Metasurface doublet-integrated bidirectional grating antenna enabling enhanced wavelength-tuned beam steering

Abstract

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.

Recent Advances in Tunable Metasurfaces: Materials, Design, and Applications

“…Dynamic control of the beam wavefront is one of the grand challenges faced by traditional optical systems for various applications, such as adaptive optics, LiDAR, display, communication, etc . ,− Tunable metasurfaces have been viewed as a promising solution to achieve full control over the characteristics of the light.…”

All-Solid-State Beam Steering via Integrated Optical Phased Array Technology

“…SiN also suffers from less nonlinear losses with respect to Si [61], which allows waveguide Another method is to enlarge the FOV of PIC-OPA assisted by metasurfaces (named meta-assisted PIC-OPA). As shown in Figure 6b, the metasurface performs like an ultra-thin lens, which can enlarge the beam steering angle θ by M times [47][48][49]. Lee et al proposed and demonstrated a bidirectional grating antenna PIC-OPA integrated with a miniaturized all-dielectric metasurface doublet formed on a glass substrate atop the antenna array.…”

“…The steering efficiency was confirmed to be boosted by a factor of ~3.1. The steering angle was up to 30 • with the wavelength from 1530 to 1595 nm [49]. However, for normal meta-OPA, the phase modulation is often generally accompanied by intensity modulation [42,44], which affects the side mode suppression ratio.…”

Dispersive silicon–nitride optical phased array incorporating arrayed waveguide delay lines for passive line beam scanning

“…OPAs exploit power splitters, phase shifters, and emitters to emit and steer the beam. The emitter configuration governs the nature of the beam emission, such as end-fire emission 6 , 7 or out-of-plane emission 8 , 9 . Current OPA developments are towards out-of-plane emission for the two-dimensional (2D) raster scanning of a point beam covering the field-of-view (FOV) of concern by tuning the laser wavelength and phase distribution across emitter channels 1 , 3 , 8 , 9 .…”

“…The emitter configuration governs the nature of the beam emission, such as end-fire emission 6 , 7 or out-of-plane emission 8 , 9 . Current OPA developments are towards out-of-plane emission for the two-dimensional (2D) raster scanning of a point beam covering the field-of-view (FOV) of concern by tuning the laser wavelength and phase distribution across emitter channels 1 , 3 , 8 , 9 . Typically, OPAs incorporate diffractive-grating-based emitters to enable longitudinal beam scanning by tuning the wavelength of the input light.…”