Photonic Switching Research Articles

Dynamically tunable third-harmonic generation with all-dielectric metasurfaces incorporating phase-change chalcogenides.

Subwavelength nonlinear optical sources with high efficiency have received extensive attention, although strong dynamic controllability of these sources is still elusive. Germanium antimony telluride (GST) as a well-established phase-change chalcogenide is a promising candidate for the reconfiguration of subwavelength nanostructures due to the strong non-volatile change of the index of refraction between its amorphous and crystalline states. Here, we numerically demonstrate an electromagnetically-induced-transparency-based silicon metasurface actively controlled with a quarter-wave asymmetric Fabry-Perot cavity incorporating GST to modulate the relative phase of incident and reflected pump beams. We demonstrate a giant third-harmonic generation (THG) switch with a modulation depth as high as ∼70dB at the resonant band. We also demonstrate the possibility of multi-level THG amplitude modulation for the fundamental C-band by controlling the crystallization fraction of GST at multiple intermediate states. This study shows the high potential of GST-based fast dynamic nonlinear photonic switches for real-world applications ranging from communications to optical computing.

The main directions of scientific research in the field of introducing promising optical technologies in the infrastructure of transport systems.

Projects for the development of the transport system of the Russian Federation involve the introduction of advanced optical technologies in the infrastructure of high-speed modern transport systems in the context of the implementation of un- manned maintenance technologies. The article presents the following areas of research carried out by the authors: — organization of high-speed super-long single-span trunk communication lines without intermediate allocation of digital channels and paths laid in areas with limited access by the maintenance personnel in areas with no infrastructure (underwater obstacles, mountainous terrain, desert and swampy areas). The authors of the article highlighted the main factors influencing the design features of high-speed ultra-long single-span communication lines; — application of photonic switching (PS) technology in high-speed backbone communication networks to ensure operational logical reconfiguration of channel structures and digital paths. Within the framework of this direction of research, the authors have proposed methods for calculating the probabilities of the occurrence of internal blockages in various structures of PS based on the use of the method of mathematical induction in order to synthesize PS structures of a given capacity; — development of effective technologies for remote monitoring of the health of transport infrastructure facilities using passive optical transmission lines. Within the framework of this line of research, the authors analyze the features of the physical prop- erties of optical fibers used as a distributed sensor on the basis of which an integrated system can be built that can measure various physical parameters, such as vibration, deformation, temperature and other parameters.

Optical soliton in a one-dimensional array of a metal nanoparticle-microcavity complex

Quantum coherence can be enhanced by placing metal nanoparticles (MNPs) in optical microcavities. Combining localized-surface plasmon resonances (LSPRs), nonlinear interaction between the LSPR and microcavity arrays of a MNP-microcavity complex offer a unique playground to observe novel optical phenomena and develop novel concepts for quantum manipulation. Here we theoretically demonstrate that optical solitons are achievable with a one-dimensional array which consists of a chain of periodically spaced identical MNP-microcavity complex systems. These differ from the solitons which stem from the MNPs with nonlinear Kerr-like response; the optical soliton here originates from LSPR-microcavity interaction. Using experimentally achievable parameters, we identify the conditions under which the nonlinearity induced by LSPR-microcavity interaction allows us to compensate for the dispersion caused by photon hopping of adjacent microcavities. More interestingly, the dynamics of solitons can be modulated by varying the radius of the MNP. The presented results illustrate the potential to utilize the MNP-microcavity complex for light manipulation, as well as to guide the design of photon switch and on-chip photon architecture.

