Electro-Optic Test (Laser Bar Test)
Edge-emitting semiconductor light sources (lasers, LED’s, SLEDS, etc) can be comprehensively tested at the bar level or sampled at the die level. Electrical contact to each individual chip can be established via the epi-side & the bottom (grind) side, light is collected & analysed from both facets simultaneously.
Electro-optical testing of large numbers of chips can most conveniently be accomplished at this stage. Probing of each individual device on the laser bar eliminates the need for mounting or packaging the chips to evaluate their properties. LIV curves, i.e. data documenting the interdependency of emitted light, applied current & compliance voltage, are a powerful tool to verify a chip’s performance before any additional processing steps have to be carried out. Spectral measurements can complement this information & lead to full characterisation of the laser bar both before & after optical coating of its facets.
Helia Photonics offers electro-optical device characterisation carried out on a custom-designed, fully automated laser bar tester. The system visually identifies the next chip to be tested, positions it with micrometre accuracy & then applies a probe in order to carry out a suite of tests tailored to the product in question. Helia are able to offer post test analysis on batches of devices to yield data such as individual laser threshold, slope efficiency, kink voltage & side-mode suppression ratio along with wafer level statistics.
Testing volumes from a few laser bars for evaluation purposes up to complete wafers are possible. Test data can be made available instantaneously via real-time FTP & guide decisions on further production steps.