Patent Document

FIELD OF THE INVENTION 
     The present application relates to a method and apparatus for aligning optical components. 
     BACKGROUND OF THE INVENTION 
     Optical components such as optical fibres, lenses, integrated optical systems, etc. are frequently aligned and coupled to one another. In general, the alignment is performed passively and/or actively. During passive alignment, the two optical components may be placed according to the expected desired orientation. During active alignment, the two optical components may be moved relative to one another while light transmitted therethrough is simultaneously monitored to determine an optimum coupling efficiency. 
     For integrated optical systems, such as optical integrated circuits (OICs), arrayed waveguide gratings (AWGs), planar waveguides (PW), etc., which generally have multiple channels extending to an array of ports at an end of the component, active alignment can be quite difficult. For example, consider the pigtailing of an integrated optical system, wherein each output port of the integrated optical system must be aligned and coupled to a specific optical fibre in a fibre array unit (FAU). 
     In many cases, to achieve optimum coupling of such multi-port components via active alignment, it is preferred that alignment be performed to a fraction of a micron and within six degrees of freedom, namely, three translational degrees of freedom and three rotational degrees of freedom. 
     According to one common prior art method of active alignment, an optical component having an input beam of light launched therethrough is mounted to a first jig, an integrated optical system which for example is an AWG is mounted to a second jig or post, and an FAU is mounted to a third jig. Relative movement between the optical components is controlled manually and/or automatically one degree of freedom at a time until an output signal indicating maximum coupling efficiency is achieved. More specifically, maximum coupling efficiency is determined typically for a first optical port/fibre pair, and subsequently for a second optical port/fibre pair. 
     Unfortunately, alignment in a first degree of freedom usually destroys alignment in a second degree of freedom. For example, alignment of the second optical port/fibre pair almost always unaligns the alignment of the first optical port/fibre pair. In the worst case scenario, the optical signal is lost and must be found again. This is usually due to the fact that the pivot points of relative movement cannot be disposed at the end of the fibre being aligned within sub-micron tolerances and/or the fact that the jigs have linear tolerances (e.g., the x, y, and z axes are not generally 100% orthogonal). 
     Accordingly, the prior art method typically involves moving one of the components in a first degree of freedom until optimum coupling is achieved, moving the component in a second degree of freedom until optimum coupling is achieved, repeating the step of moving the component in the first degree of freedom until optimum coupling is achieved, repeating the step of moving the component in the second degree of freedom until optimum coupling is achieved, moving the component in a third degree of freedom until optimum coupling is achieved, etc . . . This recursive process can make prior art methods of alignment very time consuming and difficult to automate. 
     A second disadvantage of the prior art alignment relates to the apparatuses used to provide the relative movement, which traditionally, have been based only on thumb screw drives, differential drives, and/or stepping motors. For example, stepping motors that achieve the required stepping quality are excessively slow. 
     Since the prior art active alignment methods have traditionally been very slow, as discussed above, alignment errors associated with the use of adhesives for securing the optically aligned components, have also arisen. For example, if an adhesive, such as epoxy, is applied after the optical components have been initially aligned, then as the epoxy hardens, it may shrink and pull the optical components out of alignment. As a result, prior art methods have compensated by using relatively low temperatures to set the epoxy so that the optical components can be finely aligned during the curing of the epoxy. This increases the time of the alignment. 
     Another disadvantage of prior art method/apparatuses relates to the fact that they are not easily adaptable to multi-component alignment. For example, it is common to provide only two jigs for mounting only two optical components at a time. 
