  We present a dual-comb spectrometer based on two passively mode-locked
waveguide lasers integrated in a single Er-doped ZBLAN chip. This original
design yields two free-running frequency combs having a high level of mutual
stability. We developed in parallel a self-correction algorithm that
compensates residual relative fluctuations and yields mode-resolved spectra
without the help of any reference laser or control system. Fluctuations are
extracted directly from the interferograms using the concept of ambiguity
function, which leads to a significant simplification of the instrument that
will greatly ease its widespread adoption. Comparison with a correction
algorithm relying on a single-frequency laser indicates discrepancies of only
50 attoseconds on optical timings. The capacities of this instrument are
finally demonstrated with the acquisition of a high-resolution molecular
spectrum covering 20 nm. This new chip-based multi-laser platform is ideal for
the development of high-repetition-rate, compact and fieldable comb
spectrometers in the near- and mid-infrared.
