Transmission Characteristics Of Fibers Research Articles

Enhancement of the bandwidth of W-type glass optical fibers in the infrared wavelength region

Abstract Transmission characteristics (bandwidth and steady state loss) of multimode W-type glass optical fibers are investigated by solving the time-dependent power flow equation. Results show how the bandwidth in W-type glass optical fibers can be enhanced by shifting from the red to infrared wavelength region for different depths and widths of the intermediate layer as well as for different launch excitations. Such characterization of these fibers is consistent with their manifested effectiveness in reducing modal dispersion and bending loss.

Theoretical analysis of high-sensitive seawater temperature and salinity measurement based on C-type micro-structured fiber

A new sensing method for simultaneous measurement of seawater temperature and salinity by C-type micro-structured fiber was proposed. The C-type fiber structure formed by removing the outer wall of one pore from a six holes micro-structured fiber, which would bring in birefringence and broke original pattern of degeneracy. By optimizing the parameters of this fiber structure, X polarization and Y polarization of fundamental mode were separate. Therefore, it could be used for double parameter measurement. Besides, gold film coated on the surface of structure to enhance sensing sensitivity by Surface Plasmon Resonance (SPR) principle. In this study, finite element analysis method was used to analyze the spectral transmission characteristics of C-type micro-structured optical fiber. The surface of wedge-shaped defect was contacted with seawater directly to feel salinity; meanwhile, thermo-optic material filled into pores to detect the temperature of seawater. Through model analysis, it was proved that the proposed filling structure could produce two SPR loss valleys, which had different responses to temperature and salinity. Under optimized structure, maximum salinity sensitivity of 1.402 nm/‰ was obtained for X-polarization and maximum temperature sensitivity of −7.609 nm/ °C was obtained for Y polarization, which demonstrated that the designed scheme could not only solve the cross sensitivity problem of two parameters but also achieve high sensitivity. In addition, C-type micro-structured fiber is non-cascade integrated, strong stability, and flexibility in design, which has great potential for sensing applications.

Design of a novel photonic crystal fiber filter based on gold-coated and elliptical air holes

In recent years, photonic crystal fibers have played an important role in the field of optical communications, and the addition of metal materials to photonic crystal fibers have offered new ways to improve the transmission characteristics of optical fibers. We design a new type of gold-coated photonic crystal filter, which utilizes the surface plasmon resonance effect, and study it by using the finite element method. In this paper, we optimise the structure parameters and analyze the numerical results. The numerical results show that the thickness of metal layer and the air holes near the fiber core strongly affect the performance of the polarization filter. For the operating wavelength of 1550 nm, the loss in the y-polarization direction can be as high as 906.9 dB/cm, which is much larger than the x-polarization direction. When the fiber length is longer than 100 μm, the crosstalk in the wavelength range from 1.4 μm to 1.9 μm is greater than 20 dB. The proposed optical fiber can find application as an optical fiber polarization filter.

Phase-Shift Method-Based Optical VSB Modulation Using High-Pass Hilbert Transform

This report presents a novel method of generating an optical vestigial sideband (VSB) modulated signal without using optical bandpass filters. Using a modified Hilbert transformer based on digital signal processing, an optical VSB-modulated signal is generated using the phase-shift method. The proposed method is demonstrated experimentally for an optical binary phase-shift keying (BPSK) signal. The proposed method is wavelength-transparent compared to an optical bandpass filtering method, where the wavelength dependence of the optical bandpass filter limits applications. Furthermore, the optical bandwidth of the modulated signal is readily adjustable by changing the cutoff frequency of the high-pass Hilbert transformer. Fiber transmission characteristics of a single-channel optical BPSK-VSB signal are analyzed using a 100-km transmission link. Results of fiber transmission analysis show tolerance of the proposed modulation scheme to fiber nonlinearity-based signal distortions. For a 10 Gbit/s non-return-to zero(NRZ) sequence, a self-phase modulation threshold of 13 dBm is reported for the studied system.

