SensorPhysics LaserTest beam profiler is already used for near field measurements of VCSEL laser diodes at the wafer level. This allows only known good devices to be identified for subsequent packaging. Recently the LaserWave-I was incorporated into the same wafer level inspection system to allow for rapid spectral measurement of VCSELs at the wafer level.

The wafer is positioned under a microscope and a probe delivers drive current to the device under test. As the drive current is increased the emitted light is collected via a 50um core optical fiber attached to the microscope so a series of spectra can taken. This allows devices to be quickly screened for emission wavelength and FWHM.

If a device falls outside the desired operating range it can be marked for discard or other applications use. Compared to other wavelength methods the LaserWave is easily incorporated into test systems via Lab View and allows spectra to be acquired at 30 millisecond intervals - nearly 30 times faster than typical GPIB based measurement systems. The LaserTest spatial beam profiler can be added to the same microscope to monitor the emission spatial profile simultaneously with the wavelength.