Mark W. Beranek

In package micro-aligner for fiber-optic packaging

We describe and demonstrate a 3-axis MEMS active fiber-optic micro-aligner, which will enable in-package alignment of fiber-optic and micro-optic components. The micro-aligner is a wafer level fabricated device, based on an integration of silicon micromachining and LIGA technology. The electrically controllable actuators demonstrate the high force and displacement necessary to overcome fiber-optic bending stiffness, counterforce springs, friction, and wirebonds, to perform active alignment of an optical fiber inside an optoelectronic package housing. We have demonstrated movement of >30 microns in all three axes in an in-package configuration. The first prototype devices are currently small enough (4/spl times/4/spl times/0.5 mm/sup 3/) to fit into a standard optoelectronic package. In the future we expect that micro-aligner devices with the same forces and displacements can be made smaller than 1/spl times/1/spl times/0.5 mm/sup 3/ thus allowing for multiple singlemode fiber-optic attachments inside standard optoelectronic package housings.

VCSEL optical subassembly for avionics fiber optic modules

With the growing maturation of vertical cavity surface emitting laser (VCSEL) technology as a source of commercial off-the-shelf components, the question of VCSEL suitability for use in avionics-qualifiable fiber-optic systems naturally follows. This paper addresses avionics suitability from two perspectives. First, measured performance and burn-in reliability results, determined from characterization of Honeywell VCSELs, are compared with application-based military and commercial avionics environmental requirements. Second, design guidelines for developing a cost-effective VCSEL optical subassembly (VCSEL/OSA) are outlined.

Hermeticity lifetime of a 63Sn37Pb solder sealed optical fiber feedthrough

A highly accurate prediction of hermeticity lifetime is developed for a eutectic 63Sn37Pb alloy solder sealed optical fiber-Kovar nosetube feedthrough subjected to repetitive thermal cycling. Thermally induced fatigue fracture of the 63Sn37Pb solder/Ni-Au plated Kovar interface is initially generated from creep deformation of the solder and propagates gradually through the junction in the axial direction. A nonlinear axisymmetric finite element analysis of the 63Sn37Pb fiber feedthrough seal is performed using a thermo-elastic creep constitutive equation and the solder joint fatigue life prediction based on accumulated strain energy associated with solder creep imposed by temperature cycling is analyzed. SEM/EDX metallurgical analysis of the solder/Kovar nosetube interface indicates that AuSn/sub 4/ intermetallic formed during soldering may also contribute to joint weakening. The optical fiber metallized with Ni/sub 2/P-Ni underplate and electrolytic Au overplating exhibits correspondingly similar intermetallic formation at the solder/fiber interface. Combined hermeticity testing and metallurgical analysis carried out on 63Sn37Pb alloy solder sealed optical fiber feedthroughs after repetitive temperature cycling between -40 and +125/spl deg/C validated the analytical approach taken to identify both the failure site and life expectancy.

Potential opportunities for utilizing commercial optoelectronics in avionics fiber-optic networks

Industry studies indicate the feasibility of using both MCM-L/COB and silicon microbench passive alignment technology in harsh, high reliability environments such as military and commercial avionics systems. Moreover, in many cases, if proper design, materials, and packaging approaches, and assembly and quality assurance procedures are utilized, both MCM-L/COB and silicon microbench passive alignment technologies may actually enable design ad manufacturing of low cost avionics optoelectronics modules. Silicon microbench passive alignment packaging technology has been demonstrated for LED, PIN photodiode, VCSEL and edge emitting laser diode packaging. Although MCM-L/COB and silicon microbench passive alignment technologies have been shown to be ruggedizable for the avionics environment, additional reliability testing and infrastructure development work is required before they are implemented in real avionics systems. VCSELs and edge-emitting diode lasers can be reliably used in systems with excursions to high temperature avionics environments) if the total time-at-high temperature is kept modest. Simple temperature measuring circuits and laser diode drive current monitoring circuits for onboard diagnostics and maintenance could be implemented to ensure reliable operations of high-speed laser-based transmitters in the avionics environment.

High performance, low-cost chip-on-board (COB) FDDI transmitter and receiver for avionics applications

Recent trends in the avionics industry have focused on the use of commercial-off-the-shelf electronic components for specialized system applications. Deviating from the conventional concept of high performance at any cost, the idea of producing avionics optoelectronic modules at a low cost-to-performance ratio (or high performance-to-cost ratio) is emerging. Laminate based/Chip-on-Board multichip module interconnect (MCM-L/COB) technology is a robust and flexible packaging approach which has demonstrated its effectiveness in low-cost consumer electronics for many years, and is rapidly finding acceptance in high performance electronics applications. In this paper, we present our results on the development of ARINC 636 compatible Fiber Distributed Data Interface (FDDI) fiber-optic transmitter and receiver modules using MCM-L/COB packaging technology. These modules are equivalent to the industry standard FDDI modules in footprint, but they are required to function with higher performance and be able to operate under more severe environmental conditions than commercial grade components. Through a careful MCM-L design layout and optical subassembly (OSA) selection process, we have demonstrated COB FDDI transmitter and receiver modules that exhibit excellent results over the temperature range of -40 to 110/spl deg/C. Our test results show that the transmitter minimum average output power is about -13 dBm over the operating temperature range. This is 3 dB better than the standard commercial grade FDDI transmitters. Operating at 125 Mb/s, an overall link margin greater than 22 dB can be achieved by these high performance MCM-L/COB optoelectronic modules.

Optoelectronic devices for fiber-optic sensor interface systems

A standardized interface for fiber-optic sensor systems based on wavelength-division- multiplexing (WDM) has been successfully demonstrated using a novel broad-spectrum quantum-well LED and a high-resolution waveguide spectrograph. This efficient interface allows a 40-decibel system loss in 20 sensor channels. The new broadband LED and slab- waveguide spectrograph represent key enabling components for the WDM interface system. The LED produces a spectral width a factor of 3 times larger than that from conventional edge emitting LEDs in the 750-900 nm range. The compact slab-waveguide spectrographs channel resolution (4-5 nm) and grating efficiency (>50%) compare favorably with other multimode WDM elements.

Universal detachable optical connector for military and commercial aerospace fiber optic modules

Packard-Hughes Interconnect has developed a detachable connector for plugging to military and commercial aerospace fiber-optic modules. The connector comprises floating spring loaded fiber-optic termini with 1-mm ceramic ferrules, all contained within a 0.136-in thick, low-profile connector plug body. The connector is mated to the package via a patented retention clip mechanism which secures the plug body to metal posts attached to the package sidewall. Optical alignment between the connector plug terminus and the package is accomplished by an alignment sleeve and mating 1-mm ceramic ferrule mounted in the package nosetube. Connector demating is performed by actuating a release button mechanism integral to the connector plug body. The fiber-optic termini in the connector plug body are easily maintained without replacing the entire connector. This makes the repair/replacement process for a broken fiber pigtail or damaged terminus endface a low cost, fast, and simple operation. The insertion loss for a simplex connector mated to a Boeing FDDI Transmitter receptacle package using 100/140 micrometers graded index optical fiber is less than 0.5 dB at 1.3 micrometers wavelength.