Wide beam steering by slow-light waveguide gratings and a prism lens

Abstract

A lattice-shifted photonic crystal waveguide (LSPCW) maintains slow light as a guided mode and works as an optical antenna when a kind of double periodicity is introduced. Selecting one LSPCW from its array and converting the fan beam to a spot beam using a collimator lens allows non-mechanical, two-dimensional beam steering. We employed a shallow-etched grating into the LSPCW as the double periodicity to increase the upward emission efficiency and designed a bespoke prism lens to convert the steering angle in a desired direction while maintaining the collimation condition for the steered beam. As a result, a sharp spot beam with an average beam divergence of 0.15° was steered in the range of 40 ∘ × 4.4 ∘ without precise adjustment of the lens position. The number of resolution points obtained was 4256. This method did not require complicated and power-consuming optical phase control like that in optical phased arrays, so it is expected to be applied in complete solid-state light detection and ranging.

Thermo-Optic Beam Scanner Employing Silicon Photonic Crystal Slow-Light Waveguides

“…1(e) shows a thermal image of LSPCWs, taken by microscopic thermography (ViewOhre IMAGING, MCR32), when P of 1.3 W was injected into LSPCW in a test element group (TEG) chip. Although the absolute temperature was not precisely evaluated because of the uncertain radiation coefficients of materials, we confirmed the well-concentrated heating around LSPCW; the lateral heat diffusion was distributed within ~20 m, which was narrower than the 40 m of the TiN heater of the switch that was buried in the SiO 2 -cladding [16]. Because any one of the LSPCWs is heated during the beam steering, this heat diffusion does not matter, even when the LSPCW pitch is extremely reduced, as mentioned above.…”

“…In this scheme, a thick system resulting from the lens and its focal length and a discrete lateral beam-steering may be the drawbacks. We have proposed this third scheme, and so far developed a device consisting of LSPCWs and switch trees, which are all integrated by the Si photonics complementary-metal oxidesemiconductor (CMOS) process, as well as a bespoke collimator lens [16]. We demonstrated the 2D scanning of a spot beam of ~0.15° divergence in the angular range of 40°  4.4° with an estimated resolution point, 266  16, by the combination of the  sweep and TO waveguide switching.…”

“…The structure and fabrication processes of the Si photonics chip were according those in Ref. [16]. We employed a 200mm-diameter silicon-on-insulator (SOI) with a 210-nm-thick Si layer and the CMOS process with a KrF excimer laser stepper at  = 248 nm and phase-shift masks, for which the minimum feature size was < 130 nm.…”

“…In this paper, we did not exhibit the -swept beam scanning of the device because its details are already contained in Ref. [16]. The 1D TO beam scanning characteristics are summarized in Fig.…”

Multifunctional Beam Manipulation at Telecommunication Wavelengths Enabled by an All‐Dielectric Metasurface Doublet

“…[ 66 ] Moreover, the proposed device could potentially be integrated with a solid‐state optical phased array chip to help establish a nonmechanical LiDAR module featuring enhanced angular beam steering. [ 67,68 ]…”