Phase error measurement of an arrayed-waveguide grating in the 1.3-μm wavelength region by optical low coherence interferometry

This letter reports a method for generating transistor-transistor logic clock pulses at equal intervals of one quarter of the reference laser wavelength as the optical path difference between two arms of a Mach-Zehnder interferometer increases. With this technique, the phase error of an arrayed-waveguide grating operating in the 1.3-μm band can be measured precisely with optical low coherence interferometry using a tunable laser at 1.5 μm as the reference light source.