We demonstrate the first ultrahigh-precision on-chip wavelength meter operating in the 850 nm band with an arrayed-waveguide grating (AWG) fabricated on a silicon nitride (SiN) platform. The present AWG is developed with Euler-bend-assisted broadened arrayed waveguides and achieves low adjacent channel crosstalk below −28 dB for the case with a channel spacing of 0.5 nm. Benefiting from the low thermo-optic coefficient of SiN, the AWG has a reduced wavelength-dependence as low as 11.1 pm/°C in experiments. The developed AWG wavelength meter achieves subpicometer accuracy (i.e., <0.5 pm) in the 10 nm spectral range centered at 842 nm, representing the first demonstration of an on-chip wavelength meter in the 850 nm band. Leveraging the quasi-periodic nature of the AWG’s spectral response, the present on-chip wavelength meter can be extended to work for different wavelength bands.
Shen et al. (Mon,) studied this question.