We report up to 1.165-Tb/s optical wireless WDM transmission using a wavelengthtransparent beam tracking and steering system. Over a 3.5-m perpendicular distance, beyond 1-Tb/s capacity was achieved across a lateral coverage up to 1.8 m. © 2020 The Author(s) Introduction Optical wireless communications (OWC) has attracted significant interest in recent years, largely owing to its benefits relating to the use of an unregulated bandwidth, immunity to electromagnetic interference and the potential

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... for achieving vast transmission rates [1] [2] [3] [4] [5] . In broad terms, OWC can be divided into two categories: visible light communication (VLC) and infrared OWC. By directly modulating visible light-emitting diodes (LEDs), VLC offers simultaneous illumination and data transmission. Although by their nature, LEDs can offer a broad coverage, their transmission capability is relatively limited [2] . Increasing data rate usually requires lasers rather than LEDs, as these can be modulated at higher frequencies, and results in narrow field-of view optical links. The restricted field of view is required to minimize link loss, as at high data rates receiver sensitivity reduces, and modulated source power is also more limited [3] . Therefore, beam tracking and steering is a critical issue in such systems [1] . The various solutions to address this issue have included the use of optical phased arrays [4] or an arrayed waveguide grating router (AWGR) [1]. While employing an AWGR avoids the requirement for beam tracking and allows a high overall throughput to the optical wireless channel, it does not easily lend itself to wavelength-division multiplexing (WDM) operation and the delivery of ultrahigh capacity transmission to a single receiver, since different wavelengths are steered to different locations [1]. Using a system that employs a camera-based tracking and steering, high-speed WDM transmission using the 4ary pulse amplitude modulation was recently demonstrated in [5] . In this paper, we extend the transmission capacity of this system while remaining within the eye-safety power limits, and report the delivery of up to 1.165-Tb/s adaptively-loaded discrete multitone (DMT) modulation WDM signals to a single optical wireless receiver over a distance of 3.5 m. Thanks to the wavelength-transparent property of the mirror-based steering system, similar transmission performance was achieved for all ten WDM channels. Furthermore, we confirmed that beyond 1-Tb/s transmission at a bit-error rate (BER) lower than 3.8×10 -3 was achieved across a lateral distance of up to 1.8 m.