Showing papers on "Optical switch published in 2021"

Electrical tuning of phase-change antennas and metasurfaces.

Abstract: The success of semiconductor electronics is built on the creation of compact, low-power switching elements that offer routing, logic and memory functions. The availability of nanoscale optical switches could have a similarly transformative impact on the development of dynamic and programmable metasurfaces, optical neural networks and quantum information processing. Phase-change materials are uniquely suited to enable their creation as they offer high-speed electrical switching between amorphous and crystalline states with notably different optical properties. Their high refractive index has already been harnessed to fashion them into compact optical antennas. Here, we take the next important step, by showing electrically-switchable phase-change antennas and metasurfaces that offer strong, reversible, non-volatile, multi-phase switching and spectral tuning of light scattering in the visible and near-infrared spectral ranges. Their successful implementation relies on a careful joint thermal and optical optimization of the antenna elements that comprise a silver strip that simultaneously serves as a plasmonic resonator and a miniature heating stage. Our metasurface affords electrical modulation of the reflectance by more than fourfold at 755 nm. A metasurface comprising electrically controlled heating units and a phase-change material offer non-volatile and reversible modulation of reflectance by more than fourfold.

Applications of Few-Layer Nb2C MXene: Narrow-Band Photodetectors and Femtosecond Mode-Locked Fiber Lasers.

Abstract: Although the physicochemical properties of niobium carbide (Nb2C) have been widely investigated, their exploration in the field of photoelectronics is still at the infancy stage with many potential applications that remain to be exploited. Hence, it is demonstrated here that few-layer Nb2C MXene can serve as an excellent building block for both photoelectrochemical-type photodetectors (PDs) and mode-lockers. We show that the photoresponse performance can be readily adjusted by external conditions and that Nb2C NSs exhibit a great potential for narrow-band PDs. The demonstrated mechanism was further confirmed by work functions predicted by density functional theory calculations. In addition, as an optical switch for passively mode-locked fiber lasers, ultrastable pulses can be demonstrated in the telecommunication and mid-infrared regions for Nb2C MXene, and as high as the 69th harmonic order with 411 MHz at the center wavelength of 1882 nm can be achieved. These intriguing results indicate that few-layer Nb2C nanosheets can be used as building blocks for various photoelectronic devices, further broadening the application prospects of two-dimensional MXenes.

1.6 Tbps Silicon Photonics Integrated Circuit and 800 Gbps Photonic Engine for Switch Co-Packaging Demonstration

Abstract: We describe the performance of high bandwidth-density silicon photonic based integrated circuits (SiPh ICs) that enable the first fully functional photonic engine (PE) module co-packaged with an Ethernet switch. We demonstrate the 1.6 Tbps SiPh transmitter (Tx) IC that integrates on-die all the lasers, micro ring modulators, monitor photodetectors, spot size converters, and V-grooves that are needed to support sixteen 106.25 Gbps PAM4 optical transmit channels. This SiPh Tx, together with discrete receiver (Rx) SiPh ICs, enabled an 800 Gbps PE. The PE is designed to allow up to sixteen modules to be co-packaged around a high-bandwidth switch ASIC. The PE test results described in this article were obtained using sixteen 53.125 Gbps electrical channels that were multiplexed to drive eight simultaneously operating 106.25 Gbps optical channels. We report DR4 IEEE standards compliant high-speed optical eye performance as well as full link operation. Post-FEC error-free operation over temperature and over extended time duration is demonstrated on all channels.

Low Power DSP-Based Transceivers for Data Center Optical Fiber Communications (Invited Tutorial)

Abstract: In this tutorial, we discuss the evolution of the technology deployed for optical interconnects and the trade-offs in the design of low complexity, low power DSP and implementation for direct detect and coherent, pluggable optical modules for data center applications. The design trade-offs include the choice of modulation format, baud rate, optical link design, forward error correction, signal shaping and dispersion compensation.