     Melles Griot Ltd., has proposed a positioning apparatus for aligning waveguides and optical fibres that may alleviate some of the above disadvantages. The positioning apparatus uses a signal optimization system referred to as “NanoTrak”, to scan and search for an optimum signal. More specifically, the apparatus includes positioners that radially move one of the components in a first search plane such that an optimum signal intensity is measured at the detector, and subsequently move the origin of the scan circle in the direction of the optimum signal intensity. The procedure is repeated iteratively until no appreciable signal gradient exists between iterations. It is further repeated for a plurality of search planes. For example, see UK Pat. Appl. GB 2 345 154, incorporated herein by reference. However, although the proposed apparatus may reduce the initial alignment time over traditional auto-alignment systems, it is limited in that in many cases the scan and track method loses the optimum signal and must find it again. This is particularly important in the alignment of multi-channel optical devices. Moreover, the proposed apparatus uses a combination of piezoelectric and stepping motors, which are used sequentially, to perform the alignment. Disadvantageously, this sequential and radial action slows down the alignment process. Further disadvantageously, piezoelectric motion is associated with hysteresis and/or drift. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a method and apparatus that obviates the above disadvantages. 
     It is another object of the present invention to provide a method and apparatus for efficiently aligning optical components. 
     Thus the present invention provides a method and apparatus for aligning optical components that effectively locks pairs of ports in alignment, while simultaneously allowing further alignment of the same or a different pair of ports. For example, in one embodiment the locked pair of ports includes a fibre end and a waveguide channel end. The effective locking of pairs of ports is achieved by providing a virtual pivot point close to the ports being aligned, via a relatively fast compensating movement of at least one of the optical components being aligned. For example, as the fibre end and waveguide channel end are moved/positioned relative to one another to improve the alignment, a relatively fast and simultaneous movement is provided to compensate for instances when the positioning movement destroys the alignment. More specifically, when the positioning movement destroys the alignment and the optical signal would otherwise be lost, the relatively fast compensating movement provides means for continuously monitoring the optical signal and recording the coordinates corresponding to the maximum optical signal. The coordinates are used to determine subsequent positioning movements. 
     Since the ports are locked, i.e., are always aligned with being affected by any other activities, the instant method and apparatus for alignment is suitable for automation. In the preferred embodiment, the relatively fast compensating movement is provided with at least one electromagnetic actuator. 
     Advantageously, the instant invention is applicable to the alignment of multi-channel optical components, multi-port optical components, and/or multi-component optical devices. With respect to the latter, the instant invention provides means for aligning three or more optical components at one time, which are sequentially positioned on the aligning jig. Furthermore, the instant invention is applicable to any solid state material that can be aligned optically. 
     The term ‘channel’, as used herein, refers to a waveguide within an optical component for propagating an optical signal. The term ‘port’, as used herein, refers to a location on an end face of the component for transmitting an optical signal thereto or therefrom. 
     In accordance with the present invention there is provided a method of aligning optical components comprising the steps of: mounting a first optical component having an input port and an output port to a first support; mounting a second optical component having an input port and an output port to a second support such that the output port of the first optical component is substantially aligned with the input port of the second optical component; launching a reference beam of light into the input port of the first optical component such that it at least partially emerges from the output port of the second optical component to provide a reference signal indicative of an optical coupling efficiency between the output port of the first optical component and the input port of the second optical component; providing relative movement between the first and second supports while monitoring resulting changes of the reference signal; providing a control signal indicative of the resulting changes of the reference signal; and providing further relative movement between the first and second supports in dependence upon the control signal such that a virtual pivot point is formed substantially at one of the output port of the first optical component and the input port of the second optical component. 
     In accordance with the present invention there is further provided an apparatus for aligning optical components comprising: a first support for mounting a first optical component having an input port and an output port; a second support for mounting a second optical component having an input port and an output port such that the output port of the first optical port component is substantially aligned with the input port of the second optical component; a light source for launching a reference beam of light into the input port of the first optical component; a detector for monitoring an intensity of the reference beam output the output port of the second component to provide an indication of a coupling efficiency between the first and second optical components; means for providing relative movement between the first and second optical components such that the intensity of the reference beam monitored at the output port of the second optical component is altered; and a processor for analyzing the altered intensity of the reference beam and providing feedback to the means for providing relative movement such that the means for providing relative movement are able to create a virtual pivot point substantially at one of the output port of the first optical component and the input port of the second optical component. 
