Faraday isolator based on crystalline silicon for 2-µm laser radiation

Area of Science:

• Photonics and Materials Science
• Optics and Magnetism

Background:

• Faraday isolators are critical components in high-power laser systems.
• Thermally induced depolarization limits the performance of conventional isolators.
• Single-crystal silicon's magneto-optical properties are underexplored for such applications.

Purpose of the Study:

• To investigate the magneto-optical properties of single-crystal silicon.
• To assess its potential for developing advanced Faraday isolators.
• To explore its suitability for high-power laser and gravitational wave detection applications.

Main Methods:

• Experimental investigation of magneto-optical properties versus wavelength and temperature.
• Implementation of a bulk free-space Faraday isolator using single-crystal silicon.
• Analysis of the piezo-optical anisotropy ratio for thermal depolarization compensation.

Main Results:

• Demonstrated a Faraday isolator operating at 1940 nm with a magnetic field of ~2.8 T.
• Utilized the negative piezo-optical anisotropy ratio for effective thermal depolarization compensation without a reciprocal rotator.
• Evaluated silicon's performance at room and cryogenic temperatures under high-power laser radiation.

Conclusions:

• Single-crystal silicon is a highly promising magneto-optical material for Faraday isolators.
• The material's properties allow for compensation of thermally induced depolarization.
• Potential applications include next-generation laser interferometers for gravitational wave detection.