Highly sensitive all-polymer photodetectors with ultraviolet-visible to near-infrared photo-detection and their application as an optical switch

Abstract: All-polymer photodetectors with photomultiplication were fabricated with PMBBDT and N2200 as photoactive layers, which exhibit an external quantum efficiency of 20 700% under 4 V. The signal-to-noise ratio, linear dynamic range and specific detectivity were simultaneously enhanced by empolying a PEDOT:PSS/P-TPD double hole transport layer. An optical switch system without any current amplifier was realized.

Triple plasmon-induced transparency and optical switch desensitized to polarized light based on a mono-layer metamaterial.

Abstract: A mono-layer metamaterial comprising four graphene-strips and one graphene-square-ring is proposed herein to realize triple plasmon-induced transparency (PIT). Theoretical results based on the coupled mode theory (CMT) are in agreement with the simulation results obtained using the finite-difference time-domain (FDTD). An optical switch is investigated based on the characteristics of graphene dynamic modulation, with modulation degrees of the amplitude of 90.1%, 80.1%, 94.5%, and 84.7% corresponding to 1.905 THz, 2.455 THz, 3.131 THz, and 4.923 THz, respectively. Moreover, the proposed metamaterial is insensitive to the change in the angle of polarized light, for which the triple-PIT is equivalent in the cases of both x- and y-polarized light. The optical switch based on the proposed structure is effective not only for the linearly polarized light in different directions but also for left circularly polarized and right circularly polarized light. As such, this work provides insight into the design of optoelectronic devices based on the polarization characteristics of the incident light field on the optical switch and PIT.

Reconfigurable bandpass optical filters based on subwavelength grating waveguides with a Ge 2 Sb 2 Te 5 cavity

Abstract: We demonstrate a reconfigurable optical bandpass filter based on subwavelength grating (SWG) waveguide operating in the Bragg reflection regime and integrated with a cavity of the phase-change material Ge2Sb2Te5 (GST). Partial crystallization of GST provides us with an efficient tool to modify the effective optical properties of the GST governed by the effective medium theory. Consequently, the resonance wavelength as well as the transmission peak can be tuned in the designed filters. Numerical simulations indicate that the presented SWG waveguide with a single GST cavity offers up to 8.8 nm redshift while the transmission amplitude can be modulated from 0.544 to 0.007. The presented Fabry–Perot structure can also be used as a nonvolatile optical switch with a high extinction ratio of about 24 dB at the wavelength of 1548.3 nm.

High Q-factor multi-Fano resonances in all-dielectric double square hollow metamaterials

Abstract: Exciting multiple high Q-factor Fano resonances in all-dielectric metamaterials has become an effective means of designing high performance optical devices In this paper, we present an all-dielectric metamaterial in the near infrared region by depositing silicon material on the silica substrate and etching two square air holes in the middle of each meta-molecule Combining with the bound states in the continuum (BIC) theory, four sharp Fano profiles with the modulation depth nearly 100% are excited, in which the maximum Q-factor can exceed 10 4 The toroidal dipole (TD) also characterizes our metamaterial By verifying the square inverse law satisfied by Q-factor and combining the electromagnetic field distribution characteristics, the excitation mode of the Fano resonance is expounded In addition, by turning the polarization direction of the incident light, the Fano resonance at λ = 12385 nm can be turned on or off, which performs perfect characteristics for an optical switch Utilizing the narrow linewidth and significant near-field constraints of the Fano resonances, an optical refractive index sensor can be obtained with the sensitivity of ~ 2875 n m / R I U and maximum figure of merit (FOM) of ~ 389 R I U - 1 It is believed that the proposed system can further enhance the development of high-performance biosensors, nonlinear optics, and optical switches

Steering non-Hermitian skin modes by synthetic gauge fields in optical ring resonators.

Abstract: We show that the synthetic gauge fields for photons provide a versatile approach to generate and control the non-Hermitian skin effect. By utilizing indirectly coupled optical ring resonator arrays with long-range couplings and on-site gain and loss, we find that the skin effect appears once the gauge field is not an integer multiple of π. In addition to tunable localization direction, the skin modes display anisotropic behaviors with frequency-dependent decay length, which can be explained by the split subregion of the generalized Brillouin zone (GBZ) and an effective model under adiabatic elimination. Through numerical simulation, we can also demonstrate exotic features in propagation effects enabled by the skin effect, including asymmetric transmission and reconfigurable accumulation interface. Our study paves the way to dynamically steer skin modes, which may find applications in laser, optical switch, and signal processing.

