Thermal crosstalk of laser arrays and the influence on yield

We present experimental and theoretical investigations of the thermal crosstalk of laser arrays integrated with thin film heaters. Comparing the effects of intentional geometrical variations of the device design, we found that the relative thermal crosstalk depends critically on the distance between the active area and the film heater. The most striking result is that a minimisation of the thermal resistivity of the device does not always lead to a reduced thermal crosstalk. We demonstrate that an additional heat barrier close to the active region and/or an improved heat transfer between the submount and the heat sink may reduce the relative thermal crosstalk, a result completely unexpected from intuitive considerations. Model calculations showed that the device yield can be increased by 20% improving the heat transfer between the submount and the heatsink