Real-world SDM deployment requires the development of a supporting ecosystem. Recent technological advancements allow for volume production of key components of this ecosystem, MCF fanouts, which meet demanding performance requirements.

We demonstrate a broadband, low-loss pair of fanouts fusion spliced to a 200-meter-long, 4-core, datacom MCF covering both the O- and C-bands with loss smaller than 0.6 and 0.4 dB, respectively. Near field mode profiling allows for fine adjustment of the mode field.

A cable link with 288 four-core multicore fibers and 288 pairs of fanout devices was deployed in the field and its losses were evaluated. No excess losses were observed from MCFrelated components in field installation.

We have designed, developed, and deployed the world's first ultra-dense space division-multiplexing multicore fiber link in a conduit of a metro network. In a 10-mm-diameter fiber optic-cable, 288 4-core multicore fibers are arranged in 24 200-µm spiderweb collapsible ribbons. The multicore fibers are fusion-spliced to 576 fanout devices which provide conventional single-core interfaces at patch panels at both ends of the link.

SDM using multicore fibers has the potential to increase the bandwidth density of optical links as well as to improve performance of sensing systems including 3D shape sensing and fiber optic gyroscopes. These applications are advanced by the low insertion and return loss, wide bandwidth, passive add-drop multiplexer demonstrated here.

Fiber-integrated, submersible-qualified, core-pumped, multicore EDFAs are in -dispensable for space-division-multiplexing envisioned for the next generation of submarine communication lines. Here we demonstrate a fully packaged, 63-dB counter-propagating crosstalk, and 70-dB-return-loss four-core pump-signal-combiner. This enables core-pumping of a four-core EDFA.

MCFs have been developed for submarine deployment. Reliability and insertion loss are gating factors for this demanding application. Here we demonstrate a 0.15-dB-loss fanout, which is fusion spliced to a pure-silica two-core submarine-grade MCF.

Sixty-one lasing fiber channels are passively combined in a monolithic optical resonator array to produce an output power above 200 W at two-micrometer wavelength with the central intensity enhanced by a factor of 8 compared to incoherent beam combination. The 61-channel lasing mode corresponds to a transitional state with 75-degree phase shift between neighboring cores and has a far-field peak intensity 4.6 times below theoretical prediction for a fully coherent array. A 7-channel mode corresponds to the anti-phase supermode of the Talbot cavity, which has no central lobe in the far field. The monolithic laser cavity is formed by a fiber array, which is drawn and fusion-spliced to an endcap serving as a Talbot cavity mirror without air gaps. The central intensity enhancement, which is achieved without spectral or polarization selectivity, improves as the number of channels increases. This is an important step towards a passively combined multichannel all-solid-state laser system.

SDM using uncoupled or coupled core multicore fibers promises to increase the bandwidth density in optical links. In addition, these fibers form a platform for various sensing systems, including 3D shape sensing. Both applications will be advanced by the low return loss fanout-multicore fiber assembly demonstrated here.

We have developed a multichannel output coupler enabling coherent beam combining in the two-micron spectral range. We demonstrate experimentally the combining of multiple beams utilizing a set of thulium-doped, double-clad, singlemode optical fibers. The fibers are pumped by fiber-pigtailed laser diodes at 793 nm via (4+1)x1 pump-signal combiners. The combiners are fabricated using vanishing-core technology, which allows for preservation of the mode field through the tapering process. The output of individual lasing channels is generated over a 20 nm spectral band at around 1970 nm without any spectrally selective elements. The slope efficiency of individual lasers is approximately 50% with respect to the pump power. All lasing channels are fused into a monolithic silica structure with channel spacing of 32 microns on a triangular lattice. The fused assembly is fabricated in a glass microforming tapering process with a draw ratio of 3.9. In the process, the mode field at 1970 nm expands slightly to about 15 microns at the end of the taper, while the outer diameter is reduced from 2.3 mm to approximately 590 microns. The tapered end is straight polished and fusion spliced to a 600- micron diameter silica glass rod. The rod is cleaved and optically polished at zero degrees. The length of the rod is one half of the Talbot distance for optimal coherent beam combining. In the experiment, an antiphase supermode is observed when only the seven inner channels are pumped, and an in-phase supermode is excited when the number of channels is nineteen or larger.

