Data Sheet, Rev. 4
June 2001
A1751A DWDM Analog
Forward-Path or Return-Path Laser Modules
Features
■Higher temperature rating
■Excellent linearity
■Standard ITU wavelengths
■Advanced analog chip design
■Tested for forward and return path applications
■Reduces equipment requirements in the hub
■Exceeds Telcordia Technologies* 468 specification.
Description
The A1751A laser module is a dense wavelengthdivision multiplexing (DWDM) laser for analog applications. It features a distributed-feedback (DFB) chip that has been designed specifically for radio frequency (RF) applications. The A1751A laser module has a wide temperature range for reliable performance in harsh node environments and narrow transmitter designs. It also features low adiabatic chirp to maximize signal quality in short and long lengths of fiber. The laser’s excellent inherent linearity minimizes degradation of the broadcast signals caused by the quadrature amplitude modulation (QAM) channels.
Wavelength-division multiplexing is being designed into cable television architectures. DWDM, a method for delivering targeted QAM signals to different locations, allows multiple signal sets to be combined 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 broadcast analog channels. The versatile A1751A DWDM laser module reduces cable network architecture fiber needs and lessens equipment requirements in the hub.
The A1751A is available in a wide range of standard ITU wavelengths. The lasers are offered as either for- ward-path (40 MHz—860 MHz) or return-path
(5 MHz—210 MHz) modules.
Applications
■Node capability
■Narrow transmitter housing
■Networks with limited fiber
■Architectures using separate optical wavelengths to carry targeted services
*Telcordia Technologies is a trademark of Telcordia Technologies, Inc.
A1751A DWDM Analog |
Data Sheet, Rev. 4 |
Forward-Path or Return-Path Laser Modules |
June 2001 |
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Absolute Maximum Ratings
Stresses in excess of the absolute maximum ratings can cause permanent damage to the device. These are absolute 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* |
Symbol |
Min |
Max |
Unit |
|
|
|
|
|
Operating Case Temperature Range |
TC |
–40 |
85 |
°C |
|
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Storage Temperature Range |
Tstg |
–40 |
85 |
°C |
|
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|
Monitor Photodiode Reverse Voltage |
VMPD |
— |
10 |
V |
|
|
|
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|
Laser Forward Current |
IF |
— |
150 |
mA |
|
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|
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|
Reverse Voltage (Laser) |
VR |
— |
2 |
V |
|
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TEC Current |
ITEC |
— |
1.7 |
A |
|
|
|
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RF Input Power |
PRFIN |
— |
62 |
dBm V |
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* The device can withstand continuous exposure to the specified limits without damage.
Characteristics
Table 1. Key Characteristics
Parameter |
Symbol |
Conditions |
Min |
Typ |
Max |
Unit |
|
|
|
|
|
|
|
Frequency Range:1 |
F |
— |
|
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|
MHz |
Return Path |
|
|
5 |
— |
210 |
MHz |
Forward Path |
|
|
40 |
— |
860 |
MHz |
|
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Frequency Response:1 |
— |
I F = 60 mA, |
|
|
|
|
5 MHz—210 MHz |
|
TOP = 25 °C |
— |
±0.5 |
— |
dB |
40 MHz—860 MHz |
|
|
— |
±0.5 |
— |
dB |
|
|
|
|
|
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|
RF Return Loss:1 |
RLRF |
IF = 60 mA, |
|
|
|
|
5 MHz—210 MHz |
|
|
— |
>16 |
— |
dB |
40 MHz—860 MHz |
|
|
— |
>16 |
— |
dB |
|
|
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|
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|
Optical Output Power |
PO |
IF = IOP |
6, 8, or |
— |
— |
mW |
|
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|
10 |
|
|
|
|
|
|
|
|
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|
Laser Relative Intensity |
RIN |
IF = ITH + 70 mA, |
— |
< –155 |
— |
dB/Hz |
Noise |
|
T = 25 °C |
|
|
|
|
|
|
|
|
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Composite Second Order 2, 3 |
CSO |
IF = IOP, OMI = 10% |
— |
— |
–50 |
dBc |
Composite Triple Beat 2, 4 |
CTB |
IF = IOP, OMI = 10% |
— |
— |
–60 |
dBc |
Available Wavelengths |
λ |
IP = IOP, T = TOP |
1527.94 |
— |
1563.1 |
nm |
|
|
|
|
|
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Wavelength Drift 5 |
λΔ |
IF = 60 mA, |
— |
— |
0.04 |
nm |
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T = TOP, |
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TC varied from min—>max |
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Adiabatic Chirp |
FM |
IF = 60 mA, |
40 |
— |
100 |
MHz/mA |
|
|
TOP = 25 °C, |
|
|
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|
measured at 500 MHz |
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Operating Case |
TC |
IF = IOP |
–40 |
— |
85 |
°C |
Temperature Range |
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1.Tested in a 50 Ω resistively matched system.
2.Eight channel loading with 10% OMI and 40 km fiber length.
3.Measured at 42 MHz.
4.Measured at 553.25 MHz, 577.25 MHz, and 595.25 MHz.
5.Change in wavelength as case temperature is changed.
2 |
Agere Systems Inc. |
Data Sheet, Rev. 4 |
A1751A DWDM Analog |
June 2001 |
Forward-Path or Return-Path Laser Modules |
|
|
Characteristics (continued)
Table 2. Additional Characteristics
Parameter |
Symbol |
Conditions |
Min |
Max |
Unit |
|
|
|
|
|
|
Bias Current1 |
IB |
BOL |
— |
120 |
mA |
Threshold Current |
ITH |
25 °C, BOL |
— |
30 |
mA |
|
|
|
|
|
|
Slope Efficiency2 |
η |
IP = ITH + 20 and |
0.10 |
— |
mW/mA |
|
|
ITH + 60 |
|
|
|
|
|
|
|
|
|
Monitor Photocurrent |
IMON |
IOP = 0 mA, VRM = 5 V, |
10 |
200 |
μA/mW |
|
|
TOP = 25 °C |
|
|
|
|
|
|
|
|
|
Operating Chip Temperature3 |
TOP |
IF = IOP |
18 |
35 |
°C |
TEC Current |
ITEC |
–40 °C < TC < 85 °C, |
–1.5 |
1.5 |
A |
|
|
TOP = 15 °C—35 °C, |
|
|
|
|
|
IF = 60 mA |
|
|
|
|
|
|
|
|
|
TEC Voltage |
VTEC |
TOP = 15 °C—35 °C over T C |
–2.5 |
3.8 |
V |
|
|
|
|
|
|
Thermistor Resistance |
RTH |
TOP = 25 °C |
— |
10.5 |
k Ω |
|
|
|
|
|
|
Optical Return Loss |
RL |
TC |
40 |
— |
dB |
|
|
|
|
|
|
Side Mode Suppression Ratio |
SMSR |
IF = IOP |
30 |
— |
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 |
|
NC |
14 |
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ISOLATOR |
|
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|
2 |
|
|
13 |
(+) |
|
3 |
|
|
12 |
(–) |
(–) |
4 |
|
|
11 |
(+) |
(+) |
5 |
|
NC |
10 |
|
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(+) |
6 |
|
CASE |
9 |
|
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GROUND |
|
|
(–) |
7 |
TEC |
CASE |
8 |
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GROUND |
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1-1233(F) |
Figure 1. A1751A Laser Schematic
Agere Systems Inc. |
3 |