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Hybrid Raman EDFA1.

INTRODUCTION

In the ultra-high bit rate optical transmission systems suchas 100 Gbps systems, which will be introduced in thefuture, the combination of a Raman amplifier with superior
noise characteristics and an erbium-doped optical fiber
amplifier (EDFA) with higher gain is expected to be apromising application.
To realize space-saving and low price in such applications, Furukawa Electric has commercialized a module
integrating both a Raman optical light source and anEDFA, and has started selling it as ErFA40000 Series.
This product was exhibited at OFC/NFOEC 2010 that washeld in San Diego, California, U.S.A. in March 2010, andhas earned a good review.

2.

BACKGRAUND OF THE DEVELOPMENT

Furukawa Electric has many basic patents of Raman
amplifiers (i.e., a number of patents registered in Japanand U.S. related to a Raman optical light source and thecontrol methods of its system) and has been strong in themanufacture of a complete and full range of key devices
such as erbium-doped fiber (EDF) and laser diode modules. Based on such advantages, Furukawa Electric hasbeen recognized as a leader in the market of the Raman
amplifiers and the EDFAs.
Today, Raman amplifiers are used to compensate adequately the output of EDFAs in the optical systems requiring repeaters for long distances. Future amplifiers, to be
used in the ultra-high bit rate optical transmission systems
such as 100 Gbps systems require superior signal-tonoise characteristics and also need higher gain and output power because of the increase of the transmission
loss with the increased number of optical devices.
Therefore, it is expected that, the combination of Ramanamplifiers with superior signal-to-noise characteristics andthe higher power output EDFAs, will improve the opticalsignal noise ratio (OSNR) in the ultra-high bit rate opticaltransmissions and will compensate for the losses throughoptical transmission path and optical devices. For suchapplication, Furukawa Electric, has taken advantage ofthe technologies developed on the EDFAs with highspeed control circuit and high power 1480 nm pumping
laser diode modules has commercialized the compact
and high performance Raman EDFA which integrates
Raman light sources and EDFAs and started selling it asErFA40000 Series. A picture is shown in Figure 1.

3.

FEATURES

The configuration of the product is shown in Figure 2 andthe mechanical dimensions are shown in Figure 3. The
Raman light sources consist of two pumping light sourcesat the wavelength of 1425 nm and 1452 nm. Each light
power is backward launched into the signal line in theopposite direction of the signal path. The total output
power is 500 mW and the Raman gain of 9 dB is provided
at the C-band. The automatic gain constant controlled
amplifier of the EDFA is optimized as 15 dB for the gainand 18 dBm for the output power. To stabilize the output
change during the transient event, it has a high speed
control circuit. Since the filter can be applied to level thetotal gain of the Raman gain and the EDFA gain, thefavorable wavelength characteristics are achieved asshown in Figure 4. Gain ripple represents flatness of thetotal gain of the Raman gain and the EDFA gain. Gain ripple in Figure 4 shows an example of the product (RamanEDFA) application to single mode fiber (SMF).

4.

IN CONCLUSION

To meet the demand for optical amplifiers for the ultrahigh bit rate transmissions systems, Furukawa Electric
has commercialized a space-saving and a low priceRaman EDFA by combining Raman light sources and an
EDFA in one package. The detailed specifications of theproduct for usage environmental condition, the Raman
pump module and EDFA are shown in Table 1.

Figure 1

ErFA40000 series.

Furukawa Review, No. 38

2010

1

Hybrid Raman EDFA

Table 1

Embbeded EDFA with
optimal gain ﬂattering ﬁlter
Line

Environmental conditions.

λsing

Items
λr1, λr2

Operating case temperature
Operating humidity
Storage temperature
Storage humidity
Power supply voltage

Pump 1, λr1

Pump 2, λr28 mm
4 mm

Figure 41535

Gain ripple（dB）

nm
nm
mWdB

Specifications
UnitMin.
Max.
1529
1562.5nm–408dBm
15dB
18dBm
2×4−M3 Depth 6 mm
1.0dB
7.0dB

101

1243

HEAT SINK SIDE（7.8 mm）
130 mm

1530

Unit

For more information, please contact
Administrative Department, Telecommunications Company2-M3 Depth 4 mm
Tel: +81-3-3286-3427 Fax: +81-3-3286-3708

81HEAT SINK SIDE

ELECTRICAL CONNECTOR

212 mm

R5249 50

1.00.80.6
0.40.20.0‑0.2‑0.4‑0.6‑0.8‑1.01525

Signal wavelength range
Input power range
Gain (Nominal)
Maximum output power
122
Gain flatness
NFm0m

1Figure 3

Specifications
Min.
Max.
1425
1452
500
9.04Items1

100±30°C
%RH°C
%RH
DCV

204

3Unit

Specifications of EDFA.

2（Samtec 50 PIN-2 mm PITCH）

5

Pump 1 wavelength
Pump 2 wabelength
Total Raman pump power
Average Raman gain

（84.4 mm）

7ItemsConfiguration drawing.

46Specifications
Typ.
Max.
70
8570
85
4.75
5.0
5.25
Min.
55–40

Specifications of Raman pump module.

λr1=1425 nm
λr2=1452 nm

Figure 2

Specifications.

1224

20 mm

Mechanical dimensions.

1540
1545
1550
Wavelength（nm）

1555

1560

1565

An example of wavelength characteristics.

Furukawa Review, No. 38

20102