Non-redundant optical phased array

Abstract: Optical phased arrays (OPAs) are promising beam-steering devices for various applications such as light detection and ranging, optical projection, free-space optical communication, and optical switching. However, previously reported OPAs suffer from either an insufficient number of resolvable points, or complicated control requirements due to an extremely large number of phase shifters. To solve this issue, we introduce the non-redundant array (NRA) concept to the OPA devices. Based on this design, we can realize high-resolution OPAs whose number of resolvable points scales quadratically with the number of antennas N. In contrast, that of traditional OPAs scales only linearly with N. Thus, a significant reduction in the number of required phase shifters can be attained without sacrificing the number of resolvable points. We first investigate the impact of employing the NRA theoretically by considering the autocorrelation function of the array layout. We then develop a Costas-array-based silicon OPA and experimentally demonstrate 2D beam steering with ∼19,000 resolvable points using only 127 phase shifters. To the best of our knowledge, this corresponds to the largest number of resolvable points achieved by an OPA without sweeping the wavelength.

Low-energy room-temperature optical switching in mixed-dimensionality nanoscale perovskite heterojunctions.

Abstract: Long-lived photon-stimulated conductance changes in solid-state materials can enable optical memory and brain-inspired neuromorphic information processing. It remains challenging to realize optical switching with low-energy consumption, and new mechanisms and design principles giving rise to persistent photoconductivity (PPC) can help overcome an important technological hurdle. Here, we demonstrate versatile heterojunctions between metal-halide perovskite nanocrystals and semiconducting single-walled carbon nanotubes that enable room-temperature, long-lived (thousands of seconds), writable, and erasable PPC. Optical switching and basic neuromorphic functions can be stimulated at low operating voltages with femto- to pico-joule energies per spiking event, and detailed analysis demonstrates that PPC in this nanoscale interface arises from field-assisted control of ion migration within the nanocrystal array. Contactless optical measurements also suggest these systems as potential candidates for photonic synapses that are stimulated and read in the optical domain. The tunability of PPC shown here holds promise for neuromorphic computing and other technologies that use optical memory.

External vs. Integrated Light Sources for Intra-Data Center Co-Packaged Optical Interfaces

Abstract: Co-packaging of optics and electronics for data center switches has been proposed to reduce system-level power consumption by minimizing power-hungry electrical interconnects. Co-packaging optical components near high-temperature electronics, however, can diminish their performance and reliability. Moreover, limitations of the switch environment, such as restricted footprint, power, and number of fiber attachments can limit practical co-packaging implementations. Here, we study four architectures for co-packaged optical interfaces using either single- or multi-wavelength light sources that can be either external to or integrated with the optical interfaces. We model the temperature- and current-dependent performance and reliability of the sources and calculate the link budget for switch bandwidths up to 102.4 Tb/s. We compare architectures based on coherent and direct detection and find that all coherent detection architectures support 102.4 Tb/s switching with over 13 dB link budget, while most direct detection architectures scale to 51.2 Tb/s or 102.4 Tb/s switching with link budgets less than 5 dB. In addition, we demonstrate that external-source architectures require wavelength-division multiplexing at lower switch bandwidths and consequently have link budgets 1-5 dB lower than integrated source architectures. Further, we demonstrate that higher-power lasers can scale external architectures to 102.4 Tb/s switching with over 4 dB link budgets. Finally, for 51.2 Tb/s switching, we show that a reduction in integrated source temperature improves link budgets by 2-4 dB and direct detection external-source architectures can achieve greater than 5 dB link budget with fewer than 300 fiber attachments.

