The effect of the sign of the dispersion parameter on nonlinear pulse propagation in a birefringent optical fiber is analyzed via numerical analysis. First, the concept of effective cross-dispersion is introduced to demonstrate the simultaneous existence of positive dispersions of opposite polarizations within the same waveguide, leading to the generation of a dispersive wave and supercontinuum. Then, a general set of equations is deduced to calculate the dispersive waves corresponding to x and y polarizations considering a birefringence-dependent wavelength. Using this, it is established that solitons and dispersive waves can be induced corresponding to each polarization even if the dispersions are normal. Finally, we demonstrate that spectral broadening can also be induced corresponding to one polarization despite the existence of positive dispersion, i.e., in the complete absence of solitons for the entire duration of pulse propagation.
We present measurements of nonlinear refraction and absorption in transparent conductive oxides (TCO), which are essentially highly-doped semiconductors, at Epsilon-Near-Zero (ENZ). In this spectral region, where the real part of the permittivity crosses zero, materials demonstrate interesting nonlinear properties such as enhanced harmonic generation, nonlinear absorption (NLA), and nonlinear refraction (NLR). We find that induced changes in the refractive index of Indium Tin Oxide, can be very large with respect to the initial index. This means that the even the Fresnel coefficients are highly irradiance-dependent. Therefore, the nonlinear transmission, reflection, and absorption of the material will be significantly different from conventional materials which means that it is challenging to use conventional methods such as Z-Scan and time-resolved transmission and reflection techniques to accurately determine the underlying nonlinear optical coefficients. We have studied optical nonlinearities of TCOs using the Beam-Deflection (BD) method to independently characterize the temporal dynamics and polarization dependence of the NLR. This method enables us to resolve NLR in the presence of large NLA backgrounds. In addition, we can also study the dependence on relative polarization and incidence angle of excitation and probe waves to characterize the enhancement mechanism and the physical origin of the nonlinear response. We conduct these BD measurements in conjunction with Z-Scan and transient reflection and transmission at different wavelengths, incidence angle, and polarization. Our measurements reveal that there is a strong wavelength dependence of nonlinearities around the ENZ point. We find that the wavelength dependence is quite different for excitation and probe waves.
In this research, the influence of pulse width and energy on the nonlinear refractive index (n2) and nonlinear absorption (β) in Multiwalled carbon- nanotubes (MWCNTs) were experimentally studied. For this purpose, three different MWCNTs concentrations were used and were dispersed in a Polyvinyl alcohol (PVA) solution. We found a highly dependence of n2 and β with the MWCNTs concentration, optical intensity, and pulse width.
In this work, a fiber optic microphone system was built and tested. The purpose of the fiber microphone is to sense photoacoustic waves produced by water molecules excited by an ultrafast laser. The use of a fiber sensor allows for ease of three-dimension measurement implementation for a 3-D imaging based on water amounts of different materials, this sensor can be directly submerged in water or a phantom gel without electromagnetic interference nor corrosion.
In this paper, we present a procedure to compute analytically the acousto-optic coupling coefficient between the fundamental core mode and lower LP cladding modes in fiber optics. Based on the effect of the local bending, the variations in the refractive index are modelled. A set of equations and parameters are presented in order to compute and analyze the influence of acousto-optic effect in nonlinear pulse propagation.
Using a model for the shape of tapered fiber optics, we numerically study the effect of the taper shape profile on nonlinear optical pulse propagation. We show that super-Gaussian pulses can be generated and controlled and they are independent of higher-order nonlinearities, which makes them a good candidate for optical communications. We see that it is possible to compensate for the z variation of the dispersion with the nonlinear parameter and obtain the solutions of the homogeneous nonlinear Schroedinger equation.
The supercontinuum (SC) generation has found numerous applications in spectroscopy, pulse compression and design of tunable ultrafast femtosecond laser sources, some improvement has been done in many fields. Since carbon disulfide (CS2) has highly nonlinear characteristics, this makes it a good candidate for achieving an infrared broadband source. In this work, we implemented numerical simulations of propagating ultra-fast optical pulses through a photonic crystal fiber (PCF) with two infiltrated holes using CS2. Based on supermodes theory, we calculate dispersion and nonlinear parameters in order to study the SC generation characteristic of the infiltrated PCF.
We perform theoretical analysis of dispersive waves generated by soliton in birefringent photonic crystal fibers. With Lagrangian formulation and Stokes parameters, we study the state of polarization of solitons under various levels of birefringence and third order dispersion. Then we investigate numerically the variation of dispersive wave frequency for different initial polarization angles and further consider the effect of stimulated Raman scattering.
We show an analytical and numerical study of dispersive wave (DW) frequency generated by solitons in birefringent fiber optics. We propose some analytical approximations for finding the DW frequency that agrees with numerical results for small normalized third-order dispersion. We also show that a scalar DW frequency equation is not valid for all birefringent optical fiber cases.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.