Photoic crystal nanobeam cavity devices for on-chip integrated silicon photonics

Integrated circuit(IC)industry has fully considered the fact that the Moore’s Law is slowing down or ending.Alternative solutions are highly and urgently desired to break the physical size limits in the More-than-Moore era.Integrated silicon photonics technology exhibits distinguished potential to achieve faster operation speed,less power dissipation,and lower cost in IC industry,because their COMS compatibility,fast response,and high monolithic integration capability.Particularly,compared with other on-chip resonators(e.g.microrings,2D photonic crystal cavities)silicon-on-insulator(SOI)-based photonic crystal nanobeam cavity(PCNC)has emerged as a promising platform for on-chip integration,due to their attractive properties of ultra-high Q/V,ultra-compact footprints and convenient integration with silicon bus-waveguides.In this paper,we present a comprehensive review on recent progress of on-chip PCNC devices for lasing,modulation,switching/filting and label-free sensing,etc.

Avalanche photodiodes on silicon photonics

Silicon photonics technology has drawn significant interest due to its potential for compact and high-performance photonic integrated circuits.The Ge-or III-V material-based avalanche photodiodes integrated on silicon photonics provide ideal high sensitivity optical receivers for telecommunication wavelengths.Herein,the last advances of monolithic and hetero-geneous avalanche photodiodes on silicon are reviewed,including different device structures and semiconductor systems.

Silicon photonics for telecom and data‐com applications

In recent decades,silicon photonics has attracted much attention in telecom and data-com areas.Constituted of high refractive-index contrast waveguides on silicon-on-insulator(SOI),a variety of integrated photonic passive and active devices have been implemented supported by excellent optical properties of silicon in the mid-infrared spectrum.The main advantage of the silicon photonics is the ability to use complementary metal oxide semiconductor(CMOS)process-compatible fabrication technologies,resulting in high-volume production at low cost.On the other hand,explosively growing traffic in the telecom,data center and high-performance computer demands the data flow to have high speed,wide bandwidth,low cost,and high energy-efficiency,as well as the photonics and electronics to be integrated for ultra-fast data transfer in networks.In practical applications,silicon photonics started with optical interconnect transceivers in the data-com first,and has been now extended to innovative applications such as multi-port optical switches in the telecom network node and integrated optical phased arrays(OPAs)in light detection and ranging(LiDAR).This paper overviews the progresses of silicon photonics from four points reflecting the recent advances mentioned above.CMOS-based silicon photonic platform technologies,applications to optical transceiver in the data-com network,applications to multi-port optical switches in the telecom network and applications to OPA in LiDAR system.

A Review of the Building Blocks of Silicon Photonics:From Fabrication Perspective

Silicon photonics is a disruptive semiconductor technology that taps into the extraordinary properties of light while taking full advantage of the already matured CMOS processes developed in the semiconductor industry.However,just like electronic industry in the 1970s,currently,silicon photonics is in its infancy.The fundamental building blocks of silicon photonics such as waveguides,lasers,modulators,etc.are yet to be fully optimized for low-cost-mass-manufacturing.In this paper,the current state-of-the-art related to developing and optimizing these aforementioned key components will be presented.The challenges of process integration regarding Silicon photonics will also be discussed.

Neuromorphic silicon photonics with 50 GHz tiled matrix multiplication for deep-learning applications

The explosive volume growth of deep-learning(DL)applications has triggered an era in computing,with neuromorphic photonic platforms promising to merge ultra-high speed and energy efficiency credentials with the brain-inspired computing primitives.The transfer of deep neural networks(DNNs)onto silicon photonic(SiPho)architectures requires,however,an analog computing engine that can perform tiled matrix multiplication(TMM)at line rate to support DL applications with a large number of trainable parameters,similar to the approach followed by state-of-the-art electronic graphics processing units.Herein,we demonstrate an analog SiPho computing engine that relies on a coherent architecture and can perform optical TMM at the record-high speed of 50 GHz.Its potential to support DL applications,where the number of trainable parameters exceeds the available hardware dimensions,is highlighted through a photonic DNN that can reliably detect distributed denial-of-service attacks within a data center with a Cohen’s kappa score-based accuracy of 0.636.

Progress in complementary metal–oxide–semiconductor silicon photonics and optoelectronic integrated circuits

Silicon photonics is an emerging competitive solution for next-generation scalable data communications in different application areas as high-speed data communication is constrained by electrical interconnects. Optical interconnects based on silicon photonics can be used in intra/inter-chip interconnects, board-to-board interconnects, short-reach communications in datacenters, supercomputers and long-haul optical transmissions. In this paper, we present an overview of recent progress in silicon optoelectronic devices and optoelectronic integrated circuits （OEICs） based on a complementary metal-oxide-semiconductor-compatible process, and focus on our research contributions. The silicon optoelectronic devices and OEICs show good characteristics, which are expected to benefit several application domains, including communication, sensing, computing and nonlinear systems.

Quantum dot lasers for silicon photonics [Invited]

We review recent advances in the field of quantum dot lasers on silicon. A summary of device performance,reliability, and comparison with similar quantum well lasers grown on silicon will be presented. We consider the possibility of scalable, low size, weight, and power nanolasers grown on silicon enabled by quantum dot active regions for future short-reach silicon photonics interconnects.

