Chromatic Dispersion In Single-mode Fibers Research Articles

1550 nm VCSEL-based 10 Gb/s optical NRZ signal transmission over 20 km SMF using RSOA gain saturation

Abstract A method for a 1550 nm vertical cavity surface emitting laser (VCSEL)-based 10 Gb/s optical non-return to zero (NRZ) signal transmission over 20 km single mode fiber (SMF) using reflective semiconductor optical laser amplifier (RSOA) gain saturation is presented. The optical signal distortion of 10 Gb/s optical NRZ signals caused by the inherent frequency chirp of the VCSEL and the chromatic dispersion of SMF were investigated through numerical simulations and experiments. For 20 km transmission over SMF, VCSEL-based 10 Gb/s optical NRZ signals were severely distorted and ‘1’ bit signals had different amplitudes with respect to their bit patterns. The gain saturation of RSOA can equalize the different amplitudes of ‘1’ bit signals and can mitigate the optical pulse distortion after 20 km transmission over SMF. The experimental results showed that VCSEL-based 10 Gb/s optical NRZ signals can achieve a bit error rate (BER) of 10 - 9 with a 2.4 dB dispersion penalty for 20 km transmission of SMF with RSOA gain saturation.

Analysis of fiber Bragg grating with exponential–linear and parabolic taper profiles for dispersion slope compensation in optical fiber links

In this paper, the effect of various taper profiles on dispersion slope compensation in optical fiber links is studied. Theoretical and numerical investigation of the linear and nonlinear group delays of tapered fiber Bragg grating's (T-FBG) under strain is made. Calculation is performed using Matlab code based on solving the coupled mode equation using transfer matrix method. Our study shows that the linear tapered FBG profile provide the best result than the linear-exponential profile which can compensate up to 500km. As result, the spectral characteristics of tapered grating allow them to be used efficiently in high bit rates WDM and long-haul optical communication systems for chromatic dispersion of single-mode fiber.

General Time-Domain Representation of Chromatic Dispersion in Single-Mode Fibers

In this letter, an analytical method in time domain for calculation of the effect of chromatic dispersion (CD) in a single-mode fiber is presented. By using Fourier series representation of a general pulse approach, the CD effect could be obtained for arbitrary pulse shapes. As one improvement beyond the commonly used models, this work provides an analytical way to calculate the required number of taps for a finite impulse response filter equalizer without the need for empirical values. As an example, the spreading of a pulse carved by a Mach-Zehnder interferometer in an optical communication system is calculated. The novel analytical expression is in good agreement with other published results.

Chromatic dispersion measurement using optical beating null frequency

A new technique for measuring the accumulated chromatic dispersion in single-mode fibers is presented. The proposed simple and tunable technique uses the null frequency of the optical beating signal between pump, probe, and four-wave-mixing conjugated signals as the pump and probe frequency separation is changed. The null frequency of the optical beating signals varies with the accumulated chromatic dispersion in the single mode fiber. A full mathematical model of the measurement technique is developed and is supported by experimental results. The technique is successfully demonstrated experimentally using a semiconductor optical amplifier as a phase conjugator to achieve a null frequency variation of 1.2 GHz for a difference of 960-ps/nm accumulated chromatic dispersion.

Experimental investigation of the modulation phase-shift method for the measure of the chromatic dispersion in a single-mode fiber coiled on a covered spool

The measure of the chromatic dispersion of the optic fibers used in telecommunications networks and high-speed systems is very useful because it permits chromatic-dispersion compensators to be conceived across the wavelength range of interest. The modulation phase-shift method is used to measure chromatic dispersion in a standard single-mode fiber for telecommunication between 1200 and 1600 nm, by measuring the variation of the modulation phase of the transmitted signal modulated by a radio frequency signal, relative to the transmitted signal in a short reference fiber, modulated by the same signal. We verify the reduction of the thermal transitions in the measurement setup and fiber under test, while covering the spool of the fiber. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 174–178, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21298

The measurement of chromatic dispersion in single-mode fibers by interferometric loop

A method for chromatic dispersion measurement in long-length fibers (1-10 km) based on the application of an interferometric loop (IL) with phase modulation and lamp/monochromator light source is described. The wavelength region of the measurement is 1.1-1.6 mu m and the dynamic range is >15 dB. The reproducibility error of the measured group delay and chromatic dispersion is 40 ps/km and 0.1 ps/km-nm respectively. The results obtained by the IL method and Nd-YAG/Raman laser technique are compared. The measured dispersion agrees with the theoretical results calculated from the refractive index profile of the preform. The influence of the type of phase modulation and the length source spectral width on the accuracy of chromatic dispersion measurements by IL technique is analyzed theoretically.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Chromatic dispersion in single-mode fibers with arbitrary index profiles: a simple method for exact numerical evaluation

An exact numerical method for computation of the chromatic dispersion in single-mode fibers with arbitrary profiles is presented. The method is based on matrix perturbation theory, taking the change in the fiber properties with wavelength as perturbation. This approach requires only one matrix eigenvalue evaluation (as against multiple eigenvalue evaluations in the existing methods) and a few additional simple matrix manipulations, resulting in a considerable reduction of computational effort. >

Temperature dependence of chromatic dispersion in single mode fibers

This paper describes the temperature dependence of chromatic dispersion in single-mode fibers for a temperature range of -60°- 250°C. Highly accurate dispersion measurements demonstrated a linear relationship (0.025 nm/°C) between the zero dispersion wavelength and temperature for tests conducted below 150°C. Further tests in the high-temperature range showed an increase in this dependence. For both temperature ranges, the results were independent of fiber coating and structure.

Chromatic Dispersion Measurements in Single-Mode Fibers Using Picosecond InGaAsP Injection Lasers in the 1.2- to 1.5-μm Spectral Region

We describe the use of picosecond InGaAsP injection lasers for measuring chromatic dispersion in single-mode fibers in the 1.2- to 1.5-μm spectral region. Injection lasers at various wavelengths and a single-mode fiber-to-fiber switch are used in the pulse delay and pulse-broadening measurements. The simplicity and the compactness make the setup useful for field measurements and quality control.