Technical specifications for an all-optical switch for information storage and processing systems

Abstract: Optical computation enhances speed, data transmission rate and processing power by replacing electronics with optical switching, which can be efficiently carried out in high speed signal processing through all-optical gates. This paper reviews the progressive development of the optical switching technology, and reviews a model description of all-optical switch-based beam radial. Amplitude decay time and phase decay time are also analyzed and simulated using a MATLAB program, and time response according to amplitude decay time against electric field intensity is demonstrated. The results from previous studies are also examined, and further analysis is done with simulators like RSoft Photonics. The simulation results confirm that the design can be implemented at high data rates, with the focus being on the beam radial shift effect on the performance of the switch and the deduction of the switching speed. A cross section of the all optical switch of 4 ports from left the beam entering through the LM then radically shifted to the output ports by the effect of the changeable electric field strength. A schematic diagram of the test lab for the lateral shift effect, a spatial connector has been chosen to represent the lateral shift at one port of the All Optical Switch and some Meters for power and BER.

Triboelectric-optical responsive cholesteric liquid crystals for self-powered smart window, E-paper display and optical switch

Abstract: Highlights •Mechanical stimuli-triggered optical responses of cholesteric liquid crystal devices are realized.•Self-powered bistable smart window and E-paper are demonstrated.•Self-powered optical switch is developed for remote control.Intelligent responsive devices are crucial for a variety of applications ranging from smart electronics to robotics. Electro-responsive cholesteric liquid crystals (CLC) have been widely applied in display panels, smart windows, and so on. In this work, we realize the mechanical stimuli-triggered optical responses of the CLC by integrating it with a triboelectric nanogenerator (TENG), which converts the mechanical motion into alternating current electricity and then tunes the different optical responses of the CLC. When the voltage applied on the CLC is relatively low (15–40 V), the TENG drives the switching between the bistable planar state and focal conic state of the CLC, which shows potential applications in self-powered smart windows or E-paper displays. When the voltage supplied by the TENG is larger than 60 V, a self-powered optical switch is demonstrated by utilizing the transformation between focal conic state and instantons homeotropic state of the CLC. This triboelectric-optical responsive device consumes no extra electric power and suggests a great potential for future smart electronics.

High-Performance Graphene-on-Silicon Nitride All-Optical Switch Based on a Mach–Zehnder Interferometer

Abstract: We propose and experimentally demonstrate a high-performance graphene-on-silicon nitride (Si3N4) all-optical switch based on a Mach–Zehnder interferometer (MZI). In our device, the graphene overlaying on a Si3N4 waveguide absorbs part of the pump light power and generates heat. Then, the Si3N4 waveguide underneath can be heated and its refractive index can be changed due to the thermo-optic effect. In this way, the phase of the probe light in the Si3N4 arm with graphene on top is tuned and all optical switching can then be implemented. In the experimental demonstration, an all-optical switch with a chip size of ∼0.36 mm2 is realized with an extinction ratio of 11 dB. The tuning efficiency is measured to be 0.00917 π/mW, which is insensitive to the wavelength of the pump light. All-optical switching is also demonstrated, while the rise and fall time constants are measured to be 571 ns and 1.29 μs, respectively. These results show that our proposed configuration provides a functional integrated component for the development of efficient all-optical control devices with a fast switching speed on the insulator platform. Moreover, by using integrated MZI structure, our design could potentially achieve a broad bandwidth.

On-Chip Programmable Nonlinear Optical Signal Processor and Its Applications

Abstract: We introduce an integrated device based on microring resonator (MRR) assisted Mach-Zehnder interferometer (MZI) preceded by a tunable MZ coupler for nonlinear optical signal processing The novel structure of this device provides both high programmability and switching contrast These desirable features suggest its potential use as a multi-purpose optical processor providing different high-performance functionalities We experimentally demonstrate two functionalities using the same device fabricated on a silicon-on-insulator substrate One functionality is an all-optical thresholder enabling 40× signal contrast improvement, and the other functionality is clock-less pulse carving technique that converts long-pulse signals to short-pulse signals With these functionalities, we discuss system-level applications of our device in optical interconnects and photonic neural networks

Non-volatile optical switch of resistance in photoferroelectric tunnel junctions.

