Wavelength-Selected, High-Power D2587P-Type (with Wavelength Data Sheet, Rev. 2
Locker)/D2547P-Type Isolat ed DFB Laser Modules July 2001
22 Ager e Systems Inc.
Description (continued)
Principl es of Opera ti on (C ont rolled Wave-
length)
The single-channel, wavelength-selected DFB (ILM) pack-
age contains internal wavelength-discriminating optics, i.e.,
two etalons and associated photodiodes. The output con-
sists of analog signals suitable for controlling the electrical
current of the th ermoelectric cooler (TEC) and the DFB
laser.
Controlled Feedback
The module contains an internal optical isolator that sup-
presses opt ical feedback in laser-based, fiber -opt ic sys-
tems. Light reflected back to the laser is attenuated a
minimum of 30 dB.
Controlled Temperature
An integral TEC provides stable thermal character istics.
The TEC allows f or heating and cooling of the laser chip to
maintain a temperatu re of 25 °C for ca se temperatures fro m
–25 °C to +70 °C. The laser temperatur e is monitored by
the internal thermistor, which can be used with external cir-
cuitry to control the laser chip temperature .
Controlled Power
An internal, InGaAs, PIN photodiode functi ons as t he back-
facet monitor. The photodiode monitors emission from the
rear facet of the laser and, wh en used in conjun ction with
control circuitry, can control optic al power launched int o the
fiber. Normally, this configur ation is used in a f eedback
arrangement to maintain consistent laser output power.
Standar d Package
The laser module is fabricated in a 14-pin, hermetic, metal/
ceramic butterfly package that incor porates a bias tee that
separa tes t he 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 the Agere Systems I nc. lithium
niobate modulators. It has a mode field diameter of
10.5 µm, a cladding diamet er of 125 µm ±3 µm, and a
loose tube jacketed fiber 900 µm in diameter. Figure 1
show s the orientation of polarization in the fiber.
Agere Systems’ optoelectronic components are being qual-
ified to rigorous internal standards that are consistent with
Telcordia Technologies
† TR-NWT-000468. All design and
manufacturing operations are
ISO
§ 9001 certified. The
module is being fully qualified for central offic e applications.
*
Fujikura
is a registered trademark of Fujikura Ltd.
†
Telcor dia Technologies
is a trademark of Telcordia Technologies
Inc.
§
ISO
is a registered trademark of The International Organization f or
Standardization.
Figure 1. Polarization-Maintaining Fiber
Pin Information
1.A positive current through the thermoelectric heat pump cools the
laser.
2.Both leads should be grounded for optimum performance.
Table 1. Pin Descriptions
Pin D2587P-Type D2547P-Type
1 Thermistor Thermistor
2 Thermistor Thermistor
3 Laser dc Bias
(Cathode) (–) Laser dc Bias
(Cathode) (–)
4 Back-facet Monitor
Anode (–) Back-facet Monitor
Anode (–)
5 Back-facet Monitor
Cathode (+) Back-facet Monitor
Cathode (+)
6TEC (+)
1TEC (+)1
7TEC (–)
1TEC (–)1
8 Case Ground Case Ground
9λ Photodiode 2 Anode Case Ground
10 λ Photodiode 1 Anode Case Ground
11 Laser Anode (+) 2Laser Anode (+) 2
12 RF Laser Input
Cathode (–) RF Laser Input
Cathode (–)
13 Laser Anode (+) 2Laser Anode (+) 2
14 NC Case Ground
CORE
STRESS ROD
PRINCIPLE POLARIZATION
AXIS
CLADDING
INNER COATING
OUT E R COATING
(SILICON & ACRYLATE)
1-771(C).a