Patent Publication Number: US-2021173145-A1

Title: Structures and methods for aligning and securing optical fibers in photonic integrated circuit (pic) packages using various adhesives

Description:
BACKGROUND 
     The present disclosure relates to photonic integrated circuit (PIC) packages, and more specifically, structures and methods for aligning and securing optical fiber(s) to PIC dies using various adhesives. 
     Current photonic packages include precision aligned optical fibers on the surface or at the edge of a PIC die to transmit light into and from the optical devices therein such as waveguides and grating couplers. This optical alignment is performed actively, often by providing a light source and measuring maximum optical power in a fiber with precision motion equipment, often with positional tolerances &lt;0.1 um. Thereafter an adhesive is used to permanently hold the fiber(s) in place which requires complex packaging integration schemes. Passively attached and optically coupled fibers provide numerous advantages reducing the integration and process complexity by eliminating the need to create a sensible optical signal in each fiber during alignment, retention and adhesive curing. In particular, optical fibers or optical fiber arrays are optically coupled to the PIC die and waveguides formed or positioned on the PIC die based on initial vision system registration with subsequent mechanical feature alignment of the optical light paths. Conventionally, lithographically defined grooves formed in a surface of the PIC die provide an alignment and retention feature to align an optical fiber to couple light from an end surface of the optical fiber to an exposed end of an optical waveguide in the PIC die. In this process, optical fibers are positioned by a pick-and-place tool into respective grooves in the surface of the PIC die. Grooves enable two linear contact regions for each optical fiber to align the optical fiber core to the waveguide in the PIC die. The two linear contact regions ensure optical alignment when the optical fiber is fully seated on the groove sidewalls, with the core of an optical fiber end aligned with the waveguide. Once in position, the optical fibers are secured in place using an adhesive. 
     One challenge in achieving high alignment accuracy is applying a uniform force along the optical fiber surfaces along the sidewall linear contact areas to ensure the optical fiber contacts the groove&#39;s sidewalls and/or prevent optical fibers from lifting up at the coupling end interface, i.e., to maintain position and pitch alignment within the groove. To address this situation, glass lids have been used to force the optical fibers into the groove fiber optic receptacles. In this arrangement, the glass lids are placed over the optical fiber(s) and pressed down to force the optical fiber(s) into place. More specifically, the pick-and-place tool tip is used to position and then apply a downward force to the glass lids. This situation is not ideal because the pick-and-place tool tips are typically not designed to apply force during adhesive cure, facilitate precision adhesive dispense and the process is not readily repeatable. 
     Other conventional processes may utilize distinct adhesives for securing the optical fibers within the grooves formed on the PIC die. However, accurately flowing the adhesives over the optical fibers can be difficult and/or time consuming For example, where the rheology of the adhesive used to secure the optical fibers into the grooves is difficult to predict and/or control, securing the optical fibers to the PIC die may result in undesirable overflow of the adhesive. Where the (non-optical) adhesive flows adjacent and/or is disposed over the waveguides of the PIC die, the photonic package may become inoperable. Furthermore, and dependent on the rheology of the adhesive, the combination of the flowing adhesive and the force applied by the glass lid may actually push or force the optical fiber from the groove, resulting in misalignment between the optical fiber and the corresponding waveguide. To ensure desired alignment and optical coupling, conventional processes must be slowed down by additional curing time and/or individual optical fiber installation. This in turn results in lost income because of longer manufacturing times. 
     SUMMARY 
     Accordingly, it would be beneficial to provide methods and structures for aligning optical fibers to PIC dies with improved accuracy in alignment, as well as reduced manufacturing time. 
