Despite the initial skepticism of OEM companies regarding reliability, MEMS-based devices are increasingly common
in optical networking. This presentation will discuss the use and reliability of MEMS in a variety of network
applications, from tunable lasers and filters to variable optical attenuators and dynamic channel equalizers. The failure
mechanisms of these devices will be addressed in terms of reliability physics, packaging methodologies, and process
controls. Typical OEM requirements will also be presented, including testing beyond of the scope of Telcordia
qualification standards. The key conclusion is that, with sufficiently robust design and manufacturing controls, MEMS-based
devices can meet or exceed the demanding reliability requirements for telecommunications components.
We describe the performance and reliability of multi-bar diode stacks assembled with hard solder attachment of the laser
diode bar to the conduction-cooled package substrate. The primary stack package design is based on a modular platform
that makes use of common piece parts to incorporate anywhere from 2-7 bars, operating at peak powers of 80W/bar to
200W/bar. In assembling monolithic type diode stack packages, it is typical to use a soft solder material such as indium
for P-side bar attachment into the package. Due to its low melting point and low yield stress, indium can provide a solder
joint that transfers low stress to the laser bar. However, during CW and QCW operation, indium is prone to migration
that can cause device failure due to a number of well-known mechanisms. This shortcoming of soft-solder bar
attachment can limit the number of shots the stack delivers over its operating life. By replacing the soft solder typically
used for P-side attachment with a hard solder, it is possible to greatly reduce or eliminate certain failure modes, thereby
increasing the operating life of the part. We demonstrate lifetime of > 1E9 shots at 80 W/bar, 250 us/40 Hz pulses, and
50C package operating temperature.
We present the reliability of high-power laser diodes utilizing hard solder (AuSn) on a conduction-cooled package
(HCCP). We present results of 50 W hard-pulse operation at 8xx nm and demonstrate a reliability of MTTF > 27 khrs
(90% CL), which is an order of magnitude improvement over traditional packaging. We also present results at 9xx nm
with a reliability of MTTF >17 khrs (90% CL) at 75 W. We discuss finite element analysis (FEA) modeling and time
dependent temperature measurements combined with experimental life-test data to quantify true hard-pulse operation.
We also discuss FEA and measured stress profiles across laser bars comparing soft and hard solder packaging.