Experimental demonstration of eight-wavelength distributed feedback semiconductor laser array using equivalent phase shift

An eight-wavelength distributed feedback semiconductor laser array with λ/4 equivalent phase shift based on reconstruction-equivalent-chirp technique was demonstrated. It shows very good linearity in lasing wavelengths with its deviation from -0.22 to 0.20 nm. The threshold currents are between 19 and 24 mA. The side-mode suppression ratios are all larger than 40 dB under the bias currents of 70 mA. The slope efficiencies at room temperature are all about 0.4 W/A. The grating was fabricated only by common holographic exposure and an additional micrometer-level conventional photolithography, which results in a low cost.