SFP 光模組參數
<p class="MsoNormal" style="background-position: initial initial; background-repeat: initial initial;"><b><span style="font-size:14.0pt;font-family:"新細明體","serif";
color:#333333">光模組參數</span></b><span lang="EN-US" style="font-size:10.5pt;
font-family:"新細明體","serif";color:#333333"><br>
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</span><b><span style="font-family:"新細明體","serif";color:#333333">對於硬體開發工程師而言，光模組有很多很重要的光電技術參數，但對於<span lang="EN-US">GBIC</span>和<span lang="EN-US">SFP</span>這兩種熱插拔光模組而言，只需要瞭解光模組的如下<span lang="EN-US">3</span>種主要參數就可以順利開展工作了：<span lang="EN-US"><br>
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</span>第一、中心波長：單位納米（<span lang="EN-US">nm</span>），目前主要有<span lang="EN-US">3</span>種：<span lang="EN-US"><br>
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1</span></b><b><span style="font-family:"新細明體","serif";color:#333333">）<span lang="EN-US">850nm</span>（<span lang="EN-US">MM</span>，多模，成本低但傳輸距離短，一般只能傳輸<span lang="EN-US">500M</span>）；<span lang="EN-US"><br>
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2</span>）<span lang="EN-US">1310nm (SM</span>，單模，傳輸過程中損耗大但色散小，一般用於<span lang="EN-US">40KM</span>以內的傳輸<span lang="EN-US">)</span>；<span lang="EN-US"><br>
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3</span>）<span lang="EN-US">1550nm (SM</span>，單模，傳輸過程中損耗小但色散大，一般用於<span lang="EN-US">40KM</span>以上的長距離傳輸，最遠可以無中繼直接傳輸<span lang="EN-US">120KM)</span>；<span lang="EN-US"><br>
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</span>第二、 傳輸速率：指每秒鐘傳輸資料的比特數（<span lang="EN-US">bit</span>），單位<span lang="EN-US">bps</span>，目前常用的有<span lang="EN-US">4</span>種<span lang="EN-US">: 155Mbps</span>、<span lang="EN-US">1.25Gbps</span>、<span lang="EN-US">2.5Gbps</span>、<span lang="EN-US">10Gbps</span>等。傳輸速率一般向下相容，因此<span lang="EN-US">155M</span>光模組也稱<span lang="EN-US">FE</span>（百兆）光模組，<span lang="EN-US">1.25G</span>光模組也稱<span lang="EN-US">GE</span>（千兆）光模組，這是目前光傳輸設備中應用最多的模組。此外，在光纖存儲系統（<span lang="EN-US">SAN</span>）中它的傳輸速率有<span lang="EN-US">2Gbps</span>、<span lang="EN-US">4Gbps</span>和<span lang="EN-US">8Gbps</span>；<span lang="EN-US"><br>
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</span>第三、 傳輸距離：指光信號無需中繼放大可以直接傳輸的距離，單位千米（也稱公里，<span lang="EN-US">km</span>）<span lang="EN-US">,</span>光模組一般有以下幾種規格：多模<span lang="EN-US">550m</span>，單模<span lang="EN-US">15km</span>、<span lang="EN-US">40km</span>、<span lang="EN-US">80km</span>和<span lang="EN-US">120km</span>等等。<span lang="EN-US"><br>
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</span>光模組的其他概念：<span lang="EN-US"><br>
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</span>除以上<span lang="EN-US">3</span>種主要技術參數外，光模組還有如下幾個基本概念，這些概念只需簡單瞭解就行：<span lang="EN-US"><br>
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1</span>）雷射器類別：雷射器是光模組中最核心的器件，將電流注入半導體材料中，通過諧振腔的光子振盪和增益射出鐳射。目前最常用的雷射器有<span lang="EN-US">FP</span>和<span lang="EN-US">DFB</span>雷射器，它們的差異是半導體材料和諧振腔結構不同，<span lang="EN-US">DFB</span>雷射器的價格比<span lang="EN-US">FP</span>雷射器貴很多。傳輸距離在<span lang="EN-US">40KM</span>以內的光模組一般使用<span lang="EN-US">FP</span>雷射器；傳輸距離</span></b><b><span lang="EN-US" style="font-family:"Times New Roman","serif";color:#333333">≥</span></b><b><span lang="EN-US" style="font-family:"新細明體","serif";color:#333333">40KM</span></b><b><span style="font-family:"新細明體","serif";color:#333333">的光模組一般使用<span lang="EN-US">DFB</span>雷射器；<span lang="EN-US"><br>
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2</span>）損耗和色散：損耗是光在光纖中傳輸時，由於介質的吸收散射以及洩漏導致的光能量損失，這部分能量隨著傳輸距離的增加以一定的比率耗散。色散的產生主要是因為不同波長的電磁波在同一介質中傳播時速度不等，從而造成光信號的不同波長成分由於傳輸距離的累積而在不同的時間到達接收端，導致脈衝展寬，進而無法分辨信號值。這兩個參數主要影響光模組的傳輸距離，在實際應用過程中，<span lang="EN-US">1310nm</span>光模組一般按<span lang="EN-US">0.35dBm/km</span>計算鏈路損耗，<span lang="EN-US">1550nm</span>光模組一般按<span lang="EN-US">0.20dBm/km</span>計算鏈路損耗，色散值的計算非常複雜，一般只作參考；<span lang="EN-US"><br>
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3</span>）發射光功率和接收靈敏度：發射光功率指光模組發送端光源的輸出光功率，接收靈敏度指在一定速率、誤碼率情況下光模組的最小接收光功率。這兩個參數的單位都是<span lang="EN-US">dBm(</span>意為分貝毫瓦，功率單位<span lang="EN-US">mw</span>的對數形式，計算公式為<span lang="EN-US">10lg</span>，<span lang="EN-US">1mw</span>折算為<span lang="EN-US">0dBm)</span>，主要用來界定產品的傳輸距離，不同波長、傳輸速率和傳輸距離的光模組光發射功率和接收靈敏度都會不同，只要能確保傳輸距離就行；<span lang="EN-US"><br>
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4</span>）光模組的使用壽命：國際統一標準，<span lang="EN-US">7</span>Х<span lang="EN-US">24</span>小時不間斷工作<span lang="EN-US">5</span>萬小時（相當於<span lang="EN-US">5</span>年）；<span lang="EN-US"><br>
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5</span>）光纖介面：<span lang="EN-US">SFP</span>光模組都是<span lang="EN-US">LC</span>介面的，<span lang="EN-US">GBIC</span>光模組都是<span lang="EN-US">SC</span>介面的，其他介面還有<span lang="EN-US">FC</span>和<span lang="EN-US">ST</span>等；<span lang="EN-US"><br>
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6</span>） 工作溫度：<span lang="EN-US">0~+70</span>℃； 儲藏溫度：<span lang="EN-US">-45~+80</span>℃；工作電壓：<span lang="EN-US">3.3V</span>；工作電平：<span lang="EN-US">TTL</span>。更多<span lang="EN-US"><o:p></o:p></span></span></b></p>
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