     A first aspect of the disclosure includes a photonic integrated circuit (PIC) package. The PIC package includes a PIC die including: at least one waveguide positioned on the PIC die, and at least one groove formed in a surface of the PIC die, the at least one groove corresponding to and positioned directly adjacent the at least one waveguide; at least one optical fiber operatively coupled to the at least one waveguide of the PIC die, the at least one optical fiber positioned in the groove of the PIC die and including an end positioned adjacent the at least one waveguide; a plate positioned over a section of the at least one optical fiber, the plate including: a first edge positioned adjacent the at least one waveguide of the PIC die, and a second edge positioned opposite the first edge; a first adhesive disposed along the second edge of the plate, the first adhesive disposed over a first portion of the at least one optical fiber; and a second adhesive disposed along the first edge of the plate, the first adhesive disposed over a second portion of the at least one optical fiber including the end, and a portion of the at least one waveguide. 
     A second aspect of the disclosure includes a method, including positioning an optical fiber within a groove formed in a surface of a photonic integrated circuit (PIC) die, the groove corresponding to and positioned directly adjacent a waveguide positioned on the PIC die; positioning a plate over a section of the optical fiber, the plate including: a first edge positioned adjacent the waveguide, and a second edge positioned opposite the first edge; dispensing a first adhesive along the second edge of the plate to be disposed over a first portion of the optical fiber; dispensing a second adhesive along the first edge of the plate to be disposed over a second portion of the optical fiber and a portion of the waveguide; and curing at least one of the dispensed first adhesive or the dispensed second adhesive. 
     As will be appreciated, while one optical fiber is discussed in the various aspects of the disclosure, the PIC packages may include a plurality of optical fibers and corresponding waveguides formed on the PIC dies. 
     The illustrative aspects of the present disclosure are designed to solve the problems herein described and/or other problems not discussed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments of this disclosure will be described in detail, with reference to the following figures, wherein like designations denote like elements, and wherein: 
         FIG. 1  shows an isometric view of a photonic integrated circuit (PIC) package including an optical fiber, according to embodiments of the disclosure. 
         FIG. 2  shows a top view of the PIC package of  FIG. 1 , according to embodiments of the disclosure. 
         FIG. 3  shows a front cross-sectional view of the PIC package taken along line  3 - 3  in  FIG. 2 , according to embodiments of the disclosure. 
         FIG. 4  shows a front cross-sectional view of the PIC package taken along line  4 - 4  in  FIG. 2 , according to embodiments of the disclosure. 
         FIG. 5  shows a front cross-sectional view of the PIC package taken along line  5 - 5  in  FIG. 2 , according to embodiments of the disclosure. 
         FIG. 6  shows a top view of a PIC package including an optical fiber, according to additional embodiments of the disclosure. 
         FIG. 7  shows a top view of a PIC package including a plurality of optical fibers, according to further embodiments of the disclosure. 
         FIG. 8  shows a flow chart of a process of securing an optical fiber within a PIC package, according to embodiments of the disclosure. 
     
    
    
     It is noted that the drawings of the disclosure are not to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings. 
     DETAILED DESCRIPTION 
     Reference will now be made in greater detail to various embodiments of the subject matter of the present application, some embodiments of which are illustrated in the accompanying drawings. The same reference numerals will be used throughout the drawings to refer to the same or similar parts. 
     As discussed herein, the present disclosure relates to photonic integrated circuit (PIC) packages, and more specifically, structures and methods for aligning and securing optical fiber(s) to PIC dies using various adhesives. 
     These and other embodiments are discussed below with reference to  FIGS. 1-8 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIGS. 1 and 2  show various views of a photonic integrated circuit (PIC) package  100 . More specifically,  FIG. 1  shows an isometric view of PIC package  100  and  FIG. 2  shows a top view of PIC package  100 . As discussed herein, PIC package  100 , and the various components formed thereon may improve on the quality of the manufactured part, as well as improve or reduce the manufacturing time to form PIC package  100 . 
