D2570, D2526G, D2555 Wavelength-Selected
Direct Modulated Isolated DFB Laser Module
Data Sheet, Rev. 3
July 2001
Description
(continued)
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.
Pin Information
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Name
Thermistor
Thermistor
Laser dc Bias (Cathode) (–)
Back-facet Monitor Anode (–)
Back-facet Monitor Cathode (+)
Thermoelectric Cooler (+)*
Thermoelectric Cooler (–)
†
Case Ground
Case Ground
Case Ground
Laser Anode (+)
†
RF Laser Input Cathode (–)
Laser Anode (+)
†
Case Ground
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
thermistor, which can be used with external circuitry to
control 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 consistent
laser output power.
* A positive current through the thermoelectric heat pump cools the
laser.
† Both leads should be grounded for optimum performance.
7
–
6
+
5
+
4
–
L1
160 nH
3
–
2
1
TH
10 kΩ
TEC
Standard Package
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.
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.
8
PACKAGE
GROUNDS
+
9
10
11
R1
20
Ω
–
12
ISOLATOR
NC
+
13
14
1-567F.b
Top view.
Figure 1. Circuit Schematic
*
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 ]