     In accordance with the present invention there is further provided an apparatus for aligning optical components comprising: a first support for supporting a first optical component having an input port and an output port; a second support for supporting a second optical component having an input port and an output port such that the output port of the first optical port component is substantially aligned with the input port of the second optical component; a light source for launching a reference beam of light into the input port of the first optical component; a detector for monitoring an intensity of the reference beam output the output port of the second component to provide an indication of a coupling efficiency between the first and second optical components; and means for providing relative movement between the first and second optical components to affect the coupling efficiency, the means including an electromagnetic actuator capable of moving one of the first and second components in dependence upon a power applied thereto. 
     In accordance with the present invention there is provided a method for aligning an optical channel in a first optical element with an optical channel in a second optical element, where the optical channels extend substantially parallel to a z-axis, and where the optical elements require lateral positional alignment along x and y axes that are perpendicular to each other and the z-axis, and further require angular positional alignment, the method comprising the steps of: launching a reference signal through the optical channel of the first optical element such that it is at least partially output from the optical channel of the second optical element; laterally moving the second optical element relative to the first optical element while monitoring the reference signal output from the optical channel of the second optical element until a position is reached where the monitored reference signal indicates substantial lateral alignment of the channels of the first and second optical elements; and angularly moving the second optical element relative to the first optical element while monitoring the reference signal output from the optical channel of the second optical element until a position is reached where the monitored reference signal indicates substantial angular alignment of the channels of the first and second optical elements, wherein the angular movement is performed while maintaining the substantial lateral alignment by further laterally moving the second optical element relative to the first optical element to compensate for changes in the lateral alignment caused by the angular movement. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the invention will now be described in conjunction with the drawings, in which: 
     FIG. 1 a  is a schematic illustration of two multi-port optical components; 
     FIG. 1 b  is top view of the optical components shown in FIG. 1 a , wherein one of the optical components is an AWG and the other is a FAU; 
     FIG. 1 c  is a top view showing an embodiment wherein the AWG and FAU are disposed at an angle to one another before alignment; 
     FIG. 1 d  is top view of an embodiment wherein the input end of the FAU has been polished at an angle; 
     FIG. 1 e  is side view of an embodiment wherein the optical fibres of the FAU are not parallel to the top of the FAU; 
     FIG. 1 f  is top view of an embodiment wherein the optical fibres of the FAU are not parallel to the sides of the FAU; 
     FIG. 2 a  is a schematic diagram of showing a first step in the alignment of the optical components shown in FIG. 1 b;    
     FIG. 2 b  is a schematic diagram of showing another second step in the alignment of the optical components shown in FIG. 1 b;    
     FIG. 2 c  is a schematic diagram of showing yet another step in the alignment of the optical components shown in FIG. 1 b;    
     FIG. 3 is a schematic diagram of an apparatus in accordance with one embodiment of the instant invention for aligning three optical components; and 
     FIG. 4 is a schematic diagram of one embodiment of a compensating mechanism used in the apparatus shown in FIG.  3 . 
     It will be noted that throughout the appended drawings, like features are identified by like reference numerals. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1 a , there is shown a first optical component  10  having an array of five ports  12 . Each port ( 12   a ,  12   b ,  12   c ,  12   d , and  12   e ) of the array  12  is aligned along a straight line at an end  14  of the optical component  10 . A second optical component  20  is also shown having an array of five ports  22  for mating with first array  12 . Each port ( 22   a ,  22   b ,  22   c ,  22   d ,  22   e ) of the array  22  is aligned along a straight line at an end  24  of the second optical component  20 . Notably, each array on the optical component is dependent upon the manufacturing process thereof, and is subject to various manufacturing errors. 
     In FIG. 1 b , the first optical component  10  is shown as an AWG having a single port  16  for receiving an optical signal including wavelengths λ 1 , λ 2 , λ 3 , λ 4  and λ 5  and an array of output ports  12  for outputting an optical signal corresponding to each individual wavelength. More specifically, the input optical signal is transmitted through the single port  16  to a single waveguide, is split into five separate waveguides, and is output each port  12   a ,  12   b ,  12   c ,  12   d , and  12   e  as optical sub-signals corresponding to wavelengths λ 1 , λ 2 , λ 3 , λ 4  and λ 5 , respectively. The second optical component  20  is shown as a FAU  20  including optical fibres  26   a ,  26   b ,  26   c ,  26   d ,  26   e  that are supported by fibre block  28  and extend to the end  24  of the FAU  20  at ports  22   a ,  22   b ,  22   c ,  22   d ,  22   e , respectively. For example, the optical fibres  26   a ,  26   b ,  26   c ,  26   d ,  26   e  are optionally part of a ribbon fibre  26 . 
