Chunhui Yao

University of Cambridge | Cam · Department of Engineering

Miniaturized spectrometers hold great promise for in situ, in vitro, and even in vivo sensing applications. However, their size reduction imposes vital performance constraints in meeting the rigorous demands of spectroscopy, including fine resolution, high accuracy, and ultra-wide observation window. The prevailing view in the community holds that...

Silicon photonic switches are widely considered as a cost-effective solution for addressing the ever-growing data traffic in datacenter networks, as they offer unique advantages such as low power consumption, low latency, small footprint and high bandwidth. Despite extensive research efforts, crosstalk in large-scale photonic circuits still poses a...

Recent years have seen the rapid development of miniaturized reconstructive spectrometers (RSs), yet they still confront a range of technical challenges, such as bandwidth/resolution ratio, sensing speed, and/or power efficiency. Reported RS designs often suffer from insufficient decorrelation between sampling channels, which results in limited com...

Integrated spectrometers hold great promise for in-situ, in vitro, and even in vivo near-infrared (NIR) sensing applications. However, practical NIR applications require fine resolution, high accuracy, and mostly importantly, ultra-wide observation window that spans multiple overtone regions, for capturing spectral fingerprints. In this paper, we p...

Photonic integrated circuits have been extensively explored for optical processing with the aim of breaking the speed and energy efficiency bottlenecks of digital electronics. However, the input/output (IO) bottleneck remains one of the key barriers. Here we report a photonic iterative processor (PIP) for matrix-inversion-intensive applications. Th...

Physical neural networks (PNNs) are emerging paradigms for neural network acceleration due to their high-bandwidth, in-propagation analogue processing. Despite the advantages of PNN for inference, training remains a challenge. The imperfect information of the physical transformation means the failure of conventional gradient-based updates from back...

We report for the first time a strictly non-blocking 8×8 electro-optic silicon photonic switch that counterbalances free-carrier-absorption loss in the Mach-Zehnder interferometer cells by harnessing self-heating effect. Experimentally, we demonstrate record-low crosstalk ratio of <−40dB and on-chip loss of as low as 8.5dB. ©2024 The Author(s) Intr...

We demonstrate a strictly non-blocking 8×8 silicon photonic switch fabric with centrally placed dual-stage MZI cells that effectively suppress first-order crosstalk. This thermally actuated device exhibits on-chip loss of <5dB and low-crosstalk of <-40dB.

We report a Si-SiN-SiN tri-layer switch-and-select 8×8 optical switch with 128 thermally-driven microring-resonators. Crosstalk ratio and on-chip loss are measured in the range of -33.2 to -50.8dB and 2.1 to 10.5dB, respectively, with >70GHz passband.

We present a novel reconstructive spectrometer with cascaded nanobeam mirrors. A compact SiN spectrometer is demonstrated achieving <0.5 nm resolution across 160 nm bandwidth with only 15 sampling channels, yielding a record-high spectral pixel-to-channel ratio.

Photonic computing has the potential to surpass the speed of electronic computing. Here we demonstrate the first all-optical iterative photonic integrated processor for matrix inversions and multiplications. A 4×4 matrix is inverted with an accuracy of 93% and a speed of 8.5×105 inversions per second.

We demonstrate a strictly non-blocking 8×8 silicon photonic switch fabric with centrally placed dual-stage MZI cells that effectively suppress first-order crosstalk. This thermally actuated device exhibits on-chip loss of <5dB and low-crosstalk of <-40dB.

Optical spectroscopic sensors are a powerful tool to reveal light-matter interactions in many fields. Miniaturizing the currently bulky spectrometers has become imperative for the wide range of applications that demand in situ or even in vitro characterization systems, a field that is growing rapidly. In this paper, we propose a novel integrated re...

Light-emitting diodes (LEDs) are ubiquitous in modern society, with applications spanning from lighting and displays to medical diagnostics and data communications. Metal-halide perovskites are promising materials for LEDs because of their excellent optoelectronic properties and solution processability. Although research has progressed substantiall...

Miniaturization of optical spectrometers is important to enable spectroscopic analysis to play a role in in situ, or even in vitro and in vivo characterization systems. However, scaled-down spectrometers generally exhibit a strong trade-off between spectral resolution and operating bandwidth, and are often engineered to identify signature spectral...

