Dual-wavelength InGaAs-GaAs ridge waveguide distributed Bragg reflector lasers with tunable mode separation

The design and operation of integrated dual-wavelength sources are reported. These InGaAs-GaAs ridge waveguide (RW) distributed Bragg reflector (DBR) lasers consist of a common gain section and two, separate DBR sections. Multiple current injection is not necessary for these lasers to operate in dual-wavelength, Dual-wavelength operation is easily achieved by simply biasing the gain section. A relatively low coupling coefficient kappa in the front grating reduces the added cavity loss for the back grating mode. Therefore, the back grating mode reaches threshold easily. Also, the addition of a spacing section lowers the current induced thermal interaction between the two uniform grating sections, significantly reducing the inadvertent wavelength drift. As a result, biasing the front DBR section results in tunable mode pair separations (Delta lambda) as small as 0.3 nm and as large as 6.9 nm.