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Optical Devices for Communication

Pump LD (FP-LD, FP Laser Diode)

What Is a Pump-LD (Excitation Laser)?


A pump-LD (Laser Diode) is an excitation light source for a fiber amplifier used in optical communication networks.

Types of pump-LDs include an FP-LD (Fabry-Perot Laser Diode) and FBG-LD, which connects fiber with FBG (Fiber Bragg Grating) formed on the FP-LD and provides high wavelength stability and narrow linewidth by selecting the wavelength. Spectral examples of each are indicated below.

FBG module schematic
FBG module schematic

Example FP-LD spectrum
Example FP-LD spectrum
Example FBG-LD spectrum
Example FBG-LD spectrum

FP-LDs are mainly used for EDFAs (Erbium Doped Fiber Amplifiers), and output light matching the excitation wavelength of the EDFA, particularly the 1.48 um band wavelength with good excitation efficiency.

FBG-LDs are mainly used for FRAs (Fiber Raman Amplifiers), and enable the center wavelength to be determined according to the required wavelength specifications of the FRA.

Anritsu provides both 1.48 um LD modules suitable for EDFAs and 1.4 um FBG-LD modules suitable for FRAs.

1.48 um LD modules provide a maximum optical output of 650 mW and a center wavelength of 1,475±15 nm, according to the required specifications of the EDFA.

1.4 um FBG-LD modules use a PM (Polarization Maintaining) fiber with FBG (Fiber Bragg Grating) to select the wavelength, and the center wavelength can be determined according to the required specifications of the FRA. An optical output can be provided with 300 to 500 mW.

We can also provide 1.3 um band FBG-LD modules which can be used for higher order FRA.

Anritsu LD modules comply with Telcordia GR-468-CORE for extremely high reliability, as well as the RoHS directive. The module has an industry-standard 14-pin butterfly shape and includes a TEC (Thermo-Electric Cooler) for temperature control and PD for optical output monitor.



1.48 um LD module

  • Optical output: 120 to 650 mW (in 10 mW increments)
  • Wavelength range: 1,475±15 nm
  • Fiber: Single Mode Fiber (SMF) or Polarization Maintaining Fiber (PMF)
  • Optical connector: Supports various optical connectors
  • 14-pin butterfly package
  • Includes optical isolator, monitor photo diode, and cooler

1.4 um FBG LD module

  • Optical output and wavelength range: 410 to 500 mW/1,420 to 1,485 nm, 500 to 650 mW/1,420 to 1,470 nm
  • Fiber: Polarization maintaining fiber (0.25 mm, UV coated)
  • Optical connector: Supports various optical connectors
  • 14-pin butterfly package
  • Internal monitor PD and TEC


Optical Fiber Amplifiers (EDFA/FRA)

Optical fiber amplification technology enables optical signal to be amplified without the need to convert it into electricity at a relay station, in order to compensate for transmission loss in optical fibers. The main types of optical fiber amplifiers are EDFA and FRA.

EDFA uses an optical fiber core doped with the rare earth element erbium (Er, atomic number 68) as the gain medium to amplify optical signal in the 1.55 um band via optical excitation. This EDFA that was invented in the late 1990s enables batch amplification of WDM (Wavelength Division Multiplexing) and is an important element of long hole networks such as undersea optical cables and high-capacity communication systems such as access networks.

EDFA schematic
EDFA schematic

An excitation light source for EDFA uses a 0.98 um band or 1.48 um band wavelength. Excitation light in the 0.98 um band has low quantum-conversion efficiency and a low noise figure (NF). On the other hand, excitation light in the 1.48 um band has high quantum-conversion efficiency.

Anritsu has been providing 1.48 um LD modules as excitation light sources since EDFAs started to be used as optical amplifiers for communication.

An FRA differs from an EDFA in that it is an optical amplifier that uses the optical fiber in the transmission route itself as the gain medium. It utilizes the nonlinear optical effect in the optical fiber called Stimulated Raman Scattering to have a gain band in the approximately 100 nm long wavelength region of the excitation light for optical signal in the 1.55 um band. Therefore, it can change the excitation light wavelength to amplify a signal light in a specific wavelength region.

Stimulated Raman Scattering Spectrum of Optical Fiber
Stimulated Raman Scattering Spectrum of Optical Fiber

In order to obtain a more accurate excitation light wavelength, an FBG-LD is used as the excitation light source for FRA. This FBG-LD contains fiber (FBG) with a diffraction grating inside the output fiber of the LD module. This FBG enables LD optical output with high wavelength stability and wavelength selectivity. Anritsu provides FBG modules for a wide range of wavelength in the 1.4 um band.

FRA schematic
FRA schematic
  • High optical output power (120-500 mW)
  • Low power consumption
  • Built-in optical isolator
  • Internal monitor PD, thermo-electric cooler, and thermistor
  • SMF or PMF fiber out pigtail type

Pump LD (FP-LD, FP Laser Diode)

Category Series Package Optical Output [mW] Center Wavelength [nm]
1.31 µm FP-LD AF3B310DM10Lpdf Butterfly 100 1,310
AF3B150FM20Mpdf Butterfly 500 1,320
1.48 µm FP-LD AF4Y108GA85Jpdf Cylindrical 80 1,478 to 1,490
AF4Y115HA85Jpdf Cylindrical 150 1,450 to 1,490
AF4B series Type Apdf Butterfly 120 to 180 1,465 to 1,480
AF4B series Type Bpdf Butterfly 200 to 250 1,465 to 1,480
AF4B series Type Cpdf Butterfly 300 to 400 1,465 to 1,480
AF4B series Type Dpdf Butterfly 410 to 500 1,465 to 1,480
AF4B series Type Epdf Butterfly 550 to 650 1,465 to 1,480
1.55 µm FP-LD AF5B310DM50Lpdf Butterfly 100 1,550
AF5B145FM50Mpdf Butterfly 450 1,550


Category Series Package Optical Output [mW] Center Wavelength [nm] LD operating temperature [℃]
1.4 µm FBG-LD AF4B2 series Type GB/GCpdf Butterfly 300 to 500 1,420 to 1,499 (300 to 400 mW)
1,420 to 1,485 (410 to 500 mW)
AF4B2 series Type GD Low Power Consumptionpdf Butterfly 300 to 500 1,420 to 1,485 35
1.3 µm FBG-LD AF3B250FU400Npdf Butterfly 500 1,340 25
AF3B250FU600Npdf Butterfly 500 1,360 25
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