Chromatic Dispersion Measurement Research Articles

Chromatic dispersion measurement error caused by source amplified spontaneous emission

We demonstrate the degrading effect of noise from amplified spontaneous emission on measurements of chromatic dispersion using the modulation phase-shift method. Dramatic performance improvement is achieved with a narrow-band tracking filter.

Temporal van Cittert-Zernike theorem and its application to the measurement of chromatic dispersion

A time-domain equivalent of the van Cittert–Zernike theorem is formulated. The two-time correlation function of an incoherent source after temporal gating and chromatic dispersion is derived. Significant spectral dispersion establishes partial temporal coherence, in a way similar to the establishment of partial spatial coherence in the far field for a spatially incoherent source after propagation through an aperture and diffraction. It is shown theoretically and experimentally that the temporal degree of coherence of the source after temporal gating and dispersive propagation is related to the modulus of the Fourier transform of the temporal transmission of the gate. The derivation of the two-time correlation function of such a source is applied to an interferometric measurement of chromatic dispersion that uses a time-gated incoherent source.

Simultaneous Position-Resolved Mapping of Chromatic Dispersion and Brillouin Shift Along Single-Mode Optical Fibers

We describe a new method for performing simultaneous position-resolved measurements of chromatic dispersion and Brillouin shift along single-mode optical fibers. The technique provides consistent high-resolution and low-noise results for both quantities. Our measurements indicate a certain correlation between both magnitudes, although the degree of correlation varies for the different manufacturers tested.

Chromatic Dispersion Measurement Using a Multiwavelength Frequency-Shifted Feedback Fiber Laser

In this paper, we present the realization of a fiber laser source emitting simultaneously over 17 wavelengths spread over the whole C-band. An acoustooptic frequency shifter is placed in the laser ring cavity to suppress the cross-gain saturation effects of the erbium-doped fiber. The emitted wavelengths are fixed by a set of fiber Bragg gratings (FBGs). A power uniformity reaching 6 dB is achieved by inscribing the FBGs while monitoring the laser output. We demonstrate the reliability of this laser as a source for characterization of optical components and networks by the measurement of optical fiber chromatic dispersion. The measurement is performed over the whole telecommunication C-band (1530-1560 nm) using the time-of-flight method. We perform the measurement on three different fibers with different levels of dispersion, namely a standard fiber, a nonzero dispersion shifted fiber, and a dispersion compensating fiber. The results are compared with measurements obtained using a standard network analyzer. The agreement between the two methods is better than /spl plusmn/1%, thus proving the suitability of the developed laser source for this application.

Chromatic dispersion characterization by direct instantaneous frequency measurement.

A new concept for the measurement of chromatic dispersion is presented. The group delay of the device under test is directly obtained from the instantaneous frequency of a short optical pulse after propagation in the device, itself obtained with temporal and spectral interferometry. Temporal and spectral fringe encoding provide excellent accuracy and resistance to noise, and a wide variety of dispersions can be characterized even at high insertion losses.

Accurate measurements of differential chromatic dispersion and contrasts in an hectometric silica fibre interferometer in the frame of ’OHANA project

In the frame of ’OHANA project (phase II), IRCOM institute characterizes the 300-m long silica fibres which will link the Canada–France–Hawaii-Telescope and the Gemini telescope. In this paper, we report a method to compensate the differential chromatic dispersion between two 300-m long silica polarization-maintaining fibres. We experimentally show that the differential dispersion is not the same on each neutral axis of the fibre. Moreover, thanks to a channeled spectrum analysis, we are able to foresee the evolution of the contrast as a function of the wavelength and the spectral resolution over a given spectral band. Consequently, we are able to adjust the fibre lengths in order to maximize the contrast over J spectral window.

Distributed measurement of chromatic dispersion by four-wave mixing and Brillouin optical-time-domain analysis.

