D2570, D2526G, D2555 Wavelength-Selected
Direct Modulated Isolated DFB Laser Module
Data Sheet, Rev. 3
July 2001
Description (continued)
Pin Information
Controlled Feedback
Pin
Name
1
2
3
4
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.
Laser dc Bias (Cathode) (–)
Back-facet Monitor Anode (–)
5
6
Back-facet Monitor Cathode (+)
Thermoelectric Cooler (+)*
Thermoelectric Cooler (–)†
Case Ground
Controlled Temperature
7
8
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
thermistor, which can be used with external circuitry to
control the laser chip temperature.
9
Case Ground
10
11
12
13
14
Case Ground
Laser Anode (+)†
RF Laser Input Cathode (–)
Laser Anode (+)†
Case Ground
* A positive current through the thermoelectric heat pump cools the
laser.
† Both leads should be grounded for optimum performance.
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 consistent
laser output power.
7
6
5
4
3
2
1
+
+
–
–
–
L1
160 nH
TH
10 k
TEC
Ω
ISOLATOR
R1
20
Ω
PACKAGE
GROUNDS
Standard Package
NC
+
+
–
8
Top view.
9
10
11
12
13
14
The laser module is fabricated in a 14-pin, hermetic,
metal/ceramic butterfly package that incorporates a
bias tee, which separates the dc-bias path from the RF
input. The RF input has a nominal 25 Ω impedance.
1-567F.b
Figure 1. Circuit Schematic
The laser module is equipped with SMF-28 * type fiber.
The fiber has a 900 µm tight buffer jacket. Various con-
nectors and pigtail lengths are available.
Agere Systems’ optoelectronic components are being
qualified to rigorous internal standards that are consis-
tent 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.
* ISO is a registered trademark of The International Organization for
Standardization.
†SMF-28 is a trademark of Corning Inc.
2
Agere Systems Inc.
AGERE [ AGERE SYSTEMS ]