Abstract: In the quest for energy efficient and fast memory elements, optically controlled ferroelectric memories are promising candidates. Here, we show that, by taking advantage of the imprint electric field existing in the nanometric BaTiO3 films and their photovoltaic response at visible light, the polarization of suitably written domains can be reversed under illumination. We exploit this effect to trigger and measure the associate change of resistance in tunnel devices. We show that engineering the device structure by inserting an auxiliary dielectric layer, the electroresistance increases by a factor near 2 × 103%, and a robust electric and optic cycling of the device can be obtained mimicking the operation of a memory device under dual control of light and electric fields. Designing energy efficient and fast optoelectric neuromorphic systems remains a challenge. Long et al. report that the combined optical-electric stimulus enables switching the ferroelectric polarization and cycling the resistance state of BaTiO3 tunnel barriers, showing that the optical control of resistance is non-volatile.

Ultrafast optical circuit switching for data centers using integrated soliton microcombs.

Abstract: Due to the slowdown of Moore’s law, it will become increasingly challenging to efficiently scale the network in current data centers utilizing electrical packet switches as data rates grow. Optical circuit switches (OCS) represent an appealing option to overcome this issue by eliminating the need for expensive and power-hungry transceivers and electrical switches in the core of the network. In particular, optical switches based on tunable lasers and arrayed waveguide grating routers are quite promising due to the use of a passive core, which increases fault tolerance and reduces management overhead. Such an OCS-network can offer high bandwidth, low network latency and an energy-efficient and scalable data center network. To support dynamic data center workloads efficiently, however, it is critical to switch between wavelengths at nanosecond (ns) timescales. Here we demonstrate ultrafast OCS based on a microcomb and semiconductor optical amplifiers (SOAs). Using a photonic integrated Si3N4 microcomb, sub-ns (<520 ps) switching along with the 25-Gbps non-return-to-zero (NRZ) and 50-Gbps four-level pulse amplitude modulation (PAM-4) burst mode data transmission is achieved. Further, we use a photonic integrated circuit comprising an Indium phosphide based SOA array and an arrayed waveguide grating to show sub-ns switching (<900 ps) along with 25-Gbps NRZ burst mode transmission providing a path towards a more scalable and energy-efficient wavelength-switched network for data centers in the post Moore’s Law era. Optical technologies could enable fast and power-efficient networks for data centers. Here, the authors report Si3N4 microcomb based ultrafast photonic switching to provide enhanced performance for data center applications.

50.47-Tbit/s Standard Cladding Coupled 4-Core Fiber Transmission Over 9,150 km

Abstract: Since optical submarine cable systems are a part of the global communications infrastructure, their total capacity must be continuously and dramatically enlarged. Recently, methods how to maximize the transmission capacity under electrical power limitations have been studied, and it has been reported that a single band (C-band only) transmission system with more fiber pairs (FPs) could be a promising technology. This finding has triggered work on submarine cables with more FPs. For a further increase in FPs in optical submarine cable systems, which also have space limitations in existing cable designs, space-division multiplexing (SDM) technologies such as multi-core fibers (MCFs) and multi-mode fibers (MMFs) could be promising solutions. In particular, 125-μm standard cladding SDM fibers are attractive for early deployment in submarine cable systems since they are expected to have high productivity and high mechanical reliability similar to existing single-mode fibers (SMFs) with the same cladding diameter. In this paper, we report transpacific MCF transmission over a 30-nm bandwidth using standard cladding ultralow-loss coupled 4-core fibers, extending our previous work. The Q2-factors of 608 (4 core × 152 WDM) SDM/WDM channels modulated with 24-Gbaud DP (dual polarization)-QPSK (quadrature phase shift keying) exceeded the assumed forward error correction (FEC) limits after a 9,150-km transmission. As a result, transmission capacity of 50.47 Tbit/s and a capacity-distance product of 461.8 Pbit/s·km were achieved for standard cladding diameter SDM fibers.

