Distributed feedback laser arrays fabricated by synchrotron orbital radiation lithography

Abstract
Twenty-wavelength integrated distributed feedback (DFB) laser arrays fabricated using synchrotron orbital radiation (SOR) lithography are demonstrated. All 20 DFB lasers on chip operated in a single-longitudinal mode, and their wavelengths are varied in accordance with grating periodicity. Typical optical output characteristics (light output versus current curve and lasing spectrum) are shown. Threshold is as low as 13 mA, and the output power is more than 20 mW. The maximum differential quantum efficiency reached 0.2 W/A. The side-mode suppression ratio is more than 35 dB. The characteristic temperature was found to be 50 K, and the temperature dependence of the lasing wavelength is 0.9 Å/°C