Bulk second-harmonic generation from thermally evaporated indium selenide thin films

Area of Science:

• Materials Science
• Optics
• Condensed Matter Physics

Background:

• Nonlinear optical (NLO) materials are crucial for photonics.
• Amorphous indium selenide (In-Se) thin films are promising NLO candidates.
• Understanding their second-order NLO properties is essential for device applications.

Purpose of the Study:

• To investigate the bulk second-order nonlinear optical properties of amorphous In-Se thin films.
• To characterize the second-harmonic generation (SHG) performance and its dependence on film thickness.
• To determine the nonlinear susceptibility tensor of the In-Se films.

Main Methods:

• Fabrication of amorphous In-Se thin films via thermal evaporation.
• Characterization of SHG using the Maker-fringe method.
• Analysis of interference between film and substrate SHG signals to determine nonlinear susceptibility.

Main Results:

• The amorphous In-Se thin films exhibit strong and photostable second-harmonic generation (SHG).
• A significant thickness dependence of the SHG signal was observed.
• The joint non-diagonal component of the nonlinear susceptibility tensor was determined to be 4 pm/V.

Conclusions:

• Amorphous In-Se thin films possess substantial second-order NLO properties.
• The nonlinear optical response is tunable with film thickness.
• These films are comparable to established NLO materials, indicating their potential for photonic devices.