Charles B. Kuznia

Built-in test capable fiber optic transceiver application concept

The concept of built-in test (BIT) applied to aerospace platform fiber optics has been discussed for over three decades.1-2 Today the practical realization of a digital fiber optic transceiver with transmitter signal strength indication (TSSI), receiver signal strength indication (RSSI), and in situ optical time domain reflectometry (OTDR), gives the aerospace industry a new point of departure to determine best ways to demonstrate and field fiber optic BIT on aerospace platforms.3-5This paper describes key elements to consider when developing fiber optic BIT development test plans and operational concepts.

Broken aerospace fiber optic cable characterization

This paper describes the physical and optical characterization of a fleet/field representative 100/140/172 (core/cladding/polyimide coating) aerospace fiber optic cable that failed due to cable bending/kinking.

Parallel interconnect components for optical modules utilizing flip-chip VCSEL on ultra-thin silicon-on-sapphire substrate

We report on optical components for parallel transmit and receive module, operating at 850nm, designed for short haul optical multimode fiber networks. The component is realized by flip-chip bonding of arrayed optoelectronic devices, i.e., VCSEL and PIN detector array, onto ultra-thin silicon- on-sapphire (UTSi) substrate, which is optically transparent and electrically insulated. Flip-chipped assemblies provide several advantages over conventional wire bond techniques, such as extremely low interconnection parasitics that enable high data rates at low power. Using UTSi technology further improves performance by minimizing crosstalk through its insulating substrate while providing the means for a reliable, low cost optical assembly directly onto the substrate. In addition, applying UTSi technology to optical modules allows a higher degree of functional integration within the module. The insulating substrate provides excellent isolation between mixed signal circuitry, enabling the integration of high performance transmitters, receivers and other sensitive analog circuits with digital circuitry on the same substrate. Furthermore, the integration of VCSEL and photodetector array with UTSi circuits for parallel optical interconnects yields several packaging advantages, such as parallelism, scalability, compactness and simplicity.

Fully integrated low-power flip chip bonding of arrayed optoelectronic devices on SOS

Ultra-thin silicon-on-sapphire (UTSi) CMOS technology is a commercial, high yield silicon-on-sapphire technology that yields circuitry well suited for optical communication functions on a transparent substrate. This characteristic, unique to the silicon-on-sapphire configuration, allows flip-chip bonding of optoelectronic (OE) devices onto CMOS circuitry to build Flipped Optoelectronic Chip on UTSi (FOCUTS) optical transmit and receive modules. Flip-chip bonding eliminates the wire-bond inductance between driving/receiving circuits and the OE devices which becomes problematic at data rates greater than about 2.5 Gbps. Such flip-chip integration also reduces the number of discrete components that must be handled, packaged, and aligned in a module, thereby improving reliability and reducing costs. Additional functions, such as Electrically Erasable Programmable Read Only Memory (EEPROM) and self aligned Automatic Power Control (APC) photodetectors and control circuits will be discussed. We describe measured results of flip-chip bonding of arrayed OE devices (VCSELs and photodetectors) and test results at 3 Gbps as well as recent integrating and testing of phototransistors in UTSi circuits. We also describe the radiation sensitivity of all components and applicability of this technique to remote sensing applications. These devices, operating at 850 nm, are aimed at multimode, short reach optical fiber networks.