Scalable high-precision trimming of photonic resonances by polymer exposure to energetic beams

Photonic integrated circuits (PIC) have seen an explosion in interest, through to commercialisation in the past decade. 

Most PICs rely on sharp resonances to modulate and steer, however, the special characteristics of high-quality resonances are highly sensitive to small variations in fabrication and material constants, which limits their applicability.  Active tuning mechanisms are commonly employed to account for such deviations, consuming energy and occupying valuable chip real estate.

Readily employable, accurate and highly scalable mechanisms to tailor the modal properties of PICs are urgently required.

In 'Scalable high-precision trimming of photonic resonances by polymer exposure to energetic beams' published by Nano Letters, Professor Harish Bhaskaran's research group together with Professor Pernice of Heidelberg University present an elegant and powerful solution which is achievable during the semiconductor fabrication process using existing lithography tools by exploiting the volume shrinkage exhibited by certain polymers to permanently modulate the waveguide's effective index.  This technique enables broadband and lossless tuning with immediate applicability in wide-ranging applications in optical computing, telecommunications and free-space optics.