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A 2 × 2 3-dB coupler is one of the essential photonic components, as a building block of Mach-Zehnder interferometers, to realize large-scale photonic integrated circuits. Unlike typical 2 × 2 3-dB couplers based on direction couplers or multimode interference couplers, adiabatic couplers offer various advantages such as broadband operation and superior fabrication tolerance thanks to their unique operating mechanism of adiabatic mode evolution. However, an adiabatic coupler typically requires a long device length for ideal adiabatic operation without the excitations of unwanted modes. Here, we report on a compact 2 × 2 3-dB adiabatic coupler designed using the shortest mode transformer method. By optimizing the profile of the waveguide widths and the gap spacing, the compact 3-dB coupler was designed with a short coupling length of 23.2 μm. The fabricated device exhibits a 3-dB splitting ratio with less than ± 0.3 dB power oscillation and a low excess loss of 0.23 dB over a broad wavelength range of 1485–1620 nm. To the best of our knowledge, our coupler has the shortest length among the adiabatic couplers with a minimum feature size of 200 nm, reported to date.

By providing an effective way to leverage nonlinear phenomena in integrated devices, high-Q optical resonators have led to recent advances in on-chip photonics. However, developing fabrication processes to shape any new material into a resonator with extremely smooth surfaces on a chip has been an exceptionally challenging task. Here, we describe a universal method to implement ultra-high-Q resonators with any new material having desirable properties that can be deposited by physical vapor deposition. Using this method light-guiding cores with surface roughness on the molecular-scale are created automatically on pre-patterned substrates. Its efficacy has been verified using As2S3, a chalcogenide glass that has high-nonlinearity. The Q-factor of the As2S3 resonator so-developed approached the propagation loss record achieved in chalcogenide fibers which were limited by material losses. Owing to the boosted Q-factor, lasing by stimulated Brillouin scattering has been demonstrated with 100 times lower threshold power than the previous record., High-Q resonators are used to enhance nonlinear phenomena in photonics, but developing a fabrication process to shape a new material into a resonator is challenging and costly. Here, the authors present a method using vapour deposition on pre-patterned substrates to fabricate resonators with any new material.

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.

We report on a 16-core recirculating programmable photonic array based on MEMS-tunable directional couplers. The photonic array has a compact footprint (0.04mm2/cell) and negligible static power consumption. Waveguide-coupled single-ring resonators, CROWs, and add-drop filters are demonstrated.

We present a new device platform which defines on-chip chalcogenide waveguide/resonators without directly etching chalcogenide. Using our platform, we have demonstrated chalcogenide ring resonators with record high Q-factor exceeding 1.1x107 which is 10 times larger than previous record on on-chip chalcogenide resonators. A ring cavity is designed and fabricated for Stimulated Brillouin lasing on our platform. Thanks to the high-Q factor, Brillouin lasing with threshold power of 1 mW is demonstrated. This value is more than an order of magnitude improvement than previous world record for on-chip chalcogenide Brillouin lasers. We also developed an efficient and flexible method for resonator waveguide coupling with our device platform. Coupling between a resonator and a waveguide can be varied from under coupled region to over-coupled region.

Detection of single nanoparticles or molecules has often relied on fluorescent schemes. However, fluorescence detection approaches limit the range of investigable nanoparticles or molecules. Here, we propose and demonstrate a non-fluorescent nanoscopic trapping and monitoring platform that can trap a single sub-5-nm particle and monitor it with a pair of floating nonlinear point sources. The resonant photon funnelling into an extremely small volume of ~5 × 5 × 7 nm3 through the three-dimensionally tapered 5-nm-gap plasmonic nanoantenna enables the trapping of a 4-nm CdSe/ZnS quantum dot with low intensity of a 1560-nm continuous-wave laser, and the pumping of 1560-nm femtosecond laser pulses creates strong background-free second-harmonic point illumination sources at the two vertices of the nanoantenna. Under the stable trapping conditions, intermittent but intense nonlinear optical spikes are observed on top of the second-harmonic signal plateau, which is identified as the 3.0-Hz Kramers hopping of the quantum dot trapped in the 5-nm gap., Detection of single nanoparticles or molecules often relies on the attachment of fluorescent labels. Here, the authors demonstrate trapping a single nanoparticle on a bowtie nanoantenna and monitoring via second harmonic generation from the particle.

