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Resonant label-free biosensors using silicon-on-insulator substrates represent a cutting-edge domain in optical sensing. These devices leverage the high refractive index contrast of silicon-on-insulator materials to create highly sensitive, compact sensors. They are crucial for real-time, precise biomolecular detection in healthcare diagnostics, environmental monitoring, and drug discovery, marking a significant stride in microphotonic technology and its practical applications. Different ring-based resonant configurations have been explored in this context, but a definitive comparative assessment of them was previously lacking in the literature. In our work, we experimentally compare four different ring configurations in terms of figure-of-merit (FoM), showing that the slotted ring performs better than competitive approaches. A silicon photonic chip including tens of ring resonators (RRs) was fabricated and optically characterized considering air and aqueous solutions as cladding. The best sensitivity achieved was 64 nm/RIU for the slotted ring configuration. The ring displayed a Q-factor in the order of $2.57\times 10^{{4}}$ , and the best estimated resolution was in the order of ${10}^{-{4}}~\text {RIU}$ in water. The measured FoM was greater than ${200}~\text {RIU}^{-{1}}$ .

Photonic integrated circuits are facilitating the development of optical neural networks, which have the potential to be both faster and more energy efficient than their electronic counterparts since optical signals are especially well-suited for implementing matrix multiplications. However, accurate programming of photonic chips for optical matrix multiplication remains a difficult challenge. Here, we describe both simple analytical models and data-driven models for offline training of optical matrix multipliers. We train and evaluate the models using experimental data obtained from a fabricated chip featuring a Mach-Zehnder interferometer mesh implementing 3-by-3 matrix multiplication. The neural network-based models outperform the simple physics-based models in terms of prediction error. Furthermore, the neural network models are also able to predict the spectral variations in the matrix weights for up to 100 frequency channels covering the C-band. The use of neural network models for programming the chip for optical matrix multiplication yields increased performance on multiple machine learning tasks.

Graphs have provided an expressive mathematical tool to model quantum-mechanical devices and systems. In particular, it has been recently discovered that graph theory can be used to describe and design quantum components, devices, setups and systems, based on the two-dimensional lattice of parametric nonlinear optical crystals and linear optical circuits, different to the standard quantum photonic framework. Realizing such graph-theoretical quantum photonic hardware, however, remains extremely challenging experimentally using conventional technologies. Here we demonstrate a graph-theoretical programmable quantum photonic device in very-large-scale integrated nanophotonic circuits. The device monolithically integrates about 2,500 components, constructing a synthetic lattice of nonlinear photon-pair waveguide sources and linear optical waveguide circuits, and it is fabricated on an eight-inch silicon-on-insulator wafer by complementary metal–oxide–semiconductor processes. We reconfigure the quantum device to realize and process complex-weighted graphs with different topologies and to implement different tasks associated with the perfect matching property of graphs. As two non-trivial examples, we show the generation of genuine multipartite multidimensional quantum entanglement with different entanglement structures, and the measurement of probability distributions proportional to the modulus-squared hafnian (permanent) of the graph’s adjacency matrices. This work realizes a prototype of graph-theoretical quantum photonic devices manufactured by very-large-scale integration technologies, featuring arbitrary programmability, high architectural modularity and massive manufacturing scalability.

We designed and fabricated a silicon photonic orbital angular momentum (OAM) multiplexer (MUX) chip that enables simultaneous wavelength-division multiplexing (WDM) and OAM mode-division multiplexing (MDM) in optical fiber communication systems. We successfully utilized the fabricated MUX chip to demonstrate simultaneous 3 OAM MDM transmission as well as OAM MDM/WDM transmission with an 800-m OAM ring-core fiber. In both cases, 10 Gbit/s OOK signals were utilized and BERs below the 7% FEC limit were obtained.

Light carrying orbital angular momentum constitutes an important resource for both classical and quantum information technologies. Its inherently unbounded nature can be exploited to generate high-dimensional quantum states or for channel multiplexing in classical and quantum communication in order to significantly boost the data capacity and the secret key rate, respectively. While the big potentials of light owning orbital angular momentum have been widely ascertained, its technological deployment is still limited by the difficulties deriving from the fabrication of integrated and scalable photonic devices able to generate and manipulate it. Here, we present a photonic integrated chip able to excite orbital angular momentum modes in an 800 m long ring-core fiber, allowing us to perform parallel quantum key distribution using two and three different modes simultaneously. The experiment sets the first steps towards quantum orbital angular momentum division multiplexing enabled by a compact and light-weight silicon chip, and further pushes the development of integrated scalable devices supporting orbital angular momentum modes.

