Wavelength-Selected, High-Power D2587P-Type (with Wavelength

Data Sheet, Rev. 2

Locker)/D2547P-Type Isolated DFB Laser Modules

July 2001

2

2

Agere Systems Inc.

Principles of Operation (Controlled 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 thermoelectric cooler (TEC) and the DFB

laser.

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.

Controlled Temperature

An integral 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

–25 °C to +70 °C. The laser temperature 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 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.

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

maintaining fiber (PMF). The fiber is PANDA type and is the

same fiber that is used on the Agere Systems Inc. lithium

niobate modulators. It has a mode field diameter of

10.5

µm, a cladding diameter of 125 µm ±3 µm, and a

loose tube jacketed fiber 900

µm in diameter. Figure 1

shows the orientation of polarization in the fiber.

Agere Systems’ optoelectronic components are being qual-

ified to rigorous internal standards that are consistent with

manufacturing operations are

module is being fully qualified for central office applications.

*

†

Inc.

§

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 (+)

8

Case Ground

Case Ground

9

λ Photodiode 2 Anode

Case Ground

10

λ Photodiode 1 Anode

Case Ground

11

12

RF Laser Input

Cathode (–)

RF Laser Input

Cathode (–)

13

14

NC

Case Ground

CORE

STRESS ROD

PRINCIPLE POLARIZATION

AXIS

CLADDING

INNER COATING

OUTER COATING

(SILICON & ACRYLATE)

1-771(C).a