation (MPPC), SPPC and MPPC coexisting are researched in Cu:KNSBN crystal with Q-switched single longitudinal mode YAG pulse laser pumping. The dependence of the reflectivity of phase conjugation on the incidence position and angle are obtained experimentally. The results show the optimal incident parameter exists in photorefractive phase conjugation effect.

Abstract: Solitons have been found in many physical branches. Previous investigations on solitons mainly focused on various nonlinear dispersive media in nature. It is well known that in the nonlinear dispersive medium, soliton formation is due to the exact balance between the nonlinearity and the group velocity dispersion (GVD). When the signs of nonlinearity and GVD are the same, that is, the positive (focusing) nonlinearity vs. positive (normal) GVD, or the negative (defocusing) nonlinearity vs. negative (anomalous) GVD, the interaction between nonlinearity and GVD may lead to the generation of dark solitons. In this paper, we study the formation and propagation of dark electromagnetic solitons in the metamaterials, artificial structures that display properties beyond those available in naturally occurring materials. We use an extended Tanh-function expansion method to solve the nonlinear equation for ultrashort electromagnetic pulse propagation in metamaterial with a nonlinear polarization, and get dark solitary solutions under various conditions. It is found that, due to the role of the second-order nonlinear dispersion resulted from the dispersive magnetic permeability, dark solitons can be formed in the absence of linear dispersion, or even in the case of anomalous linear GVD for a focusing nonlinearity, challenging the traditional conditions for dark soliton formation.

Abstract: Intrinsic optical bistability is of great interest and has potential applications in all-optical communication. In the present work, we have extended occurrences of bistable chromatic switching to a new rare-earth-doped system, namely single Tm-doped laser crystal pumped at 648 nm avalanche wavelength. Intrinsic bistability and chromatic switching of fluorescence emission are theoretically predicted, based on the rate equation theory. By using a four-order Runge-Kutta technique, chromatic switching spectra and bistable hysteresis loop are studied numerically in detail. The numerical results show that intrinsic chromatic switching of visible-infrared spectra is achievable experimentally corresponding to the transitions of Tm 1D2→3H6 (357 nm), 1G4→3H6 (469 nm), 3H4→3H6 (787 nm), 3F4→3H6 (1716 nm), as pump power increases far beyond avalanche threshold from low power level. Furthermore, we have found that the chromatic switching appears bistable in the emission spectra for pump intensity in the vicinity of avalanche threshold. The bistable hysteresis loops of luminescence are also demonstrated numerically for the dominant emission band. Intrinsic bistable chromatic switching in Tm-doped crystal is mediated by resonant excited-state absorption up-conversion.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Abstract: First-order hyperpolarizabilities of H-shape azobenzenes in gas and in THF have been theoretically studied by Hartree-Fock method and basis set sto-3g with Onsager model, including 4,5-bis((E)-(4-nitrophenyl)diazenyl)anthracene-1,8-diol, 4,5-bis((E)-(4-(trifluoromethyl)phenyl)diazenyl)anthracene-1,8-diol, 4,5-bis((E)-(3-chloro-4-fluorophenyl)diazenyl) anthracene-1,8-diol and 4,5-bis((E)-(4-chlorophenyl)diazenyl)anthracene-1,8-diol. Compared with corresponding azobenzene monomers, H-shape azobenzenes had much larger first-order hyperpolarizabilities. There were four factors which could obviously influence their first-order hyperpolarizabilities. Firstly, H-shape azobenzenes possessed dihedral angles of approximate ten degrees caused by coulomb repulsions with weakening dipole's changes between ground states and excited states. Meanwhile, dihedral angle induced energy gap between HOMO and LUMO to increase. Secondly, dipole-dipole interaction was considered as perturbation which caused strong energy splitting of each molecular orbital with the lessening of energy gap. Thirdly, hyper-conjugated effect existed in H-shape azobenzene and it induced energy gap to decline. Fourthly, solvent effects could obviously enhance their first-order hyperpolarizabilities by comparing results in gas with results in THF. These factors competed and affected each other. The latter three factors lastly overcame coulomb repulsion, which explained that H-shape azobenzenes' first-order hyperpolarizabilities were much larger than corresponding monomers'.

Abstract: On the basis of non-linear coupled-mode theory, the dispersion relation of a dimensional periodic structure is analyzed and slow Bragg soliton solutions are given. The approximation approach for non-linear coupled-mode theory is studied by assuming adiabatic evolution of the soliton passed through fiber Bragg grating which is apodized by using a hyperbolic tangent apodization function in the middle of the FBG. And in the presence of apodization, the velocity equation of Bragg soliton is found. In this paper, we have simulated the motion tracks and velocities of Bragg solitons, analyzed effects of different parameters on motion track and velocity of Bragg soliton, and obtained different timedisplacement curves and time-velocity curves. It is shown that the final steady velocity of soliton can be found by choosing specifical parameters, thereby, slow Bragg solitons whose propagate velocity through the grating is far lower than the speed of light in glass can obtained. We have presented detailed simulative results that agree with theoretical analysis.

Abstract: We have demonstrated efficient three-photon excitation in a number of nonlinear organic materials developed at our center or in cooperation with other research groups. The three-photon absorption (3PA) properties of these materials are studied using a femtosecond Ti:sapphire oscillator-amplifier laser system associated with an optical-parametric amplifier. Considering the transverse intensity distribution of the incident beam during measurements, the 3PA induced nonlinear transmission of the incident beam with a Gaussian transverse spatial profile is derived. Some of the 3PA-active materials are highly fluorescent while some others are nonfluorescent. In one of these materials, vibrational resonance enhanced broadband multiphoton absorption was founded. These materials can be used in optical power limiting and stabilization, frequency-upconversion imaging and microscopy etc. Some recent experiments of three-photon pumped power limiting and stabilization are briefly presented.