     In considering the active alignment of these two components  10  and  20 , there are various initial conditions. Referring to FIG. 1 c  there is shown an embodiment wherein the AWO and FAU are disposed at an angle to one another. Alternatively, or in addition, variation is introduced during manufacturing processes, such as dicing and polishing processes. 
     For example, consider variations in the FAU  20 . Although the FAU  20  is usually manufactured such that optical fibres  26   a ,  26   b ,  26   c ,  26   d ,  26   e  are substantially parallel to one another, the same fibres are not necessarily perpendicular to the input end of the FAU  20 , parallel to the top/bottom of the FAU  20 , or parallel to the side surfaces of the FAU  20 , as shown in FIGS. 1 d ,  1   e , and  1   f , respectively. Similar variations are also possible for the AWG  10 . This misalignment increases the complexity of the alignment process, and is one of the reasons why it is desirable to actively align the optical components within six degrees of freedom. 
     Referring to FIGS. 2 a - 2   c , there is shown schematic diagrams of an AWG  10  and a FAU  20 , that need to be aligned in various degrees of freedom. Notably, the axes of the waveguides in the AWG  10  are substantially parallel to the axis in the z-direction. 
     Referring to FIG. 3, there is shown an embodiment of an apparatus for aligning optical components in accordance with the instant invention. The apparatus includes a first jig  30  for mounting a first optical component which is conveniently shown as an optical fibre tube  5  having an optical fibre  34  coupled thereto, a second jig  40  for mounting a second optical component which is conveniently shown as an AWG  10 , and a third jig  50  for mounting a third optical component which is conveniently shown as an FAU  20 . The second jig is preferably in the form of a stationary support. Notably, the AWG  10  and FAU  20  are respectively similar to the AWG  10  and FAU  20 , shown in FIGS. 2 a-c . In particular, each includes an array of input/output ports (i.e.,  22   a - 22   e  and  12   a - 12   e ) aligned along a line in the x-direction, for coupling to the other. 
     The apparatus also includes a light source  60  for launching a reference signal into optical fibre  34 , a detector  70  for monitoring the reference signal output from the FAU  20  and providing a control signal indicative of the reference signal, means  80  for providing relative movement between the fibre tube  5  and the AWG  10 , and the AWG  10  and the FAU  20 , and a processor  90  for analyzing the control signal and for calculating the coordinates and the required amount of relative movement provided by the means  80  in response to the control signal. This feedback control for the relative positioning of the jigs, and thus the respective channels/ports to be aligned allows a “virtual pivot point” between the two optical components being aligned to be formed. 
     In the embodiment shown in FIG. 3, the optical source  60  includes a red laser  62  for performing a rough visual alignment, a distributed feedback (DFB) laser  64  for performing alignment of the fibre tube  5  to the AWG  10 , an erbium doped fibre amplifier (EDFA) source  66  for providing light over the wavelength range of the AWG  10  to perform alignment of the AWG  10  and the FAU  20 , and a switch  68  for switching between each of the sources. For example, in one embodiment source  60  includes a DFBX 3  source. Alternatively, the optical source includes a tunable or other laser. 
     The detector  70  is shown having a first detector  72  for coupling to a first output fibre of FAU  20 , a second detector  74  for coupling to a second output fibre of FAU  20 , and a switch  76  for switching between the first detector  72 , the second detector  74 , and a combination of detectors  72 / 74 . Typically, each detector is connected to a different power meter. 