Magneto-optic effect on the pole of the parity-time symmetric coupled cavities

We propose a compound structure constructed by two magnetic cavities with parity-time (PT) symmetric configuration. Through the calculations based on transfer matrix, we find that the structure system has some unique properties that the usual PT symmetric structures do not have. The four incident conditions of the structure produce two sets of transmittance spectra and four different reflectance spectra in which the unusual amplification and absorption are shown. The huge amplification and absorption can be precisely tuned through the magnetic field. Furthermore, the amplification and absorption around the pole can be reversed through the change of incidence directions. Although the analysis of the scattering matrix shows that the transmission and reflection are not nonreciprocal, the diverse modulation ways (magnetic field and incidence directions) will make the structure more useful in the design of photonic switching and optical modulator.

A robust and inexpensive all optical switch with chiral nematic liquid crystal

A switchable photonic band gap with optical addressing is demonstrated. The switch can tune over a broad wavelength range (about 80 nm) without deformation and degradation with high reproducibility. The material is a mixture of reactive and nonreactive mesogens, azo dye molecules and chiral dopant. The mixture of reactive monomers and nonreactive mesogens leads to a robust polymer template filled with nano-droplets. Due to a photo-induced phase transition, the edges of the bandgap shift to shorter wavelengths after illumination. Three concentrations of reactive monomers are investigated. The features of the device are interesting for several emerging applications: all optical photonic switches, lab-on-a-chip devices, and switchable optical devices such as sensors, reflectors, diffraction gratings, polarizers, shutters, notch- and band-pass filters, reflective displays, mirror-less tunable lasers and modulators.

Performance enhancement of 8$$\times$$8 dilated banyan network using crosstalk suppressed GMZI crossbar photonic switches

Performance enhancement of 8$$\times$$8 dilated banyan network using crosstalk suppressed GMZI crossbar photonic switches

Ultralow-VπL Silicon Electro-Optic Directional Coupler Switch With a Liquid Crystal Cladding

An ultralow-V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">π</sub> L photonic switch device is demonstrated utilizing the high optical and electrical field confinement in silicon slot waveguides coupled with the strong electro-optic response of nematic liquid crystals. A silicon photonic directional coupler switch with a modulation efficiency of 0.0195 V·mm and a loss-efficiency product of 0.0624 V·dB is achieved. The 1.5 mm long device is based on two-mode interference within a single slot waveguide resulting in a V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">π</sub> of 0.013 V and an extinction ratio of ~ 9dB at 1550 nm wavelength. The power consumption of the photonic switch is estimated to be below 0.6 nW and it possesses a response time of <; 1.5 ms. A comparative performance study between the directional coupler switch and a Mach-Zehnder Interferometer (MZI) switch is performed. The directional coupler switch is projected to have a smaller footprint and lower optical loss compared to a similar design MZI switch making it a strong candidate for switch matrix designs and applications.

Concept of a miniature photonic spatial switch based on an off-axis zone plate

A new concept of an all-optical wavelength-selective two-channel switch based on the photonic hook effect without the use of micromechanical devices or nonlinear materials is proposed. A prototype of such a device based on an off-axis Fresnel zone plate is considered and its main parameters are discussed. Due to the unique property of the photonic hook to change its curvature with respect to the irradiation wavelength λ, this switch is a promising candidate for the implementation of optical switching in modern optoelectronics and miniature ‘on-a-chip’ devices. Numerical simulation shows that the optical isolation of switched channels for a switch with linear dimensions of about (6λ)3 based on an off-axis zone plate can reach 18 – 20 dB during operation in the wavelength range of 1.5 – 1.9 μm.

Wavelength‐Scale Photonic Space Switch Proof‐Of‐Concept Based on Photonic Hook Effect

AbstractThe proof‐of‐concept of a new wavelength‐scaled all‐optical two‐channel switch based on the photonic hook phenomenon is proposed and demonstrated. By means of the numerical finite‐difference time‐domain simulations, several prototypes of such devices are considered based on dielectric microstructures with broken symmetry of both geometric shape and optical properties without the use of micromechanical devices or non‐linear materials. Due to the unique property of the photonic hook to change its curvature depending on the optical wavelength, the proposed switch is a promising candidate for the implementation of optical switching in modern optoelectronics and miniature “on‐chip” devices. Optical isolation that is close to 20 dB is discovered at the wavelengths of 1.5 and 1.9 µm for a dielectric Janus microbar‐based switch with linear dimensions of about (6λ)3 (λ is the wavelength of the incident plane wave).

