We present the theory of operation along with detailed device designs and initial experimental results of a new class of
uncooled thermal detectors. The detectors, termed microphotonic thermal detectors, are based on the thermo-optic effect
in high quality factor (Q) micrometer-scale optical resonators. Microphotonic thermal detectors do not suffer from
Johnson noise, do not require metallic connections to the sensing element, do not suffer from charge trapping effects,
and have responsivities orders of magnitude larger than microbolometer-based thermal detectors. For these reasons,
microphotonic thermal detectors have the potential to reach thermal phonon noise limited performance.
Cyan Systems is developing a new Extremely High Temperature Projector System Technology (XTEMPS). The XTEMPS is a multispectral emitter array based upon photonic crystals, providing high radiance and tailored spectral emission in infrared (IR) bands of interest. Cyan has teamed with a state of the art MEMS fabrication facility, Sandia National Laboratories, to develop metallic photonics crystals designed for scene projection systems. Photonic crystals have improved output power efficiency when compared to broad band "graybody" emitters due to limiting the emission to narrow bands. Photonic crystal based emitter pixels have potential for higher effective radiance output, while filtering out energy in the forbidden bandgap. Cyan has developed pixel designs using a medium format RIIC from Nova Sensors that ensures high apparent output temperatures with modest drive currents, and low voltage requirement goals of < 5 V. Cyan has developed a pixel structure for high radiative efficiency of the photonic lattice, while suppressing undesired IR sidelobes. Cyan will provide XTEMPS system performance metrics and illustrate with test structures.
We have designed, fabricated, and tested large sheets of photonic bandgap (PBG) material that have a "cubic array of cubes" structure. Structures with bandgaps in two wavebands have been fabricated: the thermal IR (8-12μm) and the visible/near IR (0.6-2.5μm). A thermal-IR PBG can modify the emission properties of structures for temperature control. Visible/near-IR PBGs can be used in photonic circuits and can improve illumination efficiency.
The LIGA microfabrication technique offers a unique method for fabricating 3-dimensional photonic lattices based on the Iowa State "logpile" structure. These structures represent the [111] orientation of the [100] logpile structures previously demonstrated by Sandia National Laboratories. The novelty to this approach is the single step process that does not require any alignment. The mask and substrate are fixed to one another and exposed twice from different angles using a synchrotron light source. The first exposure patterns the resist at an angle of 45 degrees normal to the substrate with a rotation of 8 degrees. The second exposure requires a 180 degree rotation about the normal of the mask and substrate. The resulting pattern is a vertically oriented logpile pattern that is rotated slightly off axis. The exposed PMMA is developed in a single step to produce an inverse lattice structure. This mold is filled with electroplated gold and stripped away to create a usable gold photonic crystal. Tilted logpiles demonstrate band characteristics very similar to those observed from [100] logpiles. Reflectivity tests show a band edge around 5 μm and compare well with numerical simulations.
Monolithic multi-layer optical disks have been recorded with single-beam two-photon absorption using a high-repetition- rate laser. The recorded bit shape and signal readout will be discussed. It will also present some initial experimental results in cross talk and signal quality measurements.
Testing of servo error signal detection technique for 2- photon recorded monolithic multilayer material is investigated. A standard CD voice-coil actuator follows a fluorescent track.
KEYWORDS: Luminescence, 3D optical data storage, Absorption, Data storage, Sensors, Spatial light modulators, Objectives, Signal detection, Laser systems engineering, Modulation
Two-photon 3D optical data storage techniques can achieve hundreds of GB data capacity per disk by storing data in multi-layer volumetric media. This approach can also provide fast data transfer rates by using parallel access techniques. It is a promising solution for the high data capacity demands in imaging and video applications, and the high-speed data access requirements in large-scale high- speed data processing. Development of this technology integrates and leverages developments in parallel sensors, spatial light modulators, novel optics, parallel signal processing, and micro-optic packaging.
