Embodiments presented in this disclosure generally relate to techniques for optical alignment of multiple optical fibers with waveguides of a substrate and/or photonic die.
Many approaches have been proposed for improving optical coupling between optical fiber(s) and semiconductor chips. However, such approaches can require precisely-machined interlocking features, expensive piece parts, time intensive alignment processes, and complex fiber array unit (FAU) and chip designs.
So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.
One general aspect includes an apparatus, including: an optical array unit. The optical array unit includes: a plurality of optical paths optically connected to a connection edge of the optical array unit; one or more recessed alignment features formed in the optical array unit. The apparatus also includes a photonic die including: a plurality of waveguides formed in the photonic die and optically connected to a connection edge of the photonic die; and one or more protruding alignment features extending from an alignment surface of the photonic die, where each of the one or more protruding alignment features is dimensioned to engage with a respective recessed alignment features of the one or more recessed alignment features formed in the optical array unit, where engaging the one or more protruding alignment features with the one or more recessed alignment features provides an optical alignment of the plurality of optical paths with the plurality of waveguides.
One example embodiment is an optical array unit including: a plurality of optical paths optically connected to a connection edge of the optical array unit; and one or more passive recessed alignment features formed in the optical array unit, where the one or more recessed alignment features are configured to engage with one or more protruding alignment features of a photonic die to provide an optical connection from the connection edge to the photonic die.
One example embodiment includes a method that includes: inserting a plurality of optical fibers into a plurality of grooves in a base unit of an optical array unit, affixing a lid unit to the base of the optical array unit to secure the optical fibers and to form the optical array unit, defining one or more recessed alignment features in the optical array unit, and processing the optical array unit to form the one or more recessed alignment features. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.
Optoelectronic devices and optical fibers have greatly increased the speed and reliability of electronic communication while also reducing the costs of communicating. However, one of the most costly and time-consuming steps in manufacturing optical transceivers and other photonic devices is aligning optical fibers to photonics dies of an optoelectronic device.
Optical array units, such as FAUs are joined and/or connected to photonics dies using an active alignment or passive alignment process. In an active alignment process, an FAU is aligned to a photonic die while monitoring how much light is transferred into the die. While active alignment can provide accurate results in creating an optical connection between the FAU and the photonic die, active alignment tends to be slow and costly due to various complexities in alignment processes and alignment equipment needed to solve the complexities.
In passive alignment, an FAU is joined to a photonic die without monitoring the optical power and coupling efficiency, resulting in a generally faster alignment process. However, in order to achieve low loss coupling, very precise fiducials, grooves, and other alignment reference features are needed in the FAU, which can significantly increase cost of the FAU and the photonic die.
The systems and methods described herein provide for an optical array unit with alignment features which simplifies an optical alignment process and reduces the time and equipment costs needed to join optical fibers to an optoelectronic device by forming alignment features into the optical array unit during the fabrication of the optical array unit using lower cost laser drilling and/or molding during the fabrication of the optical array unit.
As shown in
The optical paths 202 terminate at and provide an optical connection (e.g., via the optical fibers 107) to a connection edge 203 of the optical array unit 110. The connection edge 203 includes a connection surface 204 with recessed alignment features 201a and 201b formed into the connection surface 204 of the connection edge 203. In some examples, the optical paths 202 are disposed between the recessed alignment features 201a and 201b. The one or more recessed (female) alignment features 201a-b may be defined and formed into the optical array unit 110 using one or more of a sawing operation, a molding operation, a polishing operation, an etching operation, and/or a laser patterning operation as described herein. In some examples described herein, the recessed alignment features 201a and 201b include notches formed by laser drilling and molding processes, which provides a cheap and simple less complex method to produce alignment features in the optical array unit 110.
The recessed alignment features 201a and 201b may include any geometric shape which provides engagement and/or interlocking functions when matched to a respective protruding (male) alignment feature. For example, the recessed alignment features 201a and 201b may include a notch or a pair of notches, where each respective notch engages with a respective protruding alignment feature on a photonic die. While shown the recessed alignment features 201a and 201b are shown as formed in the connection surface 204 in
In the arrangement 200, the recessed alignment features 201a and 201b are formed through a bottom surface 222 of the optical array unit and pass through the base unit 212 and the lid 211 to a top surface 221 of the optical array unit 110. In some examples, the recessed alignment features 201a and 201b in the arrangement 200 are formed in the optical array unit 110 after the lid 211 is affixed to the base unit 212. The recessed alignment features 201a and 201b are dimensioned to interlock and/or engage with protruding alignment features formed in a photonic die.
