結論 - 長波段放大自發性輻射光纖光源之研究

本論文使用單幫激的組態來研究長波段放大自發輻射光纖光源，實驗的架構有 SPF、SPB、DPF 和 DPB 四種，反射端的反射量則有 0%、

4%、8% 和 80%。在 100 mW 的固定幫激功率下，我們得到 ASE 光源的最適合摻鉺光纖長度為 100 公尺。在不同的架構和各種反射端反射量，藉著調整幫激雷射功率，找到最佳的光源輸出特性。在實驗中，我們可以發現幫激功率和光纖長度會影響光纖的居量反轉程度，進而改變 ASE 頻譜輻射的波段和其功率。同時摻鉺光纖中的 lasing 效應，限制了更高功率的幫激，ASE 光源的特性因而受限。

從實驗的結果分析，後向幫激並不適合做為長波段的 ASE 光源，

前向幫激的 SPF 也不是好的架構。單幫激組態中最適當的 ASE 光源為 DPF 的架構，比較反射量 4%、8% 和 80%所量測的數據，DPF 在低反射量時有較好的特性，以反射量 8%時最佳，其輸出功率和幫激效益分別為 13.8 mW 和 13.8%，平均波長落在 1585.7 nm，頻譜線寬為 40.9 nm，

ΔP 為 1.2 dB。這樣的結果和傳統波段以 DPB 為最佳架構並不相同，原因為使用的光纖長度不同和所造成的粒子反轉程度也不同，反應在光纖所輻射的 ASE，使得 ASE 光源的特性迥異。

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表 1.1 ASE 光纖光源特性對其應用系統所產生的影響

ASE 光源的應用和

特性光纖陀螺儀低同調光反射

測量儀頻譜分割光源輸出功率

(Output Power, Pout) 信號雜訊比動態範圍信號雜訊比

平均波長

(Mean Wavelength, λm) 精確度 -

-頻譜線寬

(Spectral Linewidth, ∆λ) 同調誤差空間解析度波道數

平坦度

(Flatness, ∆P) - - 波道數

表 3.1 HighWave Optical Technologies ER741 摻鉺光纖的特性規格

l Optical specifications

Absorption coefficient

At 1532nm 7

±

1dB/m At 1480nm 3

±

0.3dB/m At 980nm 4.5

±

0.5dB/m Background Loss at 1200nm

<

10dB/km Fiber Cut-off Wavelength ëc 1000

±

50nm

Mode Field Diameter

At 980nm 3.2

±

µ

m At 1550nm 5

±

0.3

µ

l Geometric specifications

Outside Cladding Diameter 125.0

µ

±

µ

m Coating Diameter 245

µ

±

µ

m Core Diameter 3

±

0.2

µ

l Performance characterization

Numerical Aperture 0.29

±

0.03

表 3.2 ASE 光纖光源各架構在最佳條件下的光源特性

Forward Pumping Backward Pumping

Configura-tions SPF DPF,

4%

DPF, 8%

DPF,

80% SPB DPB,

4%

DPB, 80%

P

_out

(mW) 0.1 11.3 13.8 11.0 28.8 28.8 28.9

λ

(nm) 1604.7 1582.8 1585.7 1593.8 1559.6 1559.6 1559.6

∆λ (nm) 38.3 39.1 40.9 33.7 24.4 24.4 24.5

η (%) 0.1 11.3 13.8 13.8 28.8 28.8 28.9

表 3.3 C-band 和 L-band 的 ASE 光纖光源的特性比較

Configurations

C-band L-band Characteristics

DPF^＊1

DPB^＊1

DPB^＊2

DPF^＊1

Fiber mirror reflectance (%) 95 95 90 8 Optimal EDF length (m) 23 20 12 100 Pump wavelength (nm) 980 980 980 1480 Pump power (mW) 160 160 80 100

Output Power (mW) 36.1 35.3 21.5 13.8 Pump conversion efficiency (%) 22.6 22.1 26.9 13.8 Linewidth (nm) 34.4 33.9 24 40.9 Ripple,

