Flying couplers above spinning resonators generate irreversible refraction

Area of Science:

• Photonics
• Optomechanics
• Nanotechnology

Background:

• Optical isolators are crucial for many applications, enabling non-reciprocal light propagation.
• Previous methods for optical isolation faced challenges with high rotation rates and nanometre precision.
• Inspiration was drawn from the aerodynamic levitation of magnetic read heads in hard-disk drives.

Purpose of the Study:

• To engineer a novel optical isolator with high performance.
• To overcome the limitations of existing optical isolation techniques.
• To demonstrate irreversible transmission of light using spinning optical components.

Main Methods:

• Fabrication of photonic couplers (tapered fibres) that fly above spherical resonators.
• Utilizing aerodynamic principles for nanometre-scale separation between couplers and resonators.
• Achieving high-speed rotation of resonators to split counter-circulating optical modes.

Main Results:

• Demonstrated a device providing 99.6% isolation of light in standard telecommunication fibres.
• Achieved irreversible transmission, making the coupler transparent from one side and opaque from the other.
• The convex geometry of the fibre and sphere facilitates close proximity, enabling nanometre-scale separations.

Conclusions:

• The developed optical isolator offers a significant advancement in non-reciprocal light propagation.
• This technology has potential applications in fibre-based quantum interconnects.
• The novel approach may enable future surface-science studies at nanometre-scale separations.