Frequency Drift Reduction in a Four-Laser Array for TWDM PON Applications

Burst-mode operation of laser arrays suitable for next-generation passive optical networks (PON2) employing time and wavelength division multiplexing (TWDM) is impaired by frequency drifts under variable burst duration. In this work, the issue of frequency drifts under burst and wavelength switching operation is addressed in a four-laser array integrated with a multimode interference coupler using a regrowth-free technology. Frequency drifts are shown to be significantly reduced in a TWDM-PON configuration thanks to the introduction of a thermal management technique based on the use of inactive lasers in the array. Thanks to this method, up to 22% drift reduction is obtained under burst and wavelength switching operation.