Enhanced light matter interactions in plasmonic- molecular gas hybrid system

Following the excellent merits of plasmonics, such as enhanced light-matter interactions, and large sensitivity, myriad of fascinating phenomena have been demonstrated. A commonly used plasmonic configuration is the surface plasmon resonance (SPR), where resonance is obtained for a specific combination of angle and wavelength of the incident light. In spite of its merits, SPR performance is somewhat limited due to its relatively broad resonance line and the lack of referencing to a known source of absolute resonance. Hereby, we mitigate these deficiencies by exploring the coupling between plasmonic and molecular resonance in a hybrid device consisting of SPR and Acetylene. The coupled system inherits the angular sensitivity, enhanced light-matter interactions and miniaturization from the SPR while the acetylene provides the narrow and accurate resonance in the telecom band. These qualities make our hybrid system very sensitive to angular change. The great sensitivity of SPR to refractive index variations originated from the highly dispersive nature of acetylene allows for the generation of feedback signal for laser stabilization in a miniaturized volume. Taking advantage of these properties, we have stabilized a telecom laser to our hybrid system linewidth with precision better than 300 KHz at 100 s. Furthermore, we have used the high sensitivity and accuracy to demonstrate an angular sensor showing angular resolution in micro radians regime. Being able to demonstrate a hybrid plasmonic-molecular coupled system in the telecom regime may pave the way for variety of other fascinating and important directions, e.g. chip scale advanced spectroscopy, metrology and novel chip scale light sources.