Optical module performance parameter testing device
The utility model relates to the device of main test light signal transmitting and receiving separated light module performance in area of optical telecommunication networks.
Optical transceiver module has promoted main line optical transmission system to low cost future development as the core devices of Optical Access Network.Optical module is a photoelectric conversion module be made up of structural members such as opto-electronic device, functional circuit and optical interfaces.Optical module is mainly used in the transmitting-receiving of light signal, and light signal, by intelligent acess optical module, can transfer light signal to the signal of telecommunication.Also the information of the signal of telecommunication can be changed into light signal by optical module simultaneously, then be sent by optical fiber.Optical module is again optic module (transceiver module), and divide by function, optic module is divided into Optical Receivers, optical transmission module, the integrated module of optical transceiver and light forwarding module etc.Opto-electronic device comprises transmitting and receiving two parts, and radiating portion comprises several light sources such as LED, VCSEL, FP LD, DFB LD; Receiving unit comprises PIN type and APD type two kinds of photo-detectors.The encapsulation of the photoelectric device in current optical transceiver module is that master develops into based on coaxial packaging form by the dual-in-line form of large-size; The structural members such as optical interface develop into LC, MT-RJ type connector form of SC and smaller szie from ST, FC, the packing forms of corresponding optical transceiver module also develops into Plastic Package from metallic packaging, is developed into the receiver-transmitter integrated module of double nip by the separation module of single interface.Optical signal transceiver separated light module is the one of optical module.
Optical signal transceiver separated light module is the separate optical module of electro-optic conversion and photoelectric conversion interface or medium, is usually applied to Optical Access Network, ATM switch and SDH system.Electrical-optical conversion interface or medium are called as TOSA, are a kind of light-emitter assemblies signal of telecommunication being converted to light signal.Photoelectric conversion interface or medium are called as optical fiber receive module ROSA.ROSA is a kind of light receiving element light signal being converted to the signal of telecommunication.The applied environment different according to optical module, the optical module that employing TOSA, ROSA realize photoelectricity and electro-optic conversion is very common, and the optical module of the type receives light signal and emission function is be integrated in ROSA and TOSA respectively.Separately there is a class optical module, to be optical signal receiver and transmitter the be one adopted, be called BOSA, this kind of optical module is because the light signal of the light signal received and transmission is in same optical channel, and their wavelength is not Same Wavelength, therefore there is wavelength isolator in the inside of BOSA, realize the mutual interference avoiding the light signal receiving and send.Usual ROSA General Requirements:
1, will have sufficiently high responsiveness in the operation wavelength of system, namely to certain incident optical power, ROSA can export electric current large as far as possible;
2, wavelength response is wanted and 3 low loss window compatibilities of optical fiber;
3, sufficiently high responsiveness and enough bandwidth of operation is had;
4, the opto-electronic conversion linearity is good, and fidelity is high;
5, stable work in work, reliability is high, and the life-span is long.
The major parameter of optical module has: average optical transmit power AOP (Average Optical Power), Extinction ratio (Extinction Ration), spectrum width, side mode suppression ratio, sensitivity, overload luminous power, dropout luminous power, acquisition of signal luminous power, passage cost.Average optical transmit power (Average Optical Power) refers to when sending " 0 ", the modulation of " 1 " code equiprobability, the average optical power value that optical sender exports.The ratio of luminous power when luminous power when extinction ratio refers to that the signal of telecommunication " 1 " code inputs and the signal of telecommunication " 0 " code input.Extinction ratio is the bigger the better in theory, but all really not so for some situation.For two-forty such as more than 2.5G, if use single longitudinal mode laser to be there will be " warbling " phenomenon.So-called " warbling " refers to that the light path length of the resonant cavity of single longitudinal mode laser can change because of the change of Injection Current, causes its emission wavelength to offset.Spectrum width, in optical transmitter, the breadth of spectrum line of light source device is divided into RMS spectrum width and-20dB spectrum width, generally weighs with RMS spectrum width for Multi-Longitudinal Mode laser, generally weighs with-20dB spectrum width for single longitudinal mode laser.Side mode suppression ratio SMSR, this index is only for single longitudinal mode laser, it is defined as: the luminous power of main longitudinal mode and the ratio of maximum limit mould luminous power under the condition of complete modulation, general definition requires that the SMSR of transmitting terminal is greater than 30dB, and namely the luminous power of main longitudinal mode is more than 1000 times of maximum limit mould luminous power.Sensitivity, (as error rate BER=1 × 10 under the error rate condition ensureing regulation