KEYWORDS: Optical storage, Sensors, 3D optical data storage, Luminescence, Servomechanisms, Data storage, Magnetism, Absorption, Signal processing, Signal to noise ratio
Three-dimensional parallel readout of 2-photon multilayer optical disks can simultaneously offer high capacities (greater than 100 GB/disk) and high data transfer rates (greater than 1 Gb/s). The robust system tolerances should enable cost effective storage systems with capacities and transfer rates that are scaleable to match various application requirements.
KEYWORDS: Optical storage, Data storage, Absorption, Polymers, Luminescence, Signal to noise ratio, Virtual reality, Video, Digital video discs, Digital recording
The generation and application of information is rapidly evolving from text and graphics based to multimedia based, and it will shortly continue to evolve to virtual reality. The evolution between these stages introduces dramatic increases in the amount of data associated with the applications. For example, where text-based meeting notes have given way to emailed copies of vugraphs, future meeting documentation may require storing and communicating an entire collaborative virtual reality session. Even in the near term, the need to store, search for, and edit large numbers of images and digital video clips will drive data storage requirements forward in home, office, and network arenas, as shown in Fre 1 .
Volumetric memories based on the extension of conventional approaches by using the third dimension for multiple layers may offer dramatic increases in storage capacity. For such thick- media multilayer systems, the design of the optical head includes challenges in the control and tolerancing of aberration accumulation throughout the focal depth. In this paper we review the accumulation of these aberrations in high resolution thick disk media, and compare the tradeoffs associated with several aberration compensation techniques. Both analytical and simulation results of aberration accumulation as a function of the system f-number will be presented. Aberration compensation tradeoffs including compensator complexity, cost, compensation range, speed will b detailed. Simulation results of a compensation technique will be presented.
KEYWORDS: Absorption, Luminescence, Signal detection, Numerical simulations, Multilayers, Digital recording, Process modeling, Data storage, Computer simulations, Optical simulations
Three layer data recording has been demonstrated in monolithic disk media using two-photon absorption. Two dimensional data arrays have been recorded and retrieved in parallel. The recording process has been modeled and simulated. Fluorescence has been detected from a disk spinning at 1500 rpm with a signal to noise ratio of 10.
Anthony Lentine, Daniel Reiley, Robert Novotny, Rick Morrison, Jose Sasian, Martin Beckman, D. Buchholz, Stephen Hinterlong, Thomas Cloonan, Gaylord Richards, Frederick McCormick
In the past few years, the demand for telecommunications services beyond voice telephony has skyrocketed. For the growth of these services to continue at this rate, cost effective means of transporting and switching large amounts of information must be found. Although fiber optic transmission has significantly reduced the cost of transmission, switching high bandwidth signals remains expensive. While all electronic switching systems are certainly possible for these high bandwidth systems, considerable effort has been expended to reduce the cost of fiber optic connections between frames or racks of equipment separated by several meters. As an example, one can envision fiber-optic data links connecting the line units that receive and transmit data from the outside world with an electronic switching fabric. Optical data links, ODLs, can perform the optical to electrical conversions. Several of these optical data links can be electrically connected with electronic switching chips on a printed circuit board. As the demand for bandwidth increases, several hundred to several thousand optical fibers might be incident on the switching fabric. Discrete optical data links and parallel data links with up to 32 fibers per data link remain an expensive solution to transporting this information due to their per-link cost, physical size, and power dissipation. Power dissipation on the switching chips is high because of the need for electronic drivers for the high speed electrical interconnections between the switching chips and the data links. By integrating the O/E conversions directly onto the switching chips, lower cost and higher density systems can be built. In this paper, we describe preliminary results of an experimental optoelectronic switching network based on this lower cost solution. The network is designed to be part of an asynchronous transfer mode (ATM) network based on the Growable Packet Architecture. The switching chip consists of GaAs/AlGaAs multiple quantum well modulators and detectors flip- chip bonded to silicon VLSI circuitry. The optical system images the inputs from a two dimensional fiber bundle onto the switching chip, provides optical fan-out of the signals from the fibers to the switching chip, and images the outputs from the chip onto the fiber bundle.