     As shown in  FIGS. 1 and 2 , PIC package  100  may include a PIC die  102 . PIC die  102  may include any now known or later developed semiconductor photonic integrated circuit. Additionally, PIC die  102  (also known as integrated optical circuits) may define a portion of a photonics chip, and/or can be any device that includes electro-optical circuitry that integrates photonic functions for optical information signals received thereby via, e.g., optical fibers, as discussed herein. Such functions oftentimes include converting the optical information signals to electrical signals or vice versa. As discussed herein, the electro-optical circuitry may include an optical waveguide(s) operably coupled to optical fibers, each positioned on and/or within PIC die  102 . 
     In a non-limiting example, PIC die  102  may include a semiconductor material such as silicon, e.g., single crystal Si or polycrystalline Si, or a silicon-containing material. Silicon-containing materials include, but are not limited to, single crystal silicon germanium (SiGe), polycrystalline silicon germanium, silicon doped with carbon (Si:C), amorphous Si, as well as combinations and multi-layers thereof. As used herein, the term “single crystal” denotes a crystalline solid, in which the crystal lattice of the entire solid is substantially continuous and substantially unbroken to the edges of the solid with substantially no grain boundaries. PIC die  102  may include ( 100 )-oriented silicon or ( 111 )-oriented silicon, for example. In other non-limiting examples PIC die  102  may also be formed from glass or similar amorphous (e.g., not crystalline) material. 
     PIC die  102  is not limited to silicon-containing materials, however, as PIC die  102  may include other semiconductor materials, including Ge and compound semiconductors, including III-V compound semiconductors such as GaAs, InAs, GaN, GaP, InSb, ZnSe, and ZnS, and II-VI compound semiconductors such as CdSe, CdS, CdTe, ZnSe, ZnS and ZnTe. 
     PIC die  102  may be a bulk substrate or a composite substrate such as a semiconductor-on-insulator (SOI) substrate that includes, from bottom to top, a handle portion, an isolation layer (e.g., buried oxide layer), and a semiconductor material layer (e.g., silicon). 
     In the non-limiting example shown in  FIGS. 1 and 2 , PIC die  102  may include at least one electro-optical circuitry or waveguide  104  (hereafter, “waveguide  104 ”) positioned thereon. That is, waveguide  104  of PIC package  100  may be positioned and/or formed on a surface  106  of PIC die  102 . Waveguide  104  may be any suitable device or system that may integrate photonic functions for optical information signals received thereby, and/or convert and transmit optical information signals, e.g., via optical fiber(s). In a non-limiting example, waveguide  104  may be configured as a suspended waveguide that may be positioned in and/or above a void (not shown) formed in PIC die  102 . However waveguide  104  may also include, depending on application, other components such as but not limited to: a Bragg reflector, an arrayed waveguide grating or other wave guide, transistor based electronics including detectors and modulators, amplifiers, and/or an externally modulated laser diode with an electro-absorption modulator. As such waveguide  104  may be formed as any suitable device and/or component that may a conductive and confinement medium for electromagnetic radiation/light. It is understood that waveguide  104  positioned on surface  106  of PIC die  102  may include structures to guide light/signals from optical fiber coupled thereto, individually. 
     Although a single waveguide  104  is shown in the non-limiting example, it is understood that PIC package  100  may include more waveguides (see,  FIG. 7 ). As such, the number of waveguides included in PIC package  100  are illustrative, and may be dependent at least in part on the function, purpose, and/or desired operation for PIC package  100 . 
     PIC die  102  of PIC package  100  may also include at least one groove  108 . Groove  108  may be formed in surface  106  of PIC die  102 . More specifically, groove  108  may be formed in surface  106  of PIC die  102  and may be positioned and/or formed directly adjacent waveguide  104  of PIC die  102 . Additionally, and as shown in  FIGS. 1 and 2 , groove  108  formed in and/or positioned on surface  106  of PIC die  102  may extend from directly adjacent waveguide  104  to a side  110  of PIC die  102 . In non-limiting examples, surface  106  of PIC die  102  may be machined, etched (e.g., plasma, chemical), mechanical grinded, molded, and/or any combination of these processes, to form groove  108  therein. As discussed herein, groove  108  of PIC die  102  may receive an optical fiber therein and may provide alignment and/or retention of the optical fiber to optical couple light from the optical fiber to waveguide  104  of PIC die  102 . Briefly turning to  FIG. 3 , for example and as discussed herein, groove  108  may include two sloped or angled sidewalls  112 ,  118  that provide two points of contact for an optical fiber positioned therein to align the optical fiber with waveguide  104  and/or retention of the optical fiber therein. 
