Optical chip coupling system utilizing micromachine adjustable optical elements and a feedback circuit providing the micromachine with a feedback signal correlated to an optical signal parameter

An optical communication system including an integrated circuit chip, an electro-optical chip operatively integrated on the integrated circuit chip, an adjustable optical chip which includes at least one optical element disposed between the electro-optical chip and one of a source or recipient of at least one optical signal, at least one micromachine operatively coupled to the at least one optical element to selectively manipulate the at least one optical element; an optical signal sensor disposed relative to the at least one optical signal to sense an optical signal condition data, and to transmit said optical signal condition data to the integrated circuit chip, a feedback circuit between the integrated circuit chip and the at least one micromachine, the integrated circuit chip configured to receive the optical signal condition data, convert it to a corresponding feedback signal, and to transmit the feedback signal through the feedback circuit to the micromachine, thereby causing the micromachine to selectively manipulate the at least one optical element to alter the optical signal.

TECHNICAL FIELD

The invention pertains to an optical chip which uses micromachine controlled optical elements and a feedback signal system to maximize the optical coupling of the system. The feedback signal received by the micromachine is correlated to an optical signal parameter, and the micromachine in turn manipulates the optical element to alter the optical signal parameter.

BACKGROUND OF THE INVENTION

Optical communication systems are becoming more predominant in the telecommunication industry. In optical communication systems, the optical alignment of sources, connectors, detectors and other optical elements is important to the efficient operation of such systems. Prior alignment systems are not believed to be suitable for numerous closely spaced optical signals.

The alignment and optimization of optical elements can be degraded due to any one of a number of reasons, such as without limitation assembly produced tolerance, temperature effects and thermal mismatching, and environmental conditions such as vibration. Misalignment or the failure to initially, periodically and/or continuously optimize the relative alignment may entirely destroy an optical link, or produce unacceptably high bit errors.

As data transfer and other communications systems will continue to require more bandwidth and more highly parallel optical systems are further developed, a reliable and robust system to align and/or optimize the alignment of such optical communication systems will be desired.

It is therefore an object of this invention to provide a new adjustable optical chip micromachine coupling system.

SUMMARY OF THE INVENTION

Aspects of this invention include an adjustable optical chip with optical elements disposed to receive optical signals, micromachines operatively coupled to each of the optical elements selectively manipulate the optical elements in an optical path of the optical signal. This invention also includes a feedback circuit coupled to the micromachines, which are disposed to receive a feedback signal from the feedback circuit, wherein the feedback signals are correlated to an optical signal parameter and a corresponding selective manipulation of the plurality of optical elements by the micromachine. The manipulation of the optical element alters the optical signal parameter. The optical elements may be any one of a number of different types or kinds of optical elements, such as a diffractive or refractive optics, a combined micromirror and optical lens or just a micromirror. This aspect of the invention may also be part of an optical communications system which would further include an integrated circuit chip and an electro-optical chip integrated on the integrated circuit chip.

Further aspects of the invention may be an embodiment such as wherein the optical signal source is an optical connector, an optical chip on a second and adjacent integrated circuit chip and/or an optical multilayer board. The integrated circuit chip may also be mounted on a system circuit board.

A further aspect of this invention may be an embodiment wherein the integrated circuit chip and the electro-optical chip comprise one chip in any one of a number of ways, such as by flip-chip bonding. It will further be appreciated by those of ordinary skill in the art that further embodiments may be a configuration wherein the optical signal parameter and the optical signal condition data are the same.

This invention further contemplates process embodiments in an optical communication system, such as a method for adjusting an optical signal parameter. This method would generally involve transmitting the optical signal through the optical element, sensing optical signal condition data related to an optical signal parameter, transmitting a feedback signal to the micromachine , the feedback signal corresponding to the optical signal condition data, and then selectively manipulating the at least one optical element with the micromachine to alter the optical signal parameter.

DETAILED DESCRIPTION OF THE INVENTION

Many of the manufacturing, fastening, connection, integration, electrical connection and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art or science; therefore, they will not be discussed in significant detail. Furthermore, the various components shown or described herein for any specific application of this invention can be varied or altered as anticipated by this invention and the practice of a specific application or embodiment of any element may already be widely known or used in the art or by persons skilled in the art or science; therefore, each will not be discussed in significant detail.

