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Passive Optical Devices

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Last updated 6 years ago

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  • 无(电)源光噚件 (Passive Optical Device)
  • 1. 光纀连接噚 (optical fiber connector): 接倎
  • 2. 光衰减噚 (optical attenuator): 甚来减少光功率单䜍dB。该噚件类䌌电路里的电阻。
  • 3. 光耊合噚 (optical couplers): 同䞀波长分光 或 合光
  • 4. 波分倍甚噚 (optical fiber wavelength division multiplexer): 䞍同波长的分犻䞎合并
  • 5. 波长蜬换噚 (optical transponder unit): 波长蜬换劂 1310 -> 1550
  • 6. 光孊隔犻噚 (optical isolator): 隔犻反向反射光
  • 7. 光环圢噚 (optical circulator): 蜬发(重新发射)反向反射光 换䞀条路再发
  • 8. 光匀关(optical switch): 通 侎 断
  • 测光衰减噚
  • 理论䞊:
  • 实际䞊:
  • Question and Answers

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让我们先来了解䞀䞋什么是db (因䞺后面芁倧量甚到它劂果䞍知道它是什么䞜西对于皋序员来讲䌚睡䞍着芺的)

äž­æ–‡: dB是䞀䞪比倌是䞀䞪数倌是䞀䞪纯计数方法没有任䜕单䜍标泚。

The decibel (symbol: dB) is a unit of measurement used to express the ratio of one value of a power or field quantity to another on a logarithmic scale, the logarithmic quantity being called the power level or field level, respectively.

It can be used to express a change in value (e.g., +1 dB or −1 dB) or an absolute value.

In the latter case, it expresses the ratio of a value to a fixed reference value; when used in this way, a suffix that indicates the reference value is often appended to the decibel symbol.

For example, if the reference value is 1 volt, then the suffix is "V" (e.g., "20 dBV"), and if the reference value is one milliwatt, then the suffix is "m" (e.g., "20 dBm")

看起来是䞀种数倌的衚瀺方法甚来衚瀺盞对倌。比劂2dB侎1dB衚瀺: 2dB的实际功率 是 1dB实际功率 的2倍。

功率 = Power

无(电)源光噚件 (Passive Optical Device)

1. 光纀连接噚 (optical fiber connector): 接倎

2. 光衰减噚 (optical attenuator): 甚来减少光功率单䜍dB。该噚件类䌌电路里的电阻。

  • 螺䞝顺时针“玧”逆时针“束”

  • 所有接受噚件郜有接受范囎

  • 近距犻䌠蟓衰减可近䌌于0

  • 光发射机䞎光接收机的功率并䞍䞀样发射机比蟃倧接收机比蟃小所以芁甚衰减噚对发射信号进行倄理让它变小

  • 假讟那么倹圚䞭闎的

3. 光耊合噚 (optical couplers): 同䞀波长分光 或 合光

  • 平均分光

  • 1:2n1:2^n1:2n的分光噚光功率䞋降3×N dB3 \times N\ dB3×N dB

  • 2n:12^n:12n:1的分光噚光功率增益(䞊升)3×N dB3 \times N\ dB3×N dB

  • 功率 -> dB:

4. 波分倍甚噚 (optical fiber wavelength division multiplexer): 䞍同波长的分犻䞎合并

5. 波长蜬换噚 (optical transponder unit): 波长蜬换劂 1310 -> 1550

6. 光孊隔犻噚 (optical isolator): 隔犻反向反射光

7. 光环圢噚 (optical circulator): 蜬发(重新发射)反向反射光 换䞀条路再发

8. 光匀关(optical switch): 通 侎 断

测光衰减噚

理论䞊:

光源(optical source) --- 光衰减噚 --- 光功率计(power meter)

光源噚䞊的读数䞍可靠所以

实际䞊:

光源 --- 光功率计(把它的读数看䜜实际光源功率)(P1P_1P1​) --- 光衰减噚 --- 光功率计(P2P_2P2​)

  • dBm=毫瓊分莝dBm = 毫瓊分莝dBm=毫瓊分莝

  • 衰减=P1−P2衰减 = P_1 - P_2衰减=P1​−P2​

劂果把衰减噚换䞺光纀。讟䞀倎䞺A、B端䜠需芁把 A 到 B 测䞀遍B 到 A 再测䞀遍取平均倌。(我也䞍知道䞺什么光纀䌚有这䞪特性)

诎了䞀倧堆还是䞍知道它是什么意思 Let's continue!

  • dBmdBmdBm 侎 mWmWmW 郜是光功率的单䜍䜆由于光功率的数倌倪倧䞍容易让人看出盞对关系所以人们䜿甚dBmdBmdBm

  • dBm=10×lg⁡(P)dBm = 10 \times \lg(P)dBm=10×lg(P)  PPP 衚瀺功率(power)lg⁡\lglg 指以10䞺底的 log⁡\loglog

劂歀䞀来劂果䜠知道了光纀䞀端(劂A、B)的具䜓功率倌䜠就可以盎观地甚dBmdBmdBm单䜍看出䞀端之闎的差匂(是增加、增益还是减少、衰减)

dB=10×lg⁡(P1P2)=(10×lg⁡(P1))−(10×lg⁡(P2))=dBm−dBm\begin{align*} dB &= 10 \times \lg(\frac{P_1}{P_2}) \\ \\ &= (10 \times \lg(P_1)) - (10 \times \lg(P_2)) \\ \\ &= dBm - dBm \end{align*}dB​=10×lg(P2​P1​​)=(10×lg(P1​))−(10×lg(P2​))=dBm−dBm​

dBdBdB 这䞪由“减法”埗到的倌足以让我们看出信号是增加还是减少了

Question and Answers

发射端功率=P1发射端功率=P_1发射端功率=P1​
接收端功率=P2∌P3接收端功率=P_2 \sim P_3接收端功率=P2​∌P3​
光衰减噚的损耗=(P1−P2)∌(P1−P3)光衰减噚的损耗 = (P_1 - P_2) \sim (P_1 - P_3)光衰减噚的损耗=(P1​−P2​)∌(P1​−P3​)
10⋅lg⁡(功率 mw1 mw)10 \cdot \lg(\frac{功率\ mw}{1\ mw})10⋅lg(1 mw功率 mw​)
1 mw=0 dBm1\ mw = 0\ dBm1 mw=0 dBm