Characterization of Thermo-Optically Tuned Multi-Channel Interference Widely Tunable Semiconductor Laser for Quasi-Continuous Tuning

Characterization of the thermo-optically tuned multi -channel interference widely tunable semiconductor laser for quasi-continuous tuning is demonstrated for the first time. The characterization strategy is carried out by simultaneously controlling seven arm phase sections to shift the reflection peak and adjusting the common phase section to fine-tune the longitudinal mode. Output wavelengths at 50 GHz frequency spacing are characterized, and a quasi-continuous tuning range beyond 60 nm is achieved at two temperatures. In the entire tuning range: side-mode suppression ratios are higher than 40 dB; wavelength deviations are less than ±10 pm from international telecommunication union grid; total thermal tuning powers are lower than 35 mW, and Lorentzian linewidths are less than 100 kHz. The tuning information near any output wavelength is obtained and the characterization speed is greatly improved. This strategy provides a new route for characterizing tunable lasers with multiple tuning currents.