The terms “a”, “an”, and “the” as used in the claims herein are used in conformance with long-standing claim drafting practice and not in a limiting way. Accordingly, unless specifically set forth herein, the terms “a”, “an”, and “the” are not limited to one of such elements, but instead mean “at least one”.

FIG. 1is a schematic representation of one embodiment of an adjustable optical chip micromachine coupling system100as contemplated by this invention, illustrating integrated circuit chip103, electro-optical chip102and optical component110. The integrated circuit103may be mounted to system board104by any one of a number of known means, including without limitation through solder ball grid array beads108.

Optical chip101is disposed between electro optical chip102and optical component110. Optical waves133,137and141are shown between optical component110and electro-optical chip102and may be traveling in either or both directions through optical elements130,134and138, respectively. Optical elements130,134and138may be operably attached or mounted to, or contained within, optical chip101via any one of a number of known means. Optical signals133,137and141pass through optical signal passageways132,136and140, respectively, for transmission with electro-optical chip102.

The optical elements130,134and138are controlled within the contemplation of this invention by micromachines or micro electronic machines on or within optical chip101. Control components131,135and139control optical elements130,134and138, respectively. Electro-optical chip102may be any one of a number of different types of electro-optical chips102, including a laser and/or a detector chip. The electro-optical chip102may contain high-speed lasers such as vertical cavity surface emitting lasers, or high speed photodetectors, or both. Electro-optical chip102emits, transmits and/or receives optical signals via emitter/receivers142,143and144.

Optical component110may be any one of a number of optical components, including an optical connector, an optical multi-layer board, an optical chip on an adjacent board, or others, within the contemplation of this invention. Optical component110may include optical signal emitters/receivers145,146and147through which optical signals are emitted, transmitted, detected or received. In the embodiment when optical component110is an optical multilayer board, optical waves133,137,141are coupled to the waveguides of the multilayer board by optical elements such as diffractive gratings on the multilayer board.

In the embodiment illustrated inFIG. 1, optical chip101is mounted directly to integrated circuit chip103via any one of a number of known means, including without limitation, solder ball technology.

FIG. 1illustrates first feedback signal111and second feedback signal112being transmitted from integrated circuit chip103to optical chip101. Optical chip101includes first feedback circuit150and second feedback circuit151which provide the means through which one or more feedback signals may be transmitted to micromachines controlling optical elements130,134and138.

Optical chip101is shown electrically connected to integrated circuit chip103through first solder ball connectors107and second solder ball connectors106, and electro-optical chip102is illustrated operatively connected or integrated with integrated circuit chip103via solder balls105. Integrated circuit chip103is shown attached, operatively attached, connected, or integrated with system board104via balls108. Although solder balls are shown as a means of operatively connecting or integrating various components illustrated inFIG. 1, this invention is not limited to the use of solder balls for such integration but instead the components may be attached in any one of a number of known ways, including without limitation wire-bonds and stud-bonds. In some embodiments of the invention , optical chip101, electro-optical chip102and integrated circuit103may also be integrated on one chip, as shown more fully inFIG. 5.

Feedback circuit150may be electrically connected to any one or more of the micromachines controlling the optical elements on optical chip101, and feedback signal leads152,153and154respectively connect either first feedback circuit150and/or second feedback circuit151to optical elements130,134and138.

Although three optical elements and corresponding components are shown for illustrative purposes, it will be appreciated by those of ordinary skill in the art that no particular configuration or number of optical elements is required to practice this invention. It will also be appreciated by those of ordinary skill in the art that micromachine controlled optical elements provide the optical coupling between the electro-optical chip, a laser/detector chip, and the connectors or other optical paths of the optical communications systems, which are depicted by optical component110. The feedback signals, which may be the first feedback signal and/or the second feedback signal, are drive signals from the integrated circuit chip103to optical chip101and may be low frequency electrical signals, which may make the connection between the integrated circuit chip103and optical chip101easier to achieve. The feedback signals will automatically position the optical elements to achieve maximum optical coupling through positioning and steering of the optical elements, to alter an optical signal parameter such as power.

The optical elements may be any one of a number of different known optical elements, including lenses, mirrors, diffractive elements, holograms, or combinations of these elements. It will be appreciated by those of ordinary skill in the art that the optical elements may also be used for coupling the optical signals through free space transmission to another or similar configuration as shown inFIG. 1. By utilizing the feedback signal to the micromachines and thereby altering the one or more optical signal parameters, the optical coupling between the components may be bettered or optimized automatically and continuously within the contemplation of this invention.