We propose and experimentally demonstrate a high-order coupled-resonator optical waveguide (CROW) nanobeam filter with semi-symmetrical Fano resonance enhancement. Thanks to the tight arrangement of multiple nanobeams and assistance of the partial transmission element, the designed filter has a high-contrast transmission and low insertion loss. Finally, the fabricated filter has a compact size of 20µm×10µm, a high extinction ratio as much as 70 dB, and an insertion loss as low as 1 dB. This filter shows a passive structure without thermal control configuration for calibration on each resonator. This compact filter can be a basic building block for various applications requiring high extinction ratio filtering, such as single-photon source filtering of integrated photon chips.

Presents corrections to the paper, (Data-Driven Modeling of Mach-Zehnder Interferometer-Based Optical Matrix Multipliers).

General-purpose quantum computers can, in principle, entangle a number of noisy physical qubits to realize composite qubits protected against errors. Architectures for measurement-based quantum computing intrinsically support error-protected qubits and are the most viable approach for constructing an all-photonic quantum computer. Here we propose and demonstrate an integrated silicon photonic scheme that both entangles multiple photons, and encodes multiple physical qubits on individual photons, to produce error-protected qubits. We realize reconfigurable graph states to compare several schemes with and without error-correction encodings and implement a range of quantum information processing tasks. We observe a success rate increase from 62.5% to 95.8% when running a phase-estimation algorithm without and with error protection, respectively. Finally, we realize hypergraph states, which are a generalized class of resource states that offer protection against correlated errors. Our results show how quantum error-correction encodings can be implemented with resource-efficient photonic architectures to improve the performance of quantum algorithms.

Ring resonator is an essential element in silicon integrated circuit, it is widely used as filter, wavelength multiplexer and switch in single-mode operation regime. As the rapid development of mode division multiplexing (MDM) technique, ring resonator that can process multi-mode signals simultaneously and uniformly is highly desired. However, the severe modal dispersion makes identical transmission for different modes very hard. In this paper, by breaking through the limitation of conventional multi-mode manipulation design with evanescent coupling or mode interference, we propose and demonstrate a multi-mode ring resonator (MMRR) inspired by the free space geometric optics. Arbitrary number of supporting modes can be achieved by simply widening the waveguide width. For proof-of-concept demonstration, an MMRR supporting four modes is fabricated with uniform transmittance. Furthermore, architecture of cascaded four MMRRs are also demonstrated experimentally.

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 67×28µm^2 under a standard silicon photonics fabrication process without silicon air trench or undercut process, and the modulation bandwidth is measured to be 39 kHz.

Graphene has been widely used in silicon-based optical modulators for its ultra-broadband light absorption and ultrafast optoelectronic response. By incorporating graphene and slow-light silicon photonic crystal waveguide (PhCW), here we propose and experimentally demonstrate a unique double-layer graphene electro-absorption modulator in telecommunication applications. The modulator exhibits a modulation depth of 0.5 dB/μm with a bandwidth of 13.6 GHz, while graphene coverage length is only 1.2 μm in simulations. We also fabricated the graphene modulator on silicon platform, and the device achieved a modulation bandwidth at 12 GHz. The proposed graphene-PhCW modulator may have potentials in the applications of on-chip interconnections.

Graphene-based photodetectors, taking advantage of the high carrier mobility and broadband absorption in graphene, have recently seen rapid development. However, their performance with respect to responsivity and bandwidth is still limited by the weak light-graphene interaction and large resistance-capacitance product. Here, we demonstrate a waveguide-coupled integrated graphene plasmonic photodetector on a silicon-on-insulator platform. Benefiting from plasmon-enhanced graphene-light interaction and subwavelength confinement of the optical energy, a small-footprint graphene-plasmonic photodetector is achieved working at the telecommunication window, with a large a bandwidth beyond 110 GHz and a high intrinsic responsivity of 360 mA/W. Attributed to the unique electronic band structure of graphene and its ultra-broadband absorption, operational wavelength range extending beyond mid-infrared, and possibly further, can be anticipated. Our results show that the combination of graphene with plasmonic devices has great potential to realize ultra-compact, high-speed optoelectronic devices for graphene-based optical interconnects.