Passive devices at 2 μm wavelength on 200 mm CMOS-compatible silicon photonics platform [Invited]

As a promising spectral window for optical communication and sensing, it is of great significance to realize on-chip devices at the 2 μm waveband.The development of the 2 μm silicon photonic platform mainly depends on the performance of passive devices.In this work, the passive devices were fabricated in the silicon photonic multi-project wafer process.The designed micro-ring resonator with a 0.6 μm wide silicon ridge waveguide based on a 220 nm silicon-on-insulator platform achieves a high intrinsic quality factor of 3.0 × 105.The propagation loss is calculated as 1.62 d B/cm.In addition,the waveguide crossing, multimode interferometer, and Mach–Zehnder interferometer were demonstrated at 2 μm with good performances.

On-chip wireless silicon photonics: from reconfigurable interconnects to lab-on-chip devices

Photonic integrated circuits are developing as key enabling components for high-performance computing and advanced networkon-chip,as well as other emerging technologies such as lab-on-chip sensors,with relevant applications in areas from medicine and biotechnology to aerospace.These demanding applications will require novel features,such as dynamically reconfigurable light pathways,obtained by properly harnessing on-chip optical radiation.In this paper,we introduce a broadband,high directivity(4150),low loss and reconfigurable silicon photonics nanoantenna that fully enables on-chip radiation control.We propose the use of these nanoantennas as versatile building blocks to develop wireless(unguided)silicon photonic devices,which considerably enhance the range of achievable integrated photonic functionalities.As examples of applications,we demonstrate 160 Gbit s−1 data transmission over mm-scale wireless interconnects,a compact low-crosstalk 12-port crossing and electrically reconfigurable pathways via optical beam steering.Moreover,the realization of a flow micro-cytometer for particle characterization demonstrates the smart system integration potential of our approach as lab-on-chip devices.

Taking silicon photonics modulators to a higher performance level: state-of-the-art and a review of new technologies

Optical links are moving to higher and higher transmission speeds while shrinking to shorter and shorter ranges where optical links are envisaged even at the chip scale.The scaling in data speed and span of the optical links demands modulators to be concurrently performant and cost-effective.Silicon photonics(SiPh),a photonic integrated circuit technology that leverages the fabrication sophistication of complementary metal-oxide-semiconductor technology,is well-positioned to deliver the performance,price,and manufacturing volume for the high-speed modulators of future optical communication links.SiPh has relied on the plasma dispersion effect,either in injection,depletion,or accumulation mode,to demonstrate efficient high-speed modulators.The high-speed plasma dispersion silicon modulators have been commercially deployed and have demonstrated excellent performance.Recent years have seen a paradigm shift where the integration of various electro-refractive and electro-absorptive materials has opened up additional routes toward performant SiPh modulators.These modulators are in the early years of their development.They promise to extend the performance beyond the limits set by the physical properties of silicon.The focus of our study is to provide a comprehensive review of contemporary(i.e.,plasma dispersion modulators)and new modulator implementations that involve the integration of novel materials with SiPh.

On-chip light sources for silicon photonics

Serving as the electrical to optical converter,the on-chip silicon light source is an indispensable component of silicon photonic technologies and has long been pursued.Here,we briefly review the history and recent progress of a few promising contenders for on-chip light sources in terms of operating wavelength,pump condition,power consumption,and fabrication process.Additionally,the performance of each contender is also assessed with respect to thermal stability,which is a crucial parameter to consider in complex optoelectronic integrated circuits(OEICs)and optical interconnections.Currently,III-V-based silicon(Si)lasers formed via bonding techniques demonstrate the best performance and display the best opportunity for commercial usage in the near future.However,in the long term,direct hetero-epitaxial growth of III–V materials on Si seems more promising for low-cost,high-yield fabrication.The demonstration of high-performance quantum dot(QD)lasers monolithically grown on Si strongly forecasts its feasibility and enormous potential for on-chip lasers.The superior temperature-insensitive characteristics of the QD laser promote this design in large-scale high-density OEICs.The Germanium(Ge)-on-Si laser is also competitive for large-scale monolithic integration in the future.Compared with a III-V-based Si laser,the biggest potential advantage of a Ge-on-Si laser lies in its material and processing compatibility with Si technology.Additionally,the versatility of Ge facilitates photon emission,modulation,and detection simultaneously with a simple process complexity and low cost.

Stochastic collocation for device-level variability analysis in integrated photonics

We demonstrate the use of stochastic collocation to assess the performance of photonic devices under the effect of uncertainty. This approach combines high accuracy and efficiency in analyzing device variability with the ease of implementation of sampling-based methods. Its flexibility makes it suitable to be applied to a large range of photonic devices. We compare the stochastic collocation method with a Monte Carlo technique on a numerical analysis of the variability in silicon directional couplers.