In an embodiment, the integrated circuit chip103would receive optical signal condition data from one or more sensors in the optical communication system. In one implementation, the optical signal condition data is transmitted optically to optical chip101and received by photodetectors on the electro-optical integrated electro-optical chip102. The data is transferred via solder balls105to integrated circuit chip103for processing.

The integrated circuit chip may receive information related to coupling efficiency and other data related to the optical signals measured by the sensor, such as the optical power or bit error rate in the link. Based upon the condition data received by the integrated circuit chip103, the integrated circuit chip would perform processing of the data and provide the drive signal or feedback signals111and112to optical chip101to make the appropriate changes in the optical elements130,134and/or138.

The feedback signals may be specific to one or more, or all, of the micromachines and optical elements130,134and138, in controlling the system.

It will also be appreciated by those of ordinary skill in the art that the electro-optical chip102shown is exemplary and may contain semiconductor lasers such as Vertical Cavity Surface Emitting Laser (VCSEL), and/or high speed detectors, which may possibly be integrated with micro-optics to facilitate the optical coupling. The electro-optical chip may also be integrated chips or multi-chip modules within the contemplation of the invention and depending on the application. The electro-optical chips will generally perform any one or more of numerous potential functions, such as electrical to optical conversion, switching and/or routing of data, wavelength conversion, data rate conversion (such as high to low), amplification, and/or other functions.

FIG. 2is a flow diagram illustrating one embodiment of this invention, showing that the optical element is originally oriented in first step170. The optical signal is received and transmitted or forwarded by the optical element per step171, and a sensor then senses the optical signal received from the optical element and senses optical signal condition data in step172. At step173, if the optical signal condition sensed for is present (for instance sensed to determine if the signal is in an optimum range), then a feedback signal is transmitted to the micromachine controlling the optical element at step175in order to make the appropriate adjustment to the optical element. Once the appropriate adjustment is made to the optical element, the system continues to sense the optical signal for further signal condition data for further and continuous monitoring and adjusting of the optical element.

If at step173the optical signal condition sensed is not present, the system continues to maintain the optical element as last oriented and continues to sense the optical signal condition data for the condition which is out of the predetermined tolerance or condition for the optical element.

FIG. 3is a flow diagram illustrating another embodiment of this invention, showing that the optical element is originally oriented in first step270. The optical signal is received and transmitted or forwarded by the optical element per step271, and a sensor then senses the optical signal received from the optical element and senses optical signal condition data in step272. At step273, if the optical signal is optimum or in an optimum range, then a signal274is transmitted to the micromachine controlling the optical element at step278and the optical elements are fixed or retained as is. Once the optical element is fixed or set, the system would periodically continue to sense the optical signal for further signal condition data for further and continuous monitoring and adjusting of the optical element.

If at step273the optical signal sensed is not in the desired optimum range, at step or item175, the system transmits a feedback signal176to the optical element to initiate or cause an adjustment of the optical element.

The micromachine controlled reflective surfaces or micromirrors may be practiced in any one of a number of ways within the contemplation of this invention, one exemplary way being that disclosed in U.S. Pat. No. 6,215,222, for an “Optical Cross-Connect Switch Using Electrostatic Surface Actuators”, which is incorporated herein by this reference.FIGS. 6 and 7areFIGS. 2 and 3respectively from U.S. Pat. No. 6,215,222, and illustrate one embodiment of a micromachine that may be utilized in embodiments of this invention. Turning toFIG. 6, a switching device330of the optical device in accordance with an embodiment is shown. The switching device330includes a translator332and a micromirror333that are attached to a stator331. The translator332and the stator331may be made of silicon. The micromirror333may also be made of silicon with a layer of Au for the reflective surface. The translator332is attached to the stator by eight translator supports335. The translator supports335are affixed to the upper surface of the stator and to one of four E-shaped flexures336of the translator332. The flexures336allow the translator332to move in the X-direction, while the stator331remains stationary. As an example, the flexures336may have a thickness of two (2) μm and a death of one hundred (100) μm. The micromirror333is attached to the stator331by a pivoting strip350(shown inFIGS. 8 and 9) that allows the micromirror333to rotate about the side of the micromirror333that is affixed to the strip. The pivoting strip may be a thin film of silicon nitride (SiN). The translator332includes an opening334that provides enough space for the micromirror333to pivot from the non-reflective orientation. i.e., the orientation shown inFIG. 6. to the reflective orientation, i.e., a vertical orientation such that the micromirror333is parallel to the YZ plane. The micromirror333is also attached to the translator332, as shown inFIG. 7. The physical attachment of the micromirror333to the translator332allows the micromirror333to be pivoted by a lateral displacement of the translator332. The translator332and the stator331form an electrostatic surface actuator that operates to pivot the micromirror333to either the reflective or non-reflective orientation. The translator332and the stator331both include electrodes located on the opposing surfaces of the translator332and the stator331. When the electrostatic actuator is activated, the electrostatic forces created by applying voltaaes to the electrodes of the translator332and the stator can be manipulated to laterally displace the translator332with respect to the stator331in the X-direction. The lateral movement of the translator332pivots the micromirror333from the non-reflective orientation to the reflective orientation. When deactivated, the translator332is designed to move in the negative X-direction back to the original position. This reverse displacement of the translator332pivots the micromirror333from the reflective orientation to the non-reflective orientation. The pivoting of the micromirror333will be further described below.