Flexible Control of Two-Channel Transmission and Group Delay in an Optomechanical System with Double Quantum Dots Driven by External Field.

With the presence of a driving field applied to double quantum dots and a control field applied on the cavity, the transmission performance and group delay effect of a probe field have been theoretically studied in a hybrid optomechanical system (HOMS). Due to the interaction between the mechanical mode and the double quantum dots system, double optomechanically induced transparency (OMIT) arises in the HOMS. With the assistance of a driving field, the system can be tuned to switch on any one of the two OMIT windows, switch on both of the two OMIT windows or switch off both of the two OMIT windows by dynamically adjusting control of the optical field and the driving field. Furthermore, the transmitted probe fields of the two OMIT windows can be tuned to be absorbed or amplified with proper parameters of the driving field and control field. Moreover, the transmission properties of the two OMIT windows are asymmetrical. One can obtain the maximum group delay time of the probe field by optimizing the amplitude and phase of the driving field. These results provide a new way for constructing optically controlled nanostructured photonic switch and storage devices.

Ultra-Compact Optical Switches Using Slow Light Bimodal Silicon Waveguides

Switches are essential components in several optical applications, in which reduced footprints are highly desirable for mass production of densely integrated circuits at low cost. However, most conventional solutions rely on making long switching structures, thus increasing the final device size. Here, we propose and experimentally demonstrate an ultra-compact 2x2 optical switch based on slow-light-enhanced bimodal interferometry in one-dimensional silicon photonic crystals. By properly designing the band structure, the device exhibits a large group index contrast between the fundamental even mode and a higher order odd mode for TE polarization. Thereby, highly dispersive and broadband bimodal regions for high-performance operation are engineered by exploiting the different symmetry of the modes. Two configurations are considered in the experiments to analyze the dimensions influence on the switching efficiency. As a result, a photonic switch based on a bimodal single-channel interferometer with a footprint of only 63 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , a power consumption of 19.5 mW and a crosstalk of 15 dB is demonstrated for thermo-optic tunability.

Fano interference and transparency in a waveguide-nanocavity hybrid system with an auxiliary cavity* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11774262 and 11975023).

We investigate theoretically single photon transport in one-dimensional waveguide coupled to a pair of cavities, which are denoted by the first cavity and the auxiliary cavity. Two cases with no atom and one atom embedded in the first cavity are discussed. The Fano dips in the transmission spectrum and locations of transparency window are calculated. When no atom is embedded in the first cavity, there exists a transparency window under the condition that the first cavity and the auxiliary cavity are not resonant. The locations of the transparency window and Fano line type depend strongly on the eigen frequency of the auxiliary cavity and the coupling strength between the auxiliary cavity and the waveguide. When one atom is embedded in the first cavity, we show that the transparency window exists even though the first cavity, the atom and the auxiliary cavity are resonant. The Fano line type is strongly dependent on the eigen frequency of the auxiliary cavity and the coupling strength. Our results have potential applications in design of quantum devices at the level of single photon, such as single photon switch and single photon routers.

Near infrared integrated photonic switches for portable quantum sensors

A novel integrated semiconductor photonic switch, based on carrier-induced refractive index changes, has been designed and fabricated for use at near infrared wavelengths (890-920 nm, 750-780 nm and 745-775 nm). These switches are intended for use in quantum sensors which rely on the spectroscopy of caesium, rubidium or potassium atoms respectively. The beam-steering properties of the 890-920 nm device are presented and its extinction ratio measured to be 13.4 dB. This measurement was limited by coupling efficiency. Subsequent changes made to the testing equipment include the implementation of an automated testing routine. This new experimental setup will facilitate the full characterisation of the 890-920 nm device and the newly fabricated optical switches, designed for operation in the wavelength ranges 750-780 nm and 745-775 nm respectively.

