Keithley introduces flexible, configurable laser-diode test systems

Cleveland, OH—Keithley Instruments Inc. recently introduced its fully customizable System 25 test kits for light-current-voltage (LIV) characterization of laser diodes and assembled laser diode modules (LDMs).

By Control Engineering Staff May 29, 2003

Cleveland, OH— Keithley Instruments Inc. recently introduced its fully customizable System 25 test kits for light-current-voltage (LIV) characterization of laser diodes and assembled laser diode modules (LDMs).

System 25 uses Keithley’s LIV measuring instruments; combines them with accessories and cables; and supplies the package for less than individual components. System 25 provides up to 5A laser drive current, precision voltage measurements, two channels of photodetection, selectable photodiode detector types, optional laser diode mount, and up to two temperature controllers for laser cooling, all in an easy-to-assemble kit. Unlike “all-in-one” solutions, System 25 gives users the ability to choose only the features and performance they need. Moreover, System 25 kits reduce the time and cost of integrating measurement components into a production test system, while allowing unmatched speed and measurement precision.

The simple ordering process gives purchasers the flexibility to select only essential system components, so they can avoid the cost of unnecessary items. Likewise, System 25 can be modified as test needs change. It reduces testing costs for laser diode manufacturers, telecommunication system OEMs, and contract manufacturers, and lowers test system costs for integrators.

Laser diodes’ capabilities and applications have grown beyond those originally found in fiber-optic telecommunications systems, such as transmitter and pump lasers. Now, applications include optical storage devices (based on blue laser technology), defense electronic systems, industrial printing, and a wide array of other uses. As laser diode capabilities have expanded, so have testing needs.

All laser diodes, including edge emitters, vertical cavity surface emitting lasers (VCSELs), and tunable lasers, must undergo LIV testing. The test system sweeps a forward current through the laser diode, while measuring the voltage across the device and the amount of light (optical power) being emitted. Typically, collected data are displayed as a series of LIV characteristic curves. These curves can be used in laser diode R&D and by production test engineers to review device parameters that determine if a laser diode or LDM is suitable for higher level assembly. In production facilities, these tests may be performed anywhere from incoming inspection to finished LDMs mounted in higher-level assemblies.

A system can be specified in any of 144 combinations that use Keithley’s Series 2400 SourceMeter instruments; Model 2502 Fiber Alignment photodiode meters; Model 2510-AT autotuning thermoelectric cooler (TEC) controllers, Model 2500INT integrating spheres; and Model 85xx Laser Diode Mounts.

These combinations are selected based on the application: general-purpose laser diodes, transmitter/pump lasers, or high power pump lasers. For LDMs and laser diodes in cooled mounts, one or two TEC controllers can be specified for the System 25. Typically, one Model 2510-AT will be used to control an internal TEC device, while a second Model 2510-AT can be added to allow for precise control of ambient test temperature using a fixture mounted TEC. Model 2500INT 2-in. integrating sphere can be specified with either silicon, germanium, or cooled InGaAs photodetectors, depending on the wavelength response needed. For laser diodes packaged in the common 14-pin butterfly package or DIL package, a Keithley Model 85xx Laser Diode Mount can be used for easy connection of the device under test to the test equipment. Model 8544-TEC mount has a built-in TEC cooler for ambient temperature control.

Control Engineering Daily News Desk
Jim Montague, news desk