This PDF file contains the front matter associated with SPIE Proceedings Volume 6478, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

In an effort to address the need for robust optical chip I/O interconnects, we describe the fabrication and testing of microscopic polymer pillars for use as a flexible optical bridge between the chip and the substrate. The polymer pillars are photoimaged using the polymer Avatrel to a height of up to 350 &mgr;m. The photodefinable polymer Avatrel was used for the fabrication of the optical pillars due to its ease of processing and its unique material properties that include high T_g and low modulus. To evaluate the performance of the polymer pillars, the optical coupling efficiency from a light source to an optical aperture with and without an optical pillar is measured. For a light source with 12^o beam divergence, a 30x150 &mgr;m polymer pillar improves the coupling efficiency by 3 to 4.5 dB compared to pillar-free (free-space) optical coupling. Due to the high mechanical compliance of the optical pillars, we also demonstrate that polymer pillars enhance the optical coupling efficiency between the chip and the substrate when they are misaligned in the lateral direction and that the displacement tolerance can be doubled from 15 to 30 &mgr;m for a 1dB power loss budget.

A novel 16-channel optical backplane bus with volume holographic optical elements (VHOEs), operating as diffraction grating beam alignment guides, was designed and fabricated for a high-performance computing system multi-slot bus. These thin film VHOEs were fabricated to diffract light beams for each bus slot into a glass wave-guiding plate (refractive index 1.52) for total internal reflection to other slot positions. Slot-to-slot optical alignment issues, including channel crosstalk and beam alignment tolerances, were computer modeled to optimize a low cost and simple optical packaging structure. For each slot position, a 4 × 8 element optical packaging plate was then fabricated to allow insertion of 16 VCSELs and 16 Photodiodes, each in an individual TO-46 can. Through the VHOE, the slot-to-slot fan-out received beam intensities were experimentally measured for each of the 16 channels and found to be in the range of 90 &mgr;W ~ 150 &mgr;W. This 90 &mgr;W minimum fan-out power is 5dB greater than the receiver sensitivity requirement. In this study, the maximum 10 Gbps single channel bandwidth was tested and a 1.6 Gbps aggregate bandwidth was also demonstrated through a three slot 16-channel optical backplane bus. This aggregate bandwidth was limited by an electronic element in the receiver circuit (155 Mbps PD-TIA) and processor (100 Mbps FPGA). With the system's measured optical isolation of greater than 80dB, and suitably fast receiver electronics, simulation modeling indicates that Terabit per second bus data rates can be achieved in inexpensive, mechanically robust and reliable form factors.

Optical interconnects to couple light from single mode fiber to waveguides and photonic elements have remained expensive due to tight alignment tolerances, materials choices, fabrication methods and assembly processing techniques. Methods that have been used to lower the cost of optical interconnects will be reviewed and compared to current and future market application demands. Design approaches, fabrication methodologies, and assembly processing techniques for optical interconnects to meet future lower cost market application demands will be shared.

In this paper we describe empirical models for predicting the performance of high power lasers, semiconductor optical amplifiers, and superluminescent diodes. The utility of the models is verified by comparing predicted results to actual performance of devices. Based on the model, three important parameters are identified for improving the performance of high power devices. These parameters include reducing the thermal resistance, reducing the series resistance, and reducing the vertical carrier leakage. A method is described to measure the thermal resistance. We further describe experiments done to reduce the series resistance of devices to achieve a value of less than 0.5 &OHgr; for a 1 mm long ridge device. Finally the effect of carrier stopper layers is described to reduce vertical leakage of carriers.

Linear arrays of slab coupled optical waveguide lasers (SCOWL) are ideal sources for beam combining of array elements using techniques such as wavelength beam combining (WBC) and possibly coherent beam combining (CBC). SCOWL array elements have very high brightness, low divergence nearly diffraction limited output beams. Arrays of up to 1.2 cm in width containing as many as 240 elements have been demonstrated. In this presentation, the packaging techniques developed to ensure proper performance of SCOWL arrays will be described, with particular emphasis on the application to beam combining. A commercial high performance micro impingement cooler (MIC) was used to provide thermal management for these arrays. Based on performance data for this cooler, a numerical thermal model was constructed and used to investigate the thermal performance for several packaging schemes. In order to promote uniform optical performance of SCOWL array elements, assembly procedures, which included fluxless soldering using In and AuSn solder alloys, along with the use of thermal expansion matching materials were investigated. These techniques resulted in minimal contraction (≈2 &mgr;m) and smile (≈1 &mgr;m) of the laser bar during the packaging procedure. Precise control of these parameters is required in order to minimize any detrimental impact on the resultant WBC beam quality. CBC of SCOWL arrays requires phase control of the array elements. Array packaging providing for individual electrical addressability of the array elements has been developed and demonstrated, allowing for phase control by current adjustment.