12), the minimum optical power value required for optical receiver, generally in units of dBm, sensitivity is optical receiver important technology index, and the luminous power of sensitivity and optical transmitter, the decay coefficient of optical fiber determine the repeater span of optical fiber communication.Overload luminous power is ensureing under the error rate condition specified (as BER=1 × 10
-12), the maximum luminous power value that optical receiver allows, in units of dBm.(as BER=1 × 10 under the error rate condition ensureing regulation
-12), when the signal of telecommunication sent from error analyzer is synchronous with returning the error analyzer signal of telecommunication; Continue to reduce Output optical power; The luminous power being input to optical receiver corresponding when the signal of telecommunication that and if only if transmits back error analyzer turns off just.Acquisition of signal luminous power, i.e. minimum signal probe power SDA, under peak signal loses power SDD state, increase Output optical power, the luminous power being input to optical receiver corresponding when the signal of telecommunication that and if only if transmits back error analyzer recovers just.Allow optical module normally work, must ensure above-mentioned parameter all in the scope required, any one parameter exceeds standard or the normal work that all directly can affect optical module not up to standard.Ensure that the test parameter of optical module is accurate, also will improve the production efficiency of optical module, and corresponding testing apparatus is exactly crucial.
Optical transceiver module is a kind of high speed optoelectronic device, and two-forty sends and reception certainly exists complicated electromagnetic coupled and signal is assorted disturbs.The sensitivity of the parameter of optical device performance as eye pattern, extinction ratio, receiver is reflected in optical device test.The performance parameter test of optical transceiver module is the important procedure of inspection finished product.The optical transceiver module assembled must carry out parameter testing to judge whether the function that can correctly realize presetting, and the performance test of module parameter is last procedure of finished product, is also the important evidence that can judge module become qualified products.The transmitter module of light transmitting-receiving unification module and receiver module, due to functionally relatively independent, structure also can be separated, be also divided into the test of the receiver module receiving parameter of corresponding independently transmitter module emission parameter during receiving-transmitting module test.The parameter of optical module performance is various and complicated, and need the test item of test light module a lot, the test platform that needs are built is scattered and complicated.In all index parameters needing test light module, only the optical interface end face of optical module is cleaned, nearly 5 times are carried out with regard to needs, due to the frequent replacing of system, the plug factor of optical module, the clean situation of the optical interface end face of optical module differs, and causes final test to go out the scale error of optical module greatly, seriously delays the production efficiency of optical module simultaneously.In prior art, in optical module test, involved key instrument mainly comprises optical coupler, optical isolator and optical attenuator, optical coupler is mainly used in the light shunt/photosynthetic road and the optical coupling that need transmission, can be divided into welded-connecting type, mill type and integrated optical circuit type by version.Usually 1 × N star coupler is adopted in fibre system.Optical isolator is in light path, prevent light to be reflected back light source, namely only allows passive of light one-way transmission.Conventional optical isolator is primarily of the polarizer, analyzer and polarization apparatus three part composition.The key technical indexes of optical isolator is: low insertion loss (to forward incident light) and large isolation (to back emission light).Optical attenuator is device luminous power being carried out to scheduled volume decay, is divided into variable optical attenuator and fixed optical attenuator.The former is mainly used in light regulating road level, and the latter is mainly used in the too high optical fiber telecommunications line of level.The main technical requirements of optical attenuator is high attenuation accuracy, good decay repeatability, low original loss.One of most important performance index of transceiver module are receiving sensitivities, and it is defined as the required minimum average B configuration luminous power received of optical receiving end under the condition reaching certain error rate.The conventional method of sensitivity test added variable optical attenuator before optical receiving end, adjusts the attenuation of optical attenuator and observe the error rate, the reception average light power when the error rate just reaches designated value.One of most important performance index of optical transceiver module are receiving sensitivities, and it is defined as the required minimum average B configuration luminous power received of optical receiving end under the condition reaching certain error rate.The conventional method of sensitivity test added variable optical attenuator before optical receiving end, and adjust the attenuation of optical attenuator and observe the error rate, the reception average light power when the error rate just reaches designated value can think the receiving sensitivity of this module.But the error code testing time in low error rate situation is long, as needs test 1 × 10
