1、Measurement method of a half-wavelength voltage forMach-Zehnder optical modulators in wireless communication and broadcasting systemsDD IEC/PAS 62593:2008raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI British StandardsNational forewordThis Draft
2、for Development is the UK implementation of IEC/PAS 62593:2008.This publication is not to be regarded as a British Standard.It is being issued in the Draft for Development series of publications and is ofa provisional nature. It should be applied on this provisional basis, so thatinformation and exp
3、erience of its practical application can be obtained.A PAS is a Technical Specification not fulfilling the requirements for a stan-dard, but made available to the public and established in an organizationoperating under a given procedure.A review of this Draft for Development will be carried out not
4、 later than threeyears after its publication.Notification of the start of the review period, with a request for the submis-sion of comments from users of this Draft for Development, will be made inan announcement in the appropriate issue of Update Standards. Accordingto the replies received, the res
5、ponsible BSI Committee will judge whether thevalidity of the PAS should be extended for a further three years or what otheraction should be taken and pass their comments on to the relevant interna-tional committee.Observations which it is felt should receive attention before the official callfor com
6、ments will be welcomed. These should be sent to the Secretary of theresponsible BSI Technical Committee at British Standards House, 389 ChiswickHigh Road, London W4 4AL.The UK participation in its preparation was entrusted to Technical CommitteeEPL/103, Transmitting equipment for radio communication
7、.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions of acontract. Users are responsible for its correct application. BSI 2008ISBN 978 0 580 65512 8ICS 33.060.20BRITISH STANDARDDD I
8、EC/PAS 62593:2008Amendments issued since publicationDate Text affectedThis Draft for Development was published under the authority of the Standards Policy and Strategy Committee on March 200931IEC/PAS 62593Edition 1.0 2008-11PUBLICLY AVAILABLE SPECIFICATIONPRE-STANDARD Measurement method of a half-w
9、avelength voltage for Mach-Zehnder optical modulators in wireless communication and broadcasting systems INTERNATIONAL ELECTROTECHNICAL COMMISSION VICS 33.060.20 PRICE CODEISBN 2-8318-1016-4 Registered trademark of the International Electrotechnical Commission DD IEC/PAS 62593:2008 2 PAS 62593 IEC:2
10、008(E) CONTENTS FOREWORD.4 INTRODUCTION.5 1 Scope.6 2 Normative references .6 3 Terms, definitions and acronyms 6 3.1 Terms and definitions 6 4 Electro-optic material based Mach-Zehnder optical modulator 8 4.1 Type8 4.2 Structure .8 4.3 Requirements for Mach-Zehnder optical modulators 8 5 Sampling 9
11、 5.1 Sampling .9 5.2 Sampling frequency.9 6 Measurement method of half wavelength voltage9 6.1 Circuit diagram9 6.2 Circuit description and requirement .9 6.3 Measurement condition .10 6.4 Principle of measurement method .10 6.5 Measurement procedure13 Annex A (normative) Conventional Measurement me
12、thod of Optical Modulation Index .17 Annex B (informative) Calculation method of intermodulation distortions from driving voltages and half-wavelength voltage for Mach-Zehnder optical modulator .19 Annex C (informative) Characteristics of Mach-Zehnder optical modulator .27 Annex D (informative) Poin
13、ts to consider for measurement 29 Bibliography35 Figure 1 A transfer curve of a Mach-Zehnder optical modulator .7 Figure 2 8 Figure 3 Circuit diagram.9 Figure 4 11 Figure 5 The schematic block diagram of the measurement setup12 Figure 6 Driving voltage measurement setup .14 Figure 7 15 Figure 8 a) T
14、he amplitude of the optical signal is almost zero 16 Figure 8 b) The optical signal is modulated in phase with S2 element 16 Figure 8 c) The optical signal is modulated in opposite phase with S2 element 16 Figure A.1.17 Figure A.2.18 Figure B.1 Mach-Zehnder interferometer type optical modulator 19 F
