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A flat retroreflector based on metasurface doublet is proposed and created via lithographical nanofabrication. A high-speed wireless optical communication system with wide-angle tolerance is demonstrated at a telecommunications wavelength of λ = 1550 nm.

We propose and demonstrate an optical phased-array-based bidirectional grating antenna (BDGA) in silicon nitride waveguides. The BDGA is integrated with a miniaturized all-dielectric metasurface doublet (MD) formed on a glass substrate. The BDGA device, which takes advantage of alternately feeding light to its ports in opposite directions, is presumed to effectively provide a doubled wavelength-tuned steering efficiency compared to its unidirectional counterpart. The MD, which is based on vertically cascaded convex and concave metalenses comprising circular hydrogenated amorphous silicon nanopillars, is meticulously placed atop the BDGA chip to accept and deflect a beam emanating from the emission area, thereby boosting the beam-steering performance. The manufactured BDGA could achieve an enhanced beam-steering efficiency of 0.148 deg/nm as well as a stable spectral emission response in the wavelength range of 1530–1600 nm. By deploying a fabricated MD atop the silicon photonic BDGA chip, the steering efficiency was confirmed to be boosted by a factor of ∼ 3.1 , reaching 0.461 deg/nm, as intended.

A highly sensitive electro-optic (EO) probe has been proposed and realized by tethering an ultra-high-quality (Q)-factor LiNbO3 etalon to a single-mode fiber operating at around a 1550-nm wavelength. For the adopted EO etalon, the electric-field-induced refractive index modification is deemed to shift its own spectral response. An electrical modulation signal is anticipated to be produced when a probe light beam with a fixed bias wavelength impinges upon the EO etalon. The EO etalon is particularly required to exhibit a remarkably steep spectral response and thus facilitate modulation efficiency. In aiming to scrutinize the performance in terms of sensitivity, two EO probes involving profoundly different Q-factors were prepared and applied to detect the electric field emitted from a microstrip device. It was confirmed that the sensitivity could be efficiently enhanced by as much as 28 dB by boosting the Q-factor 18 times when a probe light beam operating at =∼1550 nm was properly collimated and polarized. Accordingly, the minimum detectable signal was successfully diminished.