-10the error rate , when test rate is 155Mb/s, the testing time at least needs 64s; Under 1.25Gb/s test rate, 1 × 10 be reached
-12the error rate , the testing time at least needs 800s.The testing time of length like this obviously cannot accept in large-scale production.In order to address this problem, " electronic measurement technique " 2010 Nian04Qi Deng Wesy, Cheng Shuhai, peak propose the relation curve first being gone out received optical power and the error rate by least square fitting in " discussion of optical transceiver module sensitivity test method " literary composition, recycle this curve negotiating extrapolation and carry out the method for approximate estimation based on the optical receiver sensitivity of PIN.Describe the framework of the Auto-Test System based on the method, the execution flow process of test program and algorithm realization and testing procedure.The optical receiver sensitivity of Optical Receivers is a crucial comprehensive technical indexes, relevant with several factors.Front end is had to the Optical Receivers of APD-TIA assembly, its optical receiver sensitivity is not only relevant to bit error rate (BER), transmission rate, optical coupling efficiency, waveform parameter, thermal noise, TIA transimpedance and amplifier noise etc., also relevant with reverse bias voltage, the light multiplication factor of APD, the dark current that doubles etc.
The different parameters of test light module, needs to build different test platforms usually.Such as when to the luminous power of optical module optical sender and extinction ratio test, need the test platform built shown in Fig. 3.During test, first optical module place evaluation board is powered on, then observed by light power meter, read luminous power, then light wire jumper is extracted from light power meter, be linked into light oscilloscope, test extinction ratio, after reading the delustring ratio on oscilloscope, this test terminates.
When measurement sensitivity, luminous power SDD and SDA, need the test platform built as shown in Figure 4.During test, open error analyzer test error code, then increase the pad value of light adjustable attenuator, until error code appears in error analyzer, then reduce the pad value of light adjustable attenuator, continue test, report without error code until continue for some time interior Error Detector, then think that the luminous power being now input to optical receiver is the sensitivity of this optical module, then optical fiber is extracted optical module, the test of access light power meter, reads to obtain Sensitirity va1ue.Read optical fiber is turned back to optical module again after sensitivity, then the attenuation increasing light adjustable attenuator is continued, until error analyzer count off is according to asynchronous, then measure with light power meter the luminous power SDD now entering optical receiver again, again optical fiber is turned back to optical module, reduce the attenuation of light adjustable attenuator gradually, until data syn-chronization appears in error analyzer, with light power meter reading luminous power SDA now, test terminates.Carry out spectrum test, spectrum test platform as shown in Figure 6, after being powered on by optical module, spectroanalysis instrument reads wavelength, and spectrum width and side mode suppression ratio data, this tests end.Carry out the test of passage cost, passage cost test platform as shown in Figure 7, then record the sensitivity after adding long optical fibers according to the method for measurement sensitivity, poor with lengthening the sensitivity after optical fiber and not lengthening the sensitivity of optical fiber, the value obtained is then the passage cost of this optical module.
In sum, optical module basic parameter tested and at least need to build 5 test platforms, most of the time needs flower building on test platform, and the level of resources utilization is low.
Utility model content
The purpose of this utility model is various for above-mentioned prior art optical module performance parameter, build the scattered and problem of complexity of test platform, one is provided to build test platform quantity few, structure is simple, cost is low, easy to operate, and test item is complete, testing efficiency is high, does not need to change experiment porch by USB interface to carry out optical module performance parameter testing device and the method for testing thereof of Automated condtrol.
Above-mentioned purpose of the present utility model can be reached by following measures, a kind of optical module performance parameter testing device, comprise light adjustable attenuator, optical branching device and optical switch, it is characterized in that: optical switch is provided with and connects optical module optical patchcord input interface IN and USB optical switch interface, described optical switch is also provided with two outputs, wherein, output out1 connects housing long optical fibers input interface, output out2 is by two points of optical branching devices, housing spectroanalysis instrument output interface and light oscilloscope is connected through one-to-two optical branching device, housing is also provided with and connects light adjustable attenuator output interface OUT and USB light adjustable attenuator interface, adjustable attenuator connects housing long optical fibers output interface OUT by input In through above-mentioned two points of optical branching devices.
