Direct writing of multiple-wavelength chip in InGaAs-InGaAsP structure using pulsed laser irradiation

In this paper, we report a simple laser direct writing method using pulsed photoabsorption-induced disordering (PPAID) to create high spatial bandgap selectivity and high processed material quality multiple-wavelength chip in InGaAs-InGaAsP heterostructures. Using this intermixing technology, we have achieved a spatial bandgap selectively of better than 2.5μm from a two-section InGaAs-InGaAsP chip with differential wavelength shift of over 120 nm. A theoretical model has been developed to estimate the limit spatial resolution of the PPAID process. Theoretical analysis has also been performed to investigate the relationship between the irradiation conditions and the bandgap shift. Devices such as bandgap tuned lasers, integrated extended cavity lasers, and multiple-wavelength laser chip have also been fabricated and characterized to verify the integration capability of this postgrowth bandgap engineering technique. The quality of the devices fabricated from the intermixed materials was found to be high, indicating that PPAID is a promising process for the fabrication of photonic integrated circuits.