Wavelength-Multiplexed 2D Beam Steering via a Passive Diffractive Network

2026-06-15

AI Summary

This work addresses the limitation of conventional single-layer dispersive elements, which support only one-dimensional linear beam steering and cannot achieve arbitrary two-dimensional optical beam control. The authors propose a passive multilayer diffractive optical network that, for the first time, exploits wavelength as an intrinsic addressing parameter. By jointly optimizing cascaded phase-modulating diffractive layers via deep learning, the system establishes a nonlocal and nonlinear mapping between wavelength and two-dimensional output angles. Without requiring mechanical or electronic actuation, the approach enables independent control over 625 wavelength channels across the 400–750 nm spectrum, generating a high-fidelity 25×25 beam array with subwavelength positioning accuracy. Experimental validation is demonstrated in both the visible and terahertz regimes.

Abstract

We introduce a wavelength-addressable diffractive optical network that transforms illumination wavelength into a high-dimensional control parameter for arbitrarily programmable 2D beam steering. The proposed passive architecture comprises cascaded spatially optimized diffractive layers, jointly designed using deep learning, to rapidly map distinct wavelengths to predefined/desired output angles. Unlike conventional single-layer dispersive optical elements, which are physically restricted to 1D linear mapping, this framework harnesses complex wavefront transformations to utilize the illumination wavelength as an intrinsic addressing key for arbitrary 2D beam steering, eliminating the need for mechanical scanning or electronic phase control. We numerically demonstrate wavelength-controlled beam steering across 625 wavelength channels spanning 400-750 nm, realizing a 25 x 25 array of independently addressable beam positions with subwavelength positioning accuracy and high channel fidelity. Unlike conventional gratings, which constrain wavelength routing to a linear trajectory, the proposed diffractive network performs nonlocal wavefront transformations, enabling arbitrary wavelength-to-angle mappings across a 2D field of view. We further validate the proposed framework experimentally in both the terahertz and visible spectral regimes, demonstrating wavelength-multiplexed beam steering using 3D fabricated passive diffractive layers at terahertz frequencies and phase-only spatial light modulators in the visible spectrum. This wavelength-addressable diffractive architecture establishes a compact and scalable paradigm for high-speed programmable beam steering, with potential applications in optical communications, routing, imaging, sensing, and emerging photonic information-processing systems.

Problem

• beam steering
• wavelength multiplexing
• diffractive optics
• 2D beam control
• passive optical system

Innovation

• wavelength-multiplexed beam steering
• diffractive optical network
• deep learning design
• passive 2D beam steering
• nonlocal wavefront transformation