Continuous-wave Self-phase Modulation Method Research Articles

Solid-core bismuth–tellurite glass fiber with low propagation loss and high nonlinearity

We have fabricated a single-mode bismuth-doped tellurite solid-core glass fiber using a multi-stage fiber fabrication method. Owing to the optimization of the glass composition and rod-in-tube fiber drawing technology, this fiber features a small mode area of 24.63 μm2 and low propagation loss of 0.9 dB/m at 1550 nm. By using the continuous-wave self-phase modulation method, the effective nonlinear parameter γ of this bismuth-doped tellurite glass fiber is estimated to be 417 W−1 km−1 at 1550 nm, which is the highest to date among all known solid-core tellurite glass fibers. Thus, we have developed an unprecedented high nonlinearity and low loss tellurite glass fiber. © 2019 Elsevier B.V. All rights reserved.

Development of Germano-Silicate Optical Fiber Incorporated with Germanium Nanoparticles and Its Optical Characteristics.

The germano-silicate optical fiber incorporated with Ge nanoparticles with enhanced optical nonlinearity was developed by using modified chemical vapor deposition and drawing processes. A broad photoluminescence band obtained by pumping with the 404 nm superluminescent diode was found to appear from 540 nm to 1,000 nm. The non-resonant nonlinear refractive index, n2, of the fiber measured by the continuous wave self-phase modulation method was 4.95 x 10(-20) m2/W due to the incorporated Ge nanoparticles in the fiber core. The enhancement of the non-resonant optical non-linearity may be due to the creation of the NBOs and other defects from the incorporated Ge-NPs in the fiber core.

Single-mode fluorotellurite glass fiber

By multi-stage rod-in-tube fiber drawing process, a single-mode fluorotellurite glass fiber was fabricated and reported for the first time. Benefiting from chemical–physical dehydration process to remove water and OH− groups, the propagation loss was decreased to 1.9dB/m at 1550nm and the infrared window is extended from 2.8μm to 4.2μm, i.e. a new kind of mid-infrared glass fiber. The fiber is with a small core of 3.52μm in diameter to meet single-mode condition, and the effective nonlinear parameter γ was estimated to be 236.7W−1km−1 at 1550nm by using continuous-wave self-phase modulation method. © 2015 Elsevier B.V. All rights reserved.

Gamma-Ray Radiation Effect on Non-Resonant Third-Order Optical Nonlinearity of Germano-Silicate Optical Fiber

Gamma-ray radiation effect on the non-resonant third-order optical nonlinearity of the germano-silicate optical fiber has been investigated by the continuous-wave self-phase modulation method. The nonlinear refractive index, n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , of the gamma-ray irradiated optical fiber was found to increase linearly with the increase of the gamma-ray induced absorption. The increased n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> has been mainly ascribed to the NBOs and Ge-realted radiation-induced defects having hyperpolarizabilities.

Nonlinear characterization on mid-infrared fluorotellurite glass fiber

By physical and chemical dehydration technique to remove OH group from raw materials and via built-in casting method to make glass fiber preform, mid-infrared fluorotellurite glass fibers with low loss of 3.61dB/m at 1550nm were fabricated recently. With the addition of fluoride components, fluorotellurite glass fiber cane presents a ‘water-free’ state with a broadband transparency in the range of 0.38–4.2µm. By the continuous-wave self-phase modulation method, the nonlinear refractive index n2 and the effective nonlinear parameter γ of the made fluorotellurite glass fiber were estimated to be 1.4×10−18m2/W and 20.9/W/km at 1550nm, respectively. © 2013 Elsevier B.V. All rights reserved.

