Large-scale one-dimensional (1D) waveguide surface grating arrays enable smaller antenna pitches and larger apertures for the OPAs. However, broad wavelength tuning is required for wide-angle beam steering along the transverse θ direction for 1D waveguide antennas. High-resolution and wide-angle beam steerings at visible and NIR wavelengths have not been reported in previous studies. This study presents a large-scale SiNx nanophotonic phased array with an optical aperture of 2.3 mm × 2.3 mm, which is the largest OPA aperture produced in the visible and NIR bands thus far. Broad wavelength tuning from 650 nm to 1064 nm is employed to achieve small beam divergences of 0.03° – 0.054° in a wide steering range of 53.7°. The overall losses are accordingly analyzed with 3 dB bandwidth of 150 nm from 785 nm to 935 nm. Furthermore, with a supercontinuum laser illuminated on the OPA, more than 1000 resolvable spots merge together in the free space and form a fine strip of continuous line in the far-field projection with an FOV of >50°. This study demonstrates both high steering resolution and wide steering angle at wavelengths from visible to NIR on SiNx OPAs for the first time, to the best of our knowledge.

In this Letter, a two-dimensional (2D) beam steering on silicon nitride (SiNx) nanophotonic phased arrays from visible to near-infrared wavelengths is reported for the first time, to the best of our knowledge. In order to implement beam steering along the transverse direction for one-dimensional waveguide surface grating arrays, wavelengths from 650 to 980 nm provided by the supercontinuum laser are used to excite the phased array. Then the beams are parallel radiated with steering angles in a sequence of 26.84° to − 16.54 ∘ along the transverse direction, and a continuous line in the far field consisting of parallel emitted spots is produced with a total view angle of 43.38°. Moreover, this continuous far-field line is steered along the longitudinal direction with massive wavelengths simultaneously tuned by phase shifts from − π / 2 to over + π / 2 . This method with massive parallel wavelengths emitted paves a new way for 2D steering on SiNx nanophotonic phased arrays.

We report a unique concept to implement a high-order mode pass filter using mode converters. Our proposed design method implements a high-order mode pass filter of any order, uses different mode converters available, and applies to a variety of planar lightwave circuit material platforms. We fabricate a broadband fundamental mode filter device using a Mach–Zehnder interferometer and Y-junctions to demonstrate our idea. The performance of the fabricated device is demonstrated experimentally in the wavelength range of 1.530–1.565 μm (C-band). This filter exhibits a simulated extinction ratio of 37 dB with an excess loss of 0.52 dB for the first-order mode transmission.

Highly-time-resolved and precise tracking of position, velocity, and acceleration is urgently required when highly dynamic legged robots are walking, trotting, and jumping. Frequency-modulated continuous-wave (FMCW) laser ranging is able to provide precise measurement in short distance. However, FMCW light detection and ranging (LiDAR) suffers from a low acquisition rate and poor linearity of laser frequency modulation in wide bandwidth. A sub-millisecond-scale acquisition rate and nonlinearity correction in the wide frequency modulation bandwidth have not been reported in previous studies. This study presents the synchronous nonlinearity correction for a highly-time-resolved FMCW LiDAR. The acquisition rate of 20 kHz is obtained by synchronizing the measurement signal and the modulation signal of laser injection current with a symmetrical triangular waveform. The linearization of laser frequency modulation is conducted by resampling of 1000 intervals interpolated in every up-sweep and down-sweep of 25 µs, while measurement signal is stretched or compressed in every period of 50 µs. The acquisition rate is demonstrated to be equal to the repetition frequency of laser injection current for the first time to the best of authors’ knowledge. This LiDAR is successfully used to track the foot trajectory of a jumping single-leg robot. The high velocity up to 7.15 m/s and high acceleration of 365 m/s² are measured during the up-jumping phase, while heavy shock takes place with high acceleration of 302 m/s² as the foot end strikes the ground. The measured foot acceleration of over 300 m/s², which is more than 30 times gravity acceleration, is reported on a jumping single-leg robot for the first time.

The utilization of refractive index (RI) change due to guest–host interactions between the guest volatile organic compound vapor and porous metal–organic frameworks (vapor–MOF interactions) is promising in photonic vapor sensors. Therefore, the study of light–matter interactions in nanoporous metal–organic frameworks (MOFs) is fundamental and essential for MOF-based photonic devices. In this work, the manipulation of light in MOFs to investigate the vapor–MOF interactions by using optical fiber devices is demonstrated. The vapor–MOF interactions and the light–vapor interactions (light in MOFs to sense the RI changes resulting from the vapor–MOF interactions) are investigated. The cladding mode is excited by a long-period fiber grating (LPFG) for evanescent field sensing in a ZIF-8 sensitive coating. The experimental results combining quantum chemical calculations and optical simulations reveal the relationships between the microscopic energy of vapor desorption, RI changes and evanescent field enhancement in ZIF-8 during the vapor–MOF interactions. With exceptionally large RI changes, the evanescent field of cladding mode in ZIF-8 is greatly enhanced to sense the vapor–MOF interactions. As a proof-of-concept, a LPFG sensor with ZIF-8 coating showed a high sensitivity of 1.33 pm ppm⁻¹ in the linear range from 9.8 ppm to 540 ppm for the sensing of ethanol vapor. The investigation of light–matter interactions in ZIF-8 provides a useful guideline for the design and fabrication of MOF-based optical waveguide/fiber sensors.

We report a simple concept to implement a single-wavelength beam steering based on a liquid-cladded one-dimensional (1D) optical phased array (OPA). The beam steering was realized by modifying the waveguide mode effective index through replacing the liquid upper claddings. A prototype of a 32-channel liquid-cladded OPA was fabricated and characterized. Owing to the high refractive index range of liquids ( > 0.625 ), a maximum steering angle of > 10 ∘ was achieved with the liquid range from 1.0 to 1.63 at a wavelength of 940 nm. Moreover, the liquid-cladded OPA reveals a quasi-continuous beam steering range of > 29 ∘ by combining the liquid cladding tuning and discrete wavelength tuning of λ = 785 n m , 852 nm, and 940 nm. Further integration with optofluidic systems offers the OPA potential for low power consumption and all-fluidic beam steering operating at a single wavelength.