Optical waveguides – With optical coupler – Switch
Reexamination Certificate
1999-10-12
2001-07-10
Palmer, Phan T. H. (Department: 2874)
Optical waveguides
With optical coupler
Switch
C385S016000, C385S017000, C385S033000, C385S036000
Reexamination Certificate
active
06259835
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to optical switches, and more particularly, to mechanically actuated optical switches.
2. Background
Optical switches have been developed for switching optical networks in broadband telecommunications systems. Because of increasing demand for high speed broadband data communications, optical wavebands including infrared and visible light wavelengths are increasingly being used as data carriers in telecommunications systems to satisfy the demand for high speed broadband data transmission. Conventional optical switches have been implemented in a typical optical fiber telecommunications network to switch the optical paths of information-carrying light to different optical fiber cables.
Conventional optical switches typically fall into two broad categories of non-integrated optical switches and integrated optical switches. Among the non-integrated optical switches, moving fibers have been used to change optical paths between different input or output fibers. In a conventional moving fiber switch, either the input optical fibers or the output optical fibers are moved mechanically to switch the optical path between different input or output optical fibers.
However, conventional moving fiber switches typically suffer from alignment problems because it is difficult to align the input and output fibers with a high degree of accuracy and repeatability. Alignment of single mode fibers can be especially difficult because of their small diameters. Even a slight misalignment between the selected input and output fibers through which optical transmission supposedly occurs may result in an unacceptably high insertion loss because the output fiber is not in the perfect position on the optical path to receive the light transmitted from the input fiber.
In order to avoid the problem of misalignment in a typical fiber moving switch, expensive and complicated mechanisms are usually required to move either the input or the output optical fibers to achieve acceptable alignment accuracy and repeatability. Furthermore, conventional moving fiber switches typically have slow switching speeds which may limit their applications in optical fiber communications networks which require high-speed switching operations.
Moving reflectors have also been used in conventional non-integrated optical switches to switch optical paths between different input or output optical fibers instead of moving the input or output fibers for optical alignment. Moving reflector switches are usually capable of faster switching operations than conventional moving fiber switches. However, conventional reflector switches typically also suffer from the problems of mechanical stability and repeatability. After a large number of repeated on and off switching operations, the optical reflectors in a conventional reflector switch may deviate from their designed reflection angles because of the problems with mechanical stability and repeatability. Even a slight deviation of reflection angle may cause the optical path of reflected light to be misaligned with a respective output fiber or another reflector which is supposedly positioned to receive the reflected light.
Therefore, there is a need for an optical switch with a high degree of reliability after a large number of repeated on and off switching operations which are typically required in modern optical fiber telecommunications networks. Furthermore, there is a need for an optical switch which provides accurate optical alignments between the reflectors and the optical fibers without requiring expensive or delicate mechanical assemblies for switching the reflectors between their on and off positions.
SUMMARY OF THE INVENTION
The present invention provides a mechanically actuated optical switch, roughly comprising a primary optical port, a plurality of secondary optical ports, a support plate having first and second surfaces opposite each other, a plurality of movable optical reflectors each capable of occupying an on position to reflect light from the primary optical port to a respective one of the secondary optical ports, and a plurality of actuators connected to the movable optical reflectors respectively to drive the optical reflectors between their on and off positions.
In an embodiment, light is transmitted from the primary or input optical port to the selected secondary or output optical port by using a single optical reflector to reflect the light on a first optical path from the primary optical port onto a second optical path leading to the selected secondary optical port. In another embodiment in which input and output optical fibers connected to the optical switch assembly are desired to be parallel to each other, a fixed primary reflector is provided on the support plate to reflect incoming light on the first optical path from the primary optical port onto a second optical path, and the movable secondary reflectors are positioned along the second optical path. When one of the secondary reflectors is selected to be switched to its on position while other secondary reflectors are in their off positions, light on the second optical path is reflected by the selected secondary reflector onto a third optical path leading to the respective secondary optical port for outputting the light.
In an embodiment, the on positions of the movable optical reflectors are above the first surface of the support plate whereas the actuators are positioned below the second surface of the support plate. In a further embodiment, the support plate is provided with apertures, and the actuators are connected to the movable optical reflectors respectively through a plurality of levers which are movably positioned through the apertures in the support plate to drive the respective movable optical reflectors.
A movable optical reflector is switched to its on position when it is moved by the lever away from the first surface of the support plate to a predetermined position above the first surface of the support plate to intercept light on an incident optical path. The movable optical reflector has a reflection surface angled with respect to the incident optical path when the movable optical reflector is in its on position to reflect the light onto a reflected optical path which eventually leads to one of the output optical fibers. When the movable optical reflector is switched from its on position to its of f position, it is moved by the lever away from the incident optical path toward the first surface of the support plate. In a further embodiment, the off position of the movable optical reflector is within the aperture in the support plate.
In an embodiment, the actuators comprise relay switches capable of generating repetitive movements in opposite directions. Either prisms or mirrors may be used as optical reflectors in the optical switch according to the present invention, although other types of optical reflectors may also be used. For each of the optical reflectors, the reflection surface may be angled at 45° with respect to its incident optical path to reflect the light onto a reflected optical path which is perpendicular to the incident optical path, although other reflection angles may also be used within the scope of the present invention.
In an embodiment, a plurality of lenses are provided adjacent terminations of the input and output optical fibers to collimate light on the respective optical paths. In a further embodiment, the lenses and end portions of the respective optical fibers are housed in a plurality of collimator assemblies which are fixedly connected to the first surface of the support plate. In yet a further embodiment, the collimator assemblies are connected to the first surface of the support plate by laser welding for improved mechanical stability and reliability.
Advantageously, the mechanically actuated optical switch according to the present invention can be implemented in an optical fiber telecommunications network which requires a large number of frequent switching operations with a high degree
Brobeck Phleger & Harrison LLP
Palmer Phan T. H.
Primawave Photonics, Inc.
LandOfFree
Mechanically actuated optical switch does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Mechanically actuated optical switch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mechanically actuated optical switch will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2452476