Dual-wavelength fiber Fabry-Perot cavities with engineered birefringence

Area of Science:

• Optics and Photonics
• Materials Science
• Laser Physics

Background:

• Fiber Fabry-Perot (FFP) cavities are crucial optical resonators.
• Controlling polarization mode splitting is essential for advanced optical systems.
• Existing methods for FFP cavity fabrication have limitations in precision and versatility.

Purpose of the Study:

• To present a novel method for engineering the frequency splitting of polarization eigenmodes in FFP cavities.
• To demonstrate precise control over the elliptical shape and radius of curvature of micromirrors.
• To realize dual-wavelength FFP cavities with high optical finesse.

Main Methods:

• Utilizing multiple CO2 laser pulses to machine paraboloidal micromirrors with controlled elliptical shapes.
• Fabricating FFP cavities with a wide range of radii of curvature.
• Characterizing cavity performance, including finesse and polarization mode splitting.

Main Results:

• Successfully engineered micromirrors with controlled elliptical shapes using CO2 laser machining.
• Produced FFP cavities with either maximized or near-zero polarization mode splitting.
• Achieved dual-wavelength FFP cavities with finesse exceeding 40,000 at 780 nm and 1559 nm.
• Demonstrated that birefringent frequency splitting is governed by mirror geometry.

Conclusions:

• The CO2 laser micromachining method offers versatile control over FFP cavity polarization properties.
• The geometrical shape of mirrors is the primary determinant of birefringent frequency splitting.
• Astigmatism must be considered for specific FFP cavity designs.
• This technique enables the creation of advanced optical resonators for diverse applications.