Ultrafast optical switching and power limiting in intersubband polaritonic metasurfaces

Abstract: Highly nonlinear optical materials with fast third-order nonlinear optical response are crucial for the operation of all-optical photonic devices, such as switches for signal processing and computation, power limiters, and saturable absorbers. The nonlinear response of traditional optical materials is weak, thus requiring large light intensities to induce significant changes in their properties. Here we show that optical control of the coupling rate in subwavelength patch antennas coupled to intersubband transitions in multi-quantum-well semiconductor heterostructures can provide a giant third-order nonlinear response, on the order of ${{3.4 \times 10}}^{- 13}{{{m}}^2}/{{\rm{V}}^2}$, with a response time ${\lt}{{2}}\;{\rm{ps}}$. We utilize this effect to realize intersubband polaritonic metasurfaces and demonstrate their operation as highly nonlinear saturable and reverse saturable absorbers, enabling optical power limiters and other elements for all-optical modulation and control. Our approach enables a plethora of compact, low-power, highly nonlinear devices with spectral, temporal, and structured wavefront responses tailored by design.

Potential Third-Order Nonlinear Optical Response Facilitated by Intramolecular Charge Transfer in a Simple Schiff Base Molecule: Experimental and Theoretical Exploration.

Abstract: A Schiff base, namely, 4-[(2-hydroxy-3-methoxybenzylidene) amino] benzoic acid (L1), has been synthesized by the condensation reaction. It has been characterized by Fourier transform infrared spectroscopy , UV-vis spectroscopy, single-crystal X-ray diffraction, and DFT/B3LYP calculations. Single-crystal X-ray crystallographic analysis revealed that L1 exists in the zwitterionic (N-H···...O) form. The supramolecular interactions were investigated by Hirshfeld surface analysis. In addition, third-order nonlinear optical (NLO) properties of L1 were also investigated. The nonlinear refractive index (n2), nonlinear absorption coefficient (β), and the third-order NLO susceptibility (χ(3)) have been estimated at different concentrations and at different laser powers using close and openaperture Z-scan data. The values of the parameters were found to be varying almost linearly with concentration and power. The present study revealed the utility of the material for various optoelectronic devices such as optical switches, optical data storage devices, and optical sensors. The optical limiting study reveals that this material can also be exploited as an instrument protector from unwanted laser illumination. Furthermore, the NLO behavior of L1 has also been studied by B3LYP/6-311++G(d,p) results.

Single-Molecule Vacuum Rabi Splitting: Four-Wave Mixing and Optical Switching at the Single-Photon Level.

Abstract: A single quantum emitter can possess a very strong intrinsic nonlinearity, but its overall promise for nonlinear effects is hampered by the challenge of efficient coupling to incident photons. Common nonlinear optical materials, on the other hand, are easy to couple to but are bulky, imposing a severe limitation on the miniaturization of photonic systems. In this Letter, we show that a single organic molecule acts as an extremely efficient nonlinear optical element in the strong coupling regime of cavity quantum electrodynamics. We report on single-photon sensitivity in nonlinear signal generation and all-optical switching. Our work promotes the use of molecules for applications such as integrated photonic circuits operating at very low powers.

Experimental demonstration of harmonic mode-locking in Sb2Se3-based thulium-doped fiber laser

Abstract: Studies have shown that Sb2Se3 had the potential to be used as an optical switch or a mode-locker. However, the actual performance of its optical switch capability in fiber lasers has not been proved yet. In this paper, we experimentally demonstrate the nonlinear optical modulation characteristics and optical switch capabilities of Sb2Se3 with a harmonic mode-locked thulium-doped fiber laser (TDFL). The nonlinear modulation depth and saturation power of Sb2Se3-based SA at 1930 nm are 9.3% and 4.08 kW, respectively. The fundamentally mode-locked pulses operate at the central wavelength of 1961.35 nm have the 3-dB bandwidth of 4.57 nm, repetition rate of 22.36 MHz and pulse width of 890 fs. The 2th to 31th harmonic mode locking (HML) are observed, corresponding to the pulse repetition rates ranging from 44.7 to 693 MHz. To the best of our knowledge, this is the highest operating frequency that has ever been demonstrated in a Sb2Se3-based fiber laser. The experimental results indicate that Sb2Se3 could be a promising candidate for generating ultrashort pulses with high repetition rates.

