1.5 µm D2500-Type Digital
Isolated DFB Laser Module
Data Sheet
February 2000
The minimum pigtail length is 39.4 in. (100 cm); the
minimum bend radius is 1.18 in. (30 mm).
Description
The D2500-Type Digital Isolated DFB Laser Module
contains an internally cooled, InGaAsP, MQW, distrib-
uted-feedback (DFB) laser designed for 1.5 µm appli-
cations. The laser is designed to be used in OC-12/
STM-4 (622 Mbits/s) and OC-48/STM-16 (2.488 Gbits/
s) for long-reach and extended-reach applications. It is
also capable of low dispersion penalties (<2 dB) for use
with fiber spans exceeding 170 km (3000 ps/nm).
The pigtail is a 900 µm tight buffer fiber. Various con-
nector and pigtail options are available.
Lucent Technologies Microelectronics Group optoelec-
tric components are qualified to rigorous internal stan-
dards that are consistent with Telcordia Technologies
TR-NWT-000468. All design and manufacturing opera-
tions are ISO* 9001 certified. The module is fully quali-
fied for central office applications.
The device is available with an average output power of
0 dBm (3 dBm peak), which meets the SONET/SDH
standard. To eliminate the need for optical amplifiers in
some applications, the module can also be ordered
with higher output powers.
* ISO is a registered trademark of The International Organization for
Standardization.
Pin Information
Controlled Feedback
Pin
1
Name
Thermistor
Thermistor
The module contains an internal optical isolator that
suppresses optical feedback in laser-based, fiber-optic
systems. Light reflected back to the laser is attenuated
a minimum of 30 dB.
2
3
Laser dc Bias (cathode) (–)
Back-facet Monitor Anode (–)
Back-facet Monitor Cathode (+)
Thermoelectric Cooler (+)*
Thermoelectric Cooler (–)*
Case Ground
4
5
6
Controlled Temperature
7
An integral thermoelectric cooler (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 –40 °C to +70 °C.
The laser temperature is monitored by the internal ther-
mistor, which can be used with external circuitry to con-
trol the laser chip temperature.
8
9
Case Ground
10
11
Case Ground
Laser Anode (+)†
12
13
RF Laser Input Cathode (–)
Laser Anode (+)†
14
Case Ground
Controlled Power
* A positive current through the thermoelectric heat pump cools the
laser.
†Both leads should be grounded for optimum performance.
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 con-
junction with control circuitry, can control optical power
launched into the fiber. Normally, this configuration is
used in a feedback arrangement to maintain the aver-
age laser output power.
7
6
5
4
3
2
1
–
+
+
–
–
L1
160 nH
TH
10 kΩ
TEC
ISOLATOR
Standard Package
R1
20 Ω
PACKAGE
GROUNDS
The laser module is fabricated in a 14-pin, hermetic,
metal/ceramic butterfly package. The package also
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 a sin-
gle-mode fiber with an 8 µm core and 125 µm cladding.
+
11
–
+
8
Top view.
9
10
12
13
14
1-567
Figure 1. Circuit Schematic
Lucent Technologies Inc.
2
AGERE [ AGERE SYSTEMS ]
