Wavelength-Selected, High-Power D2587P-Type (with Wavelength
Locker)/D2547P-Type Isolated DFB Laser Modules
Data Sheet, Rev. 2
July 2001
Description
(continued)
Principles of Operation (Controlled Wave-
length)
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
laser.
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
Inc.
§
ISO
is a registered trademark of The International Organization for
Standardization.
Controlled Feedback
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.
CORE
STRESS ROD
PRINCIPLE POLARIZATION
AXIS
CLADDING
INNER COATING
(SILICON & ACRYLATE)
OUTER COATING
1-771(C).a
Controlled Temperature
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.
Figure 1. Polarization-Maintaining Fiber
Pin Information
Table 1. Pin Descriptions
Pin
1
2
3
4
5
D2587P-Type
Thermistor
Thermistor
Laser dc Bias
(Cathode) (–)
Back-facet Monitor
Anode (–)
Back-facet Monitor
Cathode (+)
TEC (+)
1
TEC (–)
1
Case Ground
λ
Photodiode 2 Anode
λ
Photodiode 1 Anode
Laser Anode (+)
2
RF Laser Input
Cathode (–)
Laser Anode (+)
2
NC
D2547P-Type
Thermistor
Thermistor
Laser dc Bias
(Cathode) (–)
Back-facet Monitor
Anode (–)
Back-facet Monitor
Cathode (+)
TEC (+)
1
TEC (–)
1
Case Ground
Controlled Power
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.
Standard Package
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.
6
7
8
9
10
11
12
13
14
Case Ground
Case Ground
Laser Anode (+)
2
RF Laser Input
Cathode (–)
Laser Anode (+)
2
Case Ground
1. A positive current through the thermoelectric heat pump cools the
laser.
2. Both leads should be grounded for optimum performance.
2
Agere Systems Inc.
AGERE [ AGERE SYSTEMS ]
