Telecom vendors have learned to manufacture laser diodes to the point where their reliability is well understood and predictable. Dr Toby Strite reports.

The telecom boom of the 1990s produced incredible advances in semiconductor laser diode technologies. These advances have enabled the laser diode to evolve into a family of highly robust, reliable devices, with individual conversion efficiencies of better than 50per cent, continuous output powers of several kilowatts, modulation rates of 20GHz, and wavelengths from 400nm to beyond 2µm.
During this time, less attention was directed towards applying these advances to lasers used in industrial applications. Recently, however, the telecom downturn has motivated leading telecom diode manufacturers to leverage their best practices to industrial laser diode applications. This influx of technology has produced some quantum leaps in performance.
The low failure rates of these advanced diode technologies make it uneconomical and unnecessary to perform reliability testing under normal operating conditions. Instead, multi-cell testing is used by JDS Uniphase to develop a statistically relevant device reliability model.
To estimate failure rates at normal operating conditions, a multi-cell test is performed under highly accelerated conditions. The failure rate is accelerated by high temperature, current and/or power. Multi-cell tests are designed to probe different temperature and current/power ranges to deduce the sensitivity of device reliability of each parameter. Analysis of the observed failure rates under these high stress conditions produces a model from which the very low failure rates of these devices at normal operating conditions can be accurately extrapolated.
Given the extremely low failure rates of these devices at normal operating conditions, multi-cell testing under highly accelerated conditions is the most economically viable method to obtain statistically relevant estimates of device reliability.
When multi-cell testing is applied to industrial lasers, it is possible to estimate the mean-time-before-failure at an arbitrary operating power and temperature. Doing so, JDS Uniphase is able to rate its products at significantly higher output powers than was possible in the recent past while remaining confident of our ability to meet or exceed customer reliability expectations.
JDS Uniphase has applied these test principles and procedures into their industrial laser diode products, which are designed and built alongside similar telecom products. The transfer of best practices enables JDSU to supply industrial laser diodes with increased reliability, making them ideal for applications in materials processing, medical, military, imaging, printing and graphics arts.
Features of the 5400 Series 200mW, CW, Single-Mode GaAlAs Laser Diodes include:
* Printing/graphics - thermal film exposure.
* Metrology/inspection - particle detection wafer inspection, contour mapping.
* Ranging/illumination/targeting.
* Point-to-point (free space) communication,
And the 2300Series4 W, and 2400Series3W, CW, High-Brightness GaAlAs Laser Diodes:
* Thermal platesetting.
* Disk initialisation.
* Medical.
* Direct diode material processing.
The 6300Series4W, 910 and 980nm,InGaAs Laser Diodes:
* Optical pumps for Er+ and Yb+ doped solid state lasers and amplifiers.
* Thermal printing.
* Medical.
* Materials processing - soldering, heat treatment.
And finally the L2 High-Brightness, Broad-Area (High Power),Fibre Coupled Laser Diodes, 50 and 60µm Fibre:
* Graphics/printing - thermal CtP, flexography
* Pyrotechnic initiation
* Material state transformation - melting of solders and plastics.
* Er+ and Yb+ pumping applications.
* Industrial fibre lasers.

ENQUIRY No 44

Dr Toby Strite is with JDS Uniphase Active Components Business Unit, Hagendorn, Switzerland. www.jdsu.com