15、igure B.2 Quadrature points of a transfer cureve for a Mach-Zehnder optical modulator .23 DD IEC/PAS 62593:2008PAS 62593 IEC:2008(E) 3 Figure B.2 Dependency of IM2 on NOMI and Bias voltage of a Mach-Zehnder optical modulator .24 Figure B.4 Relation between IM3 and OMI of a Mach-Zehnder optical modul
16、ator 24 Figure B.5.25 Figure B.6 IMD2 and IMD326 Figure D.1 Errors of half-wavelength voltage measurements caused by limitations from the resolution of RF power supply.31 Figure D.2 Relative errors of half-wavelength voltage measurement caused by limitations from the resolution of RF power .32 Figur
17、e D.3 Relation between NOMI and IM3 for the Mach-Zehnder modulator (sample #1) 33 Figure D.4 Relation between NOMI and IM3 for the Mach-Zehnder modulator (sample #2) 33 Figure D.5 Relation between NOMI and IM2 for the Mach-Zehnder modulator (sample #1) 34 Table 1 Acronyms .7 Table C.127 Table C.228
18、Table D.129 Table D.2 Measurement results of half-wave voltages for Mach-Zehnder modulators.32 DD IEC/PAS 62593:2008 4 PAS 62593 IEC:2008(E) INTERNATIONAL ELECTROTECHNICAL COMMISSION _ MEASUREMENT METHOD OF A HALF-WAVELENGTH VOLTAGE FOR MACH-ZEHNDER OPTICAL MODULATORS IN WIRELESS COMMUNICATION AND B
19、ROADCASTING SYSTEMS FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning st
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26、quipment declared to be in conformity with an IEC Publication. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees an
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28、ttention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights
29、. IEC shall not be held responsible for identifying any or all such patent rights. A PAS is a technical specification not fulfilling the requirements for a standard, but made available to the public. IEC-PAS 62593 has been processed by IEC technical committee 103: Transmitting equipment for radio co
30、mmunication. The text of this PAS is based on the following document: This PAS was approved for publication by the P-members of the committee concerned as indicated in the following document Draft PAS Report on voting 103/74/PAS 103/81/RVD Following publication of this PAS, which is a pre-standard p
31、ublication, the technical committee or subcommittee concerned may transform it into an International Standard. This PAS shall remain valid for an initial maximum period of 3 years starting from the publication date. The validity may be extended for a single 3-year period, following which it shall be
32、 revised to become another type of normative document, or shall be withdrawn. DD IEC/PAS 62593:2008PAS 62593 IEC:2008(E) 5 INTRODUCTION A variety of microwave-photonic devices are used in wireless communication and broadcasting systems. An optical modulator is an interface which converts an electron
33、ic signal into an optical signal. In the field of optical fibre communication systems, the IEC 62007 series “Semiconductor optoelectronic devices for fibre optic system applications“ has been published. In the field of wireless systems, specifications of inter-modulation and composite distortion of
34、modulators have been an important issue and have typically been negotiated between users and suppliers. During an International Meeting on Microwave Photonics, a proposal was announced to address standardizations for key-devices for Radio over Fibre (RoF) systems. The RoF system is comprised mainly
35、of two parts; one is the RF to photonic converter (E/O), and the other is photonic to RF converter (O/E). Radio waves are converted into an optical signal at E/O, and the signal is transferred into the optical fibre, and then the radio waves are regenerated at O/E. The nonlinear distortion character
36、istics of both E/O and O/E are important for the performance of the system. Semiconductor photodiodes are commonly used for O/E. Several types of optical modulator are used for E/O, such as Mach-Zehnder modulators, electro-absorption modulators and directly modulated LDs. This PAS has been prepared
