Optical communications – Hybrid communication system – Including specific optical interface
Reexamination Certificate
1999-12-30
2004-03-09
Pascal, Leslie (Department: 2633)
Optical communications
Hybrid communication system
Including specific optical interface
C398S117000, C398S156000, C398S164000
Reexamination Certificate
active
06704515
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to fiber optic interface modules and associated fabrication methods and, more particularly, to fiber optic interface modules, including both fiber optic transmitter modules and fiber optic receiver modules, that are designed to maintain the high performance requirements demanded by avionics and other specialized applications in a more cost effective manner, as well as an associated fabrication method.
BACKGROUND OF THE INVENTION
Fiber Data Distributed Interface (FDDI) modules are used in a variety of applications. For example, modern commercial aircraft, such as the Boeing 777 aircraft, includes a number of FDDI modules, including both fiber optic receiver modules, fiber optic transmitter modules and fiber optic transceiver modules. In addition, FDDI modules are also utilized by a variety of less demanding commercial applications.
Typically, an FDDI module serves as a data link between stations of a local area network (LAN). In basic terms, an FDDI fiber optic receiver receives optical signals such as optical signals delivered by an optical fiber, and converts the optical signals into corresponding electrical signals that can then be processed or analyzed as desired. Conversely, an FDDI fiber optic transmitter receives electrical signals and converts the electrical signals into corresponding optical signals that are then typically launched through an optical fiber.
The fiber optic modules that are employed for avionics applications must meet high performance standards over a wide range of temperature and environmental conditions. In avionics applications, for example, the fiber optic transmitters must produce an output pulse that has well defined rising and falling edges and that has a shape as defined by a predetermined envelope over a large range of temperatures and other environmental conditions. The fiber optic receivers must also exhibit high performance characteristics, such as high sensitivity and high dynamic range and, in some instances, may have a sensitivity better than −34 dBm, over a wide range of temperatures and other environmental conditions. In this regard, the FDDI fiber optic modules must be capable of maintaining consistently high performance levels at any operating temperature from −55° C. to 110° C. and over a correspondingly wide range of humidity levels and other severe avionics environmental conditions. In addition, both the fiber optic transmitter modules and the fiber optic receiver modules must be capable of transmitting data at a high bit rate, such as at a rate of at least 125 megabits per second.
In order to meet the high performance requirements over the entire range of temperature and other environmental conditions, FDDI fiber optic modules that are designed for avionics and other specialized applications include a number of relatively expensive components, thereby driving up the overall cost of the FDDI fiber optic modules. For example, FDDI fiber optic modules that are designed for avionics applications typically include a ceramic substrate which is not only quite expensive, but which also demands relatively costly assembly procedures that further increase the cost of the resulting modules. The FDDI fiber optic modules that are designed for avionics applications also generally include a relatively expensive, gold plated, custom designed metal package which is capable of being hermetically sealed in order to protect the enclosed fiber optic module.
Additionally, avionics grade fiber optic receivers and transmitters typically include optoelectronic devices, such as light emitting diodes and the light sensitive detector diodes, that are custom made in order to fit within the package while providing the desired performance levels. The optoelectronic devices of conventional avionics grade fiber optic modules are expensive since, among other things, the optoelectronic devices generally are custom designed fiber pigtail packages which require active alignment of the optical fiber-to-the-optoelectronic device. In this regard, the optical fiber would have to be actively aligned to the light emitting diode of a fiber optic transmitter module or the light sensitive diode of a fiber optic receiver module. As will be apparent, a fiber pigtail package is relatively expensive since the preparation of the optical fiber and the alignment of the optical fiber are both time consuming and labor intensive. In addition, since the optoelectronic devices include attached pigtails, the optoelectronic devices must be more carefully handled during he manufacturing process in order to prevent the fiber pigtail from being broken.
The relatively high cost of the components of the FDDI fiber optic modules that are designed for avionics applications is exacerbated by the relatively low volume of the fiber optic modules. In this regard, the volume demand for avionics grade fiber optic modules generally ranges from a few modules per year to a thousand per year. This low volume stands in marked contrast to the fiber optic modules employed in other commercial applications that have volumes of many thousands per year. As a result of their relatively high cost, the avionics grade fiber optic modules therefore cannot effectively compete in the commercial market in an attempt to increase the sales volume and correspondingly decrease the price of the avionics grade fiber optic modules.
In an attempt to reduce the cost of avionics grade fiber optic modules, automatic alignment processes have been implemented to reduce the labor costs and time delays associated with the alignment of a fiber pigtail and an optoelectronic device. In addition, attempts have been made to increase the commonality of the components that form the fiber optic receiver modules and the fiber optic transmitter modules as well as to increase the commonality between the processes employed to fabricate the fiber optic receiver modules and the fiber optic transmitter modules. Unfortunately, these attempts have generally failed to significantly reduce the cost of the avionics grade fiber optic modules, primarily because the optoelectronic components remain quite expensive and since the fabrication process has neither a high yield nor a high throughput.
Accordingly, it would be desirable to provide lower cost FDDI modules, such as fiber optic receiver modules and fiber optic transmitter modules, that meet or exceed the high performance requirements demanded by avionics and other specialized applications over a wide range of temperatures and other environmental conditions. While conventional fiber optic interface modules that are designed for avionics and other specialized applications have excellent performance characteristics over a wide range of temperatures and other environmental conditions, these fiber optic interface modules remain quite expensive, thereby effectively limiting their use in other commercial applications that need not be designed to withstand such severe environmental conditions.
SUMMARY OF THE INVENTION
According to the present invention, more cost-effective fiber optic interface modules, such as fiber optic transmitter modules and fiber optic receiver modules, are provided that meet the high performance requirements demanded by avionics and other specialized applications over a wide range of temperatures and other environmental conditions. In this regard, the fiber optic interface module of the present invention includes a greater number of commercial components that are capable of being assembled according to newly developed commercial fabrication techniques such that the cost of the resulting fiber optic interface modules are significantly reduced relative to conventional avionics grade fiber optic interface modules, i.e., the fiber optic interface module of the present invention has a greater performance-to-cost ratio. Additionally, a method of fabricating a fiber optic interface module is provided according to another aspect of the present invention.
In one embodiment, a fiber optic transmitter module is provided tha
Chan Eric Yuen-Jun
Huang Yuing
Le Quynhgiao Nguyen
Alston & Bird LLP
Pascal Leslie
Singh Dalzid
The Boeing Company
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