Optical phased arrays (OPAs) are crucial in beam-steering applications, particularly as transmitters in light detection and ranging and free-space communication systems. In this paper, we demonstrate a on-chip OPA that emits multiple orbital angular momentum (OAM) beams in different directions, each carrying unique topological charges. By superimposing a forked 1×3 Dammann grating on the grating array, six OAM beams with topological charges of ±3, ±4, and ±5 can be radiated from the OPA region. The OPA chip was fabricated on a silicon-on-insulator platform, and the simultaneous generation of multiple OAM beams was realized experimentally. The directions of these vortices can be steered by adjusting the wavelength of the input light and the bias voltages of the phase shifters, enabling a remarkable field of view (FOV) of 140 deg×40 deg within a 120-nm wavelength range. We pave the way for developing systems with ultrawide FOVs, improving the resolution of remote sensing and broadening the possibilities of free-space communications.
Integrated electro-optic tuning devices are essential parts of optical communication, sensors, and optical machine learning. Among the available materials, silicon is the most promising for on-chip signal processing and networks. However, silicon is limited owing to the absence of efficient Pockels electro-optic tuning. Herein, we propose a new hybrid silicon-barium-titanate (Si-BTO) integrated photonic platform, in which the BTO thin film is deposited by the chemical solution deposition (CSD) method. A tunable racetrack resonator is demonstrated to confirm the Pockels electro-optic tuning potential of the BTO thin film. The hybrid racetrack resonator has a tuning efficiency of 6.5 pm/V and a high-power efficiency of 2.16 pm/nW. Moreover, the intrinsic quality factor of the fabricated racetrack resonator is 48,000, which is the highest in hybrid Si-BTO platforms, to the best of our knowledge. The high-speed test verifies the stability of the racetrack resonator. The hybrid Si-BTO technology based on the CSD method has the advantages of low equipment cost and simple fabrication process, which holds promise for low-power electro-optic tuning devices.
Integrated electro-optic tuning devices are essential parts of optical communication, sensors, and optical machine learning. Among the available materials, silicon is the most promising for on-chip signal processing and networks. However, silicon is limited owing to the absence of efficient Pockels electro-optic tuning. Herein, we propose a new hybrid silicon-barium-titanate (Si-BTO) integrated photonic platform, in which the BTO thin film is deposited by the chemical solution deposition (CSD) method. A tunable racetrack resonator is demonstrated to confirm the Pockels electro-optic tuning potential of the BTO thin film. The hybrid racetrack resonator has a tuning efficiency of 6.5 pm/V and a high-power efficiency of 2.16 pm/nW. Moreover, the intrinsic quality factor of the fabricated racetrack resonator is 48,000, which is the highest in hybrid Si-BTO platforms, to the best of our knowledge. The high-speed test verifies the stability of the racetrack resonator. The hybrid Si-BTO technology based on the CSD method has the advantages of low equipment cost and simple fabrication process, which holds promise for low-power electro-optic tuning devices.
Mode-division multiplexing (MDM) technology enables high-bandwidth data transmission using orthogonal waveguide modes to construct parallel data streams. However, few demonstrations have been realized for generating and supporting high-order modes, mainly due to the intrinsic large material group-velocity dispersion (GVD), which make it challenging to selectively couple different-order spatial modes. We show the feasibility of on-chip GVD engineering by introducing a gradient-index metamaterial structure, which enables a robust and fully scalable MDM process. We demonstrate a record-high-order MDM device that supports TE0–TE15 modes simultaneously. 40-GBaud 16-ary quadrature amplitude modulation signals encoded on 16 mode channels contribute to a 2.162 Tbit / s net data rate, which is the highest data rate ever reported for an on-chip single-wavelength transmission. Our method can effectively expand the number of channels provided by MDM technology and promote the emerging research fields with great demand for parallelism, such as high-capacity optical interconnects, high-dimensional quantum communications, and large-scale neural networks.
Fiber-chip edge couplers are extensively used in integrated silicon photonic for the coupling of light between optical fibers and planar silicon waveguide circuits. We experimentally demonstrate several novel designs of edge couplers with eased fabrication process, i.e. fork shape and dual-trident SWG shape, based on Silicon-on-Insulator platform. These edge couplers show low coupling losses and possess large bandwidths simultaneously.
We discuss light emitters and modulators in silicon photonic interconnects. In particular, we experimentally demonstrate resonant luminescence from Ge quantum dots embedded in a photonic crystal ring resonator (PCRR) at room temperature. Six sharp resonant peaks are observed, which correspond to the resonant modes supported by the PCRR. We further study a high speed silicon-graphene nanobeam modulator, and a silicon spatial light modulator. These devices show great potential in future high density and high capacity interconnection systems.
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