Wavelength Dependence of Polarization Dependent Loss

1 Page 1 Measurement Assurance Program for Wavelength Dependence of Polarization Dependent Loss in Fiber Optic Devices over the Wavelength Range from 1535 nm to 1560 nm NIST Special Publication 250-60 Rex M. Craig Chih-Ming Wang... Open at page → 2 Page 2 NIST Special Publication 250-60 NIST MEASUREMENT SERVICES: Measurement Assurance Program for Wavelength Dependence of Polarization Dependent Loss in Fiber Optic Devices over the Wavelength Range from 1535 nm to 1560 nm R... Open at page → 3 Page 3 National Institute of Standards and Technology Special Publication 250-60 Natl. Inst. Stand. Technol. Spec. Publ. 250 -60, 44 pages (February 2003) CODEN: NSPUE2 U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 2003 For sale... Open at page → 4 Page 4 iii Contents 1. Introduction…………………………………………………………………… 1 2. MAP Process Outline………………………………………………………… 2 3. MAP Transfer Standard Description and Design………………………….. 2 4. MAP Transfer Standard Implementation…………………………………..... Open at page → 5 Page 5 iv Abstract This paper provides the documentation to establish a Measurement Assurance Program (MAP) using an optical fiber diattenuator for the calibration of polarization-dependent loss (PDL) across the range of teleco... Open at page → 6 Page 6 1 Introduction Polarization-dependent loss references are important to support high-bandwidth optical fiber networks. As network bandwidth is increased, either by increasing modulation rates or by multiplexing channels i... Open at page → 7 Page 7 2 Section 3 describes the nature and design of the MAP artifact, while Sec. 4 details implementation. Section 5 outlines the sources of uncertainty and associated analysis for both the MAP artifact and the PDLl measureme... Open at page → 8 Page 8 3 Another reason for choosing fiber was the importance of simulating wavelength dependent PDL in order to allow calibration of measurement system linearity using broadband tunable sources. Because of its design, polarizi... Open at page → 9 Page 9 4 would serve to randomize the alignment between the MAP and the PDL of the detector making it impossible to compensate through a background correction. 4. MAP Transfer Standard Implementation Photographs of the MAP tran... Open at page → 10 Page 10 5 the rear-facing panel of the enclosure. This logging device is capable of sampling the device temperature over several weeks. This covers time spent in shipment and measurement at a remote location. On return, the logg... Open at page → 11 Page 11 6 5.2. Uncertainty due to Temperature Dependence of PDLl Temperature dependence of PDLl (PDL(l,T)) is characterized over wavelength by a different measurement system based on automated scans over all states of polarizati... Open at page → 12 Page 12 7 PDL at a particular temperature can be characterized in a manner similar to that in [6] with the uncertainty budget given in Table 1 of App. D. If T1 and T2 are the maximum and minimum measurement temperatures, the dif... Open at page → 13 Page 13 8 5.3. Uncertainty Due to Large Thermal Variations During Shipping Because these devices may retain some sensitivity to large temperature cycles that can shift PDLl, they must be well insulated during shipping and shippe... Open at page → 14 Page 14 9 total approximates the difference. There is no way to determine, a priori, the relative angle between the two axes. The user may estimate this uncertainty by sampling system PDL with a variety of input leads and connec... Open at page → 15 Page 15 10 well depolarized with degree-of-polarization generally less than 1% unless the source and polarizer are separated by only a very short, stable length of intervening fiber. The alternative is source-intensity normaliza... Open at page → 16 Page 16 11 7. References 1. M. J. Messerly et al., "A broad-band single polarization optical fiber," J. Lightwave Technol., vol. 9, pp. 817 – 820, 1991. 2. K. Tajima et al., "A new single-polarization optical fiber," J. Lightwav... Open at page → 17 Page 17 Appendix A 13 Assurance Procedure for the PDLl MAP 1. NIST performs calibration of its Mueller/Stokes PDL system using the BK7 3 reference. 2. NIST performs calibration of its All-States PDL system using the BK7 referenc... Open at page → 18 Page 18 Appendix B (Preliminary) 15 The PDLl Measurement System and Selected MAP Results Abstract – Building on previous work, a rapid, automated, non-mechanical measurement system for spectral characterization of polarization-d... Open at page → 19 Page 19 Appendix B (Preliminary) 16 band edge. This type of device requires higher wavelength resolution for accurate characterization. New results from an all-fiber PDLl artifact reference are also presented. This artifact is i... Open at page → 20 Page 20 Appendix B (Preliminary) 17 system PDL in conjunction with retardance, however, modifies this scenario somewhat by altering the relationship between the launched states and can potentially introduce significant uncertain... Open at page → 21 Page 21 Appendix B (Preliminary) 18 measurements () () 14LL IIllK are signal-to-reference ratios with the DUT in place. These ratios remove spectral dependence in various elements of the system as well as source fluctuations and... Open at page → 22 Page 22 Appendix B (Preliminary) 19 of a balanced differential InGaAs photoreceiver. The second directs 9 % of the light to the other input of the differential photoreceiver to act as a source-level reference. The differential p... Open at page → 23 Page 23 Appendix B (Preliminary) 20 The choice of sweep priority, (i.e., each polarization state having its own wavelength sweep rather than the launching of each of four states at every wavelength of a single spectral sweep) wa... Open at page → 24 Page 24 Appendix B (Preliminary) 21 beam cavity containing a polished BK-7 4 glass block. The block can be tilted to vary the Fresnel reflections in a predictable way to emulate a PDL. Calculated (Fresnel) and measured PDL value... Open at page → 25 Page 25 Appendix B (Preliminary) 22 · Type B Components [7] 1. Polarization-state accuracy. Launched polarization states were measured using a polarimeter. Polarization state accuracy depends on both the polarimeter and the LCVR... Open at page → 26 Page 26 Appendix B (Preliminary) 23 state and its associated matrix element. This uncertainty could be reduced through the use of a look-up table. 