Fig. 4. Calibration and testing of the reconfigurable spectrometer.

a Measured spectral responses for the 256 reconfigured sampling channels. The inset shows the transmission spectra of several examples of the sampling channels. b, c The calculated spectral self-correlation function (Δλ) and the averaged cross-correlation between 256 channels, respectively. d Reconstructed spectra for a series of narrowband spectral lines across a 115 nm bandwidth. The black dashed lines mark their center wavelengths. e Reconstructed spectra for dual spectral lines at different wavelengths: dual peaks at 1505.84 nm and 1611.08 nm (left), dual peaks at 1541.16 nm and 1562.34 nm (middle), and dual peaks with a spectral spacing of 30 pm, respectively. f Reconstructed spectra for continuous, broadband signals: the ASE from an SOA (left) and an EDFA (right) filtered by a bandpass filter, respectively