With the rapid development of Fiber Bragg Grating (FBG) sensing during recent years, FBG sensors are used in many fields; applications involving impact and vibration measurement require a high-speed interrogator. We have developed and prototyped a high-speed FBG interrogation system with a sampling rate up to 5 kHz. We show that FBG sensor optical spectral deformation may affect the performance of interrogators, such deformation can be introduced from non-uniform strain field or during FBG sensor packaging. This paper reports the experimental investigation of the impacts of the FBG spectral deformation on the interrogator accuracy, sensors with different optical spectral shapes are tested and analyzed, furthermore, we show how this high-speed interrogator is more tolerant to such deformation than peak tracking instruments.

Forecasting avionics industry fiber optic interconnect and optoelectronic packaging challenges that lie ahead first requires an assumption that military avionics architectures will evolve from today's centralized/unified concept based on gigabit laser, optical-to-electrical-to-optical switching and optical backplane technology, to a future federated/distributed or centralized/unified concept based on gigabit tunable laser, electro-optical switch and add-drop wavelength division multiplexing (WDM) technology. The requirement to incorporate avionics optical built-in test (BIT) in military avionics fiber optic systems is also assumed to be correct. Taking these assumptions further indicates that future avionics systems engineering will use WDM technology combined with photonic circuit integration and advanced packaging to form the technical basis of the next generation military avionics onboard local area network (LAN). Following this theme, fiber optic cable plants will evolve from today's multimode interconnect solution to a single mode interconnect solution that is highly installable, maintainable, reliable and supportable. Ultimately optical BIT for fiber optic fault detection and isolation will be incorporated as an integral part of a total WDM-based avionics LAN solution. Cost-efficient single mode active and passive photonic component integration and packaging integration is needed to enable reliable operation in the harsh military avionics application environment. Rugged multimode fiber-based transmitters and receivers (transceivers) with in-package optical BIT capability are also needed to enable fully BIT capable single-wavelength fiber optic links on both legacy and future aerospace platforms.

The development of integrated optical interconnections (IOIs) represents a quantum leap for the functionality of printed circuit boards (PCBs). This new technology will allow highly complex product features and hence, higher product added value. PCBs with optical interconnections will be used where applications call either for very high data streams between components, modules or functional units (e.g. backplanes or multiprocessor boards) or for a space-saving design for interconnection paths (e.g. mobile applications). We discuss the different approaches towards integrating optical waveguides into PCBs and analyze the prerequisites for a transfer to a product. Application scenarios for different markets are presented and steps proposed for required action to deliver solutions that can be driven into a market. In a second section a new and innovative concept for the integration of an optical interconnection system in PCBs is presented. This revolutionary concept is highly supporting the worldwide trend towards miniaturization of not only electronic but also optoelectronic systems in PCBs. The alignment of the optoelectronic components to the waveguides has been addressed by this concept. It is shown that the process will allow the tolerances incurred in the manufacturing processes to be dealt with in a separate process step, allowing existing standard methods for the production of electronic interconnection systems to be used.

We investigate the combined effect of the diffraction-caused crosstalk noise (DCCN) and the stray-light crosstalk noise (SLCN) on the performance of FSOI system. A numerical simulator was employed in this study to investigate OI channel design. We determine that there exists an optimal focal length, which maximises the signal-to-noise ratio (SNR) by minimising the combined effects of DCCN and SLCN. For the fundamental mode, the optimal focal length is approximately 750 &mgr;m for both LG₀₁ and LG₁₀ modes, the optimal focal length occurs between f = 650 &mgr;m and f = 700 &mgr;m, depending on the interconnection distance and array pitch.

