Photon-Sphere Modes in Curved Optical Microcavities: A Black-Hole Analogue Laser

Area of Science:

• Analogue Gravity
• Black Hole Physics
• Microcavity Photonics

Background:

• Gravitational-wave detectors routinely detect black hole merger ringdowns, interpreted as quasinormal modes.
• The physical nature of these black hole quasinormal modes remains poorly understood.
• Analogue gravity experiments use laboratory systems to mimic black hole phenomena.

Purpose of the Study:

• To emulate four-dimensional black hole metrics in a laboratory setting using optical systems.
• To analytically and experimentally investigate quasinormal modes in an optical cavity.
• To explore the physics of the black hole photon sphere using a complementary photonic platform.

Main Methods:

• Emulation of (3+1)D black hole metrics using an effective (2+1)D optical metric on a curved surface.
• Analytical computation of quasinormal modes within the optical cavity.
• Fabrication of 3D-printed, non-Euclidean, dye-doped microcavities for experimental demonstration.

Main Results:

• Identified a new family of photon-sphere modes confined around the optical analogue of the photon sphere.
• Observed lasing in both conventional whispering-gallery modes and the novel photon-sphere modes.
• Experimental results for photon-sphere modes showed excellent agreement with analytical predictions.

Conclusions:

• The optical microcavity system effectively emulates black hole physics, particularly photon sphere dynamics.
• Demonstrated lasing in photon-sphere modes provides a tabletop platform for studying black hole phenomena.
• This work offers new insights into microcavity photonics and analogue gravity research.