     The means  80  for providing relative movement is shown including a first mechanism  82  for positioning the optical components relative to one another to improve the alignment therebetween and a second mechanism  84  for compensating for instances where the positioning mechanism destroys the alignment rather than improving it. Accordingly, it is preferred that the positioning mechanism  82  have a wide dynamic range and provide a slow, stable, sequential positional motion, whereas the compensating mechanism  84  provide a faster, more accurate, and precise motion that allows the “locking-on” of the optical signal corresponding to optimum alignment. In one embodiment, the means  80  includes a positioning mechanism  82  that uses mechanical actuators or electric motors to provide relative movement in at least one degree of freedom and a compensating mechanism  84  that uses at least one electromagnetic actuator to provide relatively fast and simultaneous oscillatory movement in at least one other degree of freedom. 
     For example, a conventional  6 D positioner having a plurality of motors, drive screws, etc., for providing movement in 6 degrees of freedom is suitable for use in the positioning mechanism  82 , whereas the mechanism shown in FIG. 4 having first and second electromagnets for providing lateral movement respectively in two degrees of freedom is suitable for use in the compensating mechanism  84 . A separate driver or controller is provided to control the relative movement of each motor and electromagnet. 
     Referring to FIG. 4, the compensating mechanism  84  includes a first assembly  110   x  for providing lateral movement in the x direction and a second assembly  110   y  for providing lateral movement in the y-direction. A fixed plate  100 , which is preferably coupled to the positioning mechanism  82 , is provided for supporting the first  110   x  and second  110   y  assemblies. 
     In this embodiment, each assembly includes a u-shaped support  112 , an electromagnet  114 , a resilient connector  116 , and a ferromagnetic platen  118 . Alternatively, the platen  118  is manufactured from another type of magnetic field conductive material. Each electromagnet  114  is connected to a power supply  120  such that adjustments to the applied power affect the strength of the electromagnet  114 , and consequently, the degree to which the ferromagnetic platen  118  is attracted towards the u-shaped support  112 . For example, if power is periodically applied to the lower electromagnet  114   x  with a predetermined frequency, then the lower platen  118   x  will oscillate up and down along the x-axis with the same predetermined frequency. Similarly, if power is periodically applied to the upper electromagnet  114   y  with the predetermined frequency, then the upper platen  118   y  will oscillate from side-to-side along the y-axis with the same predetermined frequency. Accordingly, an optical component mounted to support  130  will experience relatively fast alternating translational movement in each of the x and y directions. 
     Of course, embodiments using more than one electromagnet per degree of freedom, using a different shaped support  112 , and/or using a different design are also possible, depending on the optical devices to be aligned. 
     Notably, the dynamic range of movement of the compensating mechanism  84  is limited by the applied power, the elastic range of the resilient connector  116 , electrical limits of the electromagnets  114 , and/or the distance between the u-shaped support  112  and the ferromagnetic platen  118 . The speed of movement is limited by the frequency variation of the applied power and/or the mass of the platen and/or the mass of the optical components mounted thereto. 
     In general, it is preferred that the positioning mechanism  82  and compensating mechanism  84  are coupled and/or cooperate with each other such that the positioning mechanism  82  is able to extend the travelling range of the compensating mechanism  84 . 
     Advantageously, the compensating mechanism  84  is also able to provide fine alignment between the two optical components. For example, once the positioning mechanism  82  and compensating mechanism  84  initially align the AWG  10  and FAU  20 , the power applied to the electromagnetic actuator is optionally varied to provide accurate and precise relative movement between the AWG  10  and FAU  20  via the electromagnets alone. 
     In one embodiment, the positioning mechanism  82  is designed to provide a stepping speed of 10-20 mm/min, a stepping range of 1-10 μm/step, and a dynamic range in the order of 1-30 mm, i.e., it is able to provide translational motion for up to 30 mm in the x, y, or z-directions. In contrast, the electromagnets  114  provide a continuous sweeping motion at a speed of about 1000-1500 mm/min, have an accuracy better than 0.1 μm, and have a dynamic range in the order of 50-120 μm, i.e., the electromagnets are able to provide oscillatory motion for up to 120 μm in the x, y, or z-directions. Of course, other parameters are also possible. For example, these parameters may vary depending on the optical devices to be aligned. 