In embodiments of the invention, the optical signal condition data may utilize a dedicated sensor to obtain or create the optical signal data, but the invention does not necessarily require a dedicated sensor. For example, in the fiber optic link as depicted inFIG. 4, transmitter300on first optical chip308sends optical data301to receiver302on second optical chip305. Receiver302may then generate optical signal data303(such as the optical power level) to transmitter304, which transmits optical signal data306to receiver307on first optical chip308.

The positions of the micro-lens can be adjusted with high precision insteps of an few microns using low voltage signals. This is described for instance in Storrs Haen et al (Hewlett Packard Laboratories), “Electrostatic Surface Devices: Theoretical Considerations and Fabrication”, as presented at the 1997 International Conference on Solid Sate Sensors and Actuators, Chicago, Jun. 16–19 1997.

FIG. 5is a schematic view of another embodiment of an adjustable optical chip micromachine coupling system contemplated by this invention, showing an electro-optical portion, an integrated circuit portion and an interface portion integrated into one chip. There are like items inFIG. 5fromFIG. 1which are similarly numbered, withFIG. 5illustrating an integrated chip configuration, showing an interface portion160or zone, an electro-optical portion161or zone, and an integrated circuit portion162or zone.FIG. 5further representatively shows arrows R1and R2representing rotation of the optical element and T1and T2to represent movement and/or translation of the optical element.

One embodiment of this invention for example utilizes micro-lens supported by electrostatic dipole surface drives capable of precise movement controls.

As will be appreciated by those of reasonable skill in the art, there are numerous embodiments to this invention, and variations of elements and components which may be used, all within the scope of this invention.

InFIG. 8, the translator332is situated in the original position. The original position is the resting position of the translator332. When there are no electrostatic forces generated between the translator332and the stator331. At the original position, an inner surface355of the translator332is positioned directly over a reference line356on the stator. When electrostatic forces are initially generated by applying voltages to the electrodes in a first voltage pattern, the translator332may shift slightly in either direction along the x-axis, until an equilibrium is reached. As the voltage pattern is reconfigured, the net electrostatic force along the X-axis displaces the translator332to the left. Since the actuation arm351is attached to the translator332at the location354, the actuation arm351will be pushed in the X-direction. The movement of the actuation arm351creates a torque to pivot the micromirror333in a direction of arrow353, which is caused by the fact that the micromirror333is attached to the actuation arm351at the location352and is also attached to the stator331by the pivoting strip350. InFIG. 9, the translator332has been displaced such that the inner surface355of the translator332is now positioned over a reference line357on the stator331. The displacement of the translator332over the distance between the reference lines356and1357has pivoted the micromirror333by a significant amount, as shown inFIG. 9. The micromirror333may also be pivoted to an upright position, i.e., the reflective orientation. The micromirror333can be incrementally repositioned to the non-reflective orientation, shown inFIG. 8by displacing the translator332in the negative X-direction, such that the inner surface355of the translator332is positioned over the reference line356on the stator331. The translator332can be displaced in the negative X-direction by applying voltages to the stator drive electrodes in the reverse sequence of the voltage patterns that are described above. In an alternative operation, the voltages that are applied may be terminated to eliminate the electrostatic forces that are responsible for the lateral movement of the translator332. When these electrostatic forces are removed the flexures336of the translator332will return to the normal state, thereby laterally displacing the translator332to the original position.