A new nondestructive method for measuring the spatial distribution of chromatic dispersion along an optical fiber is presented. It is based on using Brillouin optical time-domain analysis to probe the power distribution of the four-wave mixing generated by two continuous-wave lasers. The results obtained prove that this new method is capable of providing better performance than comparable techniques. Furthermore, sensing the variations of Brillouin gain maximum produces additional information about the fiber, such as presence of strain and concentration of GeO2.

40 Gbit/s CSRZ-DPSK transmission system with signed online chromatic dispersion detection

A chromatic dispersion measurement scheme based on arrival time detection, an active interferometer phase stabilisation, and a standard clock-and-data recovery circuit are used in this 40 Gbit/s carrier-suppressed return-to-zero differential phase shift keying system. Chromatic dispersion measurement noise is 100 fs/nm.

Use of an electroabsorption modulator and an autocorrelator for fibre chromatic dispersion measurement at 1550 nm

We present the measurement of chromatic dispersion around 1550 nm of a number of optical fibres with a pulse delay technique utilising an electroabsorption modulator and an autocorrelator for high temporal accuracy. In total, 10 fibres with various lengths and dispersion characteristics have been characterised, demonstrating the flexibility of the method. Mismatches between manufacturer-quoted and measured dispersion values ranged from 0.8% to 9% and it is believed that higher accuracies can be achieved by perfecting the data processing procedure. This technique may find application in research laboratories for quick and reliable fibre dispersion characterisation.

Distributed measurements of chromatic dispersion and nonlinear coefficient in low-PMD dispersion-shifted fibers

We report on the investigation of distributed chromatic dispersion (CD) and distributed nonlinear coefficient (NLC) measurements based on phase mismatched four-wave mixing in dispersion-shifted fibers (DSFs). Experimental results of the distributed CD maps for low polarization-mode dispersion (PMD) DSF fibers are discussed. We also report how nonnegligible values of PMD can adversely affect the distributed CD measurements. A new method to measure the distributed NLC map in low-PMD DSF fibers is also proposed and demonstrated experimentally.

Simultaneous measurements of non-linear coefficient, zero-dispersion wavelength and chromatic dispersion in dispersion-shifted fibers by four-wave mixing

We report on a new simple technique for the simultaneous measurement of non-linear coefficient, zero-dispersion wavelength, and chromatic dispersion in dispersion-shifted fibers based on partially degenerated four-wave mixing. Both zero-dispersion wavelength and chromatic dispersion of the dispersion-shifted fibers can be measured with high accuracy. The experiment results of two dispersion-shifted fibers will be presented and the technique for obtaining accurate chromatic dispersion and zero-dispersion wavelength will also be discussed.

Measurement of modal dispersion in optical fiber by means of acousto-optic coupling

We show that frequency-wavelength tuning characteristics of acousto-optic coupling can be used for measuring the difference of effective index, group index, and chromatic dispersion between core and cladding modes in single-mode fibers. Chromatic dispersion measurements of a 30-cm-long conventional single-mode fiber, a nonzero dispersion-shifted fiber, and a dispersion-compensating fiber with this new method are presented for the wavelength range 1500-1600 nm. Qualitative agreement with independently measured data is obtained.

A novel mode-splitting detection scheme in 43-Gb/s CS- and DCS-RZ signal transmission

Sophistication of the transmission format for 40-Gb/s/ch WDM networks is indispensable. In long-haul transmission applications, the selection of transmission format should be a principal issue. Recently, we have proposed several transmission formats including carrier-suppressed return-to-zero (CS-RZ) and duo-binary-carrier-suppressed (DCS-RZ), in so doing addressing the issue of superior performance versus fiber nonlinearity and spectral efficiency. The special spectrum structure of these formats enables a novel mode-splitting detection scheme. The scheme realizes a variety of applications in 40-Gb/s/ch transmission; including expansion of dispersion tolerance, automatic dispersion compensation, and BER improvement. We achieved 1.6 times. expansion of dispersion tolerance of 43-Gb/s DCS-RZ signals by introducing mode-splitting in the receiver. By applying the mode-splitting scheme for CS-RZ signals, we also demonstrated precise chromatic dispersion measurement with its sign detection without the need for any dithering operation and its application to automatic dispersion compensation at 43-Gb/s CS-RZ transmission.