The utility model has following beneficial effect compared to prior art.
Structure is simple, easy to operate.The utility model adopts the testing apparatus primarily of light adjustable attenuator, optical branching device and optical switch composition, and not only structure is simple, and easy to operate.No matter the utility model is all that a cost is low for production phase or development for assessment optical module performance, conveniently testing apparatus, and this device precision is high, systematic error is little.
Build test platform quantity few.The utility model can test many kinds of parameters on a platform, only need to build an experiment porch, just optical module basic parameter can be tested, not only test item is complete, and testing efficiency is high, solve prior art at least to need to build 5 test platforms, most of the time flower is being built on test platform, and the problem that the level of resources utilization is low.
Simple to operate, multiple functional.The utility model is realized by employing 1 × 2 program-controlled mechanical optical switch, 1 point of 2 optical branching device, 2 points of 2 optical branching devices and a program-controlled smooth adjustable attenuator, do not need to repeat optical patchcord of transferring, the test of Automated condtrol optical module basic parameter is carried out by USB interface, no matter be that development or automated production can adopt this device, the time that optical module manufacturer produces optical module can be saved, enhance productivity.
The utility model is applicable to the optical module of speed from 1.25Gbps to 11.3Gbps and interface shape is the optical module of SFP, SFP+ and XFP, is particularly applicable to receive light signal and send the optical module be separated.
Accompanying drawing explanation
Fig. 1 is the organigram of the utility model optical module performance parameter testing device.
Fig. 2 be the utility model optical module performance parameter testing device build test platform system schematic.
Fig. 3 is 1 × 2 program-controlled mechanical optical switch internal structure schematic diagram that the utility model adopts.
Fig. 4 is that prior art is to the test platform schematic diagram needing when optical module luminous power and extinction ratio test to build.
Fig. 5 is the test platform schematic diagram that prior art carries out optical module needing when sensitivity, luminous power SDD and SDA test to build.
Fig. 6 needs the spectrum test platform schematic diagram built when to be prior art carry out spectrum test to optical module.
Fig. 7 needs the test platform schematic diagram built when to be prior art carry out being with long optical fibers sensitivity test to optical module.
In FIG, optical module performance parameter testing device comprises light adjustable attenuator, optical branching device and optical switch.Housing is provided with and connects light adjustable attenuator output interface OUT and USB light adjustable attenuator interface, and light adjustable attenuator connects housing long optical fibers output interface OUT by input In through above-mentioned two points of optical branching devices.Light adjustable attenuator is device luminous power being carried out to scheduled volume decay, and be divided into variable light adjustable attenuator and fixed attenuator two kinds, the former is mainly used in light regulating road level, and the latter is mainly used in the too high optical fiber telecommunications line of level.Preferably, light adjustable attenuator can adopt program-controlled Variable Optical Attenuator, the GVPM model attenuator of such as Ge Lai company.The light of optical fiber input becomes directional light light beam through GRIN Lens, and collimated light beam is delivered to GRIN Lens through attenuator and is coupled to output optical fibre.The attenuator normally surperficial evaporation glass substrate of metallic absorbing layer, be reduce reverberation, attenuator and optical axis can slant settings.
