VCSELs are vertical cavity surface emitting laser diodes. They emit at 850 nm and have rather low thresholds (typically a few mA).They are very fast and can give mW of coupled power into a 50 micron core fibre. They are extremely radiation hard. VCSELs can be tested at the wafer level (as opposed to edge emitting lasers which have to be cut and cleaved before they can be tested) and hence are relatively cheap.
VCSELs in standard packages are available from different manufacturers. We have looked at VCSELs from Honeywell (4080 in ST package). The optical power coupled into a 50 micron core fibre was up to 4 mW for pulsed operation. Click here for a graph of optical power versus drive current.efor a sample of four Honeywell VCSELs. The discontinuities are a feature of the MQW type laser which is expected to have these jumps. Click here for a fine scan of one VCSEL.The The rise time was less than 1ns. The signal was measured with an optical probe and with an epitaxial Si PIN diode in a GEC package. Click here for a scope picture of the signal received by the PIN diode. A report on the waveforms of Honeywell, MITEL and Truelight VCSELs driven by the BiLED chip, LDC chip and a pulse generator is available here.
Tests of VCSELs operating in a high magnetic field have been carried out. No degredation in performance was observed. A report on these studies is available here.