1、TIASTANDARDFOTP-197Differential Group Delay Measurement Of Single-Mode Components and Devices by the Differential Phase Shift MethodTIA-455-197July 2000 TELECOMMUNICATIONS INDUSTRY ASSOCIATION ANSI/TIA/EIA-455-197-2000 Approved: June 22, 2000 Reaffirmed: April 25, 2008 NOTICETIA Engineering Standard
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6、s and to determine the applicability of regulatory limitations before its use. (From Standards Proposal No. 3-2761, formulated under the cognizance of the TIA FO-4 Fiber Optics, FO-4.3 Subcommittee on Passive Optical Devices and Components.) Published by TELECOMMUNICATIONS INDUSTRY ASSOCIATION Stand
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22、EGOING NEGATION OF DAMAGES IS A FUNDAMENTAL ELEMENT OF THE USE OF THE CONTENTS HEREOF, AND THESE CONTENTS WOULD NOT BE PUBLISHED BY TIA WITHOUT SUCH LIMITATIONS. TIA/EIA-455-197AJB,TIA SC FO-6.3.5, 05-25-00 iFOTP-197DIFFERENTIAL GROUP DELAY MEASUREMENT OF SINGLE-MODECOMPONENTS AND DEVICES BY THE DIF
23、FERENTIAL PHASE SHIFTMETHODContentsForeword iii1 Introduction 12 Normative References 23 Apparatus 34 Sampling And Specimens 105 Procedure 116 Calculations 137 Documentation 158 Specification Information 16Annex A (Informative) 17Annex B (Informative) 20Annex C (Informative) 20TIA/EIA-455-197AAA,TIA
24、 SC FO-x.x, mm-dd-yy iiThis page left blank.TIA/EIA-455-197AJB,TIA SC FO-6.3.5, 05-25-00 iiiFOTP-197DIFFERENTIAL GROUP DELAY MEASUREMENT OF SINGLE-MODECOMPONENTS AND DEVICES BY THE DIFFERENTIAL PHASE SHIFTMETHODForeword(This Foreword is informative only and is not part of this Standard.)From TIA Pro
25、ject No. 4591, formulated under the cognizance of TIA FO-6.3.5,Subcommittee on Passive Fiber Optic Devices.This FOTP is part of the series of test procedures included within RecommendedStandard EIA/TIA-455.There are three annexes, all of them informative.Key words: Polarization Mode Dispersion, Comp
26、onents, Isolators, Filters, PMD.,DGD, Group DelayTIA/EIA-455-197AAA,TIA SC FO-x.x, mm-dd-yy ivThis page left blankTIA/EIA-455-197AJB,TIA SC FO-6.3.5, 05-25-00 11 Introduction1.1 IntentA procedure is described for the measurement of polarization-sensitive DifferentialGroup delay (DGD) of one or two p
27、ort single-mode fiber components over the 1.0 to1.7 micrometer wavelength range. The DGD at each particular wavelength isdetermined from the differential group delay (phase shift) between two orthogonalpolarizations.Note that Polarization Mode Dispersion (PMD) delay is defined as the averageDGD over
28、 a specific finite wavelength range.1.2 ScopeIn this procedure, a modulated light source at a given wavelength is coupled into thecomponent under test, and the phase of the modulated signal exiting the fiber at afirst polarization state is compared with the phase at a second, orthogonalpolarization
29、state. Once the maximum phase difference has been determined,corresponding to the input states of polarization (SOPs) aligning to the twoprincipal axes of the component, this is converted to a delay difference, andreported as the DGD for the component at that wavelength.For the purposes of this docu
30、ment, the component is considered to be measured ata single wavelength, and therefore the result reported is stictly the DGD.This FOTP does not apply to components that have in excess of 10 dB ofpolarization dependent loss (PDL).1.3 BackgroundThere already exist three Test Procedures for PMD measure
31、ment in Fibers andfiber cables. Two of these methods use a Polarimetric approach to PMDmeasurement and are typically referred to as frequency domain measurements,because the techniques rely on measuring the variation of birefringence andpolarized light transmission with wavelength to determine PMD.