A 3-slot optical backplane bus demonstrator based on glass substrate with photopolymer volume gratings array (PVGA) on top surface is built to allow 16 channels of data to be broadcast from central slot to two daughter slots or uploaded from any daughter slot to central slot. VCSELs and photodetectors packaged in the form of TO-46 can are assembled on top of each PVG and interleaved to reduce the crosstalk to below noise level. By carefully aligning the fabrication system, the incident angle deviation from Bragg condition is reduced to below 0.1° to maximize optical power delivery. The orientation and period of hologram fringes are uniform in the active area by collimating recording beams. Above 4.8Gbps aggregated data transmission is successfully demonstrated using the multi-channel system. Three computer mother boards using FPGA are made to verify the data transmission among the slots. Interface boards between the FPGA boards and optical transceivers are designed and fabricated to separate the implementation of digital layer and optical layer. Single channel transmissions with 3.2Gbps and even 10Gbps data rate are also tested with above 100uW input power, showing the potential to improve the total two-way bandwidth to above 102.4Gbps. Alignment tolerance of the optical interconnect system is investigated theoretically and experimentally. By analyzing the diffractive characteristics, the bandwidth limit of the optical layer is determined to be in the order of Terahertz. Design and fabrication issues are discussed for future optical backplane bus to make terahertz bandwidth into reality. Based on the experiments for Bit-interleaved Optical Backplane bus and Multi-channel optical backplane bus demonstrators, theoretical analysis of the bandwidth limit of the optical backplane bus using photopolymer volume gratings has been carried out.

The use of the third spatial dimension in optical systems is of interest for many applications such as sensing and data communications. Furthermore, the need for small size and low cost requires suitable concepts for integration and packaging. Here, free-space optical integration based on a planarized configuration is described. Recent advances are shown in the fabrication of the elements using grey-scale lithography and micromachining. Systems demonstrations will be presented for the field of optical interconnection.

The handling of a continuously increasing amount of data leads to a strong need for high-speed short-range connections. Conventional Cu technology between chips on a board is limited. Optical interconnects will dominate the market, since they can overcome the limitations. One of the issues for materials used, e.g., for waveguides embedded in printed circuit boards (PCBs) is the compatibility with standard epoxies used for PCBs during the entire board fabrication process. Materials applied for optical interconnects should be mechanically and optically reliable, and also allow low-cost production. From the material production side, the process should be easy to up-scale. Therefore, anticipatory research strategy and suitable tailoring is asked for. The handling of light in the UV and visible range often requires the use of specially designed materials. Most polymer materials show an increased yellowing effect upon being exposed to shorter wavelength light. The major influence on the absorption in the UV and visible range of a UV curable material is related to the UV initiator, beside any other chromophores formed mainly during the exposure. Different material approaches will be presented which fulfil the requirements for highly sophisticated applications in optics / optical packaging technology. Firstly, an epoxy-based material system for optical chip-to-chip interconnection will be introduced. Secondly, the adaptation of a UV patternable inorganic-organic hybrid material (ORMOCER^®) originally developed for waveguide applications in the data and telecom regime, will be discussed with respect to applications in the visible regime. Spectroscopy and UV-DSC measurements were carried out to investigate the influence of standard photoinitiators on the optical properties for an ORMOCER^® system suitable for microoptic applications. The results show that the resulting material properties were significantly improved by exchange of the initiators compared to the originally incorporated one.

Opto-electronic devices such as LEDs, optical sensors, LCDs and color filters have the need for optically transparent encapsulants or adhesives. Maintaining the highest transmission possible of the encapsulant/adhesive throughout the life of the device is a critical criteria for the device designer. Silicones as encapsulants/adhesives in opto-electronic devices have been used throughout the last decade^{1, 2}. The high light flux and associated heat proved too much for the traditional epoxies. Data confirms silicone encapsulants/adhesives provide longer optical transmission life than epoxy encapsulants³. Almost all optical devices have some interaction with UV wavelengths. Manufacturers of Blue LEDs with wavelengths near 405nm, and other LEDs that emit wavelengths deeper into the UV (365-399nm), have concerns about the effects of this radiation on the light transmission of the encapsulant over time. LCD and sensor devices may have UV radiation from the sun to contend with. This paper looks at many different encapsulants/adhesives, silicone, epoxy and acrylate, for their change in optical transmission due to a 680-68000J/cm² dose of radiation with the following spectral output: 34% in the UVA (320-399nm), 17% in the UVB (280-319nm), and 49% concentrated at 405nm and 450nm. All samples were prepped and exposed the same way so that comparisons between the samples would be meaningful. Results show that silicones perform better than acrylates, which perform better than epoxies, and not all silicones perform equally. Data will be provided of the best performing materials and a discussion of future work given the understanding of the chemistry.

