Irradiation-induced switch power drift in optically bistable nonlinear interference filters at 514 and 830 nm

Area of Science:

• Optoelectronics
• Materials Science
• Nonlinear Optics

Background:

• Optically bistable devices offer potential for all-optical switching applications.
• ZnSe nonlinear interference filters are key components in such devices.
• Understanding operational stability, particularly light-induced effects, is crucial for practical implementation.

Purpose of the Study:

• To investigate light-induced changes in the switch power of optically bistable ZnSe nonlinear interference filters.
• To identify the underlying mechanisms responsible for power drift.
• To explore methods for mitigating these undesirable changes.

Main Methods:

• Experimental study of ZnSe nonlinear interference filters at 514 nm and 830 nm wavelengths.
• Analysis of filter performance under high internal operating irradiances.
• Correlation of power drift with filter parameters like spacer thickness, spot size, and deposition technique.

Main Results:

• Light-induced power drift is primarily caused by irreversible changes in peak wavelength and transmission.
• These changes are linked to photostructural modifications in the central spacer layer material.
• Drift is dependent on spacer thickness, incident spot size, and filter deposition method.
• Using wavelengths further from the band edge (e.g., 830 nm) significantly reduces the rate of power drift.

Conclusions:

• Photostructural modifications in ZnSe spacer layers are the main cause of light-induced power drift in optically bistable filters.
• Filter design parameters and operating wavelength significantly influence stability.
• Operating ZnSe filters at wavelengths well removed from the band edge is an effective strategy to enhance operational stability.