Detector aids pulsed power measurement solution

A novel integrating sphere photodetector can be combined with Keithley's pulsed laser diode test system to provide the industry's only complete pulsed source and measurement solution for LIV testing.

New from Keithley Instruments, the Model 2520INT integrating sphere photodetector combines with the company's Model 2520 pulsed laser diode test system to provide the industry's only complete pulsed source and measurement solution for LIV testing.

Their capabilities can produce high accuracy measurements of laser diode optical power at the wafer, bar, or chip level, prior to their integration into complete, temperature-controlled laser diode modules.

The Model 2520INT uses a 1in sphere with a germanium detector to give a wide operating range of telecomms wavelengths, maximise ease of setup and integration, and achieve superior low-level power measurement.

The Model 2520INT offers production test engineers the flexibility to test devices earlier in the production process, so noncompliant devices can be detected before they are packaged, reducing the manufacturer's investment in defective products.

The 2520INT also shortens testing time by offering an SMA fibre tap to allow measured light to be sent to another instrument simultaneously for additional optical measurements.

The 2520INT's design simplifies integration into both production and lab environments.

The Model 2520INT/2520 combination can be used for LIV (light-current-voltage) production testing of 980 and 1480nm EDFA pump lasers, Raman amplifiers, telecommunication laser diodes, and high power telecommunication vertical cavity surface emitting lasers (VCSELs).

Typically, a laser diode is coupled to a fibre-optic pigtail during the final stages of manufacturing.

At that point in the process, the module includes temperature measurement and control components, as well as the laser diode.

However, manufacturers frequently need to test laser diodes before these components are packaged in order to screen out defective devices before costly, value-added processes are performed.

The Model 2520INT integrating sphere and Model 2520 pulsed laser diode test system together allow diodes to be tested at the wafer, bar or chip level, without the risk of thermal damage that could occur when testing without the use of cooling components, and without requiring difficult and time-consuming beam alignment.

By their design, integrating spheres naturally attenuate a laser diode's output power, so that the power level at any point on the sphere surface is far less than the power of a beam that falls directly on the detector.

The Model 2520INT's highly reflective Spectralon interior surface scatters, reflects, and diffuses the light output from the DUT uniformly over the interior surface of the sphere, with minimal absorption loss.

This diffusion automatically attenuates the level of power visible to the built-in detector, and permits testing much higher power devices without damaging the detector.

Keithley developed the Model 2520INT to address the challenges specific to pulse testing laser diodes, which include short pulse periods and fast rise times.

Many optical power detectors are hampered by long rise times, so they can only measure a portion of the laser diode's light output.

The 2520INT provides the high-speed response needed to handle pulsewidths as short as 500ns, and operating wavelength ranges of 700-1700nm.

It can measure outputs of up to 7W, depending on wavelength.

Calibration constants are provided in printed form and on diskette for easy programming of test systems.

The Model 2520INT-1-GE integrating sphere is available now.

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