A1750A DWDM Analog
Forward-Path or Return-Path Laser Module
Data Sheet, Rev. 4
June 2001
Features
s
Low adiabatic chirp
s
Excellent linearity
s
Standard ITU wavelengths
s
Advanced analog chip design
s
Tested for forward-path or return-path applications
s
Reduces equipment requirements in the hub
s
Exceeds
Telcordia Technologies
* 468 specifica-
tion.
Applications
s
Networks with limited fiber
s
Architectures using separate optical wavelengths
to carry targeted services
*
Telcordia Technologies
is a trademark of Telcordia Technologies
Inc.
Description
The A1750A laser module is a dense wavelength-
division multiplexing laser with a DFB chip designed
specifically for analog RF applications. The device
features low adiabatic chirp to maximize signal qual-
ity in short and long lengths of fiber. The laser's
excellent inherent linearity minimizes degradation of
the broadcast signals caused by the QAM channels.
Wavelength-division multiplexing (WDM) has gained
widespread acceptance in the telecommunications
market and is being designed into emerging cable
television network architectures. Dense WDM, a
method for delivering targeted QAM signals to differ-
ent locations, allows multiple signal sets to be com-
bined onto a single strand of fiber for transmission
from a headend to a hub. At the hub, individual QAM
signals can be selected and combined with broad-
cast analog channels. The A1750A DWDM laser
module reduces cable network architecture fiber
requirements and lessen equipment requirements in
the hub.
The A1750A is available at a variety of standard ITU
wavelengths. The lasers are offered as either for-
ward-path (40 MHz860 MHz) or return-path mod-
ules (5 MHz210 MHz).
2
A1750A DWDM Analog
Data Sheet, Rev. 4
Forward-Path or Return-Path Laser Module
June 2001
Agere Systems Inc.
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 operational sections of the data sheet. Exposure to absolute maximum ratings for extended
periods can adversely affect device reliability.
* The device can withstand continuous exposure to the specified limits without damage.
Characteristics
1. Tested in a 50
system with 27
series matching resistor.
2. Eight-channel loading, 10% OMI, 40 km fiber.
3. Measured at 42 MHz.
4. Measured at 553.25 MHz, 577.25 MHz. and 595.25 MHz.
5. Consult an Agere Systems account manager for other wavelengths.
6. Change in wavelength as case temperature is changed.
Parameter*
Symbol
Min
Max
Unit
Operating Case Temperature Range
T
C
25
65
C
Storage Temperature Range
Tstg
40
70
C
Monitor Photodiode Reverse Voltage
V
MPD
--
10
V
Laser Forward Current
I
F
--
150
mA
Reverse Voltage (Laser)
V
R
--
2
V
TEC Current
I
TEC
1.5
1.5
A
RF Input Power
P
RFIN
--
62 dBm
V
Table 1. Key Characteristics
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
Frequency Range:
1
Return Path
Forward Path
F --
5
40
--
--
210
860
MHz
MHz
Frequency Response:
1
5 MHz--210 MHz
40 MHz--860 MHz
|S21|
I
F
= 60 mA,
T
OP
= 25 C,
--
--
0.5
0.5
--
--
dB
dB
RF Return Loss:
1
5 MHz--210 MHz
40 MHz--860 MHz
|S21|
I
F
= 60 mA,
--
>16
>16
--
--
dB
dB
Optical Output Power
P
O
I
F
= I
OP
6, 8, or
10
--
--
mW
Laser Relative Intensity
Noise
RIN
I
F
= I
TH
+ 70 mA,
T = 25 C
--
<
155
--
dB/Hz
Composite Second Order
2, 3
CSO
I
F
= I
OP
, OMI = 10%
--
<
50
--
dBc
Composite Triple Beat
2, 4
CTB
I
F
= I
OP
, OMI = 10%
--
<
60
--
dBc
Available Wavelengths
5
I
P
= I
OP
, T = T
OP
1528
--
1563
nm
Wavelength Drift
6
OP
I
F
= 60 mA,
T = T
OP,
T
C
varied from min-->max
--
--
0.04 nm
Adiabatic Chirp
FM
I
F
= 60 mA,
T
OP
= 25 C,
measured at 500 MHz
40
--
100
MHz/mA
Operating Case Tempera-
ture Range
T
C
I
F
= I
OP
20
--
65
C
3
Data Sheet, Rev. 4
A1750A DWDM Analog
June 2001
Forward-Path or Return-Path Laser Module
Agere Systems Inc.
