1、 TIA/EIASTANDARDFOTP-197Differential Group Delay Measurementof Single-Mode Components andDevices by the Differential Phase ShiftMethodTIA/EIA-455-197JULY 2000TELECOMMUNICATIONS INDUSTRY ASSOCIATIONRepresenting the telecommunications industry inassociation with the Electronic Industries Alliance ANSI
2、/TIA/EIA-455-197-2000Approved: June 22, 2000TIA/EIA-455-197Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NOTICETIA/EIA Engineering Standards and Publications are designed to s
3、erve the public interestthrough eliminating misunderstandings between manufacturers and purchasers, facilitatinginterchangeability and improvement of products, and assisting the purchaser in selecting andobtaining with minimum delay the proper product for his particular need. Existence of suchStanda
4、rds and Publications shall not in any respect preclude any member or nonmember ofTIA/EIA from manufacturing or selling products not conforming to such Standards andPublications, nor shall the existence of such Standards and Publications preclude their voluntaryuse by those other than TIA/EIA members
5、, whether the standard is to be used either domesticallyor internationally.Standards and Publications are adopted by TIA/EIA in accordance with the American NationalStandards Institute (ANSI) patent policy. By such action, TIA/EIA does not assume any liabilityto any patent owner, nor does it assume
6、any obligation whatever to parties adopting the Standardor Publication.This Standard does not purport to address all safety problems associated with its use or allapplicable regulatory requirements. It is the responsibility of the user of this Standard toestablish appropriate safety and health pract
7、ices and to determine the applicability of regulatorylimitations before its use.(From Standards Proposal No. 4591, formulated under the cognizance of the TIA FO-6.3Subcommittee on Fiber Optic Interconnecting Devices.)Published byTELECOMMUNICATIONS INDUSTRY ASSOCIATION 2000Standards and Technology De
8、partment2500 Wilson BoulevardArlington, VA 22201PRICE: Please refer to current Catalog ofEIA ELECTRONIC INDUSTRIES ALLIANCE STANDARDS and ENGINEERING PUBLICATIONS or call Global Engineering Documents, USA and Canada(1-800-854-7179) International (303-397-7956)All rights reservedPrinted in U.S.A.Copy
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11、 Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS
12、-,-,-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 DIFFERENTIAL PHASE SHIFTMETHODContentsForeword iii1 Introduction 12 Normative References 23 Apparatus 34 Sampling And Specimens 105 Procedure 116 Calculations 1
13、37 Documentation 158 Specification Information 16Annex A (Informative) 17Annex B (Informative) 20Annex C (Informative) 20Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TIA/EIA-
14、455-197AAA,TIA SC FO-x.x, mm-dd-yy iiThis page left blank.Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TIA/EIA-455-197AJB,TIA SC FO-6.3.5, 05-25-00 iiiFOTP-197DIFFERENTIAL GR
15、OUP 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 Project No. 4591, formulated under the cognizance of TIA FO-6.3.5,Subcommittee on Passive Fiber Optic Devices.This FOT
16、P 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, Components, Isolators, Filters, PMD.,DGD, Group DelayCopyright Telecommunications Industry Association Provided by IHS
17、under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TIA/EIA-455-197AAA,TIA SC FO-x.x, mm-dd-yy ivThis page left blankCopyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networkin
18、g permitted without license from IHS-,-,-TIA/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 port single-mode fiber components over the 1.0 to1.7 micrometer wavelength
19、 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 a specific finite wavelength range.1.2 ScopeIn this procedure, a modulat
20、ed 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 state. Once the maximum phase difference has been determined,correspondin
21、g 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 document, the component is considered to be measured ata single wavelength, a
22、nd 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 measurement in Fibers andfiber cables. Two of these methods use a Polarimetric a
23、pproach 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. These are theJones Matrix Eigenanalysis (JME) method (covered by FOTP-122
24、) 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), where a broadband(e.g. LED) source is used as a low-coherence source to exam
25、ine the path lengthimbalance (time delay differences) caused by the PMD. For this reason it isreferred to as a time-domain PMD method.Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS
