Adjustable RF photonic fractional Hilbert transformer based on Kerr
microcombs
- David Moss
Abstract
We demonstrate an RF photonic fractional Hilbert transformer based on an
integrated Kerr micro-comb source featuring a record low free spectral
range of 49 GHz. By programming and shaping the comb lines according to
calculated tap weights for up to 39 wavelengths across the C-band, we
achieve tunable bandwidths ranging from 1.2 to 15.3 GHz as well as
variable center frequencies from baseband to 9.5 GHz, for both standard
integral and arbitrary fractional orders. We experimentally characterize
the RF amplitude and phase response of the tunable bandpass and lowpass
Hilbert transformers with 90 and 45-degree phase shifts. The
experimental results show good agreement with theory, confirming the
effectiveness of our approach as a powerful way to implement standard
and fractional order Hilbert transformers with broad and variable
bandwidths and center frequencies, with high reconfigurability and
greatly reduced size and complexity.