Phase control by coating in 1.56 µm distributed feedback lasers

The dependence of performances on facet phase in distributed feedback lasers was studied by changing SiN film thickness on the cleaved facet. The phase relative to the corrugation could be determined with the measurement of oscillating wavelength shift in a device with and without antireflection coating on the facets. Using the facet phase measured, we could adjust the film thickness so as to reduce the threshold current and to stabilize single longitudinal mode operation which oscillated at the Bragg wavelength.