Access to 20 evenly distributed wavelengths over 100 nm using only a single current tuning in a four-electrode monolithic semiconductor laser

We report improved tuning regularity in a vertical grating assisted codirectional coupler laser with a super-structure grating distributed Bragg reflector (GCSR). Access to 20 wavelengths with SMSR better than 20 dB within a tuning range of 100 nn was obtained with a single current control in a GCSR laser. The total tuning behavior shows a potential of complete wavelength coverage over 100 nm by use of three tuning currents.>