Rotary optical switching enables low-loss microsecond-scale reconfiguration between pre-programmed interconnects with thousands of ports, supporting high-bandwidth and low-latency Rotornet datacenter architectures. We describe a 7 µs 128 × 128 port rotor switch with 4 dB fiber-to-fiber insertion loss and a 1-dB spectral bandwidth of 120 nm.

The Lightwave Energy-Efficient Datacenter (LEED) project within the ARPA-e ENLITENED program is developing novel energy-efficient multichannel lightwave networks. These networks are enabled by a new optical “rotor” switch that can reconfigure the network topology in less than 20 µs and a field-programmable-gate-array-based network interface controller called Corundum that can provide precise network-wide synchronization of packets admitted into the lightwave network. Here we review the optical networking research within LEED and discuss future directions.

A Lightwave Energy-Efficient Datacenter (LEED) is described that consists of: (1) A novel optically-switched datacenter architecture, (2) a "Rotor" optical switch that can reconfigure a network topology in less than 20 microseconds, and (3) Enhanced link margin burst-mode interconnects that can accommodate an optical switch without the need for optical amplification.

Fast beam steering is useful in applications including free space optical switching and communications. Quasi-static beam steering, where the beam rapidly switches between discrete fixed directions, presents special challenges. Here we demonstrate a fast quasi-static ‘pinwheel’ scanner by conformally mapping linear blazed gratings into curved structures fabricated onto annular sections of a rotary disk. We use Matlab and Zemax to model the effects of the conformallymapped grating on the emitted optical beam. We show a specific two-dimensional (2D) ‘pinwheel’ scanner design with 56 gratings, each deflecting 1.31 μm incident light by 11.3° in one of four directions with 75% optical efficiency. The element was fabricated by optical grey-scale lithography on a 95 mm diameter substrate, coated with gold, and mounted onto the spindle of a 3.5” format 7200 rpm magnetic disk drive. We characterize the optical beam steering efficiency, pointing, and stability, and demonstrate microsecond switching speed of a single mode fiber signal.

We describe a panoramic camera using one monocentric lens and an array of light field (LF) sensors to capture overlapping contiguous regions of the spherical image surface. Refractive sub-field consolidators divide the light before the image surface and concentrate the sub-images onto the optically active areas of adjacent CMOS sensors. We show the design of a 160° × 24° field-of-view (FOV) LF camera, and experimental test of a three sensor F/2.5 96° × 24° and five sensor (25 MPixel) F/4 140° × 24° camera. We demonstrate computational field curvature correction, refocusing, resolution enhancement, and depth mapping of a laboratory scene. We also present a 155° full circular field camera design compatible with LF or direct 164 MPixel sensing of 13 spherical sub-images, fitting within a one inch diameter sphere.

We describe a catadioptric monocentric imager using an elastic central element focused by deformation of a fold mirror. We show the design of 6 mm and 12 mm focal length F/2.8 achromats and compare design performance when focusing by translating the sensor, translating the fold mirror, and by spherically deforming the fold mirror. We tested the 12 mm focal length design using a diamond turned polystyrene element as the outer meniscus lens (and mechanical mount), filled with an optical gel in contact with the central aperture and fold mirror, and demonstrate focusing by mechanical deformation of the fold mirror. The resolution at the spherical image surface was inspected by optical relay imaging, yielding a best focus MTF50 of 52.6  lp/mm.

We propose a receiver design and simulation that optimizes a Si microlens array with micro-optic injection structures to selectively couple light into a waveguide and then to an edge-mounted detector to couple 2.5Gbps modulated input.

We describe a monocentric wide-field camera that corrects field curvature by light field processing, showing a contiguous multi-sensor design, and results from a relay-imaged testbed that sequentially captures a 72 MPixel 138° light field panorama.

Shifu Yuan and Nabeel A. Riza, General formula for cou pling-loSS characterization of Single-mode fiber collimators by use of gradient-indeX rod lenses, Applied Optics/Vol. 38, No. 15, May 20, 1999. Nabeel A. Riza, Reconfigurable Optical Wireless, IEEE Lasers and Electro-Optics Society, Vol. 1, Nov. 8–9, 1999, pp. 70–71. Nabeel A. Riza and Sarun Sumriddetchkajorn, Digitally controlled fault-tolerant multiwavelength programmable fiber-optic attenuator using a two-dimensional digital micromirror device. Optics Letters/vol. 24, No. 5/Mar. 1, 1999, pp. 282-284. Nabeel A. Riza and Sarun Sumriddetchkajorn, Multiwave length Three Dimensional 2x2 Fiber-Optic Switch Structure Using Small Tilt Micro-Mirrors,SPIE, vol. 3749, pp. 470-471, Aug. 1999. Joseph E. Ford and James A. Walker, Dynamic Spectral Power Equalization Using Micro-Opto-Mechanics, IEE Photonics Technology Letters, vol. 10, No. 10, Oct., 1998, pp. 1440-1442. Laor, Fontenot, Richards, D'Entremont, Hudson, Krozier, Performance of a 576x576 Optical Cross Connect, National Fiber Optic Engineers Conference, Sep. 26-30, 1999, pp. 276-281.