Scalable mmWave Non-Volatile Phase Change GeTe-Based Compact Monolithically Integrated Wideband Digital Switched Attenuator

Abstract: This article reports a scalable millimeter-wave (mmWave) non-volatile switched attenuator based on phase change material (PCM) germanium telluride (GeTe). The proposed attenuator is designed using four fixed attenuation bits. The PCM GeTe-based T-type switches and two single-pole ${n}$ -throw (SP ${n}\text{T}$ ) switches are monolithically integrated with four passive bridged-T resistor networks to provide a wide attenuation range. Utilizing a T-type switch as a routing core provide scalability with low loss and offers a reduced number of switches in various signal routing paths. It also offers signal routing functionality if there is a switch failure in the T-type unit-cell. The nonvolatile PCM GeTe-based switches do not consume any static dc power. The integrated planar resistors are fabricated precisely on-wafer, and capacitive coupling is added to get wideband operation with a flat response at high frequencies. The fully integrated device is fabricated in-house using a custom eight-layer microfabrication process. The Ka -band attenuator is designed at 30 GHz center frequency with 8 GHz bandwidth. The proposed circuit is highly miniaturized, with a device core size of 0.3 mm2 only. The switched attenuator exhibits a measured attenuation from 3.9 to 28 dB at the center frequency in nine discrete steps.

Multi-Band Photonic Integrated Wavelength Selective Switch

Abstract: As fiber-optic systems turn toward multi-band transmission (MBT), exploiting the complete low loss window of optical fibers, novel optical components, able to operate in bands other than the conventional C-band, become necessary. In light of this, we report on a multi-band photonic integrated $\mathbf {1\times 2}$ wavelength selective switch (WSS) operating in the O, S, C and L-bands. The photonic integrated WSS presented in this work uses a folded arrayed-waveguide grating (AWG) as the filtering element, while the wideband operation of the thermo-optic switches allows the routing of the individual channels from those bands to any of the device output ports. The operation of the WSS is experimentally validated for different bands and modulation formats. Results show error-free operation with limited penalty with intensity-modulation direct-detection (IM/DD) non-return-to-zero on-off keying (NRZ-OOK) up to 35 Gb/s in O, S, C and L-bands and up to 169.83 Gb/s with coherent 64-quadrature amplitude modulation (QAM) data transmission in the S, C and L-bands.

Multi-Functional Radar Waveform Generation Based on Optical Frequency-Time Stitching Method

Abstract: A photonic-assisted multi-functional radar waveform generator for single-chirped, counter-chirped, and dual-band linear frequency-modulated (LFM) microwave waveforms generation is proposed and experimentally demonstrated based on an optical frequency-stepped waveform (FSW) generator. The optical FSW generator is realized by an optical switch and an optical frequency shifting loop (OFSL). When an electrical rectangular LFM pulse is applied to the proposed signal generator, an optical frequency-stepped LFM signal would be generated. By carefully setting the time length and the bandwidth of the rectangular LFM pulse, we can achieve an optical linearly-chirped continuous wave. Optical frequency-time stitching is thus realized. Combining the optical linear-chirped signal with one or more optical wavelengths, and meticulously adjusting the value of the optical wavelengths, single-chirped, counter-chirped or dual-band LFM signals can be produced. An experiment is carried out. Single-chirped and counter-chirped LFM signals of 8–32 GHz over a time duration of 5 μs, and dual-band LFM signals of 8–16 GHz & 15–23 GHz and 8–20 GHz & 20–32 GHz are generated. The ambiguity functions of the generated signals are investigated.

Multiport all-logic optical switch based on thermally altered light paths in a multimode waveguide

Abstract: A generic multiport optical switch capable of generating all-logic outputs is demonstrated by altering the mode profiles and propagation characteristics in a multimode waveguide through a combination of microheaters. The principles and design rules are introduced. As proof of concept, a 3-bit all-logic switch is fabricated on a polymer waveguide platform. The experimental results are in good agreement with the simulations based on a heat solver and the eigenmode expansion method. The device shows polarization insensitive and colorless operation from 1520 to 1600 nm with an extinction ratio between “On” and “Off” states larger than 11.9 dB in all cases. The maximum heat power is 43.9 mW (for (1, 0, 0) state). The simple, compact, and easily scalable device can be used to construct 1×N and M×N switch networks, showing promising applications in on-chip photonic signal processing and computation.