     In operation, red laser light from light source  60  is launched into optical fibre  34  to provide a visual indication that the fibre tube  5  and the AWG  10  are roughly aligned. The purpose of this first step is to obtain at least a small portion of the reference signal, e.g., 5%, propagating through each of the optical components to be aligned. Optionally, red laser light from a second light source  60   b  is launched into at least one of the output fibres of the FAU  20  to provide a visual indication that the AWG  10  and FAU  20  are roughly aligned. 
     Once rough alignment is evident, the fibre tube  5  is temporarily fixed in position relative to the AWG  10 , for the duration of the initial alignment of the AWG  10  and the FAU  20 . During initial alignment, a reference signal from the EDFA  66  is launched into the optical fibre  34  such that it is transmitted through the input port  16  of the AWG  10  and propagates through each of the channels of the AWG  10  and is output each port  12   a - 12   e  of the output array  12 . The means  80  for providing relative movement are actuated to move the FAU  20  relative to the AWG  10  until a maximum intensity reading is measured at the detector  70 . This is completed in two stages, as for example, shown in FIGS. 2 a - 2   c.    
     In the first stage, a first channel of the AWG  10  is aligned with a first optical fibre of the FAU  20 , e.g., alignment of ports  12   a / 22   a . Accordingly, the detector switch  76  is actuated such that only the first detector  72  coupled to the first optical fibre is operative. To ensure that the first optical fibre of the FAU  20  is receiving light from the first channel of the AWG  10 , and not the second or third, the means  80  moves the FAU  20  in the x-direction until the output port  12   a  travels past all input ports (e.g.,  22   c ,  22   b ,  22   a ), and then moves the FAU  20  back again until the first output port  12   a  is substantially aligned with the input port  22   a  of the FAU  20 . 
     To optically align the first output port  12   a  of the AWG  10  with the input port  22   a  of the FAU  20 , the means  80  for providing relative movement is actuated to move the FAU until a maximum intensity reading is obtained at the first detector  72 . More specifically, the positioning mechanism  82  moves the FAU  20  in a first degree of freedom, while the compensating mechanism  84  moves the FAU  20  in at least one other degree of freedom. In the embodiment shown in FIGS. 2 a  and  2   b , the FAU  20  is first rotated about an axis in the x-direction while simultaneously undergoing relatively fast and alternate oscillatory translation movement in each of the x- and y-directions, and is subsequently rotated about an axis in the y-direction while simultaneously undergoing relatively fast and alternate oscillatory translational movement in each of the x- and y-directions. These two steps are optionally repeated to provide a plurality of control signals corresponding to increasing coupling efficiencies, until a maximum coupling efficiency is detected for ports  12   a / 22   a  to indicate substantial alignment therebetween. 
     Advantageously, this simultaneous action allows each control signal corresponding to an increased coupling efficiency to be actively monitored at the first detector—without being lost. Moreover, the co-ordinates and control signals detected at different regions within the oscillatory movements are optionally used to compensate for the imminent mis-alignment, by providing additional translational movement in either the x or y-directions to lock the alignment of ports  12   a / 22   a . In effect, a virtual pivot point/axis is created about outer port  12   a . Notably, this virtual pivot point is coincident with the intercept of each of the x and y virtual pivot axes formed for aligning outer ports  12   a / 22   a . In most cases, the x and y virtual pivot axes are respectively different than the x and y pivot axes about which rotation is provided. Since subsequent motion does not undo previous actions, the alignment is faster and more effective than prior art alignments. 
     In the second stage, a second channel of the AWG  10  is aligned with a second optical fibre of the FAU  20  (e.g., alignment of ports  12   e / 22   e ). Preferably, the first optical fibre is as far apart as possible from the second optical fibre of the array. The detector switch  76  is actuated such that both the first  72  and second  74  detectors are operative. The means  80  for providing relative movement moves the FAU  20  until a maximum intensity reading is obtained at each of the first  72  and second  74  detectors. 
