Investigation of dual-wavelength operation with tunable mode separation in multi-section DBR lasers

The dual-wavelength operation with tunable mode separations for InGaAs-GaAs ridge waveguide DBR lasers are studied. The DBR lasers consist of a common gain section and two separate DBR section. The two DBRs utilize uniform gratings with the same Bragg period, resulting in a single nominal lasing wavelength. Dual-wavelength operation is achieved by simultaneously lasing the front grating mode and the back grating mode. By employing a spacing section between the two DBR gratings and applying a tuning current on it, the interaction between two mode is minimized and the control over the wavelength turning is greatly improved. Three device dimensions were investigated. The relationships between two-mode operation parameters and biasing/tuning conditions for each type are analyzed. The promising applications of this multi-wavelength optical source, such as in optical generation of millimeter-wave, are discussed.