相對強度噪聲(rin)測量程序參考模板

1、Relative intensity noise (RIN) measuring procedure相對強度噪聲（RIN）測量程序This procedure describes a component test which may not be appropriate for a system level test depending on the implementation.這是一個組件測試流程，根據(jù)應(yīng)用環(huán)境來看，它可能不適合于系統(tǒng)級的測試。A.5.1 Test objective 測試目標When lasers which are subject to reflection induc

2、ed noise effects are operated in a cable plant with a low optical return loss the lasers will produce an amount of noise which is a function of the magnitude and polarization state of the reflected light.當受到反射引起的噪聲影響的激光器在具有低光回損的電纜設(shè)備中工作時，激光器將產(chǎn)生一定量的噪聲，這個噪聲是反射光的大小和偏振態(tài)的函數(shù)。The magnitude of the reflected

3、light tends to be relatively constant. However, the polarization state varies significantly as a function of many cable parameters, particularly cable placement.反射光的大小趨于相對恒定。然而，偏振態(tài)受許多電纜參數(shù)的影響而呈現(xiàn)出一定的函數(shù)關(guān)系，特別是隨電纜的放置而顯著變化。In a cable plant which is physically fixed in place the variation is slow. If the f

4、ibre is subject to motion, such as occurs in a jumper cable, the change may be sudden and extreme. The effect is unpredictable changes in the noise from the laser with the result that the communication link may exhibit sudden and unexplainable bursts of errors.在固定的電纜設(shè)備中，變化是緩慢的。如果光纖被移動，例如跳線，則可能會有突然或劇

5、烈的變化。從而造成激光器噪聲的不可預(yù)知的變化，結(jié)果是通信鏈路可能表現(xiàn)出突然和無法解釋的錯誤。The solution to this is to assure that the lasers used do not generate excessive noises under conditions of the worst case combination of polarization and magnitude of reflected optical signal.對此的解決方案是確保所使用的激光器在反射光信號的偏振態(tài)和大小的最壞組合的情況下不會產(chǎn)生過多的噪聲。The noise ge

6、nerated is a function of the return loss of the cable plant. For the Fibre Channel the specified return loss is 12 dB resulting in the notation of RIN12 for the relative intensity noise.產(chǎn)生的噪聲是電纜設(shè)備回波損耗的函數(shù)。對于光纖通道，規(guī)定的回波損耗為12 dB，所以相對強度噪聲用符號RIN12來表示。1 / 6放大器電功率計電流檢測裝置單模光纖被測設(shè)備/器件 偏振旋轉(zhuǎn)器探測器偏置輸入低通濾波器A.5.2 Ge

7、neral test description 一般測試描述The test arrangement is shown in figure A.2 The test cable between the Device Under Test (DUT) and the detector forms an optical path having a single discrete reflection at the detector with thespecified optical return loss. There must be only one reflection in the syste

8、m as the polarization rotator can only adjust the polarization state of one reflection at a time.測試裝置如圖A.2所示。被測設(shè)備（DUT）和探測器之間用測試電纜（光纖）相連，使其形成一條光路，在指定的回損范圍內(nèi)，探測器處會有一個離散的反射。偏振旋轉(zhuǎn)器一次只能調(diào)整一個反射的偏振態(tài)，因此系統(tǒng)中只能有一個反射。Two measurements are made by the photo detector. The average optical power is determined by measur

9、ing the average current, Ipd, through the detector. The second measurement is the noise, which is measured by AC coupling the detector into the high frequency electrical power meter. Ifneeded, an amplifier may be used to boost the signal to the power meter.兩個測量值由光電探測器進行測量。平均光功率是通過測量探測器的平均電流Ipd來確定。第二

10、個測量值是噪聲，它是通過將探測器交流耦合到高頻電功率計中測量的。如果需要時，可以使用放大器來增強輸入功率計的信號。A low pass filter is used between the photo-detector and the power meter to limit the noise measured to the pass band appropriate to the data rate of interest. In order to measure the noise the modulation to the DUT must be turned off. If the

11、laser is modulated the modulation power will be measured by the power meter rather than the noise power.在光電探測器和功率計之間使用低通濾波器，以將測量的噪聲限制在適合測量的數(shù)據(jù)速率的通帶。為了測量噪聲，必須關(guān)閉對DUT的調(diào)制。如果激光器被調(diào)制，則功率計會測量到更大的調(diào)制功率而非噪聲功率。A.5.3 Component descriptions 組件描述Test Cable 測試電纜The test cable and detector combination must be configu