Optical signal processing based on silicon photonics waveguide Bragg gratings： review

This paper reviews the work done by research- ers at INRS and UBC in the field of integrated microwave photonics （IMWPs） using silicon based waveguide Bragg gratings （WBGs）. The grating design methodology is discussed in detail, including practical device fabrication considerations. On-chip implementations of various fun- darnental photonic signal processing units, including Fourier transformers, Hilbert transformers, ultrafast pulse shapers etc., are reviewed. Recent progress on WBGs- based IMWP subsystems, such as true time delay elements, phase shifters, real time frequency identification systems, is also discussed.

Quantum prospects for hybrid thin-film lithium niobate on silicon photonics

Photonics is poised to play a unique role in quantum technology for computation,communications and sensing.Meanwhile,integrated photonic circuits-with their intrinsic phase stability and high-performance,nanoscale components-offer a route to scaling.However,each integrated platform has a unique set of advantages and pitfalls,which can limit their power.So far,the most advanced demonstrations of quantum photonic circuitry has been in silicon photonics.However,thin-film lithium niobate(TFLN)is emerging as a powerful platform with unique capabilities;advances in fabrication have yielded loss metrics competitive with any integrated photonics platform,while its large second-order nonlinearity provides efficient nonlinear processing and ultra-fast modulation.In this short review,we explore the prospects of dynamic quantum circuits-such as multiplexed photon sources and entanglement generation-on hybrid TFLN on silicon(TFLN/Si)photonics and argue that hybrid TFLN/Si photonics may have the capability to deliver the photonic quantum technology of tomorrow.

Nonlinear integrated photonics

The field of nonlinear photonics is in full development. This special issue of Photonics Research takes you through the current issues of this fast-growing field of research, drawing on the current state of the art and seeking, through a selection of articles, to outline some trends for the future.

Applications of thin-film lithium niobate in nonlinear integrated photonics

Photonics on thin-film lithium niobate(TFLN)has emerged as one of the most pursued disciplines within integrated optics.Ultracompact and low-loss optical waveguides and related devices on this modern material platform have rejuvenated the traditional and commercial applications of lithium niobate for optical modulators based on the electro-optic effect,as well as optical wavelength converters based on secondorder nonlinear effects,e.g.,second-harmonic,sum-,and difference-frequency generations.TFLN has also created vast opportunities for applications and integrated solutions for optical parametric amplification and oscillation,cascaded nonlinear effects,such as low-harmonic generation;third-order nonlinear effects,such as supercontinuum generation;optical frequency comb generation and stabilization;and nonclassical nonlinear effects,such as spontaneous parametric downconversion for quantum optics.Recent progress in nonlinear integrated photonics on TFLN for all these applications,their current trends,and future opportunities and challenges are reviewed.

Development trends in silicon photonics

Silicon photonics has become one of the major technologies in this very information age. It has been intensively pursued by researchers and entrepreneurs all over the world in recent years. Achieving the large scale silicon photonic integration, particularly monolithic integration, is the final goal so that high density data communication will become much cheaper, more reliable, and less energy consuming. Comparing with the developed countries, China may need to invest more to develop top down nanoscale integration capability （more on processing technology） to sustain the development in silicon photonics and to elevate its own industry structure.

Large group-index bandwidth product empty core slow light photonic crystal waveguides for hybrid silicon photonics

这份报纸在绝缘体上在硅调查慢轻的繁殖宽槽 photonic 水晶波导(PCW ) 。二个设计计划被介绍，分别地依靠洞格子和槽的分散工程。模式模式和乐队图被 3D 飞机波浪扩大方法计算。然后，联合并且慢轻的繁殖在完整的 Mach-Zehnder 干涉仪(MZI ) 用有限差别时间领域方法被建模。结果显示出高振幅干扰穗和高联合效率。设备的制造和测量超过 50 与组索引导致慢轻的繁殖，当在也观察的乐队边附近的多重散布和局部性的模式时。这研究提供卓见因为在空核心槽的损失高组织索引波导。

Wavelength-mode pulse interleaver on the silicon photonics platform

We report an 8-channel wavelength-mode optical pulse interleaver on a silicon photonic chip.Wavelength-and mode-division multiplexing techniques are combined to increase the repetition rate of the pulses without adding the complexity of a single dimension.The interleaver uses a cascaded Mach–Zehnder interferometer architecture as a wavelength-division(de)multiplexer,an asymmetric directional coupler as a mode(de)multiplexer,and various lengths of silicon waveguides as delay lines.A pulse sequence with a time interval of 125 ps is implemented with the repetition rate being eight times that of the initial one.The demonstrated wavelength-mode multiplexing approach opens a new route for the generation of high-speed optical pulses.

Light People:Professor Xianfeng Chen spoke about integrated photonics

Editorial In 1969,Stewart E.Miller published"ntegrated optics:an introduction",which outlined a proposal for a miniature form of laser beam circuitry,marking the frst research paper about what is now known as integrated photonics.Now half a century has passed,integrated photonics grew robustly from integrating a limited number of devices and functions towards versatile and industrialized photonic integrated circuits.In this interview,Light:Science&Applications invited Prof.Xianfeng Chen[see the"Short Bio"section]to share his insight about the past,present and future of integrated photonics.