Diffraction grating enhanced photoluminescence from etching-free erbium thin films

Area of Science:

• Integrated Optics
• Materials Science
• Nanofabrication

Background:

• Etching is standard for micro-structuring in integrated optics but adds cost and can degrade device performance.
• Existing etch-free methods for diffraction gratings include layer deposition on structured surfaces or grating deposition on active layers.
• High aspect ratio diffraction gratings are best made by etching, but this study explores an alternative.

Purpose of the Study:

• To develop an etch-free fabrication technique for fully structured diffraction gratings.
• To combine lift-off processing with pulsed laser deposition for micro-structuring.
• To demonstrate the efficacy of this method for enhancing luminescence in Er-doped materials.

Main Methods:

• Investigated lithography doses for lift-off processing to achieve micrometric resolution and control sidewall angles (50°–150°) in 0.5 µm layers.
• Fabricated Er-doped Y2O3 uniaxial diffraction gratings with periods from 3 to 8 µm.
• Utilized pulsed laser deposition combined with lift-off processing.

Main Results:

• Achieved micrometric spatial resolution and controlled sidewall angles in lift-off processing.
• Successfully fabricated Er-doped Y2O3 diffraction gratings.
• Observed luminescence enhancement of up to ×15 at 1.54 µm compared to unstructured layers, matching modeling predictions.

Conclusions:

• Lift-off processing combined with pulsed laser deposition is a viable etch-free technique for fabricating micro-structures.
• This method is promising for practical applications like luminescence enhancement in Er-doped layers.
• The developed technique offers an alternative to etching for creating high-performance diffraction gratings.