12、red for a single dominate reflection with an optical return loss of 12dB. (The Optical return loss may be determined by the method of FOTP-107) If multiple lengths of cable are required to complete the test setup they should be joined with splices or connectors having return losses in excess of 30dB

13、. The length of the test cable is not critical but should be in excess of 2 m.測試電纜和探測器組合必須配置為單回路反射，光回波損耗為12dB。 （光學(xué)回波損耗可以通過FOTP-107的方法來確定）如果需要多根電纜來完成測試設(shè)置，則應(yīng)該使用回波損耗超過30dB的接頭或連接器。測試電纜的長度并不重要，但應(yīng)超過2米。Polarization Rotator 偏振旋轉(zhuǎn)器The polarization rotator must be capable of transforming an arbitrary orientati

14、on elliptically polarized wave into a fixed orientation linearly polarized wave. A polarization rotator consisting of two quarter wave retarders will have the necessary flexibility. A possible construction technique is given in LeFevre, 1980 3.偏振旋轉(zhuǎn)器必須能夠?qū)⑷我舛ㄏ虻臋E圓偏振波轉(zhuǎn)換成固定方向的線偏振波。所以該偏振旋轉(zhuǎn)器將需要兩個四分之一波片來使其具

15、有必要的靈活性。 LeFevre，1980 3中給出了一種可能的結(jié)構(gòu)模型。Detector and Detector/Amplifier 探測器和探測器/放大器The detector may be of any type which is sensitive to the wavelength range of interest. The frequency response of the detector must be higher than the cut-off frequency of the low pass filter.探測器可以是對相應(yīng)（DUT）波長范圍敏感的任何類型，探測

16、器的頻率響應(yīng)必須高于低通濾波器的截止頻率。The detector should be capable of determining the average and variation of the optical signal. Typically the average optical power is determined by the current, Id, through the diode. The detector assembly should have an effective output impedance of 50. If necessary, the noise

17、may be amplified to a level consistent with accurate measurement by the power meter.探測器應(yīng)當能夠確定光信號的平均值和變化量。一般的，平均光功率由通過二極管的電流Id確定。探測器組件的等效輸出阻抗應(yīng)為50。如有必要，噪聲可以放大到與功率計測量精度一致的水平。Filter濾波器The low pass filter should have a 3dB bandwidth of approximately 75% of the bit rate. Recommended values are shown in ta

18、ble A.1. The total filter bandwidth used in the RIN calculation must take the low frequency cut-off of the d.c. blocking capacitor into consideration.低通濾波器應(yīng)該具有約為比特率75的3dB帶寬。表A.1列出了推薦值。在RIN計算中使用的總濾波器帶寬考慮到隔直電容必須采取直流的低頻截止。The filter should be placed in the circuit as the last component before the power

19、 meter so that any high frequency noise components generated by the detector/amplifier are eliminated. If ensure that the filter does not lose its rejection at extremely high frequencies.濾波器應(yīng)作為功率計之前的最后一個元件放置在電路中，以免探測器/放大器產(chǎn)生的任何高頻噪聲成分被消除。如果所使用的功率計具有非常寬的帶寬，則應(yīng)謹慎選擇濾波器，以確保濾波器在極高頻率下不會失去其抑制性能。Power Meter功率計

20、The power meter should be an RF type designed to be used in a 50 coaxial system. The meter must be capable of being zeroed in the absence of input optical power to remove any residual noise from the detector or its attendant amplifier, if used.功率計應(yīng)該是RF類型，設(shè)計用于50同軸系統(tǒng)。在沒有輸入光功率的情況下，儀表必須能被清零，以去除探測器或其伴隨的放

21、大器（如果使用的話）的任何殘余噪聲。A.5.4 Test Procedure測試程序a) Connect and turn on the test equipment. Allow the equipment to stabilize for the manufacturers recommended warm up time.連接并打開測試設(shè)備，讓設(shè)備經(jīng)過制造商建議的預(yù)熱時間后達到穩(wěn)定。b) With the DUT disconnected zero the power meter to remove the contribution of any noise power from the

22、 detector and amplifier, if used.在DUT斷開的情況下將功率計調(diào)零以消除來自檢測器和放大器（如果使用的話）的任何噪聲功率的干擾。c) Connect the DUT, turn on the laser and verify that the optical output power is at the average power appropriate for the DUT by means of the detector current. The laser should not be modulated.連接被測器件，打開激光器，通過監(jiān)控工作電流使光器件工作在其平均光功率附近，激光不應(yīng)被調(diào)制。d) Operate the polarization rotator while observing the