Light field (LF) capture and processing are important in an expanding range of computer vision applications, offering rich textural and depth information and simplification of conventionally complex tasks. Although LF cameras are commercially available, no existing device offers wide field-of-view (FOV) imaging. This is due in part to the limitations of fisheye lenses, for which a fundamentally constrained entrance pupil diameter severely limits depth sensitivity. In this work we describe a novel, compact optical design that couples a monocentric lens with multiple sensors using microlens arrays, allowing LF capture with an unprecedented FOV. Leveraging capabilities of the LF representation, we propose a novel method for efficiently coupling the spherical lens and planar sensors, replacing expensive and bulky fiber bundles. We construct a single-sensor LF camera prototype, rotating the sensor relative to a fixed main lens to emulate a wide-FOV multi-sensor scenario. Finally, we describe a processing toolchain, including a convenient spherical LF parameterization, and demonstrate depth estimation and post-capture refocus for indoor and outdoor panoramas with 15 × 15 × 1600 × 200 pixels (72 MPix) and a 138° FOV.

Fiber-coupled image sensors have attracted interest in recent years for high-resolution conformal image transfer, including mapping of the spherical image surface of a monocentric wide-angle lens to one or more flat focal plane sensors. However, image resolution is lost due to fiber bundle defects, moiré from lateral fiber-sensor misalignment, and blur due to the nonzero gap between fiber bundle and the image sensor. Here we investigate whether subpixel impulse response characterization of the strongly shift-variant impulse response can be used with existing image-processing techniques to recover the resolution otherwise lost in image transfer. We show that the submicrometer impulse response is experimentally repeatable, and can be used to recover image data and reveal fine features of the input surface structure of a 2.5 μm pitch fiber bundle.

We present design and preliminary characterization of a scalable MEMS-based “selector switch” for high performance computing networks. The 170 μs, 61-port prototype uses relay image steering to route all 61 SMF channels through one of six pre-structured interconnects.

We investigate partially configurable optical circuit switches as a means to circumvent the physical and control layer scaling challenges of optical crossbar switches. We present the optical design and characterization of a prototype partially configurable switch as well as network architectures which employ these switches.

A wink-controlled, military hands-free binocular system using polarization switching and eye-borne optics embedded within wearable scleral contact lenses is described. The lenses provide both refractive unmagnified and peripheral vision and a 2.8× magnification catadioptric telescope using four concentric annular mirrors. Self-contained eyewear with liquid crystal shutters combined with orthogonal linear polarizers within the contact lens allows for selection between the optical paths. A temple-mounted controller monitors reflection of NIR light from a diffusing retroreflector in each lens, ignoring blinks, and switching between paths in response to right- and left-eye winks. The results of testing the prototype system using a scale-model human eye with mechanical “eyelids” as well a small scale clinical (nondispensed) demonstration are discussed.

Conventional lens stops, implemented with an absorptive physical aperture, have an angle-dependent projection that introduces field dependent loss and reduces diffraction-limited resolution. Retro-telephoto lenses obtain uniform response using aberration vignetting, but this results in low wide-angle resolution and significant lens volume. However, an angle-independent "virtual" aperture can be created by total internal reflection (TIR) from a thin low index layer inside the lens. We apply this to monocentric wide-angle imaging and find a simple relationship between the filtering layer index and radius and the resulting lens F/#. We provide two detailed designs of lenses with 12 mm focal length and a F/2.5 TIR stop, one using a low index adhesive within a solid fixed-focus lens, the other using an air cavity within an adjustable focus lens. We show the designs provide absolutely uniform resolution and light collection over an angle range of 84° and 106°, respectively, resulting in a dramatic improvement of both light collection and angular resolution per unit volume over conventional wide-angle lenses.

Panoramic imaging is important for many different applications, including content for immersive virtual reality. Although compact 360 cameras can be made from an array of small-aperture ‘smartphone’ imagers, their small (typically 1.1 m) pixels provide low dynamic range. Moreover, digital single-lens-reflex and cinematographic imagers have 4–8 m pixels, but require correspondingly longer focal length lenses. Conventional ‘fisheye’ lenses are also problematic because they are bulky and have low light collection (typically F/2.8 to F/4, where F is the focal length divided by the lens aperture). An alternative path to panoramic imaging is ‘monocentric’ optics, where all surfaces—including the image surface—are concentric hemispheres.1 The symmetry of these lenses means that lateral color and off-axis aberrations (astigmatism and coma) are eliminated. In addition, the simple lens structures can be used to correct for spherical and axial color aberrations to yield extraordinarily wide angle resolution and light collection.2 The image that is produced can be coupled to a conventional focal plane, via a fiber bundle faceplate (with a curved input and flat output face).3 Fiber faceplates are solid glass elements made of small, high-index optical fibers separated by a thin, low-index cladding, used for nonimaging transfer of light between the input and output faces. From our research, within the Defense Advanced Research Projects Agency (DARPA) SCENICC (Soldier Centric Imaging via Computational Cameras) program, we have shown that fiber bundles can reach a spatial resolution of 2 m.4 We have also Figure 1. Geometry of a monocentric lens (left) and the spherical image surface it forms (right) can be coupled to CMOS focal plane(s) by an array of straight fiber bundles (top) or a single curved fiber bundle (bottom). The F-number is the focal length (f) divided by the lens aperture.

We present a first-principles analysis of the scaling of switch response speed as a function of port count, crosstalk, and insertion loss, based on physical optics and kinematics of canonical MEMS tilt mirror switch structures.