Optically pumped rare-earth-doped Al₂O₃ distributed-feedback lasers on silicon [Invited]

Area of Science:

• Materials Science
• Photonics
• Laser Technology

Background:

• Optically pumped rare-earth-doped channel waveguide lasers are crucial for integrated photonics.
• Silicon photonics platforms offer advantages for miniaturization and complex integration.
• Distributed-feedback (DFB) resonators enhance laser performance and stability.

Purpose of the Study:

• To review recent advancements in rare-earth-doped channel waveguide lasers on silicon.
• To focus on DFB resonator configurations for improved laser operation.
• To investigate the potential of amorphous aluminum oxide thin films as a host material.

Main Methods:

• Deposition of rare-earth-doped amorphous aluminum oxide thin films onto silicon wafers via RF reactive co-sputtering.
• Spectroscopic analysis and optical gain measurements of Er³⁺, Yb³⁺, Nd³⁺, and Tm³⁺ ions.
• Demonstration of near-infrared laser transitions in various waveguide geometries.

Main Results:

• Successful demonstration of laser transitions near 1 μm (Yb³⁺), 1.5 μm (Er³⁺), and 2 μm (Tm³⁺, Ho³⁺).
• Achieved output powers ranging from microwatts to hundreds of milliwatts.
• Demonstrated ultranarrow-linewidth laser operation, indicating high spectral purity.

Conclusions:

• Amorphous aluminum oxide thin films are a viable host for rare-earth-doped waveguide lasers on silicon.
• DFB resonators integrated with these waveguides enable efficient and stable laser operation.
• The demonstrated performance highlights the potential for these lasers in various photonic applications.