Signed online chromatic dispersion detection at 40 Gbit/s based on arrival timedetection with 60 attosecond dynamic accuracy

A DFB TX laser in a 40 Gbit/s optical transmission system is amplitude-modulated by 1.2% (r.m.s.). In the presence of chromatic dispersion, associated 224 MHz (r.m.s.) FM modulates signal arrival time, which is measured by lock-in detection of oscillator control voltage in RX clock recovery. Chromatic dispersion measurement noise is 33 fs/nm.

Optical fiber chromatic dispersion measurement using bidirectional modulation of an optical intensity modulator

We have proposed a simple method for measuring the chromatic dispersion and the time delay of optical fiber by using bidirectional modulation of a Mach-Zehnder modulator. To demonstrate the performance of the proposed method, we have measured the chromatic dispersion of optical fiber with length of 2.235 km by using this method over wavelength of 1500-1580 nm. The difference between the measured and the given chromatic dispersion is less than 0.19 ps/nm/km over the measured wavelength range.

Simultaneous measurement of the nonlinear refractive index and chromatic dispersion of optical fibers by four‐wave mixing

AbstractThe simultaneous measurement of the nonlinear refractive index and the chromatic dispersion measurement of dispersion shift fibers are proposed, based on the power determination of the mixing products generated by four pump waves. This method is also used with other low‐dispersion chromatic dispersion fiber, such as nonzero dispersion shifted fibers. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 305–307, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10444

Chromatic dispersion measurement of optical components using lightwave synthesized frequency sweeper

We propose a chromatic dispersion (CD) measurement method that uses a lightwave synthesized frequency sweeper (LSFS), which generates a frequency swept output with very good linearity. With the LSFS, we can measure the CD of optical components in a very short time. Moreover, the employment of a lock-in detection with phase diversity technique makes it possible to fully utilize the good wavelength resolution and accuracy of the LSFS. We describe the principle of the method and analyze the noises that are intrinsic to it. We also report an experimental result that confirmed the method's feasibility.

A novel chromatic dispersion measurement method in frequency domain using a multi-wavelength optical pulse train generated by Fabry–Perot laser diode

We propose and demonstrate a simple and robust measurement method for the chromatic dispersion of single mode fibers. Multi-wavelength picosecond optical pulse train from a gain-switched Fabry–Perot laser diode in conjunction with the highly dispersive fiber is used for multi-wavelength light source. The frequency of the separated pulse train may suffer a frequency change in dispersive optical fiber, which can be measured very accurately by an electrical spectrum analyzer. This method was applied to measure the chromatic dispersion of the standard single mode fiber for various lengths. The measured chromatic dispersion of a standard single mode fiber was 17.60 ps/nm/km at 1561 nm with an experimental standard deviation of 0.20 ps/nm/km and time resolution was less than 0.18 ps. The measurement setup is compact and economical compared to conventional methods. This technique can be applied in both long and short lengths (∼50 m) of fibers with very high accuracy.

Measurement of residual chromatic dispersion of a 40-Gb/s RZ signal via spectral broadening

In this letter, we examine the spectrum of a 40-Gb/s return-to-zero (RZ) data stream, which has been broadened by self-phase modulation in a nonlinear fiber. Spectra were recorded as the residual chromatic dispersion at the input of the nonlinear fiber was varied using a tunable dispersion element. We show that spectral broadening can provide a useful measure of the residual chromatic dispersion of the data stream.

Interferometric technique for measuring dispersionof high ordermodes in optical fibres

An interferometric technique for chromatic dispersion measurement of higher modes in short lengths of high order mode fibres is presented. The dispersion is measured using the wavelength dependence of the interference signal between the basic mode and the high order mode. Neither mode transformers nor RF circuitry are required.