     Groove  108  of PIC die  102  may correspond to waveguide  104 . That is, in the non-limiting examples discussed herein for every waveguide  104  formed in PIC die  102 , PIC die  102  may include a corresponding groove  108  that may be formed and/or positioned directly adjacent waveguide  104 . As such, although a single groove is shown in the non-limiting example of  FIGS. 1 and 2 , it is understood that PIC package  100  may include more grooves (see,  FIG. 7 ). As such, the number of grooves  108  included in PIC package  100  are illustrative, and may be dependent at least in part on the function, purpose, and/or desired operation for PIC package  100  and/or the number of waveguides  104  included within PIC die  102 . Although discussed herein as including angled sidewalls  112 ,  118  of groove  108  to aid in self alignment of optical fibers, groove  108  may include orthogonal or linear sidewalls for grooves  108 . In this non-limiting example, the orthogonal sidewalls may be sized to form a tight fit or clearance to the optical fibers and/or precise control of the depth of groove  108  to define and/or ensure alignment between the optical fiber and waveguide  104 , as discussed herein. Additionally, and as discussed herein, grooves  108  may also be used in non-electrical optical devices—such as a passive optical network that is created exclusively in glass—not an electrical device. 
     In the non-limiting example shown in  FIGS. 1 and 2 , PIC package  100  may also include at least one optical fiber  120 . Optical fiber  120  may be positioned within groove  108  of PIC die  102 . More specifically, optical fiber  120  may be positioned within groove  108 , and may extend from adjacent waveguide  104  of PIC die  102  to beyond side  110  of PIC die  102 . As shown in  FIG. 3 , Optical fiber  120  may be positioned within groove  108 , and may contact and/or may meet angled sidewalls  112 ,  118  of groove  108 , to ensure alignment with waveguide  104 , as discussed herein. Optical fiber  120  and/or groove  108  may be sized and/or may include a shape/configuration that may ensure the meeting/contacting between optical fiber  120  and groove  108 , and/or alignment of optical fiber  120  with waveguide  104 . In the non-limiting example shown in  FIG. 3 , optical fiber  120  and/or groove  108  may also be sized such that at least a portion of optical fiber  120  extends above surface  106  of PIC die  102 . In other non-limiting examples (not shown), optical fiber  120  and/or groove  108  may be sized such that the entirety of optical fiber  120  is positioned below surface  106  of PIC die  102 , or a top portion of optical fiber  120  is aligned with and/or co-planar with surface  106  of PIC die  102 . 
     Optical fiber  120  may be formed as any suitable optical element or structure that is configured to transmit and/or receive optical information signals to/from waveguide  104 . In the non-limiting example shown in  FIG. 3 , optical fiber  120  may include a core  122  and a cladding layer  124  surrounding core  122 . Cladding layer  124  of optical fiber  120  may directly contact and/or meet sidewalls  112 ,  118  of groove  108  formed in PIC die  102 . In a non-limiting example, and as discussed herein, core  122  may be formed from a silicon, silica, or silica doped material and may be aligned with and operatively coupled to waveguide  104  for sending and/or receiving optical information signals. Although only one core is shown, optical fiber may include multicore core fibers for optical coupling between optical fiber  120  and PIC die  102 /waveguide  104 . In other non-limiting examples (not shown) optical fiber  120  may also include an insulating jacket surrounding cladding layer  124 . In other non-limiting examples, optical fibers  120  may be formed as fluoride fibers, chalcogenide fibers, or plastic fibers. 