     With respect to the embodiment shown in FIGS. 2 b  and  2   c , the FAU  20  is rotated about an axis in the z-direction with simultaneous oscillatory motion in the x- and y-directions. In other words, as the FAU  20  is rotated counterclockwise about an axis in the z-direction, a comparatively fast and short distance up-down motion is provided in the x-direction followed by a similar movement in the y-direction. This simultaneous action allows the control signal corresponding to the maximum coupling efficiency of ports  12   a / 22   a  to be constantly monitored at the first detector, while the alignment of ports  12   e / 22   e  is improved. Moreover, the co-ordinates and control signals detected at different regions within the oscillatory movements are optionally used to compensate for the imminent mis-alignment, by providing additional translational movement in either the x or y-directions to lock the alignment of the outer ports  12   a / 22   a , while the alignment of the outer ports  12   e / 22   e  is improved. 
     For example, a virtual pivot axis co-axial with the optical axes of ports  12   a / 22   a  provides the efficient rotational alignment discussed above, whereas a virtual pivot point substantially at outer port  12   a  provides efficient rotational alignment about each of the x, y, and z axis. Notably, the aforementioned virtual pivot point is coincident with the intercept of each of the x, y, and z virtual pivot axes used for aligning outer ports  12   a / 22   a  and  12   e / 22   e . In general, the x, y, and z virtual pivot axes are respectively different than the x, y, and z pivot axes about which rotation is provided. 
     Once the AWG  10  and FAU  20  are initially aligned, fine alignment using only the compensating mechanism  84  is performed to obtain the maximum signal intensity at both the first  72  and second  74  detectors. Optionally, an adhesive, such as epoxy resin, is applied between the optically aligned AWG  10  and the FAU  20 , and the system is subject to an increased temperature. For example, temperatures ranging from about 50-150 degrees are typically suitable, while temperatures above 100° typically result in curing times less than about 5 minutes. As the epoxy begins to set, a final fine alignment, using only the compensating mechanism  84 , is performed to compensate for errors introduced by the epoxy, followed by a final cure. 
     Once the AWG  10  and FAU  20  are coupled, the alignment between the fibre tube  5  and the AWG/FAU pair is completed. More specifically, the source switch  68  is actuated such that the DFBX 3  light source  66  launches a beam of light having a predetermined wavelength into the optical fibre  34  and towards the input port of the AWG  10 . Preferably, the predetermined wavelength corresponds to the first channel, i.e., the DFB is tuned to the first channel. Next, the means  80  moves the fibre tube  5  relative to the AWG/FAU pair until a maximum intensity signal is measured by the first detector  72 . More specifically, the positioning mechanism  82  provides rotational movement about axes in each of the x and y directions, while the compensating mechanism  84  simultaneously provides alternate translational movement in each of the x and y directions. Since the predetermined wavelength corresponds to the wavelength of the first channel of the AWG  10 , maximum light intensity measured at the first detector  72  provides a good indication of proper alignment. Finally, the fibre tube  5  and the AWG/FAU pair are optionally coupled with an adhesive, as discussed above. 
     Since the method and apparatus in accordance with the instant invention provides a faster and more effective alignment than prior art methods, a higher temperature can be used to set the adhesive/epoxy relative to prior art methods, thus significantly shortening the setting time and further reducing the time for alignment. 
     Advantageously, the use of electromagnets provides a method and apparatus for aligning optical components that is reliable, relatively inexpensive, and easy to implement. Moreover, the instant method and apparatus are applicable to the automatic or semi-automatic alignment of multi-port, multi-component optical systems. 
     The embodiments of the invention described above are intended to be exemplary only. Numerous other embodiments may be envisaged without departing from the spirit and scope of the invention. For example, although the embodiment shown in FIG. 3 illustrates the positioning mechanism and the compensating mechanism operating on the same optical component, it is also possible to design the apparatus such that they operate on different components. 
     Of course, light sources, detection systems, and positioning mechanisms, which differ from those illustrated herein are also within the scope of the instant invention, and can be used to align optical components other than those illustrated herein, such as OICs, MEMS, and laser systems.

Technology Category: 3