Reducing thermal crosstalk in ten-channel tunable slotted-laser arrays

Given the tight constraints on the wavelength stability of sources in optical networks, the thermal crosstalk between operating devices in a ten-channel thermally-tunable slotted laser array for DWDM applications has been investigated. It was found experimentally the current standard thermal solution with the laser array chip mounted on an AlN carrier does not allow for wavelength stability of ± 25 GHz ( ± 2 K) with a temperature rise of 5 K measured in a device with 100 mA (CW) applied to a neighbouring laser (device spacing = 360 µm). A combined experimental/numerical approach revealed solid state submounts comprising diamond or highly ordered pyrolytic graphite are inadequate to reduce crosstalk below an allowable level. Numerical simulations of advanced cooling technologies reveal a microfluidic enabled substrate would reduce thermal crosstalk between operational devices on the chip to acceptable levels. Critically our simulations show this reduced crosstalk is not at the expense of device tunability as the thermal resistance of individual lasers remains similar for the base and microfluidic cases.