Compact photonic model based on coupled-mode theory for nonlinear interactions in electronic-photonic co-simulation.

This paper demonstrates a Verilog-A compact photonic model based on coupled-mode theory for nonlinear interactions, including four-wave mixing (FWM) and cross-phase modulation (XPM), to present a general framework and methodology for modeling nonlinear interactions in electronic-photonic co-simulation. The model is compatible with existing electronic design automation (EDA) platforms and can support rapid electronic-photonic co-simulation. It avoids describing the complicated physical process of the FWM and provides an easy way for system designers to monitor the dynamics of the critical optical parameters, thus accelerating the co-design and co-optimization of the electronic-photonic hybrid systems incorporating FWM.

On-chip silicon photonic nanohole metamaterials enabled high-density waveguide arrays.

High-density silicon waveguide arrays manufactured on a complementary metal-oxide-semiconductor (CMOS)-foundry platform hold great promise for optical information processing and photonic integration. However, evanescent waves arising from nanoscale confinement would cause significant optical crosstalk in waveguide arrays, which remains a vital issue in various applications. Here, by utilizing silicon photonic nanohole metamaterials, we propose a scheme to greatly suppress the crosstalk in the devices and then demonstrate ultra-compact low-crosstalk waveguide arrays.

Co-packaged optics (CPO): status, challenges, and solutions.

Due to the rise of 5G, IoT, AI, and high-performance computing applications, datacenter traffic has grown at a compound annual growth rate of nearly 30%. Furthermore, nearly three-fourths of the datacenter traffic resides within datacenters. The conventional pluggable optics increases at a much slower rate than that of datacenter traffic.

Recent advances in integrated optical directed logic operations for high performance optical computing: a review.

Optical directed logic (DL) is a novel logic operation scheme that employs electrical signals as operands to control the working states of optical switches to perform the logic functions. This review first provides an overview of the concept and working principle of DL. The developing trends of DL computing are then discussed in detail, including the fundamental optical DL gates, combinational optical DL operations, reconfigurable logic computing, low power optical logic computing, and programmable photonic network.

Resolving the scalability challenge of wavelength locking for multiple micro-rings via pipelined time-division-multiplexing control.

Micro-ring resonator (MRR) is a key photonic device that has a wide range of applications but suffers from wavelength uncertainties. For almost all practical applications, a wavelength controller is required for each MRR. The wavelength controller is usually much larger than the MRR.

Graphene plasmonic spatial light modulator for reconfigurable diffractive optical neural networks.

Terahertz (THz) diffractive optical neural networks (DONNs) highlight a new route toward intelligent THz imaging, where the image capture and classification happen simultaneously. However, the state-of-the-art implementation mostly relies on passive components and thus the functionalities are limited. The reconfigurability can be achieved through spatial light modulators (SLMs), while it is not clear what device specifications are required and how challenging the associated device implementation is.

Demonstration of an ultra-compact 8-channel sinusoidal silicon waveguide array for optical phased array.

Here we demonstrate an ultra-compact 8-channel sinusoidal silicon waveguide array for an optical phased array. In our device, based on sinusoidal bending, the cross talk (CT) between waveguides can be efficiently reduced with a waveguide pitch of only 695 nm. For the transverse electric (TE) mode, the simulation results show that the insertion loss (IL) of the 100-µm-long device is 0.

Ultra-compact multimode waveguide bend with shallowly etched grooves.

In this work, an ultra-sharp multimode waveguide bend (MWB) based on gradient shallowly etched grooves is proposed and demonstrated. With a bending radius of only 5.6 μm, our shallowly-etched-groove multimode waveguide bend (SMWB) can enable low excess loss and low-crosstalk propagation with the four lowest-order TE mode-channels, simultaneously.

Design of an ultra-compact low-crosstalk sinusoidal silicon waveguide array for optical phased array.

