Optical waveguides – With optical coupler – Switch
Reexamination Certificate
2000-01-04
2002-03-26
Lee, John D. (Department: 2874)
Optical waveguides
With optical coupler
Switch
C385S014000, C385S015000, C385S016000, C385S017000, C385S018000
Reexamination Certificate
active
06363183
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to integrated optic waveguide switch arrays and optical cross-connect networks that contain microelectromechanical system (MEMS) microstructures/actuators and micromachined optical waveguide networks on planar lightwave circuits (PLCs) and it is directed particularly to reconfigurable and scalable all-optical switching for computer systems and telecommunication networks. The invention is specifically disclosed as a Micro-Opto-Electro-Mechanical System (MOEMS) that fabricates MEMS actuators and high-bandwidth PLCs by using well-established lithographic batch processing techniques and subsequently assembles them into integrated optic waveguide switches or optical cross-connect networks.
BACKGROUND OF THE INVENTION
Recently there has been an accelerated integration of computer systems and communication networks in an attempt to satisfy the ever-increasing information processing, transmission, and distribution needs for future computer systems and communication networks. High-performance microprocessors with large integration density, diverse functionality, and high-speed operation capabilities are now in widespread use due to innovative architecture designs and improved silicon fabrication processes. Similarly there has been an increasing demand for better performance in network computing. Over the past several years, the rapidly increasing traffic volume carried by telecommunication networks clearly has been observed, and this is a result of wider use of bandwidth-intensive applications such as Internet access, electronic commerce, multimedia applications, and distributed computing. In accommodating this demand, optical telecommunication systems employing optical fibers as the transmission medium have exhibited a superior performance/cost ratio for both long-haul and short-haul routes to than any other type of telecommunication systems. In particular the emerging dense wavelength-division multiplexing (DWDM) and all-optical network communication systems have shown some promising and exciting potentials. However there still exists a need to improve delay, bandwidth, and connectivity of optical telecommunication networks, as the information system's subscriber growth continues unrestrained.
Although fiber optic cables for both long-haul and short-haul routes increasingly have been deployed by telecommunication service providers, the ever-increasing network traffic has created some constraints on communication network in terms of speed, capacity, and connectivity of networks. Telecommunication service providers have addressed these speed, capacity and connectivity constraints by either installing new fiber cables or by expanding the transmission capacity using faster devices or DWDM techniques. While timedivision multiplexing (TDM) increases the transmission speed of optical signals, DWDM increases the number of optical signals, called channels, transmitted simultaneously on a single fiber and it is ideal for high volume point-to-point or backbone links with minimal switching and routing requirements. However, in the emerging DWDM metropolitan and local area networks, the primary concern is not the network capacity but the network connectivity through reconfigurable switching. Regardless of the method used for addressing capacity constraints, the a fiber optic switching will become a major issue for optical telecommunication systems. Since the fiber optic telecommunication technology first became available, many network managers have preferred all-optical networks for benefits in terms of bandwidth, security, and segment length. Optical cross-connect networks can also improve the efficiency of all-optical networks by providing a bit-rate independent and format independent network switching. Without the all-optical networks, the signals of traditional optical telecommunication networks first must be converted from optical to electrical form at switching ports and the routing information in the information packet analyzed and utilized for proper signal routing. Then the signal must be converted to the optical form for a subsequent signal routing and transmission. These optical-to-electrical and optical-toelectrical signal form conversions reduce the overall network efficiencies as it introduces delays and noise.
It is widely believed that the DWDM network is an enabling technology for Internet applications, as the expectations of the Internet's great potential will not be realized without the bandwidth gain provide by DWDM. Direct fiber optic switching without electrical-to-optical or optical-to-electrical conversions is much needed for the all-optical DWDM network. The unprecedented record of growth being generated by Internet traffic and tremendous amount of data being dumped on the public network show no sign of slowing yet. Without optical telecommunication network and optical fiber's seemingly unlimited bandwidth potential as the fundamental transmission technology, the Internet performance will be significantly slowed as the subscriber growth increases unrestrained. Notably there is a need for fiber optic switches for all-optical DWDM networks, which can provide low cost, small crosstalk, reliable, compact, reconfigurable, modular, scalable, and wavelength/polarization insensitive characteristics.
SUMMARY OF THE INVENTION
Accordingly, it is a primary objective of the present invention to provide Micro-Opto-Electro-Mechanical System (MOEMS) for integrated optic waveguide switches and optical cross-connect networks. The MOEMS can deliver low cost, small crosstalk, reliable, compact, modular, scalable, and wavelength/polarization insensitive all-optical switching capabilities by integrating microelectromechanical system (MEMS) actuators and micromachined planar lightwave circuit (PLC) networks.
It is another objective of the present invention to provide a method of constructing integrated optic waveguide switches for two-input/two-output crossbar switching such that it allows a seamless integration of MEMS actuators and micromachined PLCs at the micro scale.
It is yet another objective of the present invention to provide a method of constructing integrated optic waveguide two-input/two-output crossbar switches for an Add/Drop switch and of Add/Drop switch applications.
Another objective of the present invention is to provide a method of constructing reconfigurable, non-blocking, and scalable optical cross-connect switches by using integrated optic waveguide switch arrays and PLC routing networks on MOEMS, which utilizes the inherent MOEMS characteristics: miniaturization, multiplicity, and micro-optoelectronics.
It is a further objective of the present invention to provide a method of constructing multifunction MEMS vertical mirror/filter actuators for DWDM Add/Drop filter and multiplexer applications, which combines out-of-plane vertical mirror or multi-layer thin-film filter plates on MEMS actuators.
It is yet a further objective of the present invention to provide a method of constructing tapered, off-set, and anti-reflection X-crossing boundary conditions for optical waveguide networks as well as providing parallel and non-parallel vertical movable plates in order to reduce insertion losses and to equalize optical signal powers.
It is yet another further objective of the present invention to provide a method of constructing a low power MEMS actuator, which exhibits zero-static power consumption.
Additional objectives, advantages and other novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention.
To achieve the foregoing and other objectives, and in accordance with one aspect of the present invention, improved Micro-Opto-Electro-Mechanical Systems (MOEMS) are provided to support the seamless and scalable integration of MEMS actuators and PLCs. Such MOEMS can integrate high-bandwidth waveguide networks of PLCs and miniaturized MEM
Koh Seungug
Lee John D.
Rahll Jerry T
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