Improvement of silicon microdisk resonators with movable waveguides by hydrogen annealing treatment

In silicon photonics, silicon microdisk resonators with movable waveguides driven by electrostatic comb-drive actuators have been used as wavelength-selective switches. However, the sidewall roughness of silicon waveguides formed by the etching process is the main cause of optical loss in such devices, which leads to the deterioration of the wavelength selectivity. In this study, we fabricated a silicon microdisk resonator with a movable waveguide and performed a hydrogen annealing treatment as a postprocessing step to remove the sidewall roughness. By using scanning electron microscopy, a reduction in sidewall roughness was confirmed following the hydrogen annealing treatment. Then, the extinction ratio at the through port was evaluated while changing the gap between the microdisk and the movable waveguide. A dip in the extinction ratio was observed at the resonant wavelength while decreasing the gap, which indicated that the fabricated device successfully functioned as a wavelength-selective switch. Due to the hydrogen annealing treatment, the quality factor of the dip increased from 7102 to 37 402. These results show that the hydrogen annealing treatment can be used as a postprocessing step and is helpful for improving the wavelength selectivity of silicon photonic wavelength-selective switches.

Broadband Compact Single-Pole Double-Throw Silicon Photonic MEMS Switch

Photonic Integrated Circuits (PICs) benefit from the technology advances in the semiconductor industry to incorporate an ever-increasing number of photonic components on a single chip to create large-scale photonic integrated circuits. We here present a broadband, compact and low-loss Silicon Photonic MEMS switch based on a Single-Pole Double-Throw (SPDT) architecture, where curved electrostatic actuators mechanically displace a movable input waveguide to redirect the optical signal on chip efficiently to either of two output waveguides. The photonic switch has been fabricated in an established silicon photonics technology platform with custom MEMS release post-processing. With a compact footprint of $\mathbf {65\times 62}\, \boldsymbol {\mu }\mathbf {m}^{\mathbf {2}}$ , the switch exhibits an extinction ratio exceeding 23 dB over 70 nm optical bandwidth, a low insertion loss and a fast response time below $1~\mu \text{s}$ , meeting the requirements for integration in large-scale reconfigurable Photonic Integrated Circuits. [2020-0391]

32 × 32 silicon photonic MEMS switch with gap-adjustable directional couplers fabricated in commercial CMOS foundry

We report on a 32 × 32 silicon photonic micro-electro-mechanical-system (MEMS) switch with gap-adjustable directional couplers. The switch is fabricated on 200-mm silicon-on-insulator wafers in a commercial complementary metal-oxide-semiconductor (CMOS) foundry. The fabricated device has a maximum on-chip loss of 7.7 dB and an extinction ratio of 50.8 dB. The switching voltage is 9.45 V and the 20-dB bandwidth is 28.7 nm. Our work shows a promising path for mass production of silicon photonic MEMS switches in commercial CMOS foundries.

PCM-net: a refractive index database of chalcogenide phase change materials for tunable nanophotonic device modelling