Characteristics
(continued)
1. Bias point at which all specifications apply.
2. For 10 mW output power. Minimum slope efficiency is lower for lower power lasers.
3. Chip temperature at which wavelength specification is met. Operating chip temperature is reported for each laser.
Electrical Schematics
Figure 1. A1750A Laser Schematic
Table 2. Additional Characteristics
Parameter
Symbol
Conditions
Min
Max
Unit
Bias Current
1
(Operating Current)
I
B
BOL
--
120
mA
Threshold Current
I
TH
25 C, BOL
--
30
mA
Slope Efficiency
2
I
P
= I
TH
+ 20 and
I
TH
+ 60
0.10
--
mW/mA
Monitor Photocurrent
I
MON
I
OP
= 0 mA, V
RM
= 5 V,
T
OP
= 25 C
10
200
A/mW
Operating Chip Temperature
3
T
OP
I
F
= I
OP
15
35
C
TEC Current
I
TEC
20
C
<
T
C
<
65
C,
T
OP
= 15 C--35 C,
I
F
= 60 mA
1.5
1.5
A
TEC Voltage
V
TEC
T
OP
= 15 C--35 C over T
C
2
2
V
Thermistor Resistance
R
TH
T
OP
= 25 C
9.5
10.5
k
Optical Return Loss
ORL
T
C
40
--
dB
Side Mode Suppression Ratio
SMSR
I
F
= I
OP
30
--
dB
1
2
3
4
5
6
7
14
13
12
11
10
9
8
CASE
GROUND
NC
(+)
()
(+)
()
TEC
()
(+)
CASE
GROUND
NC
ISOLATOR
(+)
1-1233F
4
A1750A DWDM Analog
Data Sheet, Rev. 4
Forward-Path or Return-Path Laser Module
June 2001
Agere Systems Inc.
Electrical Schematics
(continued)
Figure 2. A1750A Circuit Schematic
1
2
3
4
5
6
7
14
13
12
11
10
9
8
THERMISTOR
TEC ()
MPC CATHODE
NC
THERMISTOR
dc LASER
BIAS
MPD ANODE
CASE GROUND
TEC (+)
CASE
GROUND
CASE
GROUND
MPC CATHODE
NC
LASER
COMMON (+)
LASER
MODULATION ()
LASER
COMMON (+)
39 nH
200
0.01
f
3.3
H
1000 pf
1000 pf
0.01
f
0.01
f
SEE
SEE
3A AND 3B
FIGURES
FIGURE 4
1-1238F
Figure 3a. Impedance-Matched Configuration
Figure 3b. Resistive-Matched Configuration
C7
1 pF--
0.01
f
0.01
f
VSWR
T1*
3:5
2
3
0.5 pF--2.5 pF
SEE PIN 12,
FIGURE 2
0.01
f
FREQUENCY
RESPONSE
* T1 (75
) 3:5.
5 pF
1-1238a(F)
SEE PIN 12,
FIGURE 2
37.5
R1
37.5
R2
1-1238F.b
5
Data Sheet, Rev. 4
A1750A DWDM Analog
June 2001
Forward-Path or Return-Path Laser Module
Agere Systems Inc.
Electrical Schematics
(continued)
Note: When ordering the dc set, the following boards are included: alarm board, 9108-004; TEC board, 9028-004; constant current, 9383-004.
Figure 4. dc Set (Agere Systems-Supplied Option)
CONSTANT
ALARM
TEC
J2
1 THERMISTOR
2 THERMISTOR
3 dc LASER BIAS
4 MPD ANODE (CASE GROUND)
5 MPC CATHODE
6 TEC (+)
7 TEC ()
8 GND
9 GND
10 GND
1
2
3
4
5
6
7
THERMISTOR
TEC ()
MPC CATHODE
THERMISTOR
dc LASER
BIAS
MPD ANODE
CASE GROUND
TEC (+)
MPC CATHODE
39 nH
200
0.01
f
3.3
H
1000 pf
1000 pf
0.01
f
0.01
f
1-1238F.c
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