Carbon nanotubes (CNTs) have been intensively studied for optical applications because of their useful characteristics. However, handling of the CNTs is one of the largest problems for device applications. Several methods have been reported to fabricate optical devices, such as spray method, direct synthesis method, and polymer embedding method. These methods require complicated process and dissipate excessive amount of CNTs. Therefore, an easy and cost effective handling technique of CNTs is required. In this paper, we propose and demonstrate a novel technique to deposit CNTs onto only the core region of end facets of optical fibers. We successfully realized area selective deposition using optical tweezers. This technique requires a very simple setup and consumes only a small amount of CNTs. We confirmed presence of CNTs at the selected region by microscopic Raman spectroscopy. As an optical device application, we inserted the CNT deposited fiber into the fiber ring laser cavity as a saturable absorber, and realized passive modelocking. This technique will allow us to realize low-cost CNT-based photonic devices.

Recent developments in IC design technology for high-speed communications have led to highly improved optoelectronic (O/E) system design. Specifically, signal integrity management is a specific area of communications circuit design that is promising in playing a role in optoelectronic packaging and component cost. This paper explores the potential of these techniques in impacting O/E component design and possibilities for cost reduction. It is argued that a judicious tradeoff in system parameters such as link length and component bandwidth could impact overall cost significantly.

Polymer Optical Fibers (POF) are used in various fields of applications, e.g. in the automotive industry or the in house communication technology. Applications in these fields require increasingly more bandwidth, therefore developers become tasked with finding new solutions to increase the technical efficiency of all communications equipment. One solution is wavelength division multiplexing (WDM). WDM allows the transmission of information over more than just a single wavelength (color) and thus greatly increases the POF's bandwidth. Different wavelengths which are jointly transmitted over the fiber must be separated to regain all information. These separators are called Demultiplexers. There are several systems available on the market, which are all afflicted with certain disadvantages. The most common and grave disadvantage almost all of these systems exhibit is their costly production, which makes them unsuitable for today's price sensitive mass markets. Hence the goal of this paper is to develop an inexpensive Demultiplexer for WDM transmission over POF. The fundamental idea is to separate the chromatic light in its monochromatic components with the help of a prism with low reciprocal dispersive power. The prism and the other assemblies which are needed to adjust the optical path could be manufactured in injection molding technology. This manufacturing technique is a very simple and cost-efficient way to produce a Demultiplexer for POF.

A 10 Gb/s bi-directional optical subassembly (BOSA) with an uncooled 1300nm DFB laser and a receiving PIN-TIA had been assembled and characterized. This 10 Gb/s BOSA integrated a 45^o-tilted thin film WDM filter which can transmit the 1300nm light into the fiber and reflect the 1550nm light into the PIN-TIA. At the transmitter side, the -3dB modulation bandwidth was measured to be 11.86GHz and an OC-192 eye diagram with 19% mask margin was obtained. At the receiver side, the sensitivity was -13.1dBm at the bit error rate of 10^-9 and the eye mask margin of OC-192 was more than 30%.

Methods of coupling optical fiber and light sources to monolithic integrated photonic circuits are needed to expand future photonics communications markets. Requirements are low cost, high coupling efficiencies, and scalability to high volume production rates. Key features of the different optical coupling options will be discussed along with implementation examples. Requirements for low cost optical coupling and high volume production scalability will be shared.

The deployment of Passive Optical Networks (PON) for Fiber-to-the-Home (FTTH) applications currently represents the fastest growing sector of the telecommunication industry. Traditionally, FTTH transceivers have been manufactured using commodity bulk optics subcomponents, such as thin film filters (TFFs), micro-optic collimating lenses, TO-packaged lasers, and photodetectors. Assembling these subcomponents into a single housing requires active alignment and labor-intensive techniques. Today, the majority of cost reducing strategies using bulk subcomponents has been implemented making future reductions in the price of manufacturing FTTH transceivers unlikely. Future success of large scale deployments of FTTH depends on further cost reductions of transceivers. Realizing the necessity of a radically new packaging approach for assembly of photonic components and interconnects, we designed a novel way of hybridizing active and passive elements into a planar lightwave circuit (PLC) platform. In our approach, all the filtering components were monolithically integrated into the chip using advancements in planar reflective gratings. Subsequently, active components were passively hybridized with the chip using fully-automated high-capacity flip-chip bonders. In this approach, the assembly of the transceiver package required no active alignment and was readily suitable for large-scale production. This paper describes the monolithic integration of filters and hybridization of active components in both silica-on-silicon and silicon-on-insulator PLCs.

