Optomechanical THz detection with a sub-wavelength resonator

TL;DR

This paper introduces a novel integrated THz resonator with a mechanical component that enables room-temperature, high-frequency, and efficient terahertz detection through optomechanical coupling, revealing a Coulomb interaction-based detection mechanism.

Contribution

The work presents the first integrated meta-atom THz resonator with a mechanical oscillator for optomechanical detection at room temperature, operating at high modulation frequencies.

Findings

Achieved room-temperature THz detection with high modulation frequency (>10MHz).

Unveiled an instantaneous detection mechanism based on nano-scale Coulomb interactions.

Demonstrated a compact, uncooled bolometric detector with microsecond heat diffusion times.

Abstract

The terahertz (THz) spectral domain offers a myriad of applications spanning chemical spectroscopy, medicine, security and imaging[1]. It has also recently become a playground for fundamental studies of light-matter interactions [2-6]. THz science and technology could benefit from optomechanical approaches, which harness the interaction of light with miniature mechanical resonators [7,8]. So far, optomechanics has mostly focused on the optical and microwave domains, leading to new types of quantum experiments [9-11] and to the development of optical-microwave converters [12-14]. Here we demonstrate an integrated meta-atom [15] THz resonator with a flexible part acting as a mechanical oscillator. In this device free space THz photons are collected by the resonator and induce high frequency currents and charges that, in turn, couple to the mechanical degrees of freedom. The resulting mechanical motion is read-out optically, allowing our device to function as a compact and efficient terahertz detector at room temperature. Furthermore the device operates at high modulation frequencies (>10MHz), well beyond the cut-off frequencies of Golay cells, pyroelectric detectors and cryogenic semiconductor bolometers [16,17]. Notably, our experiments unambiguously reveal an instantaneous THz detection mechanism arising from a nano-scale Coulomb interaction, with a Noise Equivalent Power that is potentially frequency independent. Alongside this effect, our compact geometry allows for an uncooled bolometric detection [18] with extremely short heat diffusion times (few microseconds) and high detectivity.