Integrated optics provides a versatile platform for quantum information processing and transceiving with photons1–8. The implementation of quantum protocols requires the capability to generate multiple high-quality single photons and process photons with multiple high-fidelity operators9–11. However, previous experimental demonstrations were faced by major challenges in realizing sufficiently high-quality multi-photon sources and multi-qubit operators in a single integrated system4–8, and fully chip-based implementations of multi-qubit quantum tasks remain a significant challenge1–3. Here, we report the demonstration of chip-to-chip quantum teleportation and genuine multipartite entanglement, the core functionalities in quantum technologies, on silicon-photonic circuitry. Four single photons with high purity and indistinguishablity are produced in an array of microresonator sources, without requiring any spectral filtering. Up to four qubits are processed in a reprogrammable linear-optic quantum circuit that facilitates Bell projection and fusion operation. The generation, processing, transceiving and measurement of multi-photon multi-qubit states are all achieved in micrometre-scale silicon chips, fabricated by the complementary metal–oxide–semiconductor process. Our work lays the groundwork for large-scale integrated photonic quantum technologies for communications and computations.

Due to their novel electronic and optical properties, atomically thin layered two-dimensional (2D) materials are becoming promising to realize novel functional optoelectronic devices including photodetectors, modulators, and lasers. However, light–matter interactions in 2D materials are often weak because of the atomic-scale thickness, thus limiting the performances of these devices. Metallic nanostructures supporting surface plasmon polaritons show strong ability to concentrate light within subwavelength region, opening thereby new avenues for strengthening the light–matter interactions and miniaturizing the devices. This review starts to present how to use metallic nanostructures to enhance light–matter interactions in 2D materials, mainly focusing on photoluminescence, Raman scattering, and nonlinearities of 2D materials. In addition, an overview of ultraconfined acoustic-like plasmons in hybrid graphene–metal structures is given, discussing the nonlocal response and quantum mechanical features of the graphene plasmons and metals. Then, the review summarizes the latest development of 2D material–based optoelectronic devices integrated with plasmonic nanostructures. Both off-chip and on-chip devices including modulators and photodetectors are discussed. The potentials of hybrid 2D materials plasmonic optoelectronic devices are finally summarized, giving the future research directions for applications in optical interconnects and optical communications.

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Implementing large instances of quantum algorithms1–5requires the processing of many quantum information carriers in a hardware platform that supports the integration of different components6. Although established semiconductor fabrication processes can integrate many photonic components7, the generation and algorithmic processing of many photons has been a bottleneck in integrated photonics. Here, we report the on-chip generation and algorithmic processing of quantum states of light with up to eight photons. Switching between different optical pumping regimes, we implement the scattershot8,9, Gaussian10and standard boson sampling3,11–14protocols in the same silicon chip, which integrates linear and nonlinear photonic circuitry. We use these results to benchmark a quantum algorithm for calculating molecular vibronic spectra4. Our techniques can be readily scaled for the on-chip implementation of specialized quantum algorithms with tens of photons, pointing the way to efficiency advantages over conventional computers15. Experiments report the generation and manipulation of eight photons on a silicon chip. Integrating linear and nonlinear photonic circuitry, three different boson sampling approaches are implemented and used to compute molecular vibronic spectra.

Geothermal resource is one of the most promising renewable energies, which is successfully accessed by the enhanced geothermal system (EGS) characterized by a complex fracture network. Therefore, complex fracture networks with hydraulic and natural fractures of different fracture orientations and intensities are established in this study. The natural fractures are randomly distributed in the geothermal reservoir. The working fluid flowing and heat exchange in the geothermal reservoir are simulated by coupling model, considering the effects of temperature variation on the density, viscosity, thermal conductivity and specific heat capacity of working fluid, and the permeability of reservoir matrix. Effects of natural fracture orientation and intensity, position of injection and production wells, and geothermal reservoir permeability on the heat production behavior are analyzed. The simulation reveals that the low-temperature region in the geothermal reservoir could breakthrough along natural fractures. When the direction of injection and production wells is consistent with the orientation range of natural fractures, the reservoir exploitation ratio and the heat extraction rate are the largest, but the temperature stability time of the produced fluid is the shortest and the cooling rate is the fastest. Increasing the intensity of natural fractures is helpful to increase the heat extraction rate, but the temperature of production wells decreases more easily. Increasing the distance perpendicular to the hydraulic fracture can better improve the performance of production wells. High reservoir permeability is not conducive to the stability of production fluid temperature, but can greatly increase the exploitation ratio of the geothermal reservoir.

