In this paper, a novel design of a 1×N multimode-interference power splitter is proposed and investigated. By using the finite difference time domain method and particle swarm optimization algorithm, our proposed 1×N optical power splitter can be optimized to realize compact size, good uniformity, low insertion loss, and broad bandwidth. To verify the effectiveness of this design, the designed 1×4 and 1×8 multimode-interference power splitters are experimentally demonstrated on an silicon-on-insulator platform. The lengths of the designed 1×4 and 1×8 power splitters are 36 μm and 47.8 μm, respectively. Experimental results show that, for the fabricated 1×4 power splitter, the uniformity ranges from 0.07 to 0.89 dB and the corresponding maximum insertion loss is 0.62 dB within a bandwidth from 1520 to 1624 nm. For the fabricated 1×8 power splitter, within a bandwidth from 1519 to 1623 nm, the uniformity varies from 0.19 to 0.83 dB and a maximum insertion loss of 0.64 dB are obtained.

We propose a new method to change the resonant status of the microring by modifying the light-absorption ability of the waveguide. A conception of a 2 × 2 microring switch based on the graphene-silicon-waveguide is presented by inserting a single graphene flake inside the lateral slot waveguide. The resonance procedure of the microring is thoroughly blocked when the graphene is tuned to be a zero-permittivity material, which significantly enhances the waveguide's loss. Neither a high quality factor nor a large driving voltage of the microring is needed. According to the numerical analysis, an extinction ratio for is obtained in the drop port with a broad bandwidth. The extinction ratio in the through port is 34 dB. The radius of the microring is 5.1 μm and the driving voltage is 2.38 V.

We demonstrate a silicon $1\times 64$ optical phased array by using carrier-depletion-based phase shifters. The 5-mm-long phase shifter exhibits an electro-optic bandwidth of 700 MHz, a modulation efficiency of 2.3 V.cm, and an ultra-low power consumption of < 0.45 nW/ $\boldsymbol {\pi }$ . A steering range of ±18° is realized in the phased-array axis by tuning the phase of each antenna. Besides, the beam steering in the other (wavelength-controlled) axis by tuning the wavelength achieves a dispersion efficiency of 0.17° /nm. Although the carrier-depletion effect induces a nonuniform optical amplitude distribution among the antenna array, the OPA chip is still able to form high-quality far-field beam patterns with side lobe suppression ratios of $\boldsymbol {\sim }10$ dB. Our measurement and simulation results indicate that the carrier-depletion-based OPA is a promising candidate for future high-speed and power-efficient solid-state Lidars.

We demonstrate an optical switch array based on the topology of Butterfly by using dual-microring resonators which can be used in the ultra-compact network. The proposed switch is composed of 12 basic switch elements tuned by thermo-optic (TO) effect, which can build links freely without any blocking. Due to the advantages of microring resonators, the footprint switch array is smaller than 0.2 mm ² . The optical structure can complete 4- and 8-ports signal routing. It shows a large bandwidth over 50GHz, thereby performing well under condition of high-speed data transmission.

We demonstrate a fully solid-state beam scanner that incorporates a Si3N4 photonic integrated switch array, a collimator lens, and a lithographically patterned diffraction grating. The off-chip components enable nearly circular output beams under the reduced system complexity. By manipulating the optical switch array and tuning the input wavelength, two-dimensional beam steering with $32\times23$ = 736 resolvable spots across a $14.3^{\circ }\times 9.9^{\circ }$ field of view (FOV) is realized. Furthermore, the coherent ranging within 18 m is demonstrated experimentally by utilizing the triangular frequency modulation. The tested results validate the feasibility of the proposed beam scanner, which might offer a flexible, scalable, and easily-implemented solution for the solid-state frequency modulated continuous-wave (FMCW) LiDAR.

In this paper, a design of a silicon mode (de)multiplexer based on cascaded counter-tapered couplers is proposed and investigated. By using the particle swarm optimization algorithm and finite difference time domain method, structural parameters of each counter-tapered coupler in our proposed mode (de)multiplexer are optimized so that high conversion efficiencies can be obtained and coupling lengths can be significantly shortened. The coupling lengths of counter-tapered couplers in the proposed silicon four-mode (de)multiplexer operating in transverse-electric polarization are 8 μm, 9 μm, and 10 μm. The corresponding conversion efficiencies are respectively 98.98%, 99.98%, and 98.68%. Experimental results show that, the fabricated device exhibits a demultiplexed crosstalk of −32.76 dB, −27.10 dB, −32.45 dB, or −33.29 dB at 1550 nm wavelength, when the fundamental transverse-electric mode is respectively launched into the ports Input ₀ , Input ₁ , Input ₂ , or Input ₃ . The measured demultiplexed crosstalk is less than −15.15 dB from 1525 to 1596 nm and lower than −18.12 dB from 1525 to 1561 nm.