Synthetic-lattice enabled all-optical devices based on orbital angular momentum of light

Abstract

All-optical photonic devices are crucial for many important photonic technologies and applications, ranging from optical communication to quantum information processing. Conventional design of all-optical devices is based on photon propagation and interference in real space, which may rely on large numbers of optical elements, and the requirement of precise control makes this approach challenging. Here we propose an unconventional route for engineering all-optical devices using the photon’s internal degrees of freedom, which form photonic crystals in such synthetic dimensions for photon propagation and interference. We demonstrate this design concept by showing how important optical devices such as quantum memory and optical filters can be realized using synthetic orbital angular momentum (OAM) lattices in degenerate cavities. The design route utilizing synthetic photonic lattices may significantly reduce the requirement for numerous optical elements and their fine tuning in conventional design, paving the way for realistic all-optical photonic devices with novel functionalities.

Synthetic dimension in photonics

“…Inside such degenerate cavity, one can then introduce an auxiliary cavity, which incorporates spatial light modulators, in order to couple a small portion of the amplitude of a beam with an orbital angular moment l to a beam with an orbital angular moment l − 1 and l + 1. The system then is described by a tight-binding model [10,[60][61][62][63]]…”

Topological states at exceptional points

“…To address this issue and before discussing further the effect of lattice size and also couplings on the OAM beams here we propose an approach to build a very large lattice in the synthetic dimension. Creating lattices in the synthetic dimension with bidirectional coupling has been studied before where one uses a modulation defined via a pure real function to create an artificial dimension, such as frequency for instance, and make a synthetic lattice [27,28]. In contrast to what has been proposed so far here we are interested in a large lattice with artificial sites that its artificial sites are coupled in a unidirectional manner as needed for the observation of the continues family of solutions at the EP [29].…”

Topological photonic orbital-angular-momentum switch

“…Typically the FSR of the main cavity is Ω F ∼ 2π × 1GHz, and the tunneling strength, given by J s = Ω F |rs| 2 2π(1+|ts| 2 ) with r s (t s ) the reflectivity (transmissivity) of the corresponding beam splitters [13][14][15]30], can be up to tens of MHz (e.g., J 0 ∼ 2π × 20MHz and J 0 J 1 ∼ 2π × 4MHz). The pump period T ∼ 20/J 1 leads to a switching time of the order of µs.…”