     Returning to  FIGS. 1 and 2 , Optical fiber  120  may also include an end  126  positioned adjacent waveguide  104 . That is, when optical fiber  120  is positioned within groove  108  of PIC die  102 , end  126  of optical fiber  120  may be positioned adjacent waveguide  104 . Additionally, and as shown in the non-limiting example, end  126  of optical fiber  120  positioned within groove  108  may be separated from and/or positioned a distance away from waveguide  104  formed directly adjacent groove  108 . That is, a gap (G) may separate end  126  of optical fiber  120  and waveguide  104 . In a non-limiting example, the gap (G) may be approximately three (3) microns to approximately 15 microns. 
     As discussed herein, position (and securing) optical fiber  120  within groove  108  may operatively couple optical fiber  120  with waveguide  104 . That is, groove  108  may be formed in surface  106  of PIC die  102  and/or may be sized to receive and align optical fiber  120  with waveguide  104 . Once positioned within and aligned with waveguide  104 , optical fiber  120  may also be operatively coupled and/or in optical communication with waveguide  104 . In the non-limiting example, core  122  (see,  FIG. 3 ) may be operatively coupled with waveguide  104  to transmit and/or receive optical information signals to/from waveguide  104  during operation of PIC package  100 . 
     Similar to groove  108  of PIC die  102 , optical fiber  120  may correspond to waveguide  104 . That is, in the non-limiting examples discussed herein for every waveguide  104  formed in PIC die  102 , an optical fiber  120  may be aligned with and operatively coupled to waveguide  104 . As such, although a single optical fiber is shown in the non-limiting example of  FIGS. 1 and 2 , it is understood that PIC package  100  may include more optical fibers (see,  FIG. 7 ). As such, the number of optical fibers  120  included in PIC package  100  are illustrative, and may be dependent at least in part on the function, purpose, and/or desired operation for PIC package  100  and/or the number of waveguides  104  included within PIC die  102 . 
     PIC package  100  may also include a plate  128 . As shown in  FIG. 2 , plate  128  may be positioned over a section  130  of optical fiber  120 . Plate  128  may include and/or may be formed as an ultraviolet (UV) transparent glass plate. In other non-limiting examples, plate  128  may be formed from any UV transparent material to aid in the curing of adhesives dispensed and/or disposed over PIC die  102  as well as provide a force to optical fiber  120  to position optical fiber  120  within groove  108 , as discussed herein. Additionally, plate  128  may be formed from any suitable material that may have a total thickness variation (TTV) that is approximately equal to or less than 0.5 microns (μm). In the non-limiting example, plate  128  may include a first edge  132 , a second edge  134 , and a top surface  136 . First edge  132  of plate  128  may be positioned over PIC die  102 , adjacent waveguide  104  of PIC die  102 . That is, first edge  132  of plate  128  may be positioned adjacent, approximate, and/or near waveguide  104  and end  126  of optical fiber  120 . As a result of being positioned adjacent to, and not over, end  126  of optical fiber  120 , end  126  of optical fiber (as well as waveguide  104 ) may be uncovered by plate  128  and/or may be exposed on PIC die  102  of PIC package  100  in the non-limiting example. Second edge  134  of plate  128  may be positioned opposite first edge  132 . As shown in  FIGS. 1 and 2 , second edge  134  may also be positioned over PIC die  102  and, may be adjacent to and/or inward from side  110  of PIC die  102 . As such, and in the non-limiting example, section  130  of optical fiber  120  positioned under and/or covered by plate  128  may not include first end  126  of optical fiber  120  or a part of optical fiber  120  that is positioned directly adjacent to and/or extends over side  110  of PIC die  102 . Top surface  136  of plate  128  may extend between first edge  132  and second edge  134 . 
