Optical waveguides – With optical coupler – Particular coupling structure
Reexamination Certificate
2001-04-26
2003-02-04
Ullah, Akm E. (Department: 2874)
Optical waveguides
With optical coupler
Particular coupling structure
C264S001250, C029S846000
Reexamination Certificate
active
06516121
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to routing, forming and connecting (collectively, “configuring”) optical fibers between optical ports such as optical transmitters, receivers/detectors and additional fibers, and more particularly, to configuring optical fibers between optical ports where connection distances are short thus requiring small radius bends in the routing of connection fibers. The present invention further relates to optoelectronic devices involving such optical fiber configurations and apparatus for manufacturing such optoelectronic devices.
BACKGROUND OF THE INVENTION
Optical fiber communication is an important mode of data transmission around the world due in part to large bandwidth capabilities and freedom from most forms of electromagnetic interference. Additionally, as computer speeds approach one gigahertz (GHz) and beyond, parasitic Resistance, Capacitance and Inductance (RCL) of connecting wires adversely influence data transmission, making direct optical connections more desirable to, between, and within computers and other communication devices. Particularly desirable is the optical connection of all timed devices within a computing device to deliver clock distributions between chips/components in phase or otherwise with a known temporal relationship. In addition, it is not unusual for different timed modules in a device to require different voltages. In conventional wiring arrangements, timing and data transmissions must first be converted to the proper voltage before being relayed from one module to the next. This, along with the RCL problems associated with high speed transfers can cause significant delays of synchronized signals and thus, adversely affect system performance. Optical connections can reduce or eliminate these problems. However, connecting and routing optical fibers between optical ports presents an array of additional problems. These problems include: shear stress at the connection point, difficulty routing due to fiber stiffness, optical distortion caused by adhesives, light leakage from sharp bends, micro fractures, sharp fibers damaging components etc.
There have been numerous attempts to overcome the difficulties in connecting optical ports. One method entails a non-contact alignment of a connecting fiber and the corresponding optical port such that the signal propagates through space. While this method solves several problems, such as shear stress at the connection point, it causes others. For example, components typically must be precisely mounted, directed, and aligned within ‘eyesight’ of the optical ports, e.g., in a pathway of the transmitted optical beam, within the acceptance angle of an optical fiber end, or in optical alignment with a detector surface of an optoelectric transducer. Other attempts have used optical adhesives to ‘glue’ optical fibers to optical ports, however, such methods have proven difficult in mass production and often the adhesive has an impact on optical performance.
Another approach involves extruded optic transmission lines between optical transmission ports. This eliminates certain inherent problems with connecting ports with optical fibers. Since the optical pathways are formed in place, they reduce or avoid internal stresses and micro fractures that result from bending an existing optical fiber. Additionally, the extruded optical pathways are easily routed since they are formed in place in a fluid state. However, in order to obtain a good surface adhesion bond between he extruded pathways and the optical port, the temperature of the optical port must generally be elevated to ensure proper bonding. Additionally, if the extruded pathway cools too quickly, clogging can occur at the nozzle of the extruder head. These problems may be addressed by performing these extrusions at an elevated ambient temperature, e.g., between 170° and 250° Celsius. These elevated temperatures may be problematic in certain contexts involving sensitive components. Finally, such extruded optical pathways generally only address a single connection, from one optical port to a second port, and do not provide a method for forming a series of connections using a continuous optical guide.
SUMMARY OF THE INVENTION
This invention addresses problems outlined above providing the desired result of accurately connecting optical ports with an optical fiber in a simple efficient manner and without unduly degrading the fiber or its optical transmission qualities. The invention provides a simple process and associated structure for forming optical connections without intervening adhesives or free space pathways and with minimum heating of the ambient environment. Additionally, the invention allows connecting fibers to be simply lengthened and shortened and annealed in place. Processes and apparatus for fiber alignment and forming multiple connections with a single fiber are also described, as well as the resulting optoelectronic devices.
As used herein, optical ports include active optical transmission elements (such as, electronic chips with light emitters, including but not limited to LEDs, Lasers, or VCSELs (Vertical Cavity Surface Emitting Laser)) active optical receiving elements such as photodiodes and other detectors or photoelectric transducers) and passive transmission/detection elements (such as ends of optical fibers which, in turn, may be associated with active elements). Optical fibers include homogenous single strands and fibers including a core and cladding like modem telecommunication fibers. Preferably, the fiber will contain a core and cladding to improve its optical characteristics. The optical fibers may be made of various materials including quartz, glass or plastic.
According to one aspect of the present intention, a method and corresponding apparatus are provided for connecting an optical fiber between optical ports. The method involves heating an end portion of an optical fiber to soften the end portion, contacting the softened end portion to a first optical port, routing the optical fiber to a second port and connecting the fiber to the second port. In addition, to increase adhesion, the top surface of the optical port or associated structure may also be heated. Preferably, all heating is done using a localized heating process, (e.g. laser or ultrasound heating such that the potential for heat damage to nearby components is reduced. Once softened, the end may be contacted with the port to create an optical coupling. Feedback based on an optical signal transmitted through the fiber may be used for accurate fiber/port alignment as described in more detail below. The fiber is preferably a preformed fiber, accordingly, the step of routing may involve unspooling a length of fiber as well as forming, dimensioning and annealing the fiber by heating as discussed below. The fiber may be optically connected to the second port, for example, by physically terminating the fiber at the second port or by bending and bonding the fiber's longitudinal edge at the second port. In either case, the fiber may be bonded at the second port by a heating, softening, and contacting process.
As will be appreciated, the inventive optical connection method will work with multiple fiber types including fibers made of glass, plastic or quartz. More particularly, the method can utilize homogenous fibers as well as optical fibers that containing a homogenous core surrounded by a different refractive index light reflecting cladding.
With respect to the optical ports, at least two ports may be connected using an optical fiber for signal transfer therebetween. The connection generally will involve connecting at least one light emitting port with at least one light detecting port. However, connections can also be made between active components (emitters and receivers) and passive or intermediate components such as the end of a telecommunications fiber-optic cable and/or wave guides. As will be appreciated, connection to an intermediate component such as a telecommunication fiber allows the direct connection of an electronic chi
Interconnect Technology LLC
Kilpatrick & Stockton LLP
Ullah Akm E.
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