Inverse-designed ultra-compact star-crossings based on PhC-like subwavelength structures for optical intercross connect.

ABSTRACT

With the development of highly densified photonic integrated circuits, the optical cross nodes number exhibits dramatically increasing. Not only efficient but also ultra-compact waveguide crossings are required to materialize the full potential of silicon photonics for on-chip optical intercross connect. In this work, we proposed several inverse-designed 4 × 4, 5 × 5 and 6 × 6 star-crossings based on the photonic-crystal-like (PhC-like) subwavelength structures, which have ultra-high port density of about 7.1 µm2/port, 5.83 µm2/port and 7.3 µm2/port respectively. Moreover, the star-crossings are practically fabricated and experimentally characterized. The average measured insertion losses (ILs) are less than 0.75, 0.9 dB and 1.5 dB, while the crosstalks are sub-22.5 dB, -20 dB and -18 dB for other output ports over 60 nm bandwidth centered at 1550 nm wavelength.