Three direct-modulated DWDM families available to meet a number of OC-48/STM-16 applications: Extended reach (100 km) Very long reach (170 km) Metro DWDM Digital video

ITU wavelengths available from --1610.06 nm SONET/SDH compatible to OC-48/STM-16 Temperature tunable for precise wavelength selection Integrated optical isolator High-performance, multiquantum well (MQW) distributed-feedback (DFB) laser Industry-standard, 14-pin butterfly package Characterized at 2.488 Gbits/s (NRZ) InGaAs, PIN photodetector back-facet monitor Low threshold current High-reliability, hermetic packaging Excellent long-term wavelength stability can eliminate the need for external wavelength locker Qualified to meet the intent of Telcordia Technologies * 468

The Direct Modulated Isolated DFB Laser Module contains an internally cooled, InGaAs, MQW, distributed-feedback (DFB) laser designed for 1.5 �m applications. The following three direct-modulation DWDM product families have been established to meet various OC-48/STM-16 system applications:

D2526-type: designed to be used STM-16 (2.488 Gbits/s) for extended reach, dense WDM applications (1800 ps/nm). The wavelength of the laser can be temperature-tuned for precise wavelength selection by adjusting the temperature of the internal thermoelectric cooler. D2555-type: high-performance device designed for very low dispersion; used in fiber spans exceeding km (3000 ps/nm). D2570-type: high-power, direct-modulated laser eliminates the need for optical amplifiers in DWDM many applications.

The module contains an internal optical isolator that suppresses optical feedback in laser-based, fiber-optic systems. Light reflected back to the laser is attenuated a minimum of 30 dB.

Pin Name Thermistor Laser dc Bias (Cathode) Back-facet Monitor Anode Back-facet Monitor Cathode Thermoelectric Cooler Thermoelectric Cooler Case Ground Case Ground Case Ground Laser Anode RF Laser Input Cathode Laser Anode Case Ground

An integral thermoelectric cooler (TEC) provides stable thermal characteristics. The TEC allows for heating and cooling of the laser chip to maintain a temperature 25 �C for case temperatures from to +70 �C. The laser temperature is monitored by the internal thermistor, which can be used with external circuitry to control the laser chip temperature.

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.

* A positive current through the thermoelectric heat pump cools the laser. Both leads should be grounded for optimum performance.

The laser module is fabricated a 14-pin, hermetic, metal/ceramic butterfly package that incorporates a bias tee, which separates the dc-bias path from the RF input. The RF input has a nominal 25 impedance. The laser module is equipped with SMF-28 * type fiber. The fiber has 900 �m tight buffer jacket. Various connectors and pigtail lengths are available. Agere Systems' optoelectronic components are being qualified 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 office applications.

* ISO is a registered trademark of The International Organization for Standardization. is a trademark of Corning Inc.

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 performance characteristics of the data sheet. Exposure to absolute maximum ratings for extended periods can adversely affect device reliability. Parameter Laser Reverse Voltage dc Forward Current Operating Case Temperature Range Storage Case Temperature Range* Photodiode Reverse Voltage Photodiode Forward Current

To avoid the possibility of damage to the laser module from power supply switching transients, follow this turnon sequence: 1. All ground connections 2. Most negative supply 3. Most positive supply 4. All remaining connections Reverse the order for the proper turn-off sequence.

The minimum fiber bend radius in (31.25 mm). To avoid degradation in performance, mount the module on the board as follows: 1. Place the bottom flange of the module on a flat heat sink at least 0.5 in. x 1.180 in. x 30 mm) in size. The surface finish of the heat sink should be better than 32 �in. (0.8 �m), and the surface flatness must be better than 0.001 in. (25.4 �m). Using thermal conductive grease is optional; however, thermal performance can be improved 5% if conductive grease is applied between the bottom flange and the heat sink. 2. Mount four #2-56 screws with Fillister heads (M2-3 mm) at the four screw hole locations (see Outline Diagram). The Fillister head diameter must not exceed 0.140 in. (3.55 mm). Do not apply more than 1 in./lb. of torque to the screws.

CAUTION: This device is susceptible to damage as a result of electrostatic discharge. Take proper precautions during both handling and testing. Follow guidelines such as JEDEC Publication No. 108-A (Dec. 1988).

Agere Systems employs a human-body model (HBM) for ESD-susceptibility testing and protection-design evaluation. ESD voltage thresholds are dependent on the critical parameters used to define the model. A standard HBM (resistance = 1.5 k�, capacitance = 100 pF) is widely used and, therefore, can be used for comparison purposes. The HBM ESD threshold presented here was obtained using these circuit parameters: Parameter Human-body Model Agere Systems Inc. Value >400 Unit V