The sensitivity of an interferometric fiber optic gyroscope (IFOG) scales with the length of the sensing optical path. Thus, IFOG development history has seen much work devoted to shrinking ever-increasing lengths of optical fiber into a fixed volume. Indeed, the success of the IFOG as a guidance and navigation technology is founded, to a large extent, on the many advancements in fiber-optics which were required to compact numerous state-of-the-art components - including a multi-kilometer length of optical fiber - to within the size of a teacup. An exciting technology which promises to continue this trend is multicore optical fiber, in which multiple, independent optical waveguides (cores) are placed within the same glass cladding which would ordinarily contain only one core. The dense arrangement of cores in such fibers can be exploited in an IFOG by connecting them in series, and thereby increasing the instrument sensitivity proportionally. As originally proposed by Bergh [1], these features present an opportunity to increase sensitivity while reducing the sensor footprint and simplifying the optical fiber coil - a key driver of cost and complexity in IFOGs. Here we detail performance characteristics of an all-fiber multicore IFOG employing a bend-insensitive, single-mode, 7-core fiber in the sensing coil. Like the recent, first-ever demonstration by Mitani et al. [2], [3], we employ an open-loop testbed architecture with a depolarized sensing loop, in which fiber cores are connected in series via a pair of multicore fan-in/fan-out devices. Here however, the fan-in/fan-out components are tapered fiber devices, packaged in conventional fiber-optic component sleeves, and with the core interconnections made via standard fusion splices [4]. Measurements of noise and long-term stability of the instrument show that its performance is commensurate with the 7X enhanced sensitivity afforded by the optical path length increase. For this 7-core, 154 m long, 10 cm diameter fiber coil, we show long-term gyro bias stability under 0.02 deg/hr and angle random walk of 2.4 mdeg/√(hr). This compares favorably with both noise models and performance measurements in IFOGs of similar scale factor, thus confirming the sensitivity improvement conferred by use of 7-core fiber. The all-fiber configuration of the sensing loop makes this instrument highly practicable as a drop-in replacement for current IFOGs, with no change to existing front-end designs. Moreover, as multicore fiber technology continues to push the frontiers of optical fiber transmission capacity, future designs may benefit from even greater core multiplicity - an exciting prospect for the next generation of compact, low-cost, high-accuracy IFOGs.

A 16-channel spatial-division multiplexed transceiver is demonstrated using a multicore fiber coupled to a dense array of co-integrated 56Gb/s GeSi electro-absorption modulators and photodetectors, realizing 896Gb/s aggregate bi-directional bandwidth in 1.47mm 2 silicon footprint.

We review the state of the art of silicon photonic switches, with an emphasis on their scalabilities. We also describe a high-radix MEMS-actuated silicon photonic switch that is scalable to hundreds of ports.

We demonstrate an all-glass, 61-channel, flexible, two-dimensional optical fiber array with 37 inner channels matched to an array of vertical grating couplers of a multi-channel (16 Tx and 16 Rx) transceiver prototype occupying a chip area of only 0.16 mm2.

A scalable ultradense silicon photonic interface with 61 compact vertical grating couplers on a pitch of 42.3 μm is designed and fabricated to match a pitch reducing optical fiber array (PROFA) hexagonal channel pattern. Experimental results show that the designed grating couplers with a minimum insertion loss of 4.5 dB and a 3-dB bandwidth of 50 nm are obtained. The crosstalk between different channels is less than -50 dB and the maximum loss difference across the PROFA interface is ~0.7 dB. High-speed data transmission indicates that a bandwidth density as large as 27 Tb/s/mm2 could be achieved within a footprint of 0.096 mm2, demonstrating the potential of silicon photonics for broadband optical interconnection.

An ultra-dense optical off-chip I/O interface consisting of 61 grating couplers matching the pitch of a commercial two-dimensional fiber array enables tremendous bandwidth density on the order of tens of Tb/s/mm(2) towards high throughput Silicon photonics.

We have developed an all-glass, fusion spliceable polarization maintaining (6+1) x 1 pump/signal combiner for fiber lasers and amplifiers. We utilize an enhanced tapered fiber bundle technology for multimode pump channels and a vanishing core fiber for the single mode polarization maintaining large mode area (PLMA) signal channel. The signal channel of the combiner is optimized to match a double-clad PLMA fiber with 20 micron core and 400 micron glass cladding with 0.065 numerical aperture (NA). The multimode pump channels have 200 micron core and 240 micron cladding with NA of 0.22 designed to deliver high power 980 nm pump light. The same double-clad PLMA fiber is used as both the signal input channel and the combined output for the device. Polarization axes of the input and output PLMA fibers are aligned during the fusion splices to achieve polarization crosstalk below -20 dB. Utilizing this approach, we have achieved coupling loss of similar to 0.4 dB for the signal channel as measured from the input PLMA to the output PLMA at a wavelength of 1060 nm and coupling loss below 0.01 dB for all pump channels as determined from the measured temperature rise of the combiner package temperature as the optical pump power at 974 nm is increased up to 45 W. Low signal and pump losses result in high efficiency lasing or amplification at over a kW of pump power for high power applications where a single mode, high polarization extinction ratio output is required.