Fabrication and characterisation of polysiloxane optical fiber microloop interferometers

ABSTRACTWe fabricated micrometer‐order diameter polysiloxane optical fibers by drawing process of partially cured siloxane. Using a few mm long polysiloxane fibers integrated on the polydimethylsiloxane substrate or in telecommunications optical fibers, we studied the influence of looping on the transmission characteristics of a polysiloxane optical fibers. We have demonstrated an optical interferometers built of a coiled self‐touching polysiloxane fibers with a diameter of up to 25 microns. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2876–2879, 2016

Experimental research on the dispersion property of hollow core photonic bandgap fiber

Due to the unique optical properties of low loss, low nonlinearity, high threshold and low latency, hollow core bandgap fibers are endowed with high expectations in the field of high power delivery, optical fiber communication, nonlinear optics, fiber sensors, etc. Fiber dispersion, as one of the basic transmission characteristics of optical fiber, makes the light pulse broadened during transmission, thus has adverse effects on high power pulse transmission system and high speed optical communication system. Therefore, it is significant to study the dispersion characteristics of the hollow core bandgap fiber for its applications in the field of high power pulse transmission and high speed communications. Because of the simple structure of measurement system, low cost, high accuracy and relatively short length of fiber (just needing a few meters long), interferometric technique is suitable for dispersion measurement of hollow core photonic bandgap fiber. The key to obtaining the dispersion results with interferometric technique is the phase extractiton from the interferogram. In order to meet the requirements of hollow core bandgap fiber for wide bandwidth, high efficiency and high accuracy dispersion measurement, a novel phase extraction method based on interferometry is proposed in this paper, by which the precision of dispersion measurement is improved through using the whole data-set in the interferogram. Combining with the determinations of the peak and center of symmetry points, the extraction of phase information can be implemented directly from the interferogram. The experimental results of measuring a standard single mode fiber indicate that the difference between the experimental measurement and theoretical simulation is just 0.6 psnm-1km-1, which proves that this proposed method possesses high accuracy and is suitable for the measurement of hollow core bandgap fiber. Consequently, according to the proposed phase extraction method, the measurement system based on Mach-Zehnder interferometer is set up and the dispersion measurement of a 19 cell hollow core bandgap fiber with a core diameter of 26 m is carried out. Experimental results indicate that the fundamental mode dispersion curve of the 19 cell hollow core photonic bandgap fiber in a wavelength range from 1400 nm to 1630 nm can be obtained. Moreover, four high order mode dispersion curves are obtained for the first time. The measurement results are in accordance with the simulation results. These findings are of significant importance for exploring the dispersion characteristics of hollow core photonic bandgap fibers, and also conducible to their applications in the fields of high power laser delivery, high capacity data communications, optical fiber nonlinear, etc.

Transmission characteristics of photonic crystal fibers based on filling different kinds of liquid crystals

The transmission characteristics of full-filled photonic liquid crystal fibers (PLCFs) which are filled with five kinds of liquid crystals (LCs) are experimentally studied and theoretically analyzed. The influences of temperature and external electric field on the transmission characteristics of PLCFs are also discussed in this paper. The transmission spectra of PLCFs show obvious bandgaps, and the number and the central wavelengths of the bandgaps depend on the average value of the refractive indices of LCs. By changing the temperature from 20 ℃ to 80 ℃, a blue shift in the bandgap is observed, and the maximum tuning range of the bandgap is 41 nm. Then, with the voltage turning from 0 V to 250 V, the output power of the transmission spectrum decreases, while the central wavelength of the bandgap is almost unchanged. Finally, the transmission spectrum keeps a good stability, even if the polarization state of the input light changes.

Influence of the fiber design and launch beam on transmission characteristics of multimode glass W-type optical fibers

Abstract Bandwidth and steady-state loss of multimode glass W-type optical fibers (doubly clad fibers with three functional layers) are evaluated for the varied fiber design and launch beam parameters. These transmission characteristics are determined from the solution of the time-dependent power flow equation by the explicit finite difference method. Results are presented in a graph form as functions either of the fiber length or loss for the varied thickness and depth of the fiber׳s intermediate layer (inner cladding), fiber׳s coupling strength, and input beam (mean angle and width). The trade-off relation between the bandwidth and steady-state loss for designing multimode glass W-type optical fibers is shown in graphs and highlighted the text. We found that bandwidth improves with thinner and shallower intermediate layers, narrower and more central launch-beam, and stronger mode coupling.

Optical Transmission Characteristics of Air-Core Fiber Based on the Surface Plasmon Resonance Effect of a Silver Sphere

UDC 621.315.51.61:535 In this paper, we studied the optical transmission spectra of a fiber with air-core 10 μm in diameter at 1550 nm. The light field distribution and the far-field intensity distribution are studied using finite difference time domain simulation. Furthermore, we studied the optical transmission spectra of a hollow fiber taper with an air-core cone as well as the spectra of a taper with a silver microsphere in it. Collectively, these results suggest that it can be used in the fields of optical signal processing and optical sensor.

