Data Sheet
March 2000
Wavelength-Selected D2525P
Isolated DFB Laser Module with PMF
Applications
s
Telecommunications
— SONET/SDH OC-48/STM-16, OC-192/STM-64
— Extended and ultralong reach
— Undersea systems
— Dense WDM systems
Digital video
s
Description
The D2525P family of DFB laser modules is
designed to be used with a lithium niobate external
modulator (see Table 4). The laser module features a
polarization-maintaining fiber (PMF) pigtail, enabling
it to be directly connected to a modulator without the
need of a polarization controller. The PMF maintains
the polarization of the output light to a consistent ori-
entation. This allows the D2525P to be used as a CW
light source for systems requiring extremely low chirp
such as undersea or 10 Gbits/s systems. The module
contains a multiquantum-well (MQW), distributed-
feedback (DFB) laser. This device nominally has an
output power of 10 mW. The wavelength of the laser
can be temperature-tuned for more precise wave-
length selection by adjusting the temperature of the
internal thermoelectric cooler.
The 1.5
µ
m D2525P Laser Module is available in a 14-pin, her-
metic, butterfly package.
Features
s
ITU wavelengths available from
1529.55 nm —1610.06 nm
Integrated optical isolator
High-performance, multiquantum-well (MQW),
distributed-feedback (DFB) laser
Industry-standard, 14-pin butterfly package
Hermetic package
InGaAs, PIN photodetector back-facet monitor
Polarization-maintaining fiber pigtail
For use with lithium niobate modulators
High reliability
Narrow linewidth
High optical power available
s
s
s
s
s
s
s
s
s
s
Wavelength-Selected D2525P
Isolated DFB Laser Module with PMF
Data Sheet
March 2000
Description
(continued)
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
PRINCIPAL POLARIZATION
AXIS
CLADDING
INNER COATING
(SILICON & ACRYLATE)
OUTER COATING
(ACRYLATE OR NYLON)
1-771(C).a
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.
Figure 1. Polarization-Maintaining Fiber
Pin Information
Table 1. Pin Descriptions
Pin
Name
Thermistor
Thermistor
Laser dc Bias (Cathode) (–)
Back-facet Monitor Anode (–)
Back-facet Monitor Cathode (+)
Thermoelectric Cooler (+)
1
Thermoelectric Cooler (–)
1
Case Ground
Case Ground
Case Ground
Laser Anode (+)
2
RF Laser Input Cathode (–)
Laser Anode (+)
2
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.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
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 Lucent Technologies Microelec-
tronics Group’s lithium niobate modulators. It has a mode
field diameter of 10.5
µ
m, a cladding diameter of 123
µ
m—
128
µ
m, and a loose tube jacketed fiber 900
µ
m in diame-
ter. The pigtail is terminated with an
ST
®
ferrule
†
. Figure 1
shows the orientation of polarization in the fiber.
Lucent’s optoelectronic components are being qualified to
rigorous internal standards that are consistent with
Telcor-
dia Technologies
‡
TR-NWT-000468. All design and manu-
facturing operations are
ISO
§
9001 certified. The module is
being fully qualified for central office applications.
*
Fujikura
is a registered trademark of Fujikura Ltd.
† The
ST
ferrule key is not aligned to slow axis of fiber. Connector is
intended for testing purposes only.
‡
Telcordia Technologies
is a trademark of Bell Communications
Research, Inc.
§
ISO
is a registered trademark of The International Organization for
Standardization.
1. A positive current through the thermoelectric heat pump cools the
laser.
2. Both leads should be grounded for optimum performance.
7
–
6
+
5
+
4
–
L1
160 nH
TEC
3
–
TH
10 kΩ
2
1
PACKAGE
GROUNDS
+
8
9
10
11
R1
20
Ω
–
12
ISOLATOR
+
13
14
1-567
Top view.
Figure 2. Circuit Schematic
Lucent Technologies Inc.
2
Data Sheet
March 2000
Wavelength-Selected D2525P
Isolated DFB Laser Module with PMF
Absolute Maximum Ratings
Stresses in excess of the absolute maximum ratings can cause permanent damage to the device. These are abso-
lute stress ratings only. Functional operation of the device is not implied at these or any other conditions in excess
of those given in the operations sections of the data sheet. Exposure to absolute maximum ratings for extended
periods can adversely affect device reliability.
Parameter
Laser Reverse Voltage
dc Forward Current
Operating Case Temperature Range
Storage Case Temperature Range*
Photodiode Reverse Voltage
Photodiode Forward Current
* Does not apply to shipping container.
Symbol
V
RLMAX
I
FLMAX
T
C
T
stg
V
RPDMAX
I
FPDMAX
Min
—
—
–40
–40
—
—
Max
2
225
70
70
10
2
Unit
V
mA
°
C
°
C
V
mA
Handling Precautions
Power Sequencing
To avoid the possibility of damage to the laser module
from power supply switching transients, follow this
turn-on sequence:
1. All ground connections
2. Most negative supply
3. Most positive supply
4. All remaining connections
Reverse the order for the proper turn-off sequence.
Mounting Instructions
The minimum fiber bend radius is 1.50 in.
To avoid degradation in performance, mount the mod-
ule on the board as follows:
1. Place the bottom flange of the module on a flat heat
sink at least 0.5 in. x 1.180 in. (12.7 mm x 30 mm) in
size. The surface finish of the heat sink should be
better than 32
µ
in. (0.8
µ
m), and the surface flatness
must be better than 0.001 in. (25.4
µ
m). Using ther-
mal conductive grease is optional; however, thermal
performance can be improved by up to 5% if conduc-
tive grease is applied between the bottom flange and
the heat sink.
