D2500 Datasheet, PDF (2/8 Pages) Agere Systems – 1.5 m m D2500-Type Digital Isolated DFB Laser Module

1.5 µm D2500-Type Digital
Isolated DFB Laser Module
Data Sheet
February 2000
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 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.
Controlled Feedback
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.
Controlled Temperature
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.
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 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.
The minimum pigtail length is 39.4 in. (100 cm); the
minimum bend radius is 1.18 in. (30 mm).
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.
* ISO is a registered trademark of The International Organization for
Standardization.
Pin Information
Pin
Name
1
Thermistor
2
Thermistor
3
Laser dc Bias (cathode) (–)
4
Back-facet Monitor Anode (–)
5
Back-facet Monitor Cathode (+)
6
Thermoelectric Cooler (+)*
7
Thermoelectric Cooler (–)*
8
Case Ground
9
Case Ground
10
Case Ground
11
Laser Anode (+)^†
12
RF Laser Input Cathode (–)
13
Laser Anode (+)^†
14
Case Ground
* A positive current through the thermoelectric heat pump cools the
laser.
† Both leads should be grounded for optimum performance.
7
6
5
–
+
+
TEC
4
3
–
–
L1
160 nH
2
1
TH
10 kΩ
Standard Package
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.
2
PACKAGE
GROUNDS
R1 ^ISOLATOR
20 Ω
+
–+
8
9
10 11
Top view.
12 13
14
1-567
Figure 1. Circuit Schematic
Lucent Technologies Inc.