Laser Arrays With 25-GHz Channel Spacing Fabricated by Combining SAG and REC Techniques

Multiwavelength laser arrays with 25-GHz channel spacing have been fabricated by upper separate confinement heterostructure (SCH) layer selective area growth (SAG) technique. The reconstruction equivalent chirp (REC) technique is used to introduce an equivalent phase shift into the grating structure, so that a high single longitude mode yield of lasers can be ensured. Because different emission wavelengths are realized through thickness modulation of the upper SCH layer by SAG, the sampling period in the REC technique is the same for all the lasers in an array, which may alleviate the effects of the facet phase on the emission wavelength. The fabricated laser arrays have less than 0.051 nm standard deviation of wavelength deviations. Only conventional photolithography process is needed, helping to lower the fabrication cost of the laser arrays.