The alignment shelf 265 serves as a vertical alignment feature when the optical array unit 110 is joined/engaged to the photonic die 120 as shown in
In some examples, an index matching epoxy and/or other adhesives applied between the optical array unit 110 and the photonic die 120 holds the photonic die 120 and optical array unit 110 in place and together which improves coupling between the components. In some examples, the waveguides 255 include a mode size that provide a direct coupling from the optical paths 202 (e.g., the optical fibers 107) and the photonic die 120. In some examples, a lens and/or other optic device may be placed between the optical paths 202 and the waveguides 255 to provide an efficient optical coupling.
Method 600 begins at block 602, where a plurality of optical fibers are inserted into a plurality of grooves in a base unit of an optical array unit. For example, as shown top view 710 in
At block 604, a lid unit is affixed to the base of the optical array unit to secure the optical fibers and to form the optical array unit. For example, as shown in top view 720 in
At block 606, one or more recessed alignment features are defined in the optical array unit. For example, as shown in top view 730 in
In some examples, the one or more recessed alignment features are defined in a base unit of the optical array unit prior to a lid being affixed to the base unit. For example, as shown the top view 800 in
At block 608, the optical array unit is processed to form the one or more recessed alignment features. For example, as shown top view 740 in
At block 610, a shallow dicing operation is optionally performed to form a recessed surface in the optical array unit, wherein the recessed surface is recessed from a connection edge of the of the optical array unit forming an alignment protrusion for the optical array unit as described in relation to
At block 612 the one or more recessed alignment features are engaged with one or more protruding alignment features extending from an alignment surface of the photonic die. In some examples, the optical array unit 110 and the photonic die 120 are joined and/or otherwise engaged by an alignment or optical fabrication system, such as discussed in relation to
The system 900 comprises a controller 905 comprising one or more computer processors 910 and a memory 915. The one or more computer processors 910 represent any number of processing elements that each can include any number of processing cores. Some non-limiting examples of the one or more computer processors 910 include a microprocessor, a digital signal processor (DSP), an application-specific integrated chip (ASIC), and a field programmable gate array (FPGA), or combinations thereof. The memory 915 may comprise volatile memory elements (such as random access memory), non-volatile memory elements (such as solid-state, magnetic, optical, or Flash-based storage), and combinations thereof. Moreover, the memory 915 may be distributed across different mediums (e.g., network storage or external hard drives).
The memory 915 may comprise a plurality of “modules” for performing various functions described herein. In one embodiment, each module includes program code that is executable by one or more of the computer processors 910. However, other embodiments may include modules that are partially or fully implemented in hardware (i.e., circuitry) or firmware of the controller 905. As shown, the memory 915 comprises an optical assembly module 920 configured to control various stages of manufacturing (or assembling) an optical apparatus. The optical assembly module 920 is configured to communicate control signals to one or more systems via a network 925. The network 925 may include one or more networks of various types, including a personal area network (PAN), a local area or local access network (LAN), a general wide area network (WAN), and/or a public network (e.g., the Internet).
As shown, the system 900 comprises an actuation system 930, an etch system 935, an alignment system 940, and an attachment system 945, each of which is communicatively coupled with the controller 905 via the network 925. Based on control signals received from the controller 905, one or more of these systems may be configured to manipulate one or more substrates 955, such as semiconductor substrates (e.g., photonic die 120) and/or glass substrates (the optical array unit 110 and related components) when constructing the optical apparatus.
In some embodiments, the actuation system 930 is configured to alter an orientation of the substrates 955 (e.g., translation and/or rotation) between different stages of processing, maintain an orientation of the substrates 955 during the processing, and so forth. For example, the actuation system 930 may comprise one or more robotic arms and/or gripping systems.
In some embodiments, the etch system 935 is configured to etch the substrates 955 to form features therein, according to any suitable etching technique(s). For example, the etch system 935 may be configured to form openings through the substrates 955 for forming vias, form grooves from a surface of the substrates 955, form a recess from the surface, form alignment features, and so forth. In one embodiment, the etch system 935 uses an anisotropic etch process such as deep reactive-ion etching (DRIE). In an alternate embodiment, one or more functions of the etch system 935 may be performed using other techniques, such as laser drilling, sawing, polishing, or machining.