Effect of Zn Addition on Non-Resonant Third-Order Optical Nonlinearity of the Cu-Doped Germano-Silicate Optical Glass Fiber

Cu/Zn-codoped germano-silicate optical glass fiber was manufactured by using the modified chemical vapor deposition (MCVD) process and solution doping process. To investigate the reduction effect of Zn addition on Cu metal formation in the core of the Cu/Zn-codoped germano-silicate optical glass fiber, the optical absorption property and the non-resonant third-order optical nonlinearity were measured. Absorption peaks at 435 nm and 469 nm in the Cu/Zn-codoped germano-silicate optical glass fiber were contributed to Cu metal particles and ZnO semiconductor particles, respectively. The effective non-resonant optical nonlinearity, gamma, of the Cu/Zn-codoped germano-silicate optical glass fiber was measured to be 1.5097 W(-1) x km(-1) by using the continuous-wave self-phase modulation method. The gamma of the Cu/Zn-codoped germano-silicate optical glass fiber was about four times larger than that of the reference germano-silicate optical glass fiber without any dopants. The increase of the effective non-resonant optical nonlinearity, gamma, of the Cu/Zn-codoped germano-silicate optical glass fiber, can be attributed to the enhanced nonlinear polarization due to incorporated ZnO semiconductor particles and Cu metal ions in the glass network. The Cu/Zn-codoped germano-silicate optical glass fiber showed high nonlinearity and low transmission loss at the optical communication wavelength, which makes it suitable for high-speed-high-capacity optical communication systems.

NONLINEAR OPTICAL PROPERTIES OF ZINC DOPED GERMANO-SILICATE GLASS OPTICAL FIBER

Zinc doped germano-silicate glass optical fiber was developed by using the modified chemical vapor deposition and the drawing tower process. Absorption peaks of the germano-silicate glass optical fiber preform appeared at 240 nm and 330 nm were due to the incorporated Zn metal nano-particles (MNPs) and ZnO semiconductor nano-particles (SNPs), respectively and the average diameter of nano-particles (NPs) was estimated to be about 2 nm by transmission electron microscopy. However, the absorption peak of the zinc doped optical fiber due to ZnO SNPs was found to appear at 490 nm red-shifted from 330 nm can be explained by the increase in average size of ZnO SNPs in the fiber core due to growth or recrystallization of ZnO SNPs during the fiber drawing process about 2150°C. The nonlinear refractive index coefficient, n2, of the fiber was estimated to be 5.62 × 10-20 m2/W due to the stable dispersion of ZnO SNPs using the continuous-wave self-phase modulation method.

PHOTONIC PROPERTIES OF Ti DOPED OPTICAL FIBER

The photonic properties of Ti doped optical fiber were investigated for application of optical nonlinear devices and a fiber-type UV sensor based on its high third order optical nonlinearity and photoluminescence characteristics. The structure and defect states of Ti incorporated in silica glass network of the fiber core were examined by measurement of optical properties such as optical absorption, photoluminescence, Raman shift, and by transmission electron microscopy. The nonlinear refractive index, n2, of the fiber was measured to be 5.73 × 10-20 m2/W by continuous-wave self-phase modulation method, which was 2.5 times larger than that of the same optical fiber without Ti incorporation. The photoluminescence of the Ti doped optical fiber was found to appear over the range from 360 nm to 480 nm upon the Xenon-lamp illumination, and it was found to increase linearly with the increase of the lamp power.

Solid-core tellurite glass fiber for infrared and nonlinear applications

By optimizing glass composition and using a multistage dehydration process, a ternary 80TeO(2)-10ZnO-10Na(2)O glass is obtained that shows excellent transparency in the wavelength range from 0.38 microm up to 6.10 microm. Based on this optimized composition, we report on the fabrication of a single-mode solid-core tellurite glass fiber with large mode area of 103 microm(2) and low loss of 0.24-0.7 dB/m at 1550 nm. By using the continuous-wave self-phase modulation method, the non-resonant nonlinear refractive index n(2) and the effective nonlinear parameter gamma of this made tellurite glass fiber were estimated to be 3.8x10(-19) m(2)/W and 10.6 W(-1) x km(-1) at 1550 nm, respectively.

Tellurium-enhanced nonresonant third-order optical nonlinearity in a germanosilicate optical fiber

A tellurium-doped germanosilicate optical fiber was developed by modified chemical vapor deposition and solution doping techniques. Using the continuous-wave self-phase modulation method, the nonresonant nonlinear refractive index, n2, was measured to be 5.52 x 10(-20) m2/W, which is 2 to 3 times that of the undoped germanosilicate glass fiber. Polyhedron structures TeO3 and TeO4 with GeO4 and SiO4 are believed responsible for lower phonon energy, more nonbridging oxygens, and a larger hyperpolarization, leading to the observed higher nonresonant optical nonlinearity.