     As discussed herein, plate  128  may be used to position and/or force optical fiber  120  into groove  108  in order to form PIC package  100 . That is, plate  128  may apply a force to optical fibers  120  to position optical fiber  120  within groove  108 , to ensure optical fiber  120  contacts or meets sidewalls  112 ,  118  of groove  108 , and in turn is aligned with waveguide  104 , as discussed herein. Additionally, plate  128  also aids in the application and retention of adhesives to PIC package  100 , as discussed herein. Plate  128  may be sized and/or may include dimensions (e.g., thickness, width, length) that may ensure the desired section  130  of optical fiber  120  is covered when forming PIC package  100 . As discussed herein with respect to  FIG. 7 , where PIC package  100  includes a plurality of optical fibers  120 , plate  128  may be elongated and/or include larger dimensions to ensure each of the plurality of optical fibers  120  are positioned and/or forced into corresponding grooves  108  formed in PIC die  102 . 
     In the non-limiting example shown in  FIGS. 1 and 2 , PIC package  100  may also include a first adhesive  138 . First adhesive  138  may be disposed along second edge  134  of plate  128 . That is, and as discussed herein, first adhesive  138  may be disposed over PIC die  102 , linearly along and/or across second edge  134  of plate  128 . In addition to being disposed along second edge  134 , first adhesive  138  may flow, be dispensed, be disposed, and/or may be positioned over a first portion  140  of optical fiber  120  (see,  FIG. 2 ). Turning to  FIG. 3 , and with continued reference to  FIGS. 1 and 2 , first adhesive  138  is disposed over first portion  140  of optical fiber  120  and/or disposed within a first portion  142  of groove  108  receiving first portion  140  of optical fiber  120 . In the non-limiting example, first portion  140  of optical fiber  120  and/or first portion  142  of groove  108  may include areas which are covered by plate  128  and distinct areas which are uncovered and/or exposed, prior to the dispensing of first adhesive  138 . At least some (e.g., uncovered area) of first portion  140  of optical fiber  120  and/or first portion  142  of groove  108  may be positioned directly adjacent side  110  of PIC die  102 , while the remaining first portion  140  of optical fiber  120  and/or first portion  142  of groove  108  may be covered by plate  128 . As a result, and as shown in the cross-sectional view of  FIG. 3 , first adhesive  138  may be disposed and/or positioned between plate  128  and surface  106  of PIC die  102 . Additionally, and as shown in the non-limiting example of  FIG. 3 , first adhesive  138  may flow between and/or underneath optical fiber  120  to substantially cover sidewalls  112 ,  118  and/or fill groove  108  formed in PIC die  102 . 
     The rheology properties of first adhesive  138  may ensure that first adhesive  138  may flow, be disposed over, and/or dispensed on first portion  140  of optical fiber  120  and/or disposed within a first portion  142  of groove  108  receiving first portion  140  of optical fiber  120 . That is, and as discussed herein, first adhesive  138  may be formed from any suitable adhesive material that may allow first adhesive  138  to readily flow between plate  128  and surface  106  of PIC die  102 , as well as flow over first portion  140  of optical fiber  120  and/or be disposed within a first portion  142  of groove  108  receiving first portion  140  of optical fiber  120 . In a non-limiting example, first adhesive  138  may be formed from any suitable ultraviolet (UV) curable adhesive material, for example various polymers or curable epoxy, acrylate or combinations thereof. As discussed herein, first adhesive  138  may aid in securing optical fiber  120  within groove  108  of PIC die  102 . Furthermore, by forming first adhesive  138  from a curable adhesive material, first adhesive  138  may be quickly cured to arrest and/or stop the flow of first adhesive  138  after dispensing along second edge  134  of plate  128 . This in turn may prevent first adhesive  138  from flowing or being disposed over and/or contacting end  126  of optical fiber  120  and/or waveguide  104  of PIC package  100 . Additionally, or alternative, the UV curable adhesive material forming first adhesive  138  may also be thermally curable using any suitable process. 