Optical switch is a kind of for optical fiber testing system optical fiber, fiber plant test and network test, the optics of the one or more optional transmit port of Fibre Optical Sensor multiple spot monitoring system, its effect is the switch light signal in optical transmission line or integrated optical circuit being carried out to physics switching or logical operation.In fiber optic transmission system, optical switch is used for multiple monitor, local network LAN, multiple light courcess, the conversion of detector and protection Ethernet.Optical switch is classified from manufacturing process, can be divided into mechanical type, micro photo-electro-mechanical MEMS system mode switch and alternate manner switch.Preferably, the optical switch that the utility model is arranged in the housing adopts 1 × 2 program-controlled mechanical optical switch, which is provided with and connect optical module optical patchcord input interface IN and USB optical switch interface, line input interface IN and USB optical switch interface are arranged on the outside of housing.Above-mentioned optical switch is also provided with two outputs, and wherein, output out1 connects housing long optical fibers input interface, and output out2, by two point of two optical branching device, connects housing spectroanalysis instrument output interface and light oscilloscope through one-to-two optical branching device,
In fact above-mentioned optical branching device is exactly fiber coupler, also known as splitter, its principle to be intercoupled the (degree of coupling by the evanescent field changed between optical fiber, coupling length) and change point component that the fine radius of optical fiber realizes different size, production method has sintered type, micro-optic formula, light wave conduction, the overwhelming majority is accounted for sintered type production method, wherein simple, the low price of fused-tapered fiber coupler manufacture method, be easily connected to become an entirety with external fiber, and can vibrate and variations in temperature by withstanding mechanical, become the manufacturing technology of main flow at present.Fused biconical taper method is exactly two or many are gone out the optical fiber of coat to draw close with certain method, melting at high temperature heat, simultaneously to two side stretchings, the special Wave guide structure of bicone form is finally formed in the thermal treatment zone, by controlling the angle of optic fibre turning and the length of stretching, different light splitting ratios can be obtained, finally the solidification adhesive curing of La Zhui district is inserted in stainless copper pipe on quartz substrate and form optical branching device.2 point of 2 optical branching device and 1 point of 2 optical branching device have an important parameter to be exactly splitting loss, splitting loss is the dB number that the luminous power on each road of output port differs relative to input optical power, direct relation is had with splitting ratio, the difference of dB number is here that the difference of carrying out after luminous power is converted into dB calculates, such as splitting ratio is the splitter (namely 2 point of 2 optical branching device) of 50%, the optical sender of 12mW is calculate like this: 10lg12-10lg (12 × 0.5)=10.79-7.78=3.01dB in theory.
Another very important parameter of optical branching device is exactly homonymy isolation, and isolation refers to that a certain light path of optical branching device is to the isolating power of the light signal in other light paths.In all indexs, isolation is more great for the meaning of optical branching device, and in general the isolation of optical branching device generally all can at more than 40dB.Optical branching device can adopt Splitter/ Φ 3.0 × 60 (2 × 21230 ~ 1390nm/1450 ~ 1510nm50%:50%0.9mm tail optical fiber SC/UPC) and the Splitter/ Φ 3.0 × 60 (1 × 21230 ~ 1390nm/1450 ~ 1510nm50%:50%0.9mm tail optical fiber SC/UPC) of Wuhan Guang Xun scientific & technical corporation, 1 × 2 program-controlled mechanical optical switch, can adopt the FSW1 × 2-SM-C of the 34 the photoelectricity research institute exploitation in Chengdu.Can convenient tester carry out fast testing accurately to the performance of optical module.But for adopt transceiver optical device optical module then once can only test the parameter of wherein one end, sending and receiving end, need outside to add test of light source during test receiving end.If after this device goes wrong in checking procedure, checking process slightly bothers simultaneously.So generally after assurance device verification is correct, this device of easy removal, does not avoid causing system light path error change too large.
In fig. 2, on optical module performance parameter testing device, spectroanalysis instrument and light oscilloscope are connected in spectroanalysis instrument output interface and light oscilloscope interface, long optical fibers is connected in parallel between long optical fibers input interface In and long optical fibers output interface OUT, PC is respectively by USB2, the adjustable sorrow of light that USB3 connecting line is connected to optical module performance parameter testing device subtracts device interface and optical switch interface, error analyzer is connected by USB1 connecting line, error analyzer is by optical module test board, optical patchcord in standard optical module applicable is connected in optical patchcord input interface IN interface, light adjustable attenuator is connected with PC by program-controlled attenuator USB interface, code error tester is connected with PC by PC serial ports or USB interface, be built into a complete test platform.After putting up test platform, need to carry out light path calibration to the test macro of composition, by a standard optical module applicable, directly connect light power meter by optical patchcord, standard module actual transmission luminous power AOP1 is read after powering on, then the optical patchcord interface be connected on light power meter taken off and be connected to optical module performance parameter testing device optical patchcord input interface IN, and by USB interface, mechanical optical switch is set to passage 1 on PC, then can read to obtain luminous power AOP2 on light oscilloscope, the system calibration value that then can obtain luminous power is δ 1=AOP1-AOP2.
