Characterisation of diode laser for optical interconnects

There is currently a great deal of interest in monolithic integration of diode lasers and laser drive circuitry to give directly modulated transmitters for optical interconnect. However, in practice, it is likely that the high speed links for optical interconnect will be initially realised using off-the-shelf GaAs components, and optical interconnects (light pipes or waveguides) which are then hybrid integrated to form optical interconnected circuits. The author shows how the possible performance of hybrid integrated optical interconnects can be determined by characterising the optical source in terms of modulation bandwidth, modulated emitted optical power, harmonic distortion and intensity noise and then relating the performance figures obtained to characteristics of waveguides and receivers. It is shown how the above parameters, including the parasitics of the electrical interconnect between the laser and laser drive circuit, directly determine the link performance. Calculations are given to show the degree of fan out which can be obtained for different bit rates in this and other similar implementations of optical interconnects