Due to the limitation of actual shale gas reservoir conditions and fracturing technologies, artificial fracture networks are different greatly even in the same or similar stimulated reservoir volume. Deviations and even faults occur in evaluation and cognition if only the stimulated reservoir volume (SRV) is used to characterize and evaluate the effect of stimulation. In this paper, the spatial distribution of artificial fractures and natural fractures and the internal pressure state and degree of reserve recovery of stimulated shale gas reservoirs were studied by means of artificial fracture propagation numerical simulation and production numerical simulation. And three concepts were proposed, i.e., shale gas fracture network, ideal fracture network and appropriate-stimulation degree of fracture network. The study results indicate that, at the end of reservoir development, target zones can be classified into three types (i.e., relatively appropriate stimulation zone, transitional stimulation zone, and uncompleted stimulation zone) according to the recovery degree and production time of stimulated reservoirs; and that the final morphologic parameter of fracture networks and the reservoir characteristic are two main factors affecting the appropriate-stimulation degree of fracture networks. As for a specific gas reservoir, the orientation, length, conduction, height and spatial location of its fracture network are the main factors influencing its appropriate-stimulation degree if the well trajectory is set. The proposal of the theory on the appropriate-stimulation degree of hydraulic fracture networks in shale gas reservoir enriches the theoretical system of shale reservoir stimulation technology, and it can be used as the reference for characterizing the fracture systems in other unconventional reservoirs, such as tight oil and gas reservoirs.

We derive from Maxwell’s equations full-vectorial nonlinear propagation equations of four-wave mixing valid in straight semiconductor-on-insulator waveguides. Special attention is given to the resulting effective mode area, which takes a convenient form known from studies in photonic crystal fibers, but has not been introduced in the context of integrated waveguides. We show that the difference between our full-vectorial effective mode area and the scalar equivalent often referred to in the literature may lead to mistakes when evaluating the nonlinear refractive index and optimizing designs of new waveguides. We verify the results of our derivation by comparing it to experimental measurements in a silicon-on-insulator waveguide, taking tolerances on fabrication parameters into account.

A novel concept to generate a linear chirped microwave signal is proposed and experimentally demonstrated. The frequency to time mapping method is employed, where the photonic crystal waveguide Mach–Zehnder interferometer structure acts as the spectral shaper thanks to the slow light effect. By optimizing the structural parameters of the photonic crystal waveguide, a linear chirped microwave signal with the time-bandwidth product of about 30 is experimentally obtained. The impact of the slow light photonic crystal waveguide on the generated linear chirped microwave signal is also investigated. The utilization of the slow light effect brings in significant advantages, including the ultra-small footprint of 0.096  mm^2 and simple structure to our scheme, which may be of great importance towards its potential applications.

A photonic differentiator (DIFF) plays a crucial role in photonic circuits. Despite the fact that a DIFF having a terahertz bandwidth has been reported, the practical bandwidth is limited to being a bandpass response. In this Letter, we propose the concept of a bandwidth-adaptable DIFF, which exploits the slow light effect in a photonic crystal waveguide (PhCW) to overcome the inherent bandwidth limitation of current photonic DIFFs. We fabricated a PhCW Mach–Zehnder interferometer (PhCW-MZI) on the silicon-on-isolator material platform to validate our concept. Input Gaussian pulses with full width to half-maximums (FWHMs) ranging from 2.7 to 81.4 ps are accurately differentiated using our PhCW-MZI. Our all-passive scheme circumvents the bandwidth bottlenecks of previously reported photonic DIFFs and can greatly broaden the application area of photonic DIFFs.

