Optical waveguides – Accessories – External retainer/clamp
Reexamination Certificate
2001-08-17
2004-01-13
Cherry, Euncha (Department: 2872)
Optical waveguides
Accessories
External retainer/clamp
Reexamination Certificate
active
06678458
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention is related to positioning of microcomponents, and more particularly to a system and method for fixing the position of a microcomponent such that it is precisely aligned with a target position.
2. Background
Extraordinary advances are being made in micromechanical devices and microelectronic devices. Further, advances are being made in MicroElectroMechanical (“MEM”) devices, which comprise integrated micromechanical and microelectronic devices. The term “microcomponent” will be used herein generically to encompass microelectronic components, micromechanical components, as well as MEMs components. The advances in microcomponent technology have resulted in an increasing number of microcomponent applications. Accordingly, a need often arises for precise positioning of microcomponent devices. For example, it is often desirable to position a microcomponent in alignment with a target position. For instance, for certain applications it may be desirable to align a microcomponent with another device. Because of the small size of microcomponents, they often require very precise positioning (e.g., precise alignment with another device). For example, in some cases a misalignment of only a few microns may be unacceptable. In fact, in some cases the size of the microcomponent being aligned may be only a few microns. Also, microcomponents present particular difficulty in handling and positioning operations.
Microcomponents are commonly implemented in the field of optoelectronics. Generally, when coupling optoelectronic components, alignment is very important. That is, alignment of optoelectronic components is often critical for proper operation of an optoelectronic device. A relatively slight misalignment of optical components may drastically alter an optical device's performance. For example, accurate alignment of components is often important for ensuring proper propagation of an optical signal to/from/within an optoelectronic device. For instance, optoelectronic modules, such as optoelectronic receivers and optoelectronic transmitters commonly require proper alignment of microcomponents therein for proper operation. In general, proper alignment is desired to minimize the amount of attenuation within such optoelectronic devices.
One microcomponent that often requires proper alignment is an optical fiber. For example, in an optoelectronic receiver, a fiber is aligned with an optical detector, typically a PIN photodiode. Very large fibers may have light-guiding cores with a diameter of approximately 1 millimeter (mm) or 1000 microns (&mgr;m), but such fibers are rarely used in communications. Standard glass communication fibers have cladding diameter of 125 &mgr;m and light-guiding cores with diameter of approximately 8 to 62.6 &mgr;m. Proper alignment of the end of the optical fiber (which may be referred to as the “fiber pigtail”) with the optical detector is important to ensure that a light signal is properly received by the optical detector. Similarly, in an optoelectronic transmitter, an optical fiber is aligned with a light source, such as a light-emitting diode (LED) or laser diode. Proper alignment of the end of the optical fiber with the light source is important to ensure that a light signal is properly communicated from the light source to the optical fiber.
The difficulty in achieving proper alignment of optical fiber is often increased because of variances in the size of fiber core diameters. For example, typical commercial graded-index fiber commonly specify a 50 &mgr;m nominal fiber core diameter that may vary within a tolerance of ±3 &mgr;m. Also, alignment/positioning of the light-guiding core within the sleeve of a fiber optic cable often varies (i.e., the core is not always centered within the sleeve), thereby further increasing the difficulty of properly designing a fiber with another optoelectronic device.
Various techniques have been developed for handling and positioning microcomponents, such as optical fibers. According to one technique, a high-precision, external robot is utilized to align microcomponents within devices. However, such external robots are generally very expensive. Additionally, external robots typically perform microcomponent alignment in a serial manner, thereby increasing the amount of time required for manufacturing microcomponent devices. That is, such robots typically perform alignment for one component at a time, thereby requiring a serial process for assembling microcomponents utilizing such a robot.
According to another technique, microactuators, such as electrothermal actuators, may be utilized to align microcomponents, such as optical fibers. For example, microactuators may be integrated within a device to align microcomponents within the device. Accordingly, use of such microactuators may avoid the cost of the above-described external robot. Also, if implemented within a device, the microactuators may enable parallel alignment of microcomponents. That is, multiple devices may have alignment operations performed by their respective microactuators in parallel, which may reduce the amount of time required in manufacturing the devices. Examples of techniques using microactuators integrated within a device to perform alignment of an optical fiber are disclosed in U.S. Pat. Nos. 6,164,837 and 5,602,955.
Once a desired position is obtained for a microcomponent (e.g., alignment with another device) using either of the above techniques, such microcomponent may have its position fixed in some manner such that it maintains the desired position. Various techniques have been developed for fixing the position of microcomponents. According to one technique, an epoxy may be used to fix the position of a microcomponent. In another technique a low melting point bonding material, such as solder, may be used to fix the position of a microcomponent. Exemplary techniques that use solder to fix the position of an optical fiber are disclosed in U.S. Pat. No. 6,164,837, U.S. Pat. No. 5,692,086, and U.S. Pat. No. 5,745,624.
According to another technique, an “active” alignment device may be utilized to fix the position of a microcomponent. Such an alignment device is “active” in the sense that electrical power has to be maintained in order to fix the alignment of a microcomponent. For example, in certain implementations that use microactuators integrated within a device to perform alignment of microcomponents, power to such microactuators must be maintained in order to maintain (or fix) the position of the microcomponents being aligned.
BRIEF SUMMARY OF THE INVENTION
In view of the above, traditional techniques for positioning microcomponents are problematic. First, as described above, high-precision external robots may be utilized for accurately positioning microcomponents, but such robots are very expensive and do not enable parallel manufacturing of devices. Microcomponent devices have been developed in the prior art for positioning microcomponents, which are generally less expensive than the external robots and may enable parallel manufacturing of devices (e.g., may be integrated within devices to perform microcomponent positioning in their respective devices in parallel). Many such microcomponent positioning devices are active in the sense that require continuous power in order to maintain a desired positioning of a microcomponent. Such an active device is generally undesirable. For example, it is generally undesirable to require that power be maintained for positioning a microcomponent within a device that is deployed in the field. Other techniques require use of epoxy or solder to fix the position of a microcomponent. The use of such epoxy or solder increases the complexity of the fixing process, delays the manufacturing time, and may result in inaccurate positioning (because of shifting in the curing/cooling period). Also, certain bonding techniques (e.g., using certain epoxies) may not maintain a microcomponent's position over a wide range of environmental conditions (e.g.
Ellis Matthew D.
Skidmore George D.
Cherry Euncha
Haynes and Boone LLP
Zynex Corporation
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