Data Sheet, Rev. 4
June 2001
A1750A DWDM Analog
Forward-Path or Return-Path Laser Module
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 MHz–860 MHz) or return-path mod-
ules (5 MHz–210 MHz).
Features
s
s
s
s
s
s
s
Low adiabatic chirp
Excellent linearity
Standard ITU wavelengths
Advanced analog chip design
Tested for forward-path or return-path applications
Reduces equipment requirements in the hub
Exceeds
Telcordia Technologies*
468 specifica-
tion.
Applications
s
s
Networks with limited fiber
Architectures using separate optical wavelengths
to carry targeted services
*
Telcordia Technologies
is a trademark of Telcordia Technologies
Inc.
A1750A DWDM Analog
Forward-Path or Return-Path Laser Module
Data Sheet, Rev. 4
June 2001
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.
Parameter*
Operating Case Temperature Range
Storage Temperature Range
Monitor Photodiode Reverse Voltage
Laser Forward Current
Reverse Voltage (Laser)
TEC Current
RF Input Power
Symbol
T
C
Tstg
V
MPD
I
F
V
R
I
TEC
P
RFIN
Min
–25
–40
—
—
—
–1.5
—
Max
65
70
10
150
2
1.5
62
Unit
°C
°C
V
mA
V
A
dBm V
* The device can withstand continuous exposure to the specified limits without damage.
Characteristics
Table 1. Key Characteristics
Parameter
Frequency Range:
1
Return Path
Forward Path
Frequency Response:
1
5 MHz—210 MHz
40 MHz—860 MHz
RF Return Loss:
1
5 MHz—210 MHz
40 MHz—860 MHz
Optical Output Power
Laser Relative Intensity
Noise
Composite Second Order
2, 3
Composite Triple Beat
2, 4
Available Wavelengths
5
Wavelength Drift
6
Symbol
F
Conditions
—
5
40
|S21|
I
F
= 60 mA,
T
OP
= 25 °C,
I
F
= 60 mA,
—
—
—
—
—
±0.5
±0.5
>16
>16
—
<
–155
<
–50
<
–60
—
—
210
860
—
—
—
—
—
—
—
—
1563
0.04
MHz
MHz
dB
dB
dB
dB
mW
dB/Hz
dBc
dBc
nm
nm
Min
Typ
Max
Unit
|S21|
P
O
RIN
CSO
CTB
λ
∆λ
OP
I
F
= I
OP
I
F
= I
TH
+ 70 mA,
T = 25 °C
I
F
= I
OP
OMI = 10%
,
I
F
= I
OP
OMI = 10%
,
I
P
= I
OP
T = T
OP
,
I
F
= 60 mA,
T = T
OP,
T
C
varied from min—>max
I
F
= 60 mA,
T
OP
= 25 °C,
measured at 500 MHz
I
F
= I
OP
6, 8, or
10
—
—
—
1528
—
Adiabatic Chirp
FM
40
—
100
MHz/mA
Operating Case Tempera-
ture Range
T
C
–20
—
65
°C
1. Tested in a 50
Ω
system with 27
Ω
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.
2
Agere Systems Inc.
Data Sheet, Rev. 4
June 2001
A1750A DWDM Analog
Forward-Path or Return-Path Laser Module
Characteristics
(continued)
Table 2. Additional Characteristics
Parameter
Bias Current
1
(Operating Current)
Threshold Current
Slope Efficiency
2
Monitor Photocurrent
Operating Chip Temperature
3
TEC Current
Symbol
I
B
I
TH
η
I
MON
T
OP
I
TEC
Conditions
BOL
25 °C, BOL
I
P
= I
TH
+ 20 and
I
TH
+ 60
I
OP
= 0 mA, V
RM
= 5 V,
T
OP
= 25 °C
I
F
= I
OP
–20
°C <
T
C
<
65
°C,
T
OP
= 15 °C—35 °C,
I
F
= 60 mA
T
OP
= 15 °C—35 °C over T
C
T
OP
= 25 °C
T
C
I
F
= I
OP
Min
—
—
0.10
10
15
–1.5
Max
120
30
—
200
35
1.5
Unit
mA
mA
mW/mA
µA/mW
°C
A
TEC Voltage
Thermistor Resistance
Optical Return Loss
Side Mode Suppression Ratio
V
TEC
R
TH
ORL
SMSR
–2
9.5
40
30
2
10.5
—
—
V
kΩ
dB
dB
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
1
ISOLATOR
2
NC
14
13
(+)
3
12
(–)
(–)
4
11
(+)
(+)
5
NC
10
(+)
6
CASE
GROUND
CASE
GROUND
9
(–)
7
TEC
8
1-1233F
Figure 1. A1750A Laser Schematic
Agere Systems Inc.
3
A1750A DWDM Analog
Forward-Path or Return-Path Laser Module
Data Sheet, Rev. 4
June 2001
Electrical Schematics
(continued)
14
NC
13
LASER
COMMON (+)
LASER
MODULATION (–)
LASER
COMMON (+)
THERMISTOR
1
2
THERMISTOR
3
200
Ω
4
SEE
FIGURE 4
3.3
µH
39 nH
0.01
µf
SEE
FIGURES
3A AND 3B
12
dc LASER
BIAS
MPD ANODE
CASE GROUND
11
10
NC
9
MPC CATHODE
5
1000 pf
CASE
GROUND
CASE
GROUND
6
TEC (+)
7
TEC (–)
0.01
µf
0.01
µf
1000 pf
8
1-1238F
Figure 2. A1750A Circuit Schematic
0.01
µf
C7
3:5
T1*
2
3
SEE PIN 12,
FIGURE 2
0.5 pF—2.5 pF
VSWR
R1
37.5
Ω
SEE PIN 12,
FIGURE 2
R2
37.5
Ω
1-1238F.b
1 pF—
5 pF
FREQUENCY
RESPONSE
* T1 (75
Ω)
3:5.
0.01
µf
0.01
µf
Figure 3b. Resistive-Matched Configuration
1-1238a(F)
Figure 3a. Impedance-Matched Configuration
4
Agere Systems Inc.
Data Sheet, Rev. 4
June 2001
A1750A DWDM Analog
Forward-Path or Return-Path Laser Module
Electrical Schematics
(continued)
TEC
CONSTANT
ALARM
1
THERMISTOR
2
THERMISTOR
3
200
Ω
4
1000 pf
5
MPC CATHODE
1000 pf
6
TEC (+)
0.01
µf
7
TEC (–)
0.01
µf
1-1238F.c
J2
39 nH
0.01
µf
dc LASER
BIAS
MPD ANODE
CASE GROUND
3.3
µH
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
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)
Agere Systems Inc.
5
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