We report on 50 × 50 silicon photonic micro-electromechanical-system (MEMS) switches with reduced polarization dependence. The switches make use of two-level waveguide crossbars and MEMS-actuated adiabatic couplers. Simulations indicate that by eliminating all polarization-dependent elements (e.g., waveguide crossings), low polarization-dependent losses (

We report octave-spanning supercontinuum generation in etch-less As2S3 film waveguide platform. The spectrum is extended from 1.05 to 2.71 μm pumped by 45 pJ pulse energy at 1.56 μm telecommunication wavelength. © 2020 The Author(s)

We have experimentally demonstrated on-chip chalcogenide resonators with Q-factor of 1.1x107 using a new fabrication method which avoids direct etching of chalcogenide film. Low threshold power (12mW) Brillouin laser is implemented using the fabrication method. Also, cascaded lasing up to 3rd stokes have been observed with 42 mW of pump power.

We report a supercontinuum generation (SCG) in a waveguide that spontaneously forms without an etching process during the deposition of a core material on a preformed S i O 2 substructure. The mechanism of dispersion control for this new, to the best of our knowledge, type of waveguide is analyzed by numerical simulation, which results in a design rule to achieve a target dispersion profile by adjusting the substructure geometry. SCG is experimentally demonstrated with a waveguide made of A s 2 S 3 , chalcogenide glass, which has low material absorption over the mid-IR range. A dispersion-controlled waveguide with a length of 10 mm pumped with 77 pJ pulses at a telecommunication wavelength of 1560 nm resulted in a supercontinuum that extends by more than 1.5 octaves.

We report on the flip chip packaging of Micro-Electro-Mechanical System (MEMS)-based digital silicon photonic switching device and the characterization results of 12 × 12 switching ports. The challenges in packaging N 2 electrical and 2N optical interconnections are addressed with single-layer electrical redistribution lines of 25 μm line width and space on aluminum nitride interposer and 13° polished 64-channel lidless fiber array (FA) with a pitch of 127 μm. 50 μm diameter solder spheres are laser-jetted onto the electrical bond pads surrounded by suspended MEMS actuators on the device before fluxless flip-chip bonding. A lidless FA is finally coupled near-vertically onto the device gratings using a 6-degree-of-freedom (6-DOF) alignment system. Fiber-to-grating coupler loss of 4.25 dB/facet, 10-11 bit error rate (BER) through the longest optical path, and 0.4 μs switch reconfiguration time have been demonstrated using 10 Gb/s Ethernet data stream.

In this letter, we demonstrate a scalable addressing scheme for silicon photonic MEMS switches. For a crossbar architecture switch fabric of dimension $N \times N$ , the row/column addressing scales with $2\cdot N$ electrodes, much reduced from the $N^{2}$ electrodes in individual addressing. It also compares favorably with other optical switch architectures, including path-independent insertion loss, Benes, or switch-and-select networks, in terms of electrical interface. We have designed, fabricated, and experimentally characterized the performance of a $4 \times 4$ silicon photonic MEMS switch.

Optical circuit switches with fast switching times can provide rapidly reconfigurable bandwidth in data center networks. Silicon photonic switches are attractive candidates with their fast response times and CMOS process compatibility. In this paper, we report on a 50 x 50 silicon photonic switch with MEMS-actuated vertical adiabatic couplers. The switch is monolithically integrated on a 7.6 x 7.6 mm(2) chip. It has an on-chip insertion loss of 8.5 dB. Our switch exhibits a sub-microsecond switching time (0.85 mu s), a broad spectral bandwidth (1400-1700 nm), and digital switching characteristic. The switch architecture is highly scalable as light passes through only one switching element irrespective of the switch size.

We present a design for an on-chip MEMS-actuated Variable Optical Attenuator (VOA) based on Silicon Photonic MEMS technology. The VOA consists of 30 individual mechanically movable MEMS cantilevers, suspended over an integrated, 1 mu m wide bus waveguide, each terminating with two optical attenuation bars. By exploiting the pull-in instability, electrostatic actuation allows to move the individual cantilevers into proximity of the waveguide, leading to scattering of the evanescent field and thus attenuation of the remaining optical power in the waveguide. Electrodes are placed below the cantilevers for electrostatic actuation. Mechanical stoppers are used to avoid contact between the cantilevers and the electrodes and to keep the bars at a precisely defined distance of 60 nm away from the bus waveguide. The attenuator provides nearly zero insertion loss in OFF state, while in ON state, the attenuation range is defined by the number of actuated digital attenuation cantilevers and can be adjusted in discrete increments of only 1.2 dB. Owing to the small size, fast microsecond scale response time can be achieved, and electrostatic MEMS actuation allows for broadband and low-power operation. Our design exhibits a compact footprint of 30 mu m x 45 mu m, attenuation from 0 dB to 36 dB, while keeping return loss below 27 dB. To the best of our knowledge, this is the first presentation of a design of a VOA in Silicon Photonic MEMS technology.