Abstract: 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. Graphical Abstract:

In this paper, we proposed and experimentally demonstrated a route-asymmetrical light transmission scheme based on the thermal radiative effect, which means that forward and backward propagations of an optical device have different transmittances provided they are not present simultaneously. Employing a fiber-chip-fiber optomechanical system, our scheme has successfully achieved a broad operation bandwidth of at least 24 nm and an ultra-high route-asymmetrical transmission ratio (RATR) up to 63 dB. The route-asymmetrical device has been demonstrated effectively with not only the continuous- wave (CW) light but also 10 Gbit/s on-off-keying (OOK) digital signals. Above mentioned unique features can be mostly attributed to the significant characteristics of the thermal radiative effect, which could cause a fiber displacement up to tens of microns. The powerful and significant thermal radiative effect opens up a new opportunity and method for route-asymmetrical light transmission. Moreover, this research may have important applications in all-optical systems, such as the optical limiters and ultra-low loss switches.

Wavelength conversion based on degenerate four-wave mixing (FWM) was demonstrated and compared between silicon nanowire and microring resonator (MRR). 15 dB enhancement of conversion efficiency (CE) with relatively low input pump power (5 mW) was achieved experimentally in an MRR. The impacts of bus waveguide length and propagation loss were theoretically analyzed under the effect of nonlinear loss.

Silicon micro-ring resonators (MRRs) are compact and versatile devices whose periodic frequency response can be exploited for a wide range of applications. In this paper, we review our recent work on linear all-optical signal processing applications using silicon MRRs as passive filters. We focus on applications such as modulation format conversion, differential phase-shift keying (DPSK) demodulation, modulation speed enhancement of directly modulated lasers (DMLs), and monocycle pulse generation. The possibility to implement polarization diversity circuits, which reduce the polarization dependence of standard silicon MRRs, is illustrated on the particular example of DPSK demodulation.

An ultra-compact and broadband higher order-mode pass filter in a 1D photonic crystal silicon waveguide is proposed and experimentally demonstrated. The photonic crystal is designed for the lower order mode to work in the photonic band gap, while the higher order mode is located in the air band. Consequently, light on the lower order mode is prohibited to pass through the filter, while light on a higher order mode can be converted to a Bloch mode in the photonic crystal and pass through the filter with low insertion loss. As an example, we fabricate a ∼15-μm-long first-order-mode pass filter that filters out the fundamental mode and provides a measured insertion loss of ∼1.8??dB for the first-order-mode pass signals. The extinction ratio is measured to be around 50 dB (with a variation of ±10??dB due to the detection limitation of the measurement setup) in the measured wavelength range from 1480 to 1580 nm. Additionally, calculations predict the extinction ratio to be larger than 50 dB in a 170 nm broad bandwidth.

Based on the research results of lab triaxial hydraulic fracturing simulation experiments, field fracturing practice, and theory analysis, the factors affecting the growth of hydraulic fracture network in shale reservoirs, including brittleness, difference of horizontal stress, distribution and mechanical characteristics of natural fractures, fluid viscosity and fracturing parameters, etc are analyzed in this study. The results show that the growth of fracture network in shale reservoirs is affected by geological factors and engineering factors jointly. From the perspective of reservoir geological factors, the higher the rock brittleness, the more developed the natural fractures, and the poorer the natural fracture consolidation, the more likely hydraulic fracture network will be formed. From the perspective of fracturing engineering factors, lower fluid viscosity and larger fracturing scale will be more helpful to the formation of extensive fracture network. On the basis of the analysis of single factors, a multi-factor coupling index has been established to characterize the growth degree of hydraulic fracture network and evaluate the complexity of hydraulic fractures after the fracturing of shale reservoirs.

A scheme for high-speed clock recovery from return-to-zero (RZ) signal with microring resonators is presented. By using a silicon microring resonator (MRR) for clock extraction and a 3-order nonlinear series-coupled microring resonator (SCMR) for amplitude equalization, clock pulses with amplitude modulation less than 1?dB can be obtained. The proposed scheme is also designed and numerically studied by 3D full vectorial film mode matching method (FMM) and coupled mode theory (CMT). Simulation results show that clock can be recovered at 40?Gbit/s with short rise- and fall- times.

The microring resonator is a high-performance and low-cost optical waveguide device, suitable for integration with large dimensions. This paper presents the design of laterally coupled racetrack microring resonators working around 1.55m, using combinations of the 3D full vectorial film mode matching method, the coupled mode theory and the parameter model. This combined simulation technique shows convenience to perform the design process.