The rapid advance of image-dependent information processing and entertainment applications has accelerated the need for data storage solutions that offer high capacity and high data transfer rates while maintaining low system and media costs. Volume optical memories based on 2-photon absorption-induced photochromism enable random access writing and erasure to individual bits, lines, planes, or sets of planes within the volume of the memory media. The 3- dimensional nature of the storage enables high storage capacities (theoretically 1012 bits/cm2) and parallel readout for high data transfer rates (1-100 Gb/s). The customizable nature of the media (dye-doped plastic) and efficient fluorescent mechanism of the memory readout promise cost-effective system and media solutions. Characterization experiments for erasable and read-only media have been performed, and system experiments for automated recording, and portable read-only memories have been designed and constructed.
The optical transpose interconnection system (OTIS) provides a good interconnection using only a pair of lenslet arrays. We have designed and optimized various OTIS systems based on refractive, spherical diffractive, and aspheric diffractive lenslets. The optimization goal is to maximize power coupling into the elements of a detector array. The various design approaches are compared and the optimal design is extracted; the parameters of the model are then to be used for the fabrication of the lenslet array. We also address system geometry, symmetry, and illumination issues relevant to the system design.
Several optical systems, based on a combination of lenslet arrays and computer-generated holograms (CGH), are described. They provide full or neighborhood connectivity between arrays of electronic processors, each processor containing one transmitter and N detectors. Some of the system are symmetrical, and therefore bi-directional. Specific designs include a system utilizing reflection-mode modulators that provides reciprocal connections between two planes of processors, and a system requiring sources or transmissive modulators that provides the connections required by a back-propagation neural network with an arbitrary number of layers. We derive expressions governing the lengths of the lenslet-based system and of a previous design based on bulk optics and CGH. The proposed systems require fewer components, less volume, and less alignment than the bulk optics system.
Free-space digital optical systems represent a novel interconnection technology that exploits the volume surrounding an electronic circuit substrate. The potential advantage of free-space optical systems is the creation of high density, energy efficient, parallel, high bandwidth interconnections. A photonic switching network, whose function is to connect high bandwidth channels, is a natural vehicle for exploring and developing this technology. Diffractive optical components play critical roles in these free-space systems as optical power array generators and interconnection holograms. In this paper, we will examine how these diffractive elements have served in realized photonic switching demonstration systems and explore some of the issues that determine their successes and limitations.
The design, assembly, and testing details of an objective lens used to image an array of 4096 beams are discussed. The main characteristics of the lens are a 15-mm focal length, a speed of f/1.5, diffraction-limited quality, telecentricity, f-sin(θ) mapping, an external stop, and a simplicity of fabrication.
The continuing increases in clock speed and electronic complexity of today's high performance digital systems have led to widespread investigation of new multi-technology interconnect and packaging solutions. Optical interconnects may be one such solution. Free-space optical interconnects (FSOIs) offer an evolutionary means of extending the performance of electronic technology by alleviating the communication "bottlenecks" in systems needing high speed, high density intercon- nections. Rather than concentrating the optical energy via waveguides, free-space optical interconnects use the dimension perpendicular to the planes containing the electronics, transmitters, and receivers. The enabling technologies for FSOI sys- tems include optical imaging systems, opto-mechanical packaging, two-dimensional optoelectronic (OE) device arrays, and diagnostic/test equipment.
Frederick McCormick, Frank Tooley, John Brubaker, Jose Sasian, Thomas Cloonan, Anthony Lentine, Rick Morrison, Randall Crisci, Sonya Walker, Stephen Hinterlong, Michael Herron
A series of experiments has been performed to determine the critical practical issues in high-density free-space optically interconnected systems. Some ofthese experiments have implemented switching fabrics by optically interconnecting 2-D arrays of symmetric seif-electro-optic effect devices (S-SEEDs). In the first, three 16 x 8 arrays of S-SEEDs, all operating as logic gates, were optically interconnected, and in the last experiment, afully interconnected switching fabric using six 32 x 32 S-SEED arrays was demonstrated. The practical realization of this technology represents a challenge to modern optomechanics because ofthe required optical resolution, mechanical precision, stability, and number of components involved. A comparison of these experimental systems shows that significant optical power loss may be incurred when theoretically "lossless" techniques are actually implemented, mainly because of the system complexity. The use of much simpler techniques is shown to dramatically decrease system assembly and alignment times and increase system stability, with similar overall loss. The tolerancing analysis used in these systems shows thatthe worst-case optical constraints result in mechanical tolerances in the micrometer to submicrometer range. The successful operation of these systems demonstrates the ability of relatively simple optical and mechanical techniques and materials to meet these tolerances.