In this work, an ultra-compact low-crosstalk sinusoidal silicon waveguide array is proposed and analyzed. We first design a pair of low-crosstalk sinusoidal silicon waveguides with a pitch of 695 nm, where the sinusoidal bends are the key to reduce the crosstalk between waveguides. Then, based on this idea, we propose a low-crosstalk sinusoidal silicon waveguide array with a 695 nm pitch.

Self-homodyne wavelength locking of a silicon microring resonator.

We propose and experimentally demonstrate a self-homodyne locking method for a silicon microring resonator (MRR). The device employs a self-homodyne detection structure and consists of a tunable MRR with two directional couplers along the ring for monitoring, two phase shifters to calibrate the phase difference between the two monitored optical signals, and a Y-branch to combine the two signals. A single photodetector is used to detect the output power of the Y-branch.

Author Correction: All-optical control of light on a graphene-on-silicon nitride chip using thermo-optic effect.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Single-resonance silicon nanobeam filter with an ultra-high thermo-optic tuning efficiency over a wide continuous tuning range.

Energy-efficient tunability is highly desired for silicon photonic devices. We demonstrate a thermo-optic tunable filter with an ultra-high tuning efficiency based on a suspended photonic crystal nanobeam cavity. Attributed to the ultra-small mode volume and free-standing waveguide structure, a tuning efficiency of 21 nm/mW is achieved over a wide single-resonance tuning range of ∼43.

Compact CWDM interleaver based on an interfering loop containing a one-dimensional Fabry-Perot cavity.

We propose and experimentally demonstrate a compact silicon photonic interleaver based on an interfering loop containing a 1D Fabry-Perot (FP) cavity for coarse wavelength division multiplexing (CWDM) applications. The interleaver consists of a directional coupler and a FP cavity designed to minimize the channel crosstalk. Instead of using an off-chip optical circulator, the reflection light of the interleaver can be separated from the input by placing two identical interleavers in a Mach-Zehnder interferometer (MZI) structure for practical applications.

All-optical control of light on a graphene-on-silicon nitride chip using thermo-optic effect.

All-optical signal processing avoids the conversion between optical signals and electronic signals and thus has the potential to achieve a power efficient photonic system. Micro-scale all-optical devices for light manipulation are the key components in the all-optical signal processing and have been built on the semiconductor platforms (e.g.

Ultra-compact tunable silicon nanobeam cavity with an energy-efficient graphene micro-heater.

We propose and experimentally demonstrate an ultra-compact silicon photonic crystal nanobeam (PCN) cavity with an energy-efficient graphene micro-heater. Owing to the PCN cavity with an ultra-small optical mode volume of 0.145 µm, the light-matter interaction is greatly enhanced and the thermo-optic (TO) tuning efficiency is increased.

Silicon photonic bandpass filter based on apodized subwavelength grating with high suppression ratio and short coupling length.

A compact silicon bandpass filter with high sidelobe suppression is proposed and experimentally demonstrated using an apodized subwavelength grating (SWG) coupler. The device is implemented by placing a SWG waveguide next to a strip waveguide, and apodization is employed with a Gaussian profile to taper the gap between the two waveguides. A high sidelobe suppression ratio of 27 dB can be obtained with a 3-dB bandwidth of 8.

High-extinction-ratio silicon polarization beam splitter with tolerance to waveguide width and coupling length variations.

We demonstrate a compact silicon polarization beam splitter (PBS) based on grating-assisted contradirectional couplers (GACCs). Over 30-dB extinction ratios and less than 1-dB insertion losses are achieved for both polarizations. The proposed PBS exhibits tolerance in width variation, and the polarization extinction ratios remain higher than 20 dB for both polarizations when the width variation is adjusted from + 10 to -10 nm.

Wavelength and bandwidth-tunable silicon comb filter based on Sagnac loop mirrors with Mach-Zehnder interferometer couplers.