     PIC package  100  may include a second optically functional adhesive  144 . Second adhesive  144  may be disposed along first edge  132  of plate  128 . That is, and as discussed herein, second adhesive  144  may be disposed over PIC die  102 , linearly along and/or across first edge  132  of plate  128 . In addition to being disposed along first edge  132 , second adhesive  144  may flow, be dispensed, be disposed, and/or may be positioned over a second portion  146  of optical fiber  120 , including end  126 , as well as a portion  148  of waveguide  104  (see,  FIG. 2 ). Turning to  FIG. 4 , and with continued reference to  FIGS. 1 and 2 , second adhesive  144  is disposed over second portion  146  of optical fiber  120  and/or disposed within a second portion  150  of groove  108  receiving second portion  146  of optical fiber  120 . In the non-limiting example, second portion  146  of optical fiber  120  and/or second portion  150  of groove  108  may include areas which are covered by plate  128  and distinct areas which are uncovered and/or exposed, prior to the dispensing of second adhesive  144 . At least some (e.g., uncovered area) of second portion  146  of optical fiber  120  and/or second portion  150  of groove  108  may be positioned directly adjacent waveguide  104  of PIC die  102 , while the remaining second portion  146  of optical fiber  120  and/or second portion  150  of groove  108  may be covered by plate  128 . In this non-limiting example, second adhesive  144  may be disposed over and/or may cover end  126  of optical fiber  120  included in second portion  146 . As a result, and as shown in the cross-sectional view of  FIG. 4 , second adhesive  144 , like first adhesive  138 , may be disposed and/or positioned between plate  128  and surface  106  of PIC die  102 . Additionally, and as shown in the non-limiting example of  FIG. 4 , second adhesive  144  may flow between and/or underneath optical fiber  120  to substantially cover sidewalls  112 ,  118  and/or fill groove  108  formed in PIC die  102 . 
     Similar to first adhesive  138 , the rheology properties of second adhesive  144  may ensure that second adhesive  144  may flow, be disposed over, and/or dispensed on second portion  146  of optical fiber  120  and/or disposed within second portion  150  of groove  108  receiving second portion  146  of optical fiber  120 . That is, and as discussed herein, second adhesive  144  may be formed from any suitable adhesive material that may allow second adhesive  144  to readily flow between plate  128  and surface  106  of PIC die  102 , as well as flow over second portion  146  of optical fiber  120  and/or be disposed within second portion  150  of groove  108  receiving second portion  146  of optical fiber  120 . In a non-limiting example, second adhesive  144  may be formed from any suitable optical adhesive material, for example various polymer resins or silicone. As discussed herein, second adhesive  144  may aid in securing optical fiber  120  within groove  108  of PIC die  102 . Furthermore, second adhesive  144  formed as an optical adhesive may be configured and/or may include properties/material characteristics that may optically couple optical fiber  120  to waveguide  104  of PIC die  102 . In a non-limiting example, the optical adhesive forming second adhesive  144  may include refractive index of about 1.2 to 1.6, and including ranges between any of the foregoing values, a viscosity (at 23° C.) of 200 to 600 centipoise (cP), a glass transition temperature (T g ) of 0° C. to 140° C., an optical transmittance (at 1.3 microns) of at least 85%, e.g., 85, 88, 90, 92 or 94%, including ranges between any of the foregoing values, and a bond strength of 100 to 200 kgf/cm 2 . These material characteristics may ensure second adhesive  144  optically couples optical fiber  120 , and more specifically core  122 , with waveguide  104 . Additionally, the optical adhesive forming second adhesive  144  may be UV curable and/or thermally curable using any suitable process. 
