Separating arbitrary free-space beams with an integrated photonic processor

Abstract

Free-space optics naturally offers multiple-channel communications and sensing exploitable in many applications. The different optical beams will, however, generally be overlapping at the receiver, and, especially with atmospheric turbulence or other scattering or aberrations, the arriving beam shapes may not even be known in advance. We show that such beams can be still separated in the optical domain, and simultaneously detected with negligible cross-talk, even if they share the same wavelength and polarization, and even with unknown arriving beam shapes. The kernel of the adaptive multibeam receiver presented in this work is a programmable integrated photonic processor that is coupled to free-space beams through a two-dimensional array of optical antennas. We demonstrate separation of beam pairs arriving from different directions, with overlapping spatial modes in the same direction, and even with mixing between the beams deliberately added in the path. With the circuit’s optical bandwidth of more than 40 nm, this approach offers an enabling technology for the evolution of FSO from single-beam to multibeam space-division multiplexed systems in a perturbed environment, which has been a game-changing transition in fiber-optic systems.

Electro- and Thermo-Optics Response of X-Cut Thin Film LiNbO3 Waveguides

“…[5]. Besides allowing individual device trimming, this feature is the key enabler of core functionalities in PICs for neuromorphic computing [6], free-space transceiver [7], microwave photonics [8], datacenter interconnects [9], as well as quantum state tomography in discrete and continuous variable regimes [10].…”

Finding best orthogonal channels through arbitrary optical systems using integrated photonic processors

“…Here, instead, we use a pair of MZI architectures -one at the input and one at the output -to "analyze" an unknown medium and find the elements of its SVD factorization [14]; at the same time, this process physically sets up the orthogonal channels or communications modes, which are the best coupled and lowest cross-talk channels through the medium or optical system, no matter what that medium or optical system is. Specifically, we use programmable meshes of integrated MZIs coupled to arrays of surface gratings, capable of generating [27,28], detecting [28,29] and spatially resolving [30] complex optical beams with arbitrary shapes. The computation of the mesh settings for these waves is performed physically without any need for calibration of the mesh elements and without any knowledge of the media, based only on overall power minimization or maximization algorithms.…”

Time‐Multiplexed Control of Programmable Silicon Photonic Circuits Enabled by Monolithic CMOS Electronics

“…A real-time active control layer, currently implemented by electronic feedback loops through external circuitry connected to on-chip light sensors and actuators, is thus needed to ensure reliable optical operations. [2][3][4][5][6][7][8][9][10] Although effective, the scaling of this approach is limited by the number of required electrical input/output (I/O) connections, [11,12] that approaches a prohibitive level in large-scale architectures. Flip-chip electronic-photonic interconnection via copper-pillar technology [13] enables larger I/O port counts with respect to wire bonding, yet implying extra assembly and packaging costs.…”