Exploiting mechanical movement of surface micromachined waveguides on a passive silicon photonics platform provides scalable opportunities for efficient on-chip manipulation of optical signals in complex photonic integrated circuits for future photonic networks.

We present the design of an analog Silicon Photonic MEMS phase shifter based on vertically moving adiabatic couplers. Using a two-step electrostatic actuation method, the phase shifter can be turned on selectively by applying an actuation voltage on a first pair of electrodes, and the phase of the optical signal can be tuned continuously by applying an actuation voltage at a second electrode pair. A mechanical movement of only 20nm at 19V actuation voltage allows for a full π phase shift. The design exhibits a compact footprint of 60um × 44um and low excess insertion loss below 0.1dB.

We review the state of the art of silicon photonic switches with MEMS actuation, which have high scalability, low power consumption, and digital switching characteristic. We also present the potential of polarization insensitive switching by MEMS-actuated silicon photonic switches.

We present a design for an analog phase shifter based on Silicon Photonic MEMS technology. The operation principle is based on a two-step parallel plate electrostatic actuation mechanism to bring a vertically movable suspended tapered waveguide in a first step into proximity of the bus waveguide and to tune the phase of the propagating coupled mode in a second step by actuation of the suspended waveguide to tune the vertical gap. In the coupled state, the effective index of the optical supermode and the total accumulated phase delay can be varied by changing the vertical separation between the adiabatically tapered suspended and the fixed bus waveguides. Simulations predict that pi phase shift can be achieved with an actuation voltage of 19 V, corresponding to a displacement of 19 nm. With an adiabatic coupler geometry, the optical signal can be coupled between the moving waveguide and the bus waveguide with low loss in a wide wavelength range from 1.5 mu m to 1.6 mu m keeping the average insertion loss below 0.3 dB. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

We report on 4x20 silicon photonic MEMS switch that is capable of multicasting. The switch is built on passive optical crossbar network with gap-adjustable directional couplers. The switch has high on-off extinction ratio (59 dB), low insertion loss (< 4.0 dB), small footprint (1.2x4.5 mm2), and fast response (9.8 µs). The switching voltage is 9.6 V and 20 dB bandwidth is 31.5 nm. One-to-two and one-to-four multicast operations are demonstrated.

We report on the first electrical and optical packaging of digital silicon photonic MEMS switches with 12×12 ports, 13∼18dB fiber-to-fiber loss, 10−11 BER for 10-Gb/s datastream, 0.4μs switch reconfiguration time, and

Large-scale (50x50 and 64x64) integrated photonic switches have been realized by combining silicon photonics with efficient micro-electro-mechanical-system (MEMS) switching mechanisms. Low on-chip loss (0.058dB/port) and sub-microsecond switching time have been achieved.

Silicon photonics offers unprecedented capability to integrate large-scale optical switches on a chip. We review the current state-of-the-art of silicon photonic switches, and describe our large-scale (64×64) switches with microsecond switching time.

Large-scale silicon photonic switches with high port counts (64×64) and low on-chip losses have been realized by integrating micro-electro-mechanical-system (MEMS) actuators with silicon photonics. The switch has fast (sub-microsecond) switching time, and has potential applications in reconfigurable networks for data-intensive computing.

We report on monolithically integrated 64×64 broadband digital silicon photonic MEMS switches with sub-microsecond switching time (0.9 μs), high extinction ratio (65 dB), low on-chip insertion loss (5.1 dB), broadband operation (1460–1580 nm wavelength) and compact footprint (7×7 mm2).

We present a scalable silicon photonic MEMS switch with an actuation scheme requiring only 2N electrical contacts for an N×N switch matrix. Unit cell size is 145µm × 145µm and switching loss 1.5dB at 1550nm.