32、These are theJones Matrix Eigenanalysis (JME) method (covered by FOTP-122) and the FixedAnalyzer (FA) technique (covered by FOTP-113). The latter is subdivided withExtrema Counting (FAEC) and Fourier Transform (FAFT) processing methods.The third Technique is Interferometry (covered by FOTP-124), whe
33、re a broadband(e.g. LED) source is used as a low-coherence source to examine the path lengthimbalance (time delay differences) caused by the PMD. For this reason it isreferred to as a time-domain PMD method.TIA/EIA-455-197AAA,TIA SC FO-x.x, mm-dd-yy 2A key part of the measurement of fibers is the co
34、ncept of statistical averaging ofthe properties of the fiber over many wavelengths, in order to determine the averageDGD (called PMD) of the fiber. A fourth FOTP, FOTP-196 (SP-4355) describeshow to apply these techniques to fiber components especially with regard to thespectral bandwidth of the devi
35、ce under test (DUT), and to use a deterministicapproach to DGD and PMD measurement.A fundamental limitation of all the techniques cited above is that a finite (a few nmto 10s of pm) of wavelength range is required in order to perform the measurement.The technique described herein uses a comparitivel
36、y small wavelength range inorder to make the measurement of DGD, and therefore will find applications in avariety of DWDM component testing applications. This particularly true when usingnarrow band fixed or tunable laser sources.1.4 Light SourcesTypical optical sources suitable for this measurement
37、 include laser diodes orfiltered light-emitting diodes.1.5 OtherThis method can be applied to laboratory, factory and field measurements of DGDin components and the wavelength range can be tailored as required.The test method can be applied to DUTs that are transmissive or reflective. In thelatter c
38、ase, the DUT connection is via a coupler, which has a known very low PMDvalue.This test method can be combined with test methods to measure the chromaticdelay in the DUT such as FOTP-169 or FOTP-175, which use very similar hardware.2 Normative referencesTest or inspection requirements may include, b
39、ut are not limited to, the followingreferences:EIA/TIA-455-A, (Example: Standard Test Procedure for Fiber Optic Fibers, Cables,Transducers, Sensors, Connecting and Transmitting Devices, and Other Fiberoptic components.)FOTP-113 (EIA/TIA-113), (Polarization Mode Dispersion Measurement for Single-Mode
40、 Optical Fibers by the Fixed Analyzer method.)TIA/EIA-455-197AJB,TIA SC FO-6.3.5, 05-25-00 3FOTP-122 (EIA/TIA-122), (Polarization-Mode Dispersion Measurement for Single-Mode Optical Fibers by Jones Matrix Eigenanalysis.)FOTP-124 (EIA/TIA-124), (Polarization-Mode Dispersion Measurement for Single-Mod
41、e Optical Fibers by Interferometric Method.)FOTP-157 (EIA/TIA-157), (Polarization-Dependent Loss Measurement in PassiveOptical Components)FOTP-196 (EIA/TIA-196), (Guideline for Polarization-Mode DispersionMeasurement in Single-Mode Fiber Optic Components and Devices)Users of these FOTPs are encourag
42、ed to specify the most recent edition.3 ApparatusThe basic apparatus is shown in Figure 1. Figure 1 shows alternative connectionsto the DUT for the measurement of its reflection performance.3.1 Light Source(s)For the measurement of DGD at each specified wavelength, use multiple laserdiodes, tunable
43、lasers or light-emitting diodes filtered by monochromator or otherfilter(s). A key issue involved in the selection of a suitable source is that the sourcelinewidth should be equal to or less than the bandwidth of the DUT (for amplifierDUTs, use the gain bandwidth). In general, use a laser or tunable
44、 laser to obtain thelowest linewidths.3.1.1 Laser DiodesThe center wavelength and modulated output phase of the laser source shall bestable over the measurement time period at the bias current, modulation frequencyand diode temperature encountered.Single-longitudinal-mode laser diodes with temperatu
45、re control and output powerstabilization (e.g. PIN feedback) are typically suitable for use with single-modeoptical fiber.TIA/EIA-455-197AAA,TIA SC FO-x.x, mm-dd-yy 4Figure 1: Apparatus to make the DGD measurement(Items shown with dashed lines are alternative implementations)3.1.2 Filtered Light Emi
46、tting DiodesUse one or more light emitting diodes. The center wavelength and modulated outputphase of the source shall be stable over the measurement time period at the biascurrent, modulation frequency and diode temperature encountered.Filter the optical spectrum to give a spectral line of full wid
47、th at half maximum in therange 1 to 5 nm. A monochromator may be used for filtering or selecting thewavelength.3.1.3 Tunable diode lasersUse one or more tunable diode lasers. The center wavelength and modulated outputphase of each laser at each wavelength used shall be stable over the measurementtim
48、e period at the bias current, modulation frequency and diode temperatureencountered. Typically completely self-contained temperature controlled external-cavity laser units may be employed.3.2 ModulationModulate the intensity of the light sources to produce a waveform with a singledominant Fourier co
49、mponent. The frequency of the modulation shall be sufficientlyhigh and sufficiently stable to ensure adequate measurement precision.Light source(e.g.Laser)PolarisationControllerDeviceunder testOpticalReceiverPhasemeasurementelectronicsHF oscillatorf =0.01-10GHzmodulationComputerRef.DirectionalCoupler orCirculatorOpticalSwitchModulatorTIA/EIA-455-197AJB,TIA SC FO-6.3.5, 05-25-00 5Modulation may be achieved by direct (internal) current injection to the laser diodeor LED. Other (external) forms of modulation means may also be used. Examplesare electro-optic modulator devices place