Transmission characteristics of photonic crystal fiber gas cell used in frequency stabilized laser

We measure the transmission characteristics of hollow-core photonic crystal fiber (HC-PCF) gas cells with ferrule- and fusion-spliced configurations, and near- and far-field images of the HC-PCF are observed. Results show that the center of mass (COM) of the far-field image varies with the laser frequency and temperature, and the moving COM relates to the oscillatory transmission. Using a model of the spatial interference, we first demonstrate that mainly the modes with asymmetric phase distributions affect the COM position. The frequency stabilization performances of the lasers are compared. The fusion-spliced gas cell shows better performance than the ferrule-spliced one.

Influence of intermediate layer on transmission characteristics of W-type optical fibers

Abstract Transmission characteristics of multimode W-type optical fibers (doubly clad fibers with three layers) are investigated by solving the time-dependent power flow equation. A numerical solution has been obtained by the explicit finite difference method. Results show how the bandwidth in W-type optical fibers varies with depth and width of the intermediate layer for different coupling strengths and excitations. The trade-off between the bandwidth and steady-state loss is also specified. Such characterization of these fibers is consistent with their manifested effectiveness in reducing modal dispersion and bending loss.

介质金属膜椭圆太赫兹空芯光纤的传输特性研究

介质金属膜椭圆太赫兹空芯光纤的传输特性研究

基于温度变化的涂覆型熔锥光纤传输特性

基于温度变化的涂覆型熔锥光纤传输特性

Fiber transmission characteristics of phase only pulse and its dispersion compensation in high power regime

We investigated fiber transmission characteristics of phase only pulses (POPs) that had constant intensity and pulse-shaped phase waveforms. A 10-ps-wide Gaussian-shaped POP was generated by an optical pulse synthesizer that generates arbitrary waveforms through a frequency-domain modulation. It was transmitted through a standard single mode fiber and a dispersion compensating fiber. The POP was nonlinearity-tolerant due to the constant intensity and, consequently, its initial pulse waveform was successfully regenerated by dispersion compensation even in a high power regime.

Difference Absorption Optical Fiber Methane Gas Sensor Based on FBG <sup></sup>

In this paper, based on analysis of the near infrared spectral absorption of methane molecule and considering factors such as compatibility with the transmission characteristics of silica optical fiber and the price, using Fiber Bragg Grating (FBG) filters to replace the the traditional interference filter, a novel kind of all-fiber remote sensor utilizing FBG filters and 1.33μm high power light-emitting diode (LED) was developed for real time measurement of methane gas concentration. FBG has a low insert loss and can be produced easily compared with dielectric interference filters. Theory and experiment proved that the system has simple construct and high sensibility.

Fiber Transmission Characteristics of Parabolic Pulses Generated by Optical Pulse Synthesizer

We generated parabolic pulses by using an optical pulse synthesizer and investigated their fiber transmission characteristics in detail. The generated pulses had a rms difference of less than 0.03 between the target pulse shapes and their shapes. We transmitted them through standard single-mode fibers and dispersion-shifted fibers to evaluate the influences of their dispersions and nonlinearities on the pulse shapes. We compared the experimental results with simulated results calculated by the split-step Fourier method. The two results were well matched with each other. In the high power regime, the pulses experienced the higher order nonlinearities and were strongly distorted.

Fiber Transmission Characteristics of Parabolic Pulses Generated by Optical Pulse Synthesizer

Fiber Transmission Characteristics of Parabolic Pulses Generated by Optical Pulse Synthesizer

Coupled-mode analysis for single-helix chiral fiber gratings with small core-of fset

Using conventional coupled-mode theory, a set of coupled-mode equations are formulated for single-helix chiral fiber long-period gratings. A helical-core fiber is analyzed as an example. The analysis is simple in mathematical form and intuitive in physical concept. Based on the analysis, the polarization independence of mode coupling in special fiber gratings is revealed. The transmission characteristics of helical-core fibers are also simulated and discussed.

Transmission characteristics of versatile D-shaped fibers with temperature and ambient index change depending on input polarization states

Transmission characteristics of versatile D-shaped fibers with temperature and ambient index change depending on input polarization states

Effect of Surface Roughness Variation on the Transmission Characteristics of D-shaped Fibers with Ambient Index Change

Effect of Surface Roughness Variation on the Transmission Characteristics of D-shaped Fibers with Ambient Index Change