Abstract: We regard the bilayer consisting of a subwavelength layer of linear negative index material (NIM) and a Kerr-type nonlinear layer of conventional positive index material as a combined defect for a one-dimensional photonic crystal and investigate the effect of the thin film on the hysteretic behavior of the Goos-HAƒÂ¤nchen shift and the incident intensity. We find that a subwavelength layer of linear negative index material (NIM) significantly modifies the characteristic of hysteretic behavior of lateral shift for the transmitted beam. Anomalous bistable shift occurs as the absolute value of magnetic permeability of the NIM layer increases. We also find that the sequence of the thin film of NIM and the nonlinear layer has a major impact on bistable shift. These results may be useful for NIMs characterization and for designing novel photonic-crystal-based devices.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Abstract: The magnitude and dynamic response of the third-order optical nonlinearities of squarylium and croconium dyes in methanol solution were measured by femtosecond degenerate four-wave mixing (DFWM) technique at 800 nm. Ultrafast nonlinear optical responses have been observed, and the magnitude of the second-order hyperpolarizabilities was evaluated to be 5.80 × 10-31 esu for the squarylium dye and 8.69 × 10-31 esu for the croconium dye, respectively. The large optical nonlinearities of the dyes can be attributed to their rigid and intramolecular charge transfer structure, and the instantaneous NLO responses of dyes are shorter than the experimental time resolution (50 fs), which is mainly contributed from the electron delocalization. The fast nonlinear response and large third-order optical nonlinearities show that the studied squarylium and croconium dyes might a kind of promising materials for the applications in all-optical switching and modulator.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Abstract: Interesting in generation and exploration of mid-infrared radiation has induced using optical parametric effect in nonlinear optical crystal with high nonlinearity, high transmission, phase-matching ability, and high sensitivity in room temperature, such as AgGaSe2(AGSe), AgGaS2(AGS) crystals. To achieve mid-infrared radiation, we use difference frequency generation (DFG) in AGS or AGSe crystals by pumping with the output of optical parametric oscillator. The mid-infrared radiation tunable characteristics of AGS and AGSe crystals under type-I phase-matching have been analyzed based on optical parameter DFG theory. Beam walk-off angle and acceptance angle limit conversion efficiency and restrict the DFG tuning wavelength range. We focus to research for effective nonlinear coefficient, walk-off angle and acceptance angle as functions of wavelength, the relationship between conversion efficiency and acceptance angle, and crystals length impact on the process of frequency conversion. We obtained 10 μm wavelength with a 10 mm crystal length, 1030nm pump, walk-off angles and acceptance angles of AGS and AGSe crystals are 1.19°and 0.68°, 0.107°and 0.171°respectively. Results are very useful for mid-infrared experimental studies on AgGaS2 and AgGaSe2 crystals.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Abstract: Self- and cross-phase modulation (SPM, XPM) in fiber is expected to play a major role in ultrafast all-optical analog-to-digital conversion(ADC), which can overcome the obstacles of inherently limited operating speed of electronic ADC. In this paper, we propose novel optical coding method for all-optical ADC using nonlinear optical switches based on the Sagnac interferometer. The multiperiod transfer function, which is the key to coding, is achieved through an exact design of the Sagnac interferometer. We conducted proof-of-principle experiments and successfully demonstrated 2.6-bit all optical ADC with Gray code output. The proposed optical coding, combined with existing optical sampling and quantizing techniques, will enable ultrafast photonic ADC without electronics.

Abstract: Three ytterbium phthalocyanine compounds, ytterbium bis- phthalocyanine (Yb(Pc)2), ytterbium bis- [(tetrakis- (tertiary-pentyloxy) phthalocyanine)] [Yb(Pc(t-OR5)4)2], bis-ytterbium tris- [(tetrakis- (tertiary-pentyloxy) phthalocyanine)] [Yb2(Pc(t-OR5)4)3] have been synthesized and characterized by electronic spectrum, MS and element analysis. The Uv-vis spectrum indicated lower aggregation trend and red shift of Q bands with phthalocyanine ring increasing from dimer to trimer. The nonlinear optical properties of these compounds in THF solution were investigated by Z-scan method used 532 nm picosecond laser under open and close aperture condition. Both compounds showed reverse saturation absorption and nonlinear self-focus refraction effect. The nonlinear absorption and refraction capacity decreased with the order: Yb2(Pc(t-OR5)4)3 >Yb(Pc(t-OR5)4)2> Yb(Pc)2.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Abstract: In order to improve the efficiency of optical polymers' function in photonic applications, the effect of local environment on small molecules of Disperse Red 1 and their dynamic behavior is studied. Poly Styrene Sulfonic Acid polymer used as host material to make highly doped polymeric thin films. By studying the samples' spectra in vitro and in situ, and investigating the photo-anisotropic effects on samples, it is shown that dye-polymer interaction can be the dominant factor in local environment around the dye molecules. Therefore, it can be used to increase significantly the response intensity and improve the performance of photonic devices.

Abstract: In this paper, we consider spatial soliton propagation in Kerr nonlinear media with harmonic modulation of the refractive index, and investigate the effect of the lattice modulation for small-scale self-focusing of beam in optical lattice. Based on the modulation instability theory, the effect of lattice modulation on small-scale self-focusing of beam in optical lattice is studied both analytically and numerically. It is investigated how the perturbation changes with lattice modulation. Comparing the gain spectrum in lattice modulation with that without lattice modulation, we find that without the lattice modulation the perturbation gain increases with the input power when the input power is large enough to initiate the modulation instability. The gain of the noise is controlled when the lattice modulation is induced.