Energy-efficient on-chip optical diode based on the optomechanical effect

Energy-efficient integrated silicon optical phased array

An optical phased array (OPA) is a promising non-mechanical technique for beam steering in solid-state light detection and ranging systems. The performance of the OPA largely depends on the phase shifter, which affects power consumption, insertion loss, modulation speed, and footprint. However, for a thermo-optic phase shifter, achieving good performance in all aspects is challenging due to trade-offs among these aspects. In this work, we propose and demonstrate two types of energy-efficient optical phase shifters that overcome these trade-offs and achieve a well-balanced performance in all aspects. Additionally, the proposed round-spiral phase shifter is robust in fabrication and fully compatible with deep ultraviolet (DUV) processes, making it an ideal building block for large-scale photonic integrated circuits (PICs). Using the high-performance phase shifter, we propose a periodic OPA with low power consumption, whose maximum electric power consumption within the field of view is only 0.33 W. Moreover, we designed Gaussian power distribution in both the azimuthal ([Formula: see text]) and polar ([Formula: see text]) directions and experimentally achieved a large sidelobe suppression ratio of 15.1 and 25 dB, respectively.

Energy-efficient thermo-optic silicon phase shifter with well-balanced overall performance

Silicon photonic integrated circuits (PICs) show great potential for many applications. The phase tuning technique is indispensable and of great importance in silicon PICs. An optical phase shifter with balanced overall performance on power consumption, insertion loss, footprint, and modulation bandwidth is essential for harnessing large-scale integrated photonics. However, few proposed phase shifter schemes on various platforms have achieved a well-balanced performance. In this Letter, we experimentally demonstrate a thermo-optic phase shifter based on a densely distributed silicon spiral waveguide on a silicon-on-insulator platform. The phase shifter shows a well-balanced performance in all aspects. The electrical power consumption is as low as 3 mW to achieve a π phase shift, the optical insertion loss is 0.9 dB per phase shifter, the footprint is 67×28µm² under a standard silicon photonics fabrication process without silicon air trench or undercut process, and the modulation bandwidth is measured to be 39 kHz.

All-optical tunable microwave filter with ultra-high peak rejection and low-power consumption

We propose and experimentally demonstrate microwave photonic filters (MPFs) with high rejection ratios and large tuning ranges of the central frequency and bandwidth leveraging four cascaded opto-mechanical microring resonators (MRRs). As half waveguides of each MRR are free-hanging in the air, the nonlinear effects in the opto-mechanical MRRs could be efficiently excited. Consequently, the transmission characteristics of the cascaded MRRs could be flexibly manipulated by adjusting the input pump powers. When the resonant wavelengths of every two MRRs are tuned to be aligned, the transmission spectrum of the silicon device is a notch bimodal distribution with high extinction ratios. The optical carrier is fixed at the flat region of the bimodal distribution. Under optical double sideband (ODSB) modulation, MPFs with high rejection ratios could be achieved due to the high extinction ratio of the cascaded rings. Moreover, the central frequency and bandwidth of the MPFs could be tuned by properly adjusting the pump powers. In the experiment, with a low power of 2.56 mW, the MPF central frequency and bandwidth could be tuned from 7.12 GHz to 39.16 GHz and from 11.3 GHz to 17.6 GHz, respectively. More importantly, the MPF rejection ratios are beyond 60 dB. Furthermore, during the bandwidth tuning process, an MPF response with approximately equiripple stopband could be realized. Owing to the dominant advantages of high rejection ratios, large tuning ranges, low power consumption and compact size, the silicon device has many significant applications in on-chip microwave systems.

On-chip passive optical diode with low-power consumption

We propose and experimentally demonstrate an all-silicon passive optical diode with low-power consumption and high nonreciprocal transmission ratios (NTRs) based on cascaded opto-mechanical microring resonators (MRRs). As the oxide substrates of the opto-mechanical MRRs are removed, the nonlinear effects in the free-hanging waveguides could be efficiently activated by low optical powers. The operation principle of the optical diode is based on the asymmetric resonance red-shifts of the two MRRs in the forward and backward transmissions, which could be effectively induced by the nonlinear effects. In the experiment, with injecting an optical power low as 0.96 dBm, a high NTR of 33.6 dB and a relatively broad 20-dB bandwidth of 0.11 nm are achieved. The proposed passive optical diode is competent to process optical signals with dominant advantages of CMOS-compatibility, a compact footprint, low-power consumptions and high NTRs, which has significant applications for on-chip signal processing systems, such as logic gates and optical computing.