Wavelength Dependence Of Birefringence Research Articles

Influence of the Wavelength Dependence of Birefringence in the Generation of Supercontinuum and Dispersive Wave in Fiber Optics

In this paper, we perform numerical analysis about the influence of the wavelength dependence of birefringence (WDB) in the Supercontinuum (SC) and dispersive wave (DW) generation. We study different birefringence profiles such as constant, linear, and parabolic. We see that, for a linear and parabolic profile, the generation of SC practically does not change, while this does so when the constant value of the birefringence varies. Similar situation happens with the generation of dispersive waves. In addition, we observe that the broadband of the SC increases when the Stimulated Raman Scattering (SRS) is neglected for all WDB profiles.

Influence of filler metal on birefringent optical properties of photonic crystal fiber with integrated electrodes

We present a comprehensive study of the influence of the filler metal on the birefringent optical properties of a photonic crystal fiber containing two integrated electrodes. Bismuth and indium were used to examine the effects of the electrode composition on the temperature sensitivity of this special microstructured fiber. We found that the fiber microstructure significantly influences the metal-induced sensitivity of the wavelength dependent birefringence, making the behavior of the birefringence change strongly with the electrode material. By modeling the anisotropic changes induced by the metal expansion in the refractive index within the fiber we examine the essential features of the fiber birefringence.

Temperature-dependent optical response of phase-only nematic liquid crystal on silicon devices

Wavelength-dependent birefringence and dielectric anisotropy, two major optical properties of the nematic liquid crystal materials used in phase-only liquid crystal on silicon (LCOS) devices, are measured as a function of operating temperatures. The dynamic phase modulation depth and threshold voltage of these phase-only LCOS devices are also measured in the corresponding temperature range and compared with theoretical predictions. The results show that the dynamic response time can be reduced significantly by an appropriate increase of device operative temperature, while the necessary device elements, such as phase modulation depth and threshold voltage, can be maintained at the same time.

Nonlinear pulse propagation in wavelength dependence of birefringence fiber optics

We perform an analytical and numerical analysis of the influence of wavelength dependence of birefringence (WDB) during nonlinear pulse propagation through fiber optics. We find a set of coupled nonlinear equations, which allows for the study of the WDB in fibers. For the first time, to the best of our knowledge, the concept of cross-dispersion birefringence (CDB) is introduced to show what makes spectral pulse evolution broaden faster than usual. Some linear and nonlinear phenomena are analyzed, such as polarization trajectories, four-wave mixing, and supercontinuum (SC) generation. We show that the WDB changes the polarization states dramatically and Stokes and anti-Stokes waves linearly move toward longer and shorter wavelengths, respectively. Finally, we demonstrate that CDB has the capability to generate SC with immunity to the initial polarization angle.

Growth and characterization of large CdSiP 2 single crystals

Large, optically transparent crystals of CdSiP 2 (CSP) have been grown for the first time from a stoichiometric melt. The material is a high temperature analog to ZnGeP 2 with promising characteristics for IR frequency conversion. Crystals are birefringent and are transparent from 0.5 to 9 μm. Polycrystalline charges were successfully synthesized from high purity elemental starting materials by two-temperature vapor transport despite the very high equilibrium vapor pressure (∼22 atm) at the melting point of CdSiP 2 (1133 °C). Single crystals were grown using the horizontal gradient freeze (HGF) technique in high-temperature transparent furnaces. Over the course of several growth runs, the material proved to be prone to cracking and to twinning along (1 1 2) planes. Twinning was eliminated by seeded growth along directions normal to the 112 planar boundaries. Further modifications to growth conditions resulted in high optical quality, crack- and twin-free single crystals 70×25×8 mm 3. The largest CdSiP 2 single crystals previously reported in the literature were grown through either halogen assisted vapor transport or from a molten Sn flux and measured 2×2×0.2 mm 3. The HGF growth of large CdSiP 2 crystals has allowed several bulk properties to be measured for the first time, including the thermal expansion coefficients, thermal conductivity, and wavelength dependent birefringence and dispersion. Measurements of the optical and thermal properties reveal this to be an extremely promising material for 1-, 1.5-, and 2 μm-pumped mid-IR lasers.