3. Retarder temperature dependence The LCVR retardance has an uncertainty due to... Open at page → 27 Page 27 Appendix B (Preliminary) 24 sweep system noise and incorporates all effects such as optical interference and detector noise that average down over multiple measurements. Combined standard uncertainty for the measurement... Open at page → 28 Page 28 Appendix B (Preliminary) 25 represents the uncertainty in a typical measurement. The expanded uncertainty is then 2uMS = 0.016 dB. · Wavelength Calibration Uncertainty. Based on sampling density, the wavelength uncertain... Open at page → 29 Page 29 Appendix B (Preliminary) 26 thereby reducing measurement uncertainty arising from output connector and detector PDL, and produces a more accurate calibration. Hot-wire splicing was found to produce the most reliable join... Open at page → 30 Page 30 Appendix B (Preliminary) 27 measure PDL. The level of these reflections can be inferred from the observed interference modulation of PDLl as measured with a highly coherent source such as a tunable laser. The magnitude o... Open at page → 31 Page 31 Appendix B (Preliminary) 28 6. Conclusions An accurate, rapid, non-mechanical technique of characterizing the wavelength dependence of polarization-dependent loss for both single-mode and bulk-optic devices has been deve... Open at page → 32 Page 32 Appendix B (Preliminary) 29 References [1] M. Gadonna and A. Mabrouki "Polarization Sensitivity Measurements Methods for Passive Optical Components," Conference on European Fibre Optic Communications and Networks, EFOC&N... Open at page → 33 Page 33 Appendix C 31 Qualification of Artifacts and Measurement System Prototype Qualification Prior to Final Assembly Low yields in the assembly of the MAP artifact prompted preliminary testing of the artifacts after splicing... Open at page → 34 Page 34 Appendix C 32 Prototypes that pass this selection criteria are further immobilized through the use of a thermally conductive, shock-absorbing dielectric gel poured into the tray, covering the PZ fiber section and fiber s... Open at page → 35 Page 35 Appendix D 33 Uncertainties Associated with All-States Measurement The uncertainties associated with the secondary all-states measurement system used for thermal characterization of PDLl MAP artifact are given in Table 1... Open at page → 36 Page 36 Appendix E Sample Certificate. Actual certificate to be sent following MAP measurement National Institute of Standards & Technology Measurement Assurance Program for Photometric Polarization-Dependent Loss Measurement in... Open at page → 37 Page 37 Appendix E Sample Certificate. Actual certificate to be sent following MAP measurement Certified Values and Uncertainties: This transfer standard is certified for wavelength-dependent PDL (PDLl), which is the maximum mea... Open at page → 38 Page 38 Appendix E Sample Certificate. Actual certificate to be sent following MAP measurement uncertainty in source center wavelength of the PDLl scan range, and ()dPDLdllis the linear- regression slope of the combined PDLl sca... Open at page → 39 Page 39 Appendix E Sample Certificate. Actual certificate to be sent following MAP measurement Instructions for Use: Make calibrating measurements at a nominal temperature of 23 °C. As discussed in the section on Temperature Dep... Open at page → 40 Page 40 Appendix E Sample Certificate. Actual certificate to be sent following MAP measurement 26 °C. This temperature dependence has been added in quadrature to the other uncertainties to give the final uncertainty listed in Ta... Open at page → 41 Page 41 Appendix E Sample Certificate. Actual certificate to be sent following MAP measurement to each artifact will constantly monitor the temperature environment. Upon return, the thermal history will be analyzed for any tempe... Open at page → 42 Page 42 Appendix E Sample Certificate. Actual certificate to be sent following MAP measurement References 1. Craig, R. M., and Wang, C. M., " Measurement Assurance Program for Wavelength Dependence of Polarization Dependent Loss... Open at page → 43 Page 43 Appendix F 43 Effect of Source Spectral Symmetry Given the significant dependence of PDL on wavelength, the user may find it important to consider not only the source bandwidth but also the spectral symmetry across that... Open at page → 44 Page 44 Appendix G 45 Shipping and Handling Instructions Because the transfer-standard assembly retains some sensitivity to thermal and mechanical shock, it is shipped as rapidly as possible in a specially padded and insulated s... Open at page → 45 Page 45 46 This page intentionally left blank Open at page → 46 Page 46 Appendix H 47 PDLl Artifact Tray/MM Depolarizer Mount The following is a schematic of the aluminum artifact mounting tray and depolarizer spool. Units given are in inches rather than SI. The upper tray holds the fiber sp... Open at page →