∆

P/2 (dB) 3.2 3.0 NA 0.6 Reference 47 47 49 This Work

＊1 Experimental data

＊2 Simulated data

Ω ω

P_i Ω τ

Ω ω

P_i Ω τ

圖 1.1 轉動的圓形環狀干涉儀

圖 1.2 低同調光反射測量儀的基本架構

Optical

Source

DUT

Mirror Coupler

Detector

Isolator Optical

Source

DUT

Mirror Coupler

Detector

Isolator

Broadband Light Source

WDM MUX WDM

DEMUX

Broadband Light Source

WDM MUX WDM

DEMUX

圖 1.3 頻譜分割光源的基本架構 Mod

Input

WDM #1 WDM #2

Pump LD Pump LD

Isolator 1 Isolator 2

Output

x x

EDF

圖 2.1 典型的摻鉺光纖放大器之架構圖

圖 2.2 Er³⁺離子的部分能階圖

圖 2.3 1.58-

µ

m 波段之放大原理說明

EDF

圖 2.5 在光源頻譜上，功率密度變化量ΔP 的定義 Wavelength

Power (dBm)

ΔP

EDF

-60 -50 -40 -30 -20 -10

1450 1460 1470 1480 1490 1500

Wavelength (nm)

Optical Power (dBm)

圖 3.2 幫激雷射的頻譜

0 5 10 15 20 25 30

1440 1490 1540 1590 1640

Wavelength (nm)

Insertion Loss of Coupler (dB)

圖 3.3 1480/1580 nm 波長選擇耦合器的插入損失頻譜

Port 1 Port 2

Port 3

Port 1 to Port 2

Port 1 to Port 3

0 0.5 1 1.5 2 2.5

1500 1520 1540 1560 1580 1600

Wavelength (nm)

Insertion Loss of Isolator (dB)

圖 3.4 光隔離器的插入損失頻譜

0 1 2 3 4 5

1450 1500 1550 1600 1650

Wavelength (nm) Insertion Loss of Fiber Mirror (dB)

圖 3.5 光纖反射鏡的插入損失頻譜

0 Output Power (mW)

SPF DPF, 4%

1550

Mean Wavelength (nm)

SPF

Pump Power (mW)

Output Power (mW)

SPF

-50

1510 1530 1550 1570 1590 1610 1630

Wavelength (nm)

Optical Power (dBm)

圖 3.10 後向幫激架構 ASE 光源在 100 mW 幫激功率時的光源輸出頻譜

1550 1570 1590 1610 1630

Wavelength (nm)

Optical Power (dBm)

圖 3.11 前向幫激架構 ASE 光源的輸出頻譜。(SPF、DPF, 4%和 DPF, 8%

-50 -40 -30 -20 -10 0

1510 1530 1550 1570 1590 1610 1630

Wavelength (nm)

Optical Power (dBm)

圖 3.12 SPB 架構 ASE 光源在各種幫激功率的頻譜，曲線由上而下分別為在幫激功率 100, 80, 60, 40, 20 mW 時的頻譜

1545 1555 1565 1575 1585 1595 1605 1615 1625

0 20 40 60 80 100 120

Pump Power (mW)

Mean Wavelength (nm)

SPF DPF, 4%

DPF, 8% DPF, 80%

SPB DPB, 4%

DPB, 80%

圖 3.13 ASE 光源平均波長對幫激功率的關係

20 25 30 35 40 45 50

0 20 40 60 80 100 120

Pump Power (mW)

Linewidth (nm)

SPF DPF, 4%

DPF, 8% DPF, 80%

SPB DPB, 4%

DPB, 80%

圖 3.14 ASE 光源線寬對幫激功率的關係

-70 -60 -50 -40

1560 1580 1600 1620 1640

Wavelength (nm)

Optical Power (dBm)

圖 3.15 SPF 架構 ASE 光源在各種幫激功率的頻譜，曲線由上而下分別為在幫激功率 100, 80, 60, 40, 20 mW 時的頻譜

-60 -50 -40 -30 -20 -10

1550 1570 1590 1610 1630

Wavelength (nm)

Optical Power (dBm)

圖 3.16 DPF 架構反射量 4%時，ASE 光源在各種幫激功率的頻譜，曲線由上而下分別為在幫激功率 100, 80, 60, 40 mW 時的頻譜

-60 -50 -40 -30 -20 -10

1550 1570 1590 1610 1630

Wavelength (nm)

Optical Power (dBm)

圖 3.17 DPF 架構反射量 80%時，ASE 光源在各種幫激功率的頻譜，曲線由上而下分別為在幫激功率 80, 60, 40, 20 mW 時的頻譜

-60 -50 -40 -30 -20 -10

1550 1570 1590 1610 1630

Wavelength (nm)

Optical Power (dBm)

圖 3.18 DPF 架構反射量 8%時，ASE 光源在各種幫激功率的頻譜，曲線由上而下分別為在幫激功率 100, 80, 60, 40 mW 時的頻譜

在文檔中長波段放大自發性輻射光纖光源之研究 (頁 34-59)