Measurement of Er-Doped Fiber Nonlinearity Using Continuous-Wave Self-Phase Modulation Method

The intensity-dependent nonlinear coefficient n 2/A eff of a short Er-doped, amplifying fiber is determined using a method thoroughly studied for measurements of passive fibers. Measurement uncertainty of 3.0% is achieved using modified continuous-wave self-phase modulation method. In addition to metrological aspects, we also discuss limitations and conditions imposed by the Er-doped fiber as compared with the measurement of a pure silica core fiber. The used measurement method is advantageous as compared with other techniques due to its reliability and ease of implementation.

Non-Resonant Optical Nonlinearity of Germano-Silicate Optical Fiber Incorporated with Si Nanocrystals

Non-Resonant Optical Nonlinearity of Germano-Silicate Optical Fiber Incorporated with Si Nanocrystals Hye Jin Cho, Aoxiang Lin, Songbae Moon and Won-Taek Han Department of Information and Communications, School of Photon Science and Technology, Gwangju Institute of Science and Technology, Gwangju 500-712 Bok Hyeon Kim Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 500-712 (Received 12 December 2007) The non-resonant optical nonlinearity of a germano-silicate glass optical ber with silicon (Si) nanocrystals incorporated, fabricated by using a modi ed chemical vapor deposition process, was investigated by the continuous-wave self-phase modulation method. The measured non-resonant nonlinear refractive index, n2 = 5:70 10 20 m2/W, of the ber was found to be 2 times larger than that of the ber without Si incorporation. PACS numbers: 42.70.-a, 42.65.wi, 78.67.Bf

Pb 2+/Al 3+ codoped germano-silicate optical fiber with high non-resonant third-order nonlinearity

A germano-silicate optical fiber codoped with Pb 2+ and Al 3+ was developed by modified chemical vapor deposition and solution doping techniques. The non-resonant third-order optical nonlinearity was measured to be 6.9105 × 10 −20 m 2/W by using the continuous-wave self-phase modulation method. The enhanced non-resonant nonlinearity was ascribed to the increasing number of non-bridging oxygens due to the incorporation of the glass modifiers Pb 2+ and Al 3+, the large molar refraction from heavy metal ions Pb 2+, and the enhanced hyper-polarization from PbO doped into the core of the made fiber.

Reliable Determination of Optical Fiber Nonlinearity Using Dispersion Simulations and Improved Power Measurements

We have improved the accuracy of the continuous-wave self-phase modulation method for measuring the nonlinearity of optical fibers. Evaluation of the measurement uncertainty shows that the most significant source of uncertainty is the measurement of fiber-optic power. However, chromatic dispersion can also have a significant effect on the apparent results if it is not taken properly into account. We demonstrate means to achieve an expanded uncertainty of 2% (coverage factor k=2) for the measurement of the nonlinear coefficient n2 /Aeff. Also, the metrological aspects related to the determination of the nonlinear coefficient and the measurement uncertainty are discussed

Cu^2+-doped germano-silicate glass fiber with high resonant nonlinearity

We firstly report on the fabrication of Cu(2+)-doped germano-silicate glass fiber for nonlinear optical devices application by using modified chemical vapor deposition and solution doping processes. Broadband absorption near 700nm due to the 3d-shell electron transitions of Cu(2+) ions from the ground state to the excited states was observed. The resonant nonlinearity of the Cu(2+)-doped fiber was estimated to be 5.5x10(-17)m(2)/W by measuring the phase shift of the fringes obtained from the long-period fiber grating pair upon pumping with a laser diode at 980nm and non-resonant nonlinearities were also measured to be 4.114x10(-21)m(2)/W by the continuous wave self-phase modulation method.

Universal conditions for estimating the nonlinear refractive index n2 of dispersion-compensating fibers by the CW-SPM method

We investigated universal conditions for measuring the nonlinear refractive index n/sub 2/ of dispersion-compensating fibers by the continuous wave self-phase modulation (CW-SPM) method both theoretically and experimentally. We showed that the required fiber length and the minimum power for n/sub 2/ estimation can be expressed as simple functions in terms of chromatic dispersion D. Moreover, we confirmed experimentally that the present conditions for n/sub 2/ estimation are reasonable.