Free-space optical interconnections offer a means to alleviate many high speed, high density communications problems in digital systems. The realization of this new technology involves the application of many classical optical testing techniques, as well as the development of several novel tools and techniques. We describe the design and implementation of a free-space optically interconnected switching fabric, and the fabrication and testing techniques involved. The lenses, polarizing beam-splitters, lasers, and diffractive optics used in the experiment were tested for optical transmission efficiency and uniformity, and wavefront quality.
The results of an experimental investigation of the use of prismatic mirror arrays as a crossover interconnect are presented. Analysis of the precision with which it is necessary to fabricate and align the interconnect is discussed. This precision is found to be proportional to the mirror array size.
We will discuss the optomechanical design of components used for free space optical switch prototypes built to develop potential solutions for the high-speed digital switching problems of bandwidth, interconnection, and density. In our free space optical switching fabrics, arrays of light beams propagate between array of optical transceiver devices called Symmetric Self Electro-Optic Effect Device (S-SEED). These arrays have been operated with more than a thousand beams incident on device windows typically 5 microns in diameter. To image the arrays required high resolution optics, tight component tolerances, and stable mounting techniques. This paper explains the optomechanical design and construction of the components of the free space optical switching fabric, designed under requirements of small size, high resolution of movement, mechanical stability, and minimal cost. Comparisons are made between two versions of experimental components, including S-SEED mounts and mounting plates.
Frederick McCormick, Frank Tooley, John Brubaker, Jose Sasian, Thomas Cloonan, Anthony Lentine, Rick Morrison, Randall Crisci, Sonya Walker, Stephen Hinterlong, Michael Herron
Parts of a multistage switching network were implemented by optically interconnecting arrays of symmetric self electro-optic effect devices. In an experiment completed last Spring, three 16 X 8 arrays of S-SEEDs, all operating as logic gates, were optically connected. A fully-interconnected switching fabric using six 32 X 32 S-SEED arrays is currently being tested. These are the latest in a series of experiments to investigate and develop this technology, and they substantially involve optomechanics. The practical realization of this technology represents a challenge to modern optomechanics due to the required precision, stability, and number of components involved. An overview of free-space photonic switching and the required experimental hardware subsystems is presented, followed by details of the optical systems to interconnect the switching device arrays and the mechanical systems which locate and position the optics and devices. The tolerancing analysis used in these systems is reviewed and comparisons between the two systems are made.
3D networks and 2D network have been proposed for use in photonic switching systems and they may be able to provide higher density connectivity between logic devices than similar electronic implementations. In this paper optical implemen-. tations of both 2D and 3D crossover networks will be described. We show that crossover networks can be used for connecting multiple stages of 2-input 2-output switching elements as well as 2-input logic gates. We also show that these switching elements can be implemented using optical logic gates such as Symmeuic SEED devices. We then describe simple conversion steps that can be used to convert 2D crossover networks into 3D crossover networks. Since both network types can be implemented with low-loss optical imaging systems these networks may prove to be useful in future optical computing and photonic switching applications. 1. BACKGROIJND ON CROSSOVER NETWORKS The 2D crossover network is a multistage interconnection network that is based on crossover interconnectionsJ11 A 2D crossover network with N inputs and N outputs is shown in Fig. 1. The 2-input 2-output nodes within the network can be operated as 2-input 2-output switching elements or as 2-input logic gates. Crossover networks with 2-input 2-output nodes require that N where m is a positive integer. In addition fully-connected crossover networks have log2(N) nodestages with N nodes per node-stage and they have log2(N)-1 link-stages with N links per link-stage. In Fig. 1
We demonstrate a prototype digital free-space photonic switching fabric consisling of three cascaded 16x8 arrays of Symmetric Self Electro-optic Effect Devices used as logic gates. 1.
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