Interfacial reactions, surface morphology, and current-voltage (I-V) characteristics of Ti/Al/4H-SiC and TiN/Al/4H-SiC were studied before and after high-temperature annealing. It was observed that surface smoothness of the samples was not significantly affected by the heat treatment at up to 900°C, in contrast to the case of Al/SiC. Transmission electron microscopy (TEM) observation of the Ti(TiN)/Al/SiC interface showed that Al layer reacted with the SiC substrate at 900°C and formed an Al-Si-(Ti)-C compound at the metal/SiC interface, which is similar to the case of the Al/SiC interface. The I-V measurement showed reasonable ohmic properties for the Ti/Al films, indicating that the films can be used to stabilize the Al/SiC contact by protecting the Al layer from the potential oxidation and evaporation problem, while maintaining proper contact properties.

We report on monolithically integrated 50×50 digital silicon photonic switches with MEMS actuation, sub-microsecond switching time, low optical insertion loss (

We report on monolithic 4×20 silicon photonic MEMS switches capable of multicast functions. The switch has small footprint (1.2×4.5mm2), low optical insertion loss (

We report on 50x50 MEMS-actuated silicon photonic switches with 16V switching voltage and microsecond switching time. 2,500 MEMS cantilever 1x2 waveguide switches have been integrated on 9mmx9mm chips

We have shown that optically active second-harmonic generation is allowed in a uniaxial fluid medium. A homeotropically aligned chiral smectic-A liquid crystal was used as an example. Phase matching was achievable by angle tuning. Chiral nonlinear susceptibility for the liquid crystal was deduced. The signal dropped precipitously as the sample underwent the transition from smectic-A to isotropic.

Large-scale photonic switches are essential devices for energy-and cost-efficient optical communication networks in cloud and data-intensive computing. Silicon photonics is an attractive platform for high-density photonic integrated circuits with low manufacturing costs through the leveraging of existing advanced complementary metal-oxide-semiconductor processes. Many optical components such as lasers, modulators, splitters, and photodetectors have been successfully integrated on silicon; however, the quest for large-scale silicon photonic switches has remained elusive. Previous silicon photonic switches made of cascaded 1 x 2 or 2 x 2 building blocks have a limited port count (= 8 x 8) or excessive optical losses (> 15 dB). Here, we present a 64 x 64 digital silicon photonic switch with a low on-chip insertion loss (3.7 dB) and broadband operation (300 nm). The measured switching time is 0.91 mu s, and the extinction ratio is larger than 60 dB. The matrix switch with 4096 microelectromechanical-systems-actuated vertical adiabatic couplers has been integrated on a 8.6 mm x 8.6 mm chip. To our knowledge this is the largest monolithic switch, and the largest silicon photonic integrated circuit, reported to date. The passive matrix architecture of our switch is fundamentally more scalable than that of multistage switches. (C) 2016 Optical Society of America

We report on fully reconfigurable CROWs with MEMS-tunable waveguides. Resonatorto-resonator and resonator-to-waveguide coupling are fully tunable. Resonance of a resonator is also widely tunable to cover its full FSR. The static power consumption per tunable coupler is below 10nW. (C) 2021 The Author(s)

We demonstrate a die level release process for silicon photonic MEMS structures, that is compatible with dies from a standard silicon photonics foundry process which are only several square millimeters in size.

We developed chalcogenide-silica hybrid platform without direct patterning and achieved a record high Q-factor of 13 million in the hybrid resonator. Stimulated Brillouin lasing at 1 mW threshold power is implemented by flip-chip coupling.

Fast optical circuit switches (OCSs) with high port count offer reconfigurable bandwidth in optical networks and have the potential to significantly increase the performance and efficiency of modern datacenters. In this paper, we report on a new type of integrated OCS that combines silicon photonics with MEMS actuation. The switch is built on a 50 × 50 passive crossbar network with very low optical loss (0.04 dB/crossing). Efficient switching is achieved by a pair of directional couplers with moving waveguides and an actuation voltage of 14 V. 2500 MEMS-actuated directional coupler switches have been integrated with the crossbar network to form a strictly nonblocking 50 × 50 OCS on a 9 mm×9 mm chip. The measured switching time is 2.5 μs, and the extinction ratio is 26 dB. To our knowledge, this is the largest silicon photonic switch reported to date. The switch architecture is highly scalable because the light travels through only one active switching element, regardless of the size of the switch. © 2015, Optical Society of America.

Large-scale integrated photonic switches (50x50 and 64x64) have been realized by combining silicon photonics with efficient MEMS switching mechanisms. These switches are based on passive crossbar architecture, which is fundamentally more scalable than other switches.