Optical spectroscopic sensors are a powerful tool to reveal light-matter interactions in many fields, such as physics, biology, chemistry, and astronomy. Miniaturizing the currently bulky spectrometers has become imperative for the wide range of applications that demand in situ or even in vitro characterization systems, a field that is growing rapi...

Photonic integration platforms have been explored extensively for optical computing with the aim of breaking the speed and power efficiency limitations of traditional digital electronic computers. Current technologies typically focus on implementing a single computation iteration optically while leaving the intermediate processing in the electronic...

We present a novel approach for designing 2×2 electro-optic switch elements with ultra-high extinction ratio that offsets the impact of modulating-indueced free-carrier absorption. A curved directional coupler with tunable coupling efficiency and a differential electro-optic phase shifter pair are employed to correct any loss and phase imbalance in...

We demonstrate the first chip-based real-valued direct photonic matrix inverter using coherent sources. At a rate of 2×10 ⁵ inversions/s, a 16×16 diagonal matrix and a 2×2 arbitrary matrix are inverted with 99.2% and 93.7% accuracy.

We found that temperature-dependent infrared spectroscopy measurements (i.e., reflectance or transmittance) using a Fourier-transform spectrometer can have substantial errors, especially for elevated sample temperatures and collection using an objective lens. These errors can arise as a result of partial detector saturation due to thermal emission...

We present a compact and highly tolerant vertical coupling structure, which can be a generic design that bridges the gap between conventional resonant couplers and adiabatic couplers for heterogeneously integrated devices. We show insights on relaxing the coupler alignment tolerance and provide detailed design methodology. By the use of a multi-seg...

We present a compact, highly tolerant vertical coupling structure, which can be a generic design that bridges the gap between conventional resonant couplers and adiabatic couplers for heterogeneously integrated devices. We show insights on relaxing the coupler alignment tolerance and provide a detailed design methodology. By the use of a multisegme...

The proliferation of Internet-of-Things has promoted a wide variety of emerging applications that require compact, lightweight, and low-cost optical spectrometers. While substantial progresses have been made in the miniaturization of spectrometers, most of them are with a major focus on the technical side but tend to feature a lower technology read...

An induced-transmission filter (ITF) uses an ultrathin layer of metal positioned at an electric-field node within a dielectric thin-film bandpass filter to select one transmission band while suppressing other transmission bands that would have been present without the metal layer. Here, we introduce a switchable mid-infrared ITF where the metal fil...

Mode-division multiplexing can scale the capacity of optical communications and optical interconnects. We demonstrate an ultra-compact and fabrication-error tolerant silicon three-mode multiplexer by shallowly etching rectangular trenches on a multi-mode interferometer. Depending on the selected input port, the TE0 mode is converted to the eigenmod...

We found that temperature-dependent infrared spectroscopy measurements using a Fourier-transform spectrometer can have substantial errors, especially for elevated sample temperatures and collection using an objective lens (e.g., using an infrared microscope). These errors arise as a result of partial detector saturation due to thermal emission from...

The cover image, referring to article number 2000996 by Yikai Su and co‐workers, shows three on‐chip mode‐order converters based on multi‐mode silicon waveguides. An input light can be converted to an output with a different mode order via two‐dimensional refractive‐index perturbation on the waveguide. The proposed compact and efficient mode conver...

Generation and manipulation of optical modes are of general interest to the photonics community. Mode conversion is an essential requirement in mode‐division multiplexed systems. In this paper, a scalable method to simultaneously manipulate multiple waveguide modes on chip is proposed. As one experimental demonstration, simultaneous multi‐mode conv...

Thermal emission is the radiation of electromagnetic waves from hot objects. The promise of thermal‐emission engineering for applications in energy harvesting, radiative cooling, and thermal camouflage has recently led to renewed research interest in this topic. However, accurate and precise measurements of thermal emission in a laboratory setting...

We present a silicon two-mode multiplexer with a footprint of 1.5×7.24 μm2. The operation principle is based on simultaneous multi-mode conversion. In the wavelength range of 1521nm~1571nm, the crosstalk is below –15 dB.

We describe and demonstrate general procedures for thermal-emission measurements that are applicable to most experimental conditions, including more-challenging cases such as thermal emitters with temperature-dependent emissivity and emitters that are not in thermal equilibrium.