Wavelength-Selected, High-Power D2587P-Type (with Wavelength
Locker)/D2547P-Type Isolated DFB Laser Modules
Data Sheet, Rev. 2
Principles of Operation (Controlled Wave-
The single-channel, wavelength-selected DFB (ILM) pack-
age contains internal wavelength-discriminating optics, i.e.,
two etalons and associated photodiodes. The output con-
sists of analog signals suitable for controlling the electrical
current of the thermoelectric cooler (TEC) and the DFB
The module contains an internal optical isolator that sup-
presses optical feedback in laser-based, fiber-optic sys-
tems. Light reflected back to the laser is attenuated a
minimum of 30 dB.
An integral TEC provides stable thermal characteristics.
The TEC allows for heating and cooling of the laser chip to
maintain a temperature of 25 °C for case temperatures from
–25 °C to +70 °C. The laser temperature is monitored by
the internal thermistor, which can be used with external cir-
cuitry to control the laser chip temperature.
An internal, InGaAs, PIN photodiode functions as the back-
facet monitor. The photodiode monitors emission from the
rear facet of the laser and, when used in conjunction with
control circuitry, can control optical power launched into the
fiber. Normally, this configuration is used in a feedback
arrangement to maintain consistent laser output power.
The laser module is fabricated in a 14-pin, hermetic, metal/
ceramic butterfly package that incorporates a bias tee that
separates the dc-bias path from the RF input. The RF input
has a nominal 25 Ω impedance.
The laser module is equipped with Fujikura* polarization-
maintaining fiber (PMF). The fiber is PANDA type and is the
same fiber that is used on the Agere Systems Inc. lithium
niobate modulators. It has a mode field diameter of
10.5 µm, a cladding diameter of 125 µm ±3 µm, and a
loose tube jacketed fiber 900 µm in diameter. Figure 1
shows the orientation of polarization in the fiber.
Agere Systems’ optoelectronic components are being qual-
ified to rigorous internal standards that are consistent with
Telcordia Technologies † TR-NWT-000468. All design and
manufacturing operations are ISO § 9001 certified. The
module is being fully qualified for central office applications.
* Fujikura is a registered trademark of Fujikura Ltd.
† Telcordia Technologies is a trademark of Telcordia Technologies
§ ISO is a registered trademark of The International Organization for
(SILICON & ACRYLATE)
Figure 1. Polarization-Maintaining Fiber
Table 1. Pin Descriptions
3 Laser dc Bias
4 Back-facet Monitor
5 Back-facet Monitor
6 TEC (+)1
7 TEC (–)1
8 Case Ground
9 λ Photodiode 2 Anode
10 λ Photodiode 1 Anode
11 Laser Anode (+) 2
12 RF Laser Input
13 Laser Anode (+) 2
Laser dc Bias
Laser Anode (+) 2
RF Laser Input
Laser Anode (+) 2
1. A positive current through the thermoelectric heat pump cools the
2. Both leads should be grounded for optimum performance.
2 Agere Systems Inc.