Automated PXI-based screening and characterisation of tunable lasers

Abstract

Fast, rugged measurement of optical outputs from complex semiconductor devices like tunable lasers is pre-requisite for the growth of that sector of the optoelectronics industry. The need to deliver smart transmitters with accompanying control data at low cost is highly dependent on reliable, high-speed test and measurement (T+M). We report principle of operation and performance for a suite of T+M modules that deliver look-up-table (LUT) data that is individual to each device-under-test. This LUT accompanies the laser for its 20-year life-cycle and even incorporates adaptive control to cater for potential ageing. Examples that relate to DBR (10 nm tunability or quarter C-band) and full C-band lasers will be given where the test platform relies on the PXI (PCI derivative) bus with a "de-skilling" graphical user interface. The general concept has also been deployed for HB-LED screening. Optical outputs are power and wavelength while inputs are multiple analogue drive currents that control each laser section; there may be up to eleven electrodes on these laser diode chips. The chip-on-carrier (C-on-C) is first screened by a fast probe station to ascertain full tunability with high power. The butterfly-packaged device is fully characterised later through another application producing the individual digital LUT. Fast wavelength mapping for a multitude of control possibilities is essential at 100 kHz sweeps and slow GPIB must be substituted by PXI bus, which is extended PCI for instrumentation. Custom optics allows photodiodes to work in the wavelength domain. The complete platform, deployable R/D to production, and illustrative results will be described.