We propose and experimentally demonstrate a wavelength and bandwidth-tunable comb filter based on silicon Sagnac loop mirrors (SLMs) with Mach-Zehnder interferometer (MZI) couplers. By thermally tuning the MZI couplers in common and differential modes, the phase shift and reflectivity of the SLMs can be changed, respectively, leading to tunable wavelength and bandwidth of the comb filter. The fabricated comb filter has 93 comb lines in the wavelength range from 1535 nm to 1565 nm spaced by ~0.

Proposed high-speed micron-scale spatial light valve based on a silicon-graphene hybrid structure.

We propose a new ultracompact CMOS-compatible variable-transmission spatial light valve based on a silicon-graphene hybrid structure. Normally incident ∼1560  nm light can be coupled to a silicon-graphene-based 1D photonic crystal cavity through a perturbation-based diffractive coupling scheme. The lightwave modulation is achieved by tuning the Fermi level of the graphene, which can change both the loss and the resonant wavelength of the cavity.

Broadband photodetection in a microfiber-graphene device.

We propose and experimentally demonstrate a microfiber-graphene device. Owing to the interaction between the graphene film and the evanescent field leaked from the microfiber, the hybrid photoconductive device exhibits a high photoresponse. A maximum photocurrent responsivity of ~2.

Analysis of an electro-optic modulator based on a graphene-silicon hybrid 1D photonic crystal nanobeam cavity.

We propose and numerically study an on-chip graphene-silicon hybrid electro-optic (EO) modulator operating at the telecommunication band, which is implemented by a compact 1D photonic crystal nanobeam (PCN) cavity coupled to a bus waveguide with a graphene sheet on top. Through electrically tuning the Fermi level of the graphene, both the quality factor and the resonance wavelength can be significantly changed, thus the in-plane lightwave can be efficiently modulated. Based on finite-difference time-domain (FDTD) simulation results, the proposed modulator can provide a large free spectral range (FSR) of 125.

Bottom-up Fabrication of Graphene on Silicon/Silica Substrate via a Facile Soft-hard Template Approach.

In this work, a novel soft-hard template method towards the direct fabrication of graphene films on silicon/silica substrate is developed via a tri-constituent self-assembly route. Using cetyl trimethyl ammonium bromide (CTAB) as a soft template, silica (SiO2) from tetramethoxysilane as a hard template, and pyrene as a carbon source, the self-assembly process allows the formation of a sandwich-like SiO2/CTAB/pyrene composite, which can be further converted to high quantity graphene films with a thickness of ~1 nm and a size of over 5 μm by thermal treatment. The morphology and thickness of the graphene films can be effectively controlled through the adjustment of the ratio of pyrene to CTAB.

High-capacity and low-cost long-reach OFDMA PON based on distance-adaptive bandwidth allocation.

We propose and experimentally demonstrate a distance-adaptive bandwidth allocation scheme to realize high-capacity long-reach orthogonal frequency division multiple access passive optical network (OFDMA PON) with cost-effective electro-absorption modulator (EAM). In our scheme, the subcarriers in downstream OFDM signal are properly allocated to the optical network units (ONUs) with different fiber transmission lengths. By this means, the detrimental influence of power fading induced by dispersion and chirp can be avoided, thus all OFDM subcarriers can be modulated with high-order quadrature amplitude modulation (QAM) format, leading to a high transmission capacity.

Reconfigurable electro-optical directed-logic circuit using carrier-depletion micro-ring resonators.

Here we demonstrate a reconfigurable electro-optical directed-logic circuit based on a regular array of integrated optical switches. Each 1×1 optical switch consists of a micro-ring resonator with an embedded lateral p-n junction and a micro-heater. We achieve high-speed on-off switching by applying electrical logic signals to the p-n junction.

Efficient modulation of 1.55 μm radiation with gated graphene on a silicon microring resonator.

The gate-controllability of the Fermi-edge onset of interband absorption in graphene can be utilized to modulate near-infrared radiation in the telecommunication band. However, a high modulation efficiency has not been demonstrated to date, because of the small amount of light absorption in graphene. Here, we demonstrate a ∼ 40% amplitude modulation of 1.