Butterfly-packaged multi-channel interference widely tunable semiconductor laser with improved performance

A multi-channel interference (MCI) widely tunable semiconductor laser is described in detail with improved performance in this paper. The MCI laser without the common phase section was packaged into a standard 14-pin butterfly package. The device realized a tuning range of more than 40 nm with side mode suppression ratios (SMSRs) higher than 48 dB and about 7 dBm fiber power. By making the gain section and the phase sections to be surface ridge waveguides, threshold currents of the laser have become less than 18 mA across the tuning range. Besides, tuning characteristics of the MCI laser were experimentally studied in detail for the first time. The MCI laser can be treated as a combination of eight Fabry-Pérot (FP) cavity lasers which share the same gain section. It is found that when the eight arm phase sections are completely in phase at the lasing wavelength, the operating currents are at maxima of the output power curves. The relationship between the lasing wavelength and the injection currents of the eight arm phase sections has been introduced and analyzed.