Optical characterization of the nematic lyotropic chromonic liquid crystals: Light absorption, birefringence, and scalar order parameter

We report on the optical properties of the nematic (N) phase formed by lyotropic chromonic liquid crystals (LCLCs) in well aligned planar samples. LCLCs belong to a broad class of materials formed by one-dimensional molecular self-assembly and are similar to other systems such as "living polymers" and "wormlike micelles." We study three water soluble LCLC forming materials: disodium chromoglycate, a derivative of indanthrone called Blue 27, and a derivative of perylene called Violet 20. The individual molecules have a planklike shape and assemble into rodlike aggregates that form the phase once the concentration exceeds about 0.1 M. The uniform surface alignment of the N phase is achieved by buffed polyimide layers. According to the light absorption anisotropy data, the molecular planes are on average perpendicular to the aggregate axes and thus to the nematic director. We determined the birefringence of these materials in the N and biphasic N-isotropic (I) regions and found it to be negative and significantly lower in the absolute value as compared to the birefringence of typical thermotropic low-molecular-weight nematic materials. In the absorbing materials Blue 27 and Violet 20, the wavelength dependence of birefringence is nonmonotonic because of the effect of anomalous dispersion near the absorption bands. We describe positive and negative tactoids formed as the nuclei of the new phase in the biphasic N-I region (which is wide in all three materials studied). Finally, we determined the scalar order parameter of the phase of Blue 27 and found it to be relatively high, in the range 0.72-0.79, which puts the finding into the domain of general validity of the Onsager model. However, the observed temperature dependence of the scalar order parameter points to the importance of factors not accounted for in the athermal Onsager model, such as interaggregate interactions and the temperature dependence of the aggregate length.

Birefringence-induced splitting of the zero-dispersion wavelength in nonlinear photonic crystal fibers.

We investigate how the strongly wavelength-dependent birefringence in nonlinear photonic crystal fibers leads to a splitting in the zero-dispersion wavelength for the two polarizations. We translate the requirements for the maximum splitting of the zero-dispersion wavelength to requirements for transverse structural uniformity by adopting a simple effective-index approach in which the birefringence is calculated in a step-index fiber with an elliptical core. We find that to reduce the splitting to less than 1 nm the birefringence should be less than 2 x 10(-5), resulting in a transverse uniformity requirement of 1-3%, depending on the index step from the core to the cladding.

Effects of Wavelength Dependent Birefringence inside a Fiber Cavity on the Fiber Laser Output Characteristics with a Nonlinear Amplifying Loop Mirror

We have theoretically analyzed and experimentally observed the effects of wavelength dependent birefringence inside a laser cavity on the output characteristics of fiber lasers with a figure eight geometry. The spectral and polarization characteristics of fiber lasers are found to be very susceptible to the resultant birefringence composed of the intrinsically existing wavelength dependent birefringence and the externally induced birefringences inside the fiber. For the variation of twist-induced birefringence inside the nonlinear amplifying loop mirror, the laser output power and center wave-length of continuous wave lasers change periodically, but the polarization characteristics remains nearly unchanged. The changes of the birefringence inside the linear loop has little effect on the spectral characteristics but changes the polarization properties such as the polarization direction.

Measurement of the wavelength dependence of birefringence for optical disk substrates

The in-plane and vertical birefringence of polycarbonate plastic substrates of optical disks are measured for wavelengths between 360 and 860 nm, which covers the full range of interest for blue as well as for the current red and infrared recording. It is found that the birefringence generally decreases as the measurement wavelength is increased. In a typical case, the in-plane birefringence, Δn‖ goes from 1.7 × 10(-5) to 1.2 × 10(-5), and the vertical birefringence, Δn⊥, drops from 7.5 δ 10(4-) to 5.7 × 10(4-) in the wavelength range from 360 to 860 nm.

Realization of broad-band phase devices by using W-type eccentric-core optical fibers

Axially nonsymmetric W-type optical fibers are proposed as broadband phase devices for optical-fiber systems to provide the Fresnel's rhomb retarder in classical optical systems. Propagation characteristics of the W-type eccentric-core optical fibers are investigated theoretically using the boundary-integral method. The results of the numerical analysis indicate that such broadband phase devices can be realized by using the wavelength-dependent birefringence of axially nonsymmetric W-type optical fibers. It is theoretically found in the case of eccentric cores that a relative bandwidth of 18.2% with a phase retardation error of 2% is realizable without the propagation of higher-order mode waves.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Mean electronic resonant wavelength of liquid crystals

Mean electronic resonant wavelength of some single substance liquid crystals obtained by ultraviolet transmission spectrum and by wavelength dependent birefringence agrees very well. Both ground and higher state π→π* electronic transitions are found to make a major contribution to the observed birefringence of those liquid crystals containing delocalized π electrons. The role of the σ→σ* electronic transitions may or may not be significant, depending on the liquid crystal composition.

Wavelength dependence of birefringence in single-mode fiber

Real single-mode fibers generally exhibit elliptical birefringence caused by deviations of the core shape from circularity, by transverse internal stress, and by residual twist. These three contributions can be individually determined by analyzing on a Poincaré sphere the wavelength dependence of the output state of polarization of a short section of fiber with fixed input polarization. Various types of polarization eigenstates of a twisted birefringent fiber are discussed, and the resulting group delay difference is derived.