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News Release from: Keithley Instruments | Subject: Model 2520 pulsed laser diode test system
Edited by the Electronicstalk Editorial
Team on 18 May 2001
Single-box L-I-V test solution for
pulsed lasers
The Keithley Instruments Model 2520 pulsed laser diode test system is designed for electrical characterisation of laser diodes in either the chip/bar state or in finished modules.
The Keithley Instruments Model 2520 pulsed laser diode test system is designed for electrical characterisation of laser diodes in either the chip/bar state or in finished modules The Model 2520 is the only single-instrument system for testing laser diodes in pulse mode up to 5A peaks
This article was originally published on Electronicstalk on 21 Aug 2008 at 8.00am (UK)
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It allows pulsewidths as short as 500ns with rise and fall times less than 60ns, while protecting the laser diode with output short and voltage compliance functions.
In addition to its pulsed current output, this fully integrated instrument has three measurement channels with a remote digitising head connected by cables.
One channel measures voltage across the laser diode.
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Two voltage-biased current measurement channels are used for simultaneous measurement of the front and back photodiode detector outputs needed to characterise edge-emitting lasers.
Moreover, the single-box design of the Model 2520 makes set up and data collection much faster, and represents a significant savings in cost of ownership compared to traditional solutions.
Applications and Markets The Model 2520 was designed for production testing of laser diode chips and bars.
These components find use as optical sources in optical networks and in optical read/write heads of data storage systems.
However, its pulsed current and V-I compliance capabilities make it useful for testing a wide range of electronic devices that must be protected from destructive voltages or self-heating while under test.
Along with a user-supplied PC controller, the Model 2520 typically is used with an optical spectrum analyser and wavelength meter for spectral measurements (which may also require an active cooling system to control the laser diode temperature).
Because source and measurement algorithms are contained within the Model 2520, they do not have to be developed by a programmer, nor do they have to be sent over the external databus from the PC controller.
This feature speeds up measurements and increases test throughput.
Throughput is further enhanced by a source memory list in the Model 2520 that stores multiple test sequences internally, and by a memory buffer that stores data until the end of a test sequence.
These features eliminate much of the GPIB traffic during a test, and allow data to be downloaded on test completion.
The Model 2520 is supplied in a half-rack-size box with IEEE-488 and RS-232 interfaces.
It allows complete light intensity-current-voltage (L-I-V) testing without the need for separate current-to-voltage convertors, multichannel digital oscilloscope, "boxcar averagers" or customised software.
The Model 2520 has a 14bit A/D convertor for accurate determination of the laser diode's lasing threshold current, L-I efficiency and I-V linearity.
This allows the manufacturer to characterise the relationship between drive current and light output in the linear region above the lasing threshold.
Identification of any "kinks" (nonlinearities) in this region is a very important quality assurance test, as it indicates mode hopping within the optically resonant cavity of the laser diode.
Such anomalies disqualify laser diodes from use in wavelength division multiplexed (WDM) communication systems.
For users who develop laser diode test applications with LabWindows CVI and LabVIEW, instrument drivers for these packages can be downloaded from the Keithley website.
Application demonstration programs in LabVIEW, LabWindows CVI, and Visual Basic will be provided free of cost on request.
For those who want a complete turnkey system, Keithley works with a select group of system integrators who add optical test hardware and develop the test application program.
The Model 2520 will be available from stock on 1st June 2001. Request a free brochure from Keithley Instruments ...
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