Optomechanical detection of light with orbital angular momentum

Area of Science:

• Optomechanics
• Photonics
• Quantum Optics

Background:

• Orbital angular momentum (OAM) of light is a key property for advanced optical applications.
• Sensitive detection of OAM is crucial for applications like optical communication and sensing.
• Existing methods for OAM detection face limitations in sensitivity and photon number resolution.

Purpose of the Study:

• To design and demonstrate an optomechanical device for sensitive transduction of light's OAM.
• To enable the measurement of OAM by detecting optically induced mechanical motion.
• To explore the potential for detecting low-photon-number optical pulses carrying OAM.

Main Methods:

• Utilized a photonic crystal cavity optomechanical system to detect optically induced mechanical twist.
• Integrated a sub-wavelength grating for scattering photons into new OAM states.
• Proposed detection mechanisms based on photon absorption or scattering by the mechanical element.

Main Results:

• Demonstrated a scheme capable of detecting optical pulses with l=1 OAM.
• Achieved detection of pulses with an average photon number of 3.9 × 10^3 at a 5 MHz repetition rate.
• The system's sensitivity is limited by detector noise, not the optomechanical transduction itself.

Conclusions:

• The designed optomechanical device offers sensitive OAM transduction.
• The scheme is extendable to higher-order OAM states.
• This work provides a novel approach for OAM sensing and measurement with potential for low-light applications.