Concept of the photonic-molecule spectrometer. (IMAGE)
Caption
a Artist’s view of the integrated spectrometer using a dispersion-engineered photonic molecule. b The structure consists of two identical tunable micro-ring resonators. The unknown input spectrum is scanned via thermo-optical tunning to generate an output signal. The goal is to restore the spectral information from the signal with a calibrated transmission matrix. c For a single resonator, the information at different free-spectral ranges (FSR) are indistinguishable. If a pair of resonators are strongly coupled, then each resonance will split into a symmetric mode and an anti-symmetric mode, which resembles a two-level molecule. Furthermore, the splitting strength is proportional to the coupling strength between resonators. Consequently, by tailoring the dispersion, the splitting strength will vary over multiple FSRs. d For two wavelengths spaced by a integral multiple of FSRs (λ₂ = λ₁ + m∙FSR), their power scanning traces can be identified from the distinct peak spacing induced by the dispersive mode splitting. In this way, all wavelength channels are decorrelated, making it possible to reconstruct the spectrum beyond the FSR limit.
Credit
by Hongnan Xu, Yue Qin, Gaolei Hu, and Hon Ki Tssang
Usage Restrictions
Credit must be given to the creator.
License
CC BY