As part of constructing the optical apparatus, a semiconductor laser, a plurality of optical fibers, and/or other optical and/or electronic components may be placed on the substrates 955. In some embodiments, the alignment system 940 is configured to perform an optical alignment of the semiconductor laser and/or the plurality of optical fibers. For example, the alignment system 940 may comprise an active alignment system configured to provide optical signals to the optical fibers and/or apply an electrical signal to the semiconductor laser to generate an optical signal.
In some embodiments, the alignment system 940 is used to optically align the semiconductor laser and the plurality of optical fibers after attachment to the substrates 955. For example, the alignment system 940 may manipulate the substrates 955 to align the semiconductor laser and the plurality of optical fibers with respective waveguides formed in a semiconductor substrate. In other embodiments, the alignment system 940 may operate in conjunction with the actuation system 930 to manipulate the substrates 955 and/or the semiconductor substrate.
In some embodiments, the attachment system 945 is configured to attach the substrates 955 with one or more of: other substrates, substrates 955, the semiconductor substrate, the plurality of optical fibers, the semiconductor laser, and other optical and/or electronic components according to any suitable techniques. In some embodiments, the attachment system 945 may be used in multiple attachment stages. For example, the attachment system 945 may be configured to apply an epoxy between the optical fibers and a first one of the substrates 955, to apply an epoxy between the first one and a second one of the substrates 955, to apply an epoxy between the first one of the substrates 955 and a semiconductor substrate, and so forth. The attachment system 945 may further be configured to cure the epoxy, e.g., by applying an ultraviolet (UV) light.
In some embodiments, the attachment system 945 may further be configured to apply conductive material to couple the semiconductor laser and/or other electronic components with conductive traces on the substrates 955. For example, the attachment system 945 may apply a conductive layer to bond conductive contacts of the semiconductor laser with conductive traces on the substrates 955. The attachment system 945 may further be configured to couple conductive traces on the substrates 955 with conductive portions of the semiconductor substrate. For example, the attachment system 945 may wire bond or apply solder/conductive epoxy to connect the conductive traces on the substrates 955 with corresponding conductive traces on the semiconductor substrate.
The controller 905 may be implemented in any suitable form. In some embodiments, the controller 905 comprises a singular computing device providing centralized control of the construction process. In other embodiments, the controller 905 represents multiple, communicatively coupled computing devices, which may or may not have centralized control. For example, some or all of the actuation system 930, the etch system 935, the alignment system 940, and the attachment system 945 may comprise local controllers that are in communication with the controller 905 via the network 925. In an alternate embodiment, the operation of the actuation system 930, the etch system 935; the alignment system 940, and the attachment system 945 may be achieved independently of centralized control.
Further, while the system 900 is described primarily in terms of manipulating the substrates 955, the various systems described herein may interact with other components as part of constructing the optical apparatus. For example, the actuation system 930 may be configured to manipulate the plurality of optical fibers, the semiconductor laser, and other electrical and/or optical components.
To further improve optical coupling, vision-assisted alignment or active alignment may be performed in a limited number of axes. Since interlocking the alignment features or other features of the substrate is effective to provide at least a coarse alignment of the optical fibers with the waveguides of the substrate, the vision-assisted alignment or the active alignment may be used to provide a finer alignment while adding minimal process time. Use of these simple and inexpensive mechanical features to “pre-align” the optical fibers to the photonic chip can reduce or eliminate the cost of automation (e.g., precision placement and peak searching algorithms), ultimately reducing the overall cost of alignment.
In the preceding, reference is made to embodiments presented in this disclosure. However, the scope of the present disclosure is not limited to specific described embodiments. Instead, any combination of the described features and elements, whether related to different embodiments or not, is contemplated to implement and practice contemplated embodiments. Furthermore, although embodiments disclosed herein may achieve advantages over other possible solutions or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the scope of the present disclosure. Thus, the preceding aspects, features, embodiments and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s).
As will be appreciated by one skilled in the art, the embodiments disclosed herein may be embodied as a system, method or computer program product. Accordingly, aspects may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, aspects may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.
Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium is any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus or device.
A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.
Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.
Computer program code for carrying out operations for aspects of the present disclosure may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).
Aspects of the present disclosure are described below with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments presented in this disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.
The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.
The flowchart and block diagrams in the Figures illustrate the architecture, functionality and operation of possible implementations of systems, methods and computer program products according to various embodiments. In this regard, each block in the flowchart or block diagrams may represent a module, segment or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In view of the foregoing, the scope of the present disclosure is determined by the claims that follow.