Phonon-assisted second harmonic generation in As(1)(-)(x)Bi(x)Te(3)-CaBr(2)-PbBr(2) glasses

Area of Science:

• Materials Science
• Optics
• Condensed Matter Physics

Background:

• Nonlinear optical phenomena like second harmonic generation (SHG) are crucial for optical technologies.
• Understanding electron-phonon interactions is key to tailoring material properties.
• Glasses offer tunable properties for investigating fundamental physical processes.

Purpose of the Study:

• To experimentally investigate infrared-induced second harmonic generation (SHG) in As(1-x)Bi(x)Te3-CaBr2-PbBr2 glasses.
• To explore the relationship between SHG and electron-phonon interactions.
• To determine the influence of varying As/Bi ratios on SHG and anharmonic phonon modes.

Main Methods:

• Experimental measurement of IR-induced SHG in synthesized glasses.
• Utilizing a fifth-order nonlinear optical susceptibility formalism.
• Varying the As/Bi composition to control electron-phonon anharmonicity.

Main Results:

• Observed SHG in the mid-IR region (0.92-10.5 µm), dependent on electronic band gap and quasi-phonon energies.
• SHG signal correlated with IR-induced anharmonic phonon modes (1.5-4.8 µm).
• Maximum SHG achieved at specific pump-probe delays (12.5-20 ps) and saturated at ~1.73 GW/cm² pump power.

Conclusions:

• IR-induced SHG in these glasses is directly linked to anharmonic electron-phonon interactions.
• The degree of electron-phonon anharmonicity significantly influences the SHG output.
• Compositional tuning of glasses provides a method to control and optimize SHG properties.