Active on-chip dispersion control using a tunable silicon Bragg grating

Klitis, Charlambos and Sorel, Marc and Strain, Michael J. (2019) Active on-chip dispersion control using a tunable silicon Bragg grating. Micromachines, 10 (9). 569. ISSN 2072-666X (

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Actively controllable dispersion in on-chip photonic devices is challenging to implement compared with free space optical components where mechanical degrees of freedom can be employed. Here we present a method by which continuously tunable group delay control is achieved by modulating the refractive index profile of a silicon Bragg grating using thermo-optic effects. A simple thermal heater element is used to create tunable thermal gradients along the grating length, inducing chirped group delay profiles. Both effective blue and red chirp are realised using a single on-chip device over nanometre scale bandwidths. Group delay slopes are continuously tunable over a few ps/nm range from red to blue chirp, compatible with on-chip dispersion compensation for telecommunications picosecond pulse systems.