The main issue for a fiber coupling structure with a nanophotonic circuit is of course to reach very low insertion losses. However, another major issue is the polarization sensitivity as optical networks usually use non polarization maintaining optical fibers. Therefore, to implement a nanophotonic circuit into optical networks, the fiber coupling structures must have a very low polarization sensitivity, especially concerning the coupling from the fiber towards the circuit. Surface grating couplers are very interesting fiber coupling structures as they allow for coupling anywhere on a circuit without the need for cleaving and polishing facets, which makes wafer-scale testing of photonic circuits possible. However, one-dimensional gratings couplers are well-known to be polarization sensitive. In this paper, we show that a one-dimensional grating may have very similar coupling performances for TE and TM polarizations. Only the optimal injection angle may still differ between TE and TM polarizations. Therefore, packaging consideration is discussed to design an optical coupling system between the fiber and the grating coupler which should allow the optimization of the incident angle for both fundamental polarized modes. This way a low polarization sensitive coupler using a simple one-dimensional grating coupler is proposed.

Silicon photonics is an area of active research and commercial interest due in part to its leveraging of the existing mature fabrication processes and infrastructure of the CMOS integrated circuit industry. Its suitability for use at the telecom wavelengths, low cost, and compact devices enhance the value of silicon for photonics applications. One critical issue that continues to be investigated is the efficient coupling of optical signals between the outside world and the photonic chip, which is hampered by the large optical mode mismatch between the glass fiber and high index contrast silicon waveguide. We introduce a new device that enables efficient coupling from the fiber to single mode silicon waveguide called the vertical J-coupler, so named in reference to its parabolic shape. Grayscale lithography is used to fabricate the three-dimensional topology of the coupler, enabled by the high energy beam sensitive (HEBS) glass grayscale photomask. The principle of operation is total internal reflection, which is inherently polarization insensitive and broadband. Electro-magnetic simulations validate the efficient operation of the device while experimental results demonstrate its successful operation in coupling light into the silicon waveguide.

Long period gratings (LPGs) in singlemode fibers have been used in recent years to make optical sensors. The grating-assisted coupling of light from the bound fibre mode to a cladding mode is sensitive to local influences such as temperature and stress. In this paper, we investigate the possibility of using LPGs to modify the behavior of planar multimode interference (MMI) devices by coupling power between selected bound modes of the planar device. In particular, it is shown that by applying an LPG to a MMI 1xN splitter, the splitting ratio can be changed. By making the grating dynamic, a tunable splitter can be realized. Examples are given for 1x2, 1x3 and 1x5 splitters. Possible methods for realizing such devices are discussed.

We have numerically and experimentally determined the effect of crosstalk from adjacent gold wiregrid micropolarizer pixels in a midwave infrared (MWIR) focal plane array (FPA). Fabrication of a snapshot polarization-imaging device involves gluing a micropolarizer array substrate on top of an FPA. We evaluated several arrays of super-cells of four pixelated polarizers by modeling the near fields behind the devices. Each polarizer in the super-cell is oriented to allow solving three Stokes parameters by themselves or four Stokes parameters in conjunction with a birefringent waveplate. In addition, we fabricated sets of super-cells for determining optimum polarizer-FPA separation. Modeling and empirical data indicate cross talk between the adjacent pixels at several microns after crossing the polarizer plane. Cross talk between adjacent pixels increases uncertainty in the measured polarization states of a scene of interest. Data shows that the extinction ratio will decrease by 17% when moving the FPA from 0.5 &mgr;m to 1.0 &mgr;m away from the polarizer. These changes in extinction ratio are important given that typical glue separation is approximately 10 &mgr;m.

An all-optical nonlinear threshold gate based on weakly-coupled, high-order microring resonators were investigated using the transmission matrix formalism. A Kerr nonlinear enhancement factor of exceeding 2.5x10³ can be obtained at the ring-coupling coefficient of 0.02. Simulation results show that the nonlinear optical threshold gate has a sharp optical intensity-dependant switching property with a low switching threshold (> 80%) of -10dBm.