Action from tunable periodic structures. II. Experimental observation of electric field-induced diffraction peaks

Area of Science:

• Materials Science
• Optics
• Solid State Physics

Background:

• The linear electro-optic effect in crystalline materials is a well-established phenomenon.
• Previous theoretical work predicted the possibility of electric field-induced diffraction in specific configurations.

Purpose of the Study:

• To experimentally observe and characterize electric field-induced diffraction peaks.
• To interpret the observed diffraction patterns based on the electro-optic effect.
• To quantify the refractive index change induced by an electric field.

Main Methods:

• Experiments were conducted using a lithium niobate (LiNbO3) crystal with interdigital planar electrodes.
• Diffraction patterns were analyzed in both transmission and reflection geometries under applied electric fields.
• The magnitudes of diffraction peaks were compared between transmission and reflection modes.

Main Results:

• Electric field-induced diffraction peaks were successfully observed, confirming previous predictions.
• Reflection experiments showed diffraction peak magnitudes approximately ten times larger than transmission experiments.
• The observed phenomena were attributed to field-induced refractive index changes creating period-doubled gratings.

Conclusions:

• The linear electro-optic effect in LiNbO3 can induce significant changes in refractive index, leading to observable diffraction.
• The experimental results validate the theoretical model involving superposition of diffracted light from phase-shifted, period-doubled gratings.
• An estimated refractive index change of 0.004 was determined from the relative intensities of the diffraction peaks.