Multiwavelength laterally complex coupled distributed feedback laser arrays with monolithically integrated combiner fabricated by focused-ion-beam lithography

A multiwavelength laser array with four complex coupled distributed feedback lasers was fabricated by focused-ion-beam lithography. The laser array was monolithically integrated with a combiner network to allow simultaneous operation and coupling of four wavelengths into one single-mode fiber. To reduce the fabrication complexity, focused-ion-beam technology was used to define complex coupled gratings lateral to pumped ridge waveguide sections without any further overgrowth step. A four wavelength output with 6-nm-wavelength spacing and side-mode suppression ratios of more than 35 dB were obtained with output powers up to 6 mW per channel.