A novel fabrication technique for multiple-wavelength photonic-integrated devices in InGaAs-InGaAsP laser heterostructures

We report the fabrication of multiple wavelength chips in InGaAs-InGaAsP laser structure using a novel ion implantation induced quantum-well (QW) intermixing technique. This technique first consists of using a gray mask photolithography and reactive ion etching process to create a SiO₂ implant mask with variable thickness on the sample. This is followed by a single 360-keV phosphorus ion implantation at a dose of 1 × 10¹⁴ cm^-2 at 200°C, which creates different amounts of point defects in the sample depending on the local thickness of the SiO₂ mask. A subsequent thermal annealing step induces QW intermixing through the diffusion of the point defects across the structure. With this technique, we have successfully fabricated 10-channel multiple wavelength laser diodes, with lasing wavelength spreading over 85 nm (between 1.47 and 1.55 μm), monolithically integrated on a single chip. Only a limited increase of threshold current density of 17% (i.e., from 1.2 to 1.4 kA/cm²), has been observed between the least intermixed and the most intermixed lasers.