And then the passage 2 of mechanical optical switch is selected by upper PC, light adjustable attenuator OUT place optical patchcord is connected to light power meter, by upper PC, light adjustable attenuator is set to fixing output, and it is poor with the reading of actual light power meter, carry out light path calibration by the control software design of adjustable attenuator, make Output optical power that the interface of control software design shows equal with the actual luminous power read at light adjustable attenuator OUT place.The benefit done like this optical fiber need not be extracted the luminous power received by light power meter measurement from optical module, directly can from the control software design interface of adjustable attenuator and the readable actual light power obtaining tested module and receive.
After putting up test platform, need to carry out light path calibration to this system.Optical module performance parameter testing device is verified with a standard 10G XFP40KM wavelength division multiplexing DWDM C21 optical module.The index parameter of 10G XFP 40KM DWDM C21 requires as follows, luminous power :-1dBm < AOP <+2dBm, extinction ratio: ER > 8.2dB, centre wavelength: λ-0.2 < λ < λ+0.2,-20dB spectrum width: RMS < 0.3nm, side mode suppression ratio: SMSR > 35dB, sensitivity: Sens < 16dBm, passage cost: Dispersion Penalty < 2dB.Verification comprises the steps, first program-controlled mechanical optical switch is set to passage 1 can use, directly pass through light power meter connecting fiber wire jumper to standard optical module applicable, read this module actual transmission luminous power, suppose it is 1.5dBm, ideally optical switch is less than decay, but due to reasons such as Insertion Loss, generally have the loss of 0.5dB, again through 2 points of 2 optical branching devices and 1 point of 2 optical branching device, each splitter has 3dB decay, and therefore ideally entering oscillographic luminous power is 1.5dBm-0.5dB-6dB=-5dBm.Again because oscillographic systematic error is unfixed, so be generally adopt directly on light oscilloscope for the light path calibration of system, read luminous power is assumed to be-6.5dBm, the system attenuation amount that then can obtain luminous power is δ=1.5dBm-(-6.5dBm)=8dB, it is generally acknowledged that attenuation amount and the theoretical value deviation of measurement luminous power are no more than 3dB, if if the attenuation of the system of this place calculation is greater than 11dB, just think that optical patchcord exists the dirty or optical patchcord of end face and has problem, or optical patchcord be connected with problem, then need progressively to investigate, otherwise because the problem such as dirty can produce light reflections affect eye diagram quality and passage cost test result, and then select the passage 2 of program-controlled mechanical optical switch, namely the OUT2 passage in figure, light adjustable attenuator OUT place optical patchcord is connected to light power meter, by host computer, light adjustable attenuator is set to fixing output example as-20dBm, and and the reading such as-19.8dBm of actual light power meter, adjustable attenuator control software design set point and actual light power meter reading are made difference and obtains 0.2, calibrated by the control software design of light adjustable attenuator, compensate 0.2dB, the control software design reading that now can obtain light adjustable attenuator is consistent with the reading of actual light power meter.Read centre wavelength is 1560.61nm additionally by spectroanalysis instrument, and readable that side mode suppression ratio is 48dB.Can see light eye pattern on light oscilloscope, extinction ratio is 11.2dB simultaneously, and so far system calibration and verification terminate, and the operating state that simultaneously determined this device is normal.
After calibration, change tested optical module, use upper PC by mechanical optical switch selector channel 1, the eye pattern of optical module can be seen on light oscilloscope, testing out extinction ratio is 10.5dB,, readable luminous power is-7dBm simultaneously, actual light module utilizing emitted light power AOP=-7dBm+ δ dB=-7dBm+8dB=1dBm; In spectroanalysis instrument, also can see the spectrum of optical module optical sender, the centre wavelength obtaining tested module is 1560.60nm, spectrum width be 0.123nm and side mode suppression ratio is 40dB parameter; And then carry out sensitivity test by the attenuation of upper PC control light adjustable attenuator, result is that-18dBm, SDA test as-20.2dBm and SDD is-18.9dBm; Finally select to regulate mechanical optical switch, selector channel 2, carry out long range propagation test, record maximum attenuation amount when keeping continuous 90s error analyzer to report without error code, readable from upper computer software must received optical power now be-17dBm, according to passage cost computing formula Δ==-17dBm-(-18dBm)=1dB.The basic parameter of optical module is completed all thus, and does not need to change experiment porch, only needs reading and carries out simple computation.
Above-mentionedly be typical embodiment.