All-reflective Michelson, Sagnac, and Fabry-Perot interferometers based on grating beam splitters

Area of Science:

• Optics
• Gravitational-wave astronomy
• Laser interferometry

Background:

• Gravitational-wave detectors rely on high-power lasers and precise interferometry.
• Transmissive optics in high-power laser systems can cause thermal aberrations, affecting wavefront quality.
• All-reflective optical designs are explored to mitigate these thermal effects.

Purpose of the Study:

• To experimentally demonstrate all-reflective Michelson, Sagnac, and Fabry-Perot interferometers.
• To utilize grating beam splitters as a key component in these all-reflective configurations.
• To assess the potential of these designs for future gravitational-wave detectors.

Main Methods:

• Utilized a 1200-groove/mm grating as a near-50/50 beam splitter for Michelson and Sagnac interferometers.
• Reintroduced diffracted beams back to the grating to form all-reflective Sagnac and Michelson interferometers.
• Employed a 1700-groove/mm grating in a Littrow configuration as a cavity coupler for a Fabry-Perot interferometer.

Main Results:

• Successfully demonstrated all-reflective Michelson, Sagnac, and Fabry-Perot interferometers at 1064 nm.
• Achieved 48.2% efficiency for each diffracted order (0 and -1) using the 1200-groove/mm grating.
• Obtained 91% blazing efficiency with the 1700-groove/mm grating in the Littrow configuration.

Conclusions:

• All-reflective interferometers based on grating beam splitters are feasible for gravitational-wave detection.
• These designs avoid volume thermal effects inherent in transmissive optics.
• The demonstrated configurations provide a promising pathway for improved wavefront quality in high-power laser interferometry.