Linewidth reduction in wavelength tunable laser diodes by voltage control

The spectral linewidth of wavelength tunable laser diodes usually broadens during tuning due to injection-recombination shot noise in the tuning regions. This broadening dominates the linewidth of large range continuously tunable laser diodes. An effective suppression of this broadening mechanism is obtained by control of the tuning region voltage instead of current. Impacts for the design of large range tunable narrow linewidth devices are discussed.