37、in order to provide industry standard measurement methods for evaluating electro-optic material based Mach-Zehnder optical modulators to be used in wireless communication and broadcasting systems. When the optical modulation index (OMI) is calculated from the half-wavelength voltage measurement resu
38、lts, the intermodulation distortion of the Mach-Zehnder optical modulator can be obtained. In this PAS, the measurement method of the half-wavelength voltage for Mach-Zehnder optical modulators is described. The details of calculations of the second order intermodulation distortion (IM2) and the thi
39、rd order intermodulation distortion (IM3) are described in Annex B. DD IEC/PAS 62593:2008 6 PAS 62593 IEC:2008(E) MEASUREMENT METHOD OF A HALF-WAVELENGTH VOLTAGE FOR MACH-ZEHNDER OPTICAL MODULATORS IN WIRELESS COMMUNICATION AND BROADCASTING SYSTEMS 1 Scope This PAS gives a measurement method of half
40、-wavelength voltage applicable to Mach-Zehnder optical modulators in wireless communication and broadcasting systems. In addition, this method is also effective for the estimation of the intermodulation distortion of Mach-Zehnder optical modulators. Frequency range: 10 MHz to 30 GHz. Wavelength band
41、: 0,8 m, 1,0 m, 1,3 m and 1,5 m. Electro-optic material based Mach-Zehnder optical modulators and their modules. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated referen
42、ces, the latest edition of the referenced document (including any amendments) applies. IEC 62007-1, Semiconductor optoelectronic devices for fibre optic system applications - Part 1: Specification template for essential ratings and characteristics IEC 62007-2 Semiconductor optoelectronic devices for
43、 fibre optic system applications - Part 2: Measuring methods 3 Terms, definitions and acronyms 3.1 Terms and definitions For the purpose of this document, the terminology concerning the physical concept, the type of devices, the general terms, those related to rating and characteristics in IEC 62007
44、-1 and IEC 62007-2, as well as the following terms and definitions, apply. 3.1.1 Half-wavelength voltage: V The voltage required for a Pockels effect material based optical modulator to shift phase of the light by one-half a wavelength relative to the other. It corresponds to an ON/OFF voltage of th
45、e Mach-Zehnder optical modulator. DD IEC/PAS 62593:2008PAS 62593 IEC:2008(E) 7 Input VoltageOutputOpticalPowerVQuad.Figure 1 A transfer curve of a Mach-Zehnder optical modulator 3.1.2 Normalized optical modulation index: NOMI For the Mach-Zehnder optical modulator, the ratio of driving voltage and h
46、alf-wavelength voltage of the modulator, NOMI = (Vpp/ V) 100 % (3.1) where Vppis the driving voltage (peak to peak voltage); Vis the half-wavelength voltage. NOTE NOMI does not denote actual optical modulation index defined as the ratio of the optical modulated signal power and the average optical p
47、ower. The detailed explanations of OMI including measurement method are described in Annex A. 3.1.3 Extinction Ratio The ratio of two optical power levels of the optical signal generated by the optical modulator: Rext= 10log(P1/P2) (3.2) where P1is the optical power level generated when the output p
48、ower is “on,“; P2is the power level generated when the output power is “off.“ NOTE The extinction ratio is sometimes expressed as a fraction, not in dB. 3.1.4 Acronyms and symbols The acronyms and symbols are shown in Table 3.1. Table 1 Acronyms and Symbols VA Half wavelength voltage OMI Optical Mod
49、ulation IndexNOMI Normalized OMIIM2 Second-order Inter-Modulation distortion IM3 Third-order Inter-Modulation distortion CSO Composite Second-Order distortion CTB Composite Triple-Beats distortion DD IEC/PAS 62593:2008 8 PAS 62593 IEC:2008(E) 4 Electro-optic material based Mach-Zehnder optical modulator 4.1 Type The optical modulators and their modules consist of basic parts as follows Mach-Zehnder interferometer type optical modulator input and output fibre pigtails (w
