Design and Analysis of 2-μm InGaSb/GaSb Quantum Well Lasers Integrated Onto Silicon-on-Insulator (SOI) Waveguide Circuits Through an Al2O3 Bonding Layer

Abstract

GaSb-based quantum well (QW) laser diode, with emission wavelength ∼2 μm, integrated onto a silicon-on-insulator (SOI) waveguide circuit through a high-thermal-conductivity Al2O3 bonding layer has been designed and analyzed. Prior to bonding, the fabricated Fabry–Perot GaSb QW laser worked under continuous wave operation at room temperature, with a low threshold current of 37 mA at the emission wavelength of 2019 nm, demonstrating high material quality. A tapered structure has been used for evanescent coupling of light from the GaSb laser to the underlying Si waveguide. Instead of using SiO2 for direct bonding or Benzocyclobutene for adhesive bonding, the use of Al2O3 to directly bond GaSb lasers onto SOI wafers is proposed. The optical mode distribution simulations by a beam propagation method software show that light can be coupled efficiently to the underlying Si waveguide through the tapered structure without compromise in optical coupling efficiency. Furthermore, there is a significant reduction (∼70%) in the total thermal resistance compared with the same structure using a SiO2 bonding layer. Our results suggest that the Al2O 3 bonding layer could be a promising candidate for III–V lasers integrated on SOI circuits, where thermal dissipation is very critical.