2. Mount four #2-56 screws with Fillister heads
(M2-3 mm) at the four screw hole locations (see Out-
line Diagram). The Fillister head diameter must not
exceed 0.140 in. (3.55 mm). Do not apply more than
1 in.-lb. of torque to the screws.
0.118
(3.00)
0.086
(2.18)
Electrostatic Discharge
CAUTION: This device is susceptible to damage as
a result of electrostatic discharge. Take
proper precautions during both han-
dling and testing. Follow guidelines
such as JEDEC Publication No. 108-A
(Dec. 1988).
Lucent employs a human-body model (HBM) for ESD-
susceptibility testing and protection-design evaluation.
ESD voltage thresholds are dependent on the critical
parameters used to define the model. A standard HBM
(resistance = 1.5 k
Ω
, capacitance = 100 pF) is widely
used and, therefore, can be used for comparison pur-
poses. The HBM ESD threshold presented here was
obtained using these circuit parameters:
Parameter
Human-body Model
Lucent Technologies Inc.
Value
>400
Unit
V
0.062 (1.58)
0.031 (0.79)
0.140
(3.56)
0.129 (3.28) R
0.041 (1.04)
Note: Dimensions are in inches and (millimeters).
1-532(C)
Figure 3. Fillister Head Screw
3
Wavelength-Selected D2525P
Isolated DFB Laser Module with PMF
Data Sheet
March 2000
Characteristics
Table 2. Electrical Characteristics
(at 25
°
C laser temperature)
Parameter
Threshold Current
Drive Current Above Threshold
Laser Forward Voltage
Monitor Reverse-bias Voltage*
Monitor Current
Monitor Dark Current
Input Impedance
Thermistor Current
Resistance Ratio
†
Thermistor Resistance
TEC Current
TEC Voltage
TEC Capacity
Symbol
I
TH
—
V
LF
V
RMON
I
RMON
I
D
Z
IN
I
TC
—
R
TH
I
TEC
V
TEC
∆
T
Test Conditions
—
L
F
= 10 mW
L
F
= 10 mW (CW)
—
P
O
= 10 mW (CW)
I
F
= 0, V
RMON
= 5 V
—
—
—
T
L
= 25
°
C
T
L
= 25
°
C, T
C
= 70
°
C
T
L
= 25
°
C, T
C
= 70
°
C
T
C
= 70
°
C
Min
—
—
—
3
0.200
—
—
10
9.1
9.5
—
—
50
Typ
15
—
1.3
5
—
0.01
25
—
9.6
—
—
—
—
Max
40
110
1.8
10
—
0.1
—
100
10.1
10.5
1.0
2.0
—
Unit
mA
mA
V
V
mA
µ
A
Ω
µ
A
—
k
Ω
A
V
°
C
* Standard operating condition is 5.0 V reverse bias.
† Ratio of thermistor resistance at 0
°
C to thermistor resistance at 50
°
C.
Table 3. Optical Characteristics
(at 25
°C
laser temperature)
Parameter
Peak Optical Output Power
Center Wavelength*
(See Table 4.)
Line Width (3 dB full width)
Relative Intensity Noise
Side-mode Suppression Ratio
Optical Isolation
Optical Polarization Extinction
Ratio
†
Symbol
P
P
λ
C
∆λ
RIN
SMSR
—
—
Test Conditions
—
T
L
= 25
°C
CW Wavelength
CW, P
F
= 10.0 mW
CW, P
F
= 10.0 mW,
200 MHz < f < 10 GHz
CW
T
C
= 0
°C
to 75
°C
0
°C
to 75
°C
Min
10.0
1529.55
—
—
33
30
20
Typ
—
—
2
—
—
—
—
Max
—
1610.06
10
–135
—
—
—
Unit
mW
nm
MHz
dB/Hz
dB
dB
dB
* Custom wavelengths available.
† The
ST
ferrule key is not aligned to slow axis of fiber. Connector is intended for testing purposes only.
4
Lucent Technologies Inc.
Data Sheet
March 2000
Wavelength-Selected D2525P
Isolated DFB Laser Module with PMF
Outline Diagram
Dimensions are in inches and (millimeters). Tolerances are
±0.005
in. (±0.127 mm).
1.025 (26.04)
0.508
±
0.008
(12.90
±
0.2)
PIN 1
0.020 (0.51) TYP
TRADEMARK, CODE, LASER SERIAL NUMBER,
AND DATE CODE IN APPROX. AREA SHOWN
STRAIN
RELIEF
0.500
(12.70)
0.605
0.350
(15.37)
(8.89)
MAX
0.10
±
0.002
(0.25
±
0.064)
0.036
(0.91)
0.200
(5.08)
0.078 (1.98)
0.105 (2.67) DIA
TYP (4) PLACES
PIN 14
0.213 (5.40) TYP
0.100 (2.54) TYP
39.37 (1000.00)
MIN
2.03 (51.6)
0.180 (4.56)
0.820 (20.83)
0.700 (17.78)
0.863 (21.91)
0.575 (14.61)
0.260 (6.60)
0.10
(2.5)
0.056 (1.42)
0.365
(9.27)
MAX
1.180 (29.97)
HEAT SINK
0.215 (5.45)
0.030 (0.75)
0.215
(5.47)
REF
1-520.g
Lucent Technologies Inc.
5
京公网安备 11010802033920号
EEWORLD