A simple approach based on six transfer cells and simulated annealing algorithm for analyzing and tailoring the spectra of arbitrary microring resonator arrays is presented. Coupling coefficients, ring sizes, and waveguide lengths of microring resonator arrays can be arbitrary in this approach. After developing this approach, several examples are demonstrated and optimized for various configurations of microring resonator arrays. Simulation results show that this approach is intuitive, efficient, and intelligent for applications based on microring resonator arrays.

The present study shows that COS‐7 cells transiently transfected and maintained on positively charged (trimethylamine‐coated) microcarrier beads synthesize recombinant protein at higher levels and for longer periods of time than cells transfected and maintained on polystyrene flasks in monolayer culture. Sustained, high‐level synthesis was observed with secreted chimeric proteins (murine E‐selectin– and P‐selectin‐human IgM chimeras) and a secreted hematopoietic growth factor (granulocyte‐macrophage colony‐stimulating factor). Studies with green fluorescent protein indicated that the transfected cells attached more firmly to the trimethylamine‐coated microcarriers than to polystyrene flasks. After 10–14 days in culture, most of the transfected cells detached from the surface of the polystyrene flasks, whereas most transfected cells remained attached to the microcarriers. The transiently transfected microcarrier cultures produced higher levels of protein per transfected cell due to this prolonged attachment. The prolonged attachment and higher output of transfected cells on microcarriers resulted in a 5‐fold increase in protein production from a single transfection over two weeks. Thus, microcarrier‐based transient transfection yields quantities of recombinant proteins with a significant savings of time and reagents over monolayer culture.

We design and fabricate an ultrahigh coupling efficiency (CE) fully etched apodized grating coupler on the silicon-on-insulator (SOI) platform using subwavelength photonic crystals and bonded aluminum mirror. Fabrication error sensitivity and coupling angle dependence are experimentally investigated. A record ultrahigh CE of −0.58  dB with a 3 dB bandwidth of 71 nm and low back reflection are demonstrated.

We present an efficient method to design apodized grating couplers with Gaussian output profiles for efficient coupling between standard single mode fibers and silicon chips. An apodized grating coupler using fully etched photonic crystal holes on the silicon-on-insulator platform is designed, and fabricated in a single step of lithography and etching. An ultralow coupling loss of −1.74  dB (67% coupling efficiency) with a 3 dB bandwidth of 60 nm is experimentally measured.

We propose and demonstrate a polarization splitter and rotator (PSR) built on a silicon-on-insulator platform. The PSR is constructed with a tapered waveguide followed by a 2×2 multimode interferometer and can be simply fabricated in a single lithography and etching step. A low insertion loss (<2.5  dB with minimum insertion loss of 0.6 dB) and a low polarization crosstalk (<−12  dB) over a wide operation bandwidth (∼100  nm) with a large fabrication tolerance (>50  nm) are experimentally demonstrated.

We propose and demonstrate the use of a single semiconductor optical amplifier (SOA) and optical filtering to time demultiplex tributaries from an optical time division multiplexing-differential phase shift keying (OTDM-DPSK) signal. The scheme takes advantage of the fact that phase variations added to the target channel by cross-phase modulation from the control signal are effectively subtracted in the differential demodulation scheme employed for DPSK signals. Demultiplexing from 80 to 40?Gbit/s is demonstrated with moderate power penalty using an SOA with recovery time twice as long as the bit period at 80?Gbit/s. Large dynamic ranges for the input power and SOA current are experimentally demonstrated. The scheme is expected to be scalable toward higher bit rates.

An efficient TE–TM polarization converter built on a silicon-on-insulator nanophotonic platform is demonstrated. The strong cross-polarization coupling effect in air-cladded photonic-wire waveguides is employed to realize the conversion. A peak TE–TM coupling efficiency of 87% (−0.6?dB insertion loss) is measured experimentally. A polarization conversion efficiency of >92% with an overall insertion loss of <−1.6?dB is obtained in a wavelength range of 40?nm. The proposed device is compact, with a total length of 44?μm and can be fabricated with one lithography and etching step.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

We demonstrate a very high coincidence-to-accidental ratio of 673 using continuous-wave photon-pair generation in a silicon strip waveguide through spontaneous four-wave mixing. This result is obtained by employing on-chip photonic-crystal-based grating couplers for both low-loss fiber-to-chip coupling and on-chip suppression of generated spontaneous Raman scattering noise. We measure a minimum heralded second-order correlation of , demonstrating that our source operates in the single-photon regime with low noise.