Nanoscale light–matter interactions in atomic cladding waveguides

Abstract

Alkali vapours, such as rubidium, are being used extensively in several important fields of research such as slow and stored light nonlinear optics quantum computation, atomic clocks and magnetometers. Recently, there is a growing effort towards miniaturizing traditional centimetre-size vapour cells. Owing to the significant reduction in device dimensions, light–matter interactions are greatly enhanced, enabling new functionalities due to the low power threshold needed for nonlinear interactions. Here, taking advantage of the mature platform of silicon photonics, we construct an efficient and flexible platform for tailored light–vapour interactions on a chip. Specifically, we demonstrate light–matter interactions in an atomic cladding waveguide, consisting of a silicon nitride nano-waveguide core with a rubidium vapour cladding. We observe the efficient interaction of the electromagnetic guided mode with the rubidium cladding and show that due to the high confinement of the optical mode, the rubidium absorption saturates at powers in the nanowatt regime.

Fano resonances and all-optical switching in a resonantly coupled plasmonic–atomic system

“…This procedure is perturbative in its nature, as it neglects the effect of the Rb atoms on wave vectors of the SPP mode. Yet, it can be easily justified because of the low density of the atoms, and it was already shown to provide excellent match to experimental results 30,[34][35][36][37] . Based on this procedure, we find the evanescent decay length and the effective index of the SPP mode at the wavelength of 780 nm to be B500 nm and 1.03, respectively.…”

“…A detailed description of the procedure is given in ref. 30. To calculate the effective susceptibility, we need to find the wave vectors describing the SPP mode.…”

“…Using this approach, we have demonstrated light-matter interactions on a chip, with nanoscale dimensions and low light level linear and nonlinear interactions 30 . These efforts towards miniaturization and integration of light-vapour systems may be further motivated by using integrated plasmonic structures with the benefit of extreme light confinement.…”

Coupling Thermal Atomic Vapor to Slot Waveguides

“…Currently, various strategies exist to interface atoms with confined light fields, for example, atoms in hollow waveguides (ARROWs) [1,2], hollow core fibers [3,4], and tapered nanofibers [5][6][7]. A further scheme has recently been demonstrated by combining chip-based solid core waveguides [8][9][10], MachZehnder interferometers [8], and ring resonators [11,12] with thermal atomic vapor. The performance of such devices depends on the efficiency of the atom-light coupling, which is conventionally improved by employing cavities to increase the interaction time.…”

3-D near-field imaging of guided modes in nanophotonic waveguides

“…The success of the nanofiber platform for fundamental studies has led to proposals to use integrated waveguides, which offer scalability, structural integrity, and control of complex waveguide geometries [10][11][12]. An added benefit provided by the structural integrity is that not only are spatial intensity fluctuations substantially reduced but also, the exact intensity profiles of guided modes can be directly imaged.…”