The growing demand for multifunctional nanophotonic devices has led to the exploration, and utilization, of a plethora of exotic electro-optical materials. Recently, chalcogenide glass based phase change materials (PCMs) have shown utility as a tuning material for a range of nanophotonic devices. Owing to their low loss, ultrafast switching speeds and wide waveband operation, PCMs are integrated in an increasing number of next-generation tunable components, including integrated photonic switches, metasurface optics and tunable spectral filters. Nonetheless, modelling of PCM-based devices is challenging—both in terms of accurate representation of experimentally derived material properties in different phase states, and standardization of results across the research community. Further, as each device requires optimization of specific performance metrics dependent on their respective application, any inaccuracies will lead to erroneous outcomes. In this work, we introduce PCM-net (http://nekocloud.com/pnet/): an online database of the complex refractive indices of a variety of chalcogenide glass PCMs (such as GeSbTe), as an accessible and indexed repository for data sharing across the PCM community. Refractive indices (n) and extinction coefficients (k) between amorphous and crystalline states are directly extracted from experimentally derived data in numerous academic research articles, and collated into the material resource database. Due to the inaccuracies associated with our data collection methods, this data is supplemented with additional computationally generated data, obtained through WVASE® —a commercial ellipsometry analysis software package. To demonstrate the utility of PCM-net, we provide a NASA application-driven device optimization example using the optical properties of PCMs collected with our database. We anticipate the database providing great use to the PCM community and coordinated research efforts enabled by PCM-net will promote the shared repository for the selection of appropriate PCMs for tunable nanophotonic device design for a range of applications.

Proposal and proof-of-principle demonstration of fast-switching broadband frequency shifting for a frequency-multiplexed quantum repeater

A proposal for fast-switching broadband frequency-shifting technology making use of frequency conversion in a nonlinear crystal is set forth, whereby the shifting is imparted to the converted photons by creating a bank of frequency-displaced pump modes that can be selected by a photonic switch and directed to the nonlinear crystal. Proof-of-principle results show that the expected frequency-shifting operation can be achieved. Even though the dimensions of the currently employed crystal and significant excess loss in the experimental setup prevented conversion of single-photon-level inputs, thorough experimental and theoretical analysis of the noise contribution allowed for estimation of the system performance in an optimized scenario, where the expected signal-to-noise ratio (SNR) for single-photon conversion and frequency shifting can reach up to 25 dB with proper narrowband filtering and state-of-the-art devices. The proposed frequency-shifting solution figures as a promising candidate for applications in frequency-multiplexed quantum repeater architectures with 25 dB output SNR (with 20% conversion efficiency) and capacity for 16 channels spread around a 100 GHz spectral region.

Optical Tuning of Resistance Switching in Polycrystalline Gallium Phosphide Thin Films.

The nanoscale resistive switching characteristics of gallium phosphide (GaP) thin films directly grown on Si are investigated as a function of incident light. The formation of conductive channels along the grain boundaries is attributed to the presence of point defects and structural disorder, which provide the ideal environment to enable the filamentary switching process. Both first-principles calculations and UV-vis and photoluminescence spectroscopy strongly point to the possibility of mid-gap electronic states in the polycrystalline GaP film due to such defects. To study the photonic excitation, photoconductive atomic force microscopy (phAFM) measurement is conducted. We observe photocurrents even for incident photon energies lower than the band gap, consistent with the presence of mid-gap electronic states; the photocurrents increase in direct proportion to the incident photon energy with a concomitant decrease in the filament resistance. This demonstrates GaP directly integrated on Si can be a promising photonic resistive switching materials system.

Towards Maximum Energy Efficiency of Carrier-Injection-Based Silicon Photonics

We present carrier-injection-based photonic switches, engineered for optical pulse distribution with maximum energy efficiency. We apply small-signal analysis and for the first time large-signal modelling to methodically optimize the switches for minimum energy consumption and to classify the electronic contributions from resistance, capacitance, and diode. We present optimized electronic switch activation, which yields a sixfold reduction in energy consumption and we show how static power consumption becomes a negligible factor for optical pulse switching. We demonstrate that with adjusted phase shifter dimensions, MZI-based switches can operate with additional 50% enhanced energy efficiency with down to 4 pJ per switching operation. We show even further efficiency improvement using ring-based designs, allowing an additional improvement of 50% in energy efficiency and we discuss the trade-off between efficiency and optical bandwidth associated to the Q-factor. We benchmark carrier-injection-based switches together with comparable technologies of the silicon photonics platform and identify carrier-injection to be the most suitable technology for pulse switching applications.