26、-,-,-TIA/EIA-455-197AAA,TIA SC FO-x.x, mm-dd-yy 2A key part of the measurement of fibers is the concept 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 appl
27、y these techniques to fiber components especially with regard to thespectral bandwidth of the device 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
28、is required in order to perform the measurement.The technique described herein uses a comparitively 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 fix
29、ed or tunable laser sources.1.4 Light SourcesTypical optical sources suitable for this measurement 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 r
30、equired.The test method can be applied to DUTs that are transmissive or reflective. In thelatter case, 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, wh
31、ich use very similar hardware.2 Normative referencesTest or inspection requirements may include, but 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 Fibero
32、ptic components.)FOTP-113 (EIA/TIA-113), (Polarization Mode Dispersion Measurement for Single-Mode Optical Fibers by the Fixed Analyzer method.)Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without licens
33、e from IHS-,-,-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-Mode Optical Fibers by Interferome
34、tric 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 encouraged to specify the most recent e
35、dition.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 lasers or light-emitting diodes
36、 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 laser to obtain thelowest line
37、widths.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 temperature control and output powerstab
38、ilization (e.g. PIN feedback) are typically suitable for use with single-modeoptical fiber.Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TIA/EIA-455-197AAA,TIA SC FO-x.x, mm-d
39、d-yy 4Figure 1: Apparatus to make the DGD measurement(Items shown with dashed lines are alternative implementations)3.1.2 Filtered Light Emitting DiodesUse one or more light emitting diodes. The center wavelength and modulated outputphase of the source shall be stable over the measurement time perio
40、d at the biascurrent, modulation frequency and diode temperature encountered.Filter the optical spectrum to give a spectral line of full width 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
41、 diode lasers. The center wavelength and modulated outputphase of each laser at each wavelength used shall be stable over the measurementtime period at the bias current, modulation frequency and diode temperatureencountered. Typically completely self-contained temperature controlled external-cavity
42、laser units may be employed.3.2 ModulationModulate the intensity of the light sources to produce a waveform with a singledominant Fourier component. The frequency of the modulation shall be sufficientlyhigh and sufficiently stable to ensure adequate measurement precision.Light source(e.g.Laser)Polar
43、isationControllerDeviceunder testOpticalReceiverPhasemeasurementelectronicsHF oscillatorf =0.01-10GHzmodulationComputerRef.DirectionalCoupler orCirculatorOpticalSwitchModulatorCopyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or net
44、working permitted without license from IHS-,-,-TIA/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 placed aft
45、er the laser (see Figure 1) tomodulate the light before it is passed into the DUT. The modulator must besufficiently stable to ensure adequate measurement precision.A sinusoidal, trapezoidal or square wave modulation is acceptable. A frequencystability of 0.01 ppm is typically sufficient.It is essen
46、tial to prevent ambiguities of 360.n degrees (n an integer) in measuringthe phase shift. This can be done by means such as reducing the modulatorfrequency for large PMD coefficients.For example, the modulation frequency must be chosen lower than the frequencythat gives a differential phase shift of
47、360 degrees. This limiting frequency can beestimated asfmax = 1012 Hertz (1)DGDmaxwhere:-DGDmax is the maximum expected typical DGD value, in ps, at the wavelength.In fact, for typical DGD values of 10 GHz, generally exceeding themaximum practical frequencies that can be generated or used.The modula
48、tion at frequency, f, will impart sidebands at +/-f Hz away from the centerwavelength of the source, and in some very narrow band DUTs this might prove alimitation. To ensure accurate phase measurement, the total occupied bandwidthincluding the sidebands of the modulation and the source linewidth itself must beless than or equal to the DUT bandwidth. The frequency f is typically chosen as thatconvenient to phase detection electronics, within any limitations posed by thedevice bandwidth. f is typically in the range 10 MHz to 10 G
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