     Turning to  FIG. 5 , and with continued reference to  FIG. 2 , a cross-sectional front view of PIC package  100  is shown. The cross-sectional view is taken along line  5 - 5  in  FIG. 5 . In the non-limiting example shown in  FIG. 5 , first adhesive  138  and second adhesive  144  dispensed on PIC die  102  may be separated from one another. That is, in the non-limiting example shown in  FIGS. 2 and 5  the portions of first adhesive  138  and second adhesive  144  that flow and/or are disposed between plate  128  and surface  106  of PIC die  102  are separate from one another and/or do not touch. This may be a result of controlling volume of each of the first adhesive  138  and/or second adhesive  144  dispensed or disposed on PIC die  102 . In another non-limiting example, and as discussed herein, second adhesive  144  may be separated from first adhesive  138  as a result of curing first adhesive  138  after dispensing and/or deposition. That is, first adhesive  138  may be cured to arrest and/or stop the flow of first adhesive  138  after dispensing along second edge  134  of plate  128 , and/or to prevent first adhesive  138  from flowing over end  126  of optical fiber  120  and/or waveguide  104 . In this example, the volume of second adhesive  144  and/or thermally curing second adhesive  144  after the dispensing process may also prevent second adhesive  144  from contacting with first adhesive  138 . 
       FIG. 6  shows a top view of another non-limiting example of PIC package  100  including optical fiber  120 , plate  128 , first adhesive  138 , and second adhesive  144 . It is understood that similarly numbered and/or named components may function in a substantially similar fashion. Redundant explanation of these components has been omitted for clarity. 
     Distinct from the non-limiting example discussed herein with respect to  FIGS. 1-5 , the example of  FIG. 6  depicts first adhesive  138  and second adhesive  144  contacting, touching, and/or mixing on PIC die  102 . That is, in the non-limiting example, first adhesive  138  and second adhesive  144  may not be separated and/or spaced apart on PIC die  102 , but rather, may contact one another after being disposed (and cured) on surface  106  of PIC die  102 . In the non-limiting example, both first adhesive  138  and second adhesive  144  may be dispensed onto PIC die  102  as discussed herein, prior to either adhesive being cured. Once dispensed, disposed, and/or flowed to over the desired portions of optical fiber  120  and/or waveguide  104 , first adhesive  138  and second adhesive  144  may be (thermally) cured together. First adhesive  138  and second adhesive  144  do not have to be dispensed separately from one another, nor do first adhesive  138  and second adhesive  144  have to be dispensed than cured prior to dispensing the distinct adhesive. Rather, to aid in the alignment/securing of optical fiber  120  within groove  108  and optically coupling optical fiber  120  with waveguide  104 , first adhesive  138  must cover or be disposed over first portion  140  of optical fiber  120 , while second adhesive  144  cover or be disposed over second portion  146  of optical fiber  120  including end  126 , as well as portion  148  of waveguide  104 . 
       FIG. 7  shows a top view of another non-limiting example of PIC package  100  including a plurality of features. It is understood that similarly numbered and/or named components may function in a substantially similar fashion. Redundant explanation of these components has been omitted for clarity. 
     In the non-limiting example shown in  FIG. 7 , PIC package  100  may include a plurality of waveguides  104 A,  104 B position on PIC die  102 . The plurality of waveguides  104 A,  104 B may be positioned adjacent one another and/or may be formed substantially parallel to one another in surface  106  of PIC die  102 . Additionally as shown in  FIG. 7 , PIC package  100  may include a plurality of grooves  108 A,  108 B formed in surface  106  of PIC die  102 . Each groove  108 A,  108 B may correspond to and may be positioned direct adjacent one of the plurality of waveguides  104 A,  104 B. For example, first groove  108 A may correspond to, may be positioned directly adjacent, and/or may be aligned with first waveguide  104 A of PIC die  102 . Similarly, second groove  108 B may correspond to, may be positioned directly adjacent, and/or may be aligned with second waveguide  104 B of PIC die  102 . Like waveguides  104 A,  104 B, grooves  108 A,  108 B may be formed (e.g., machined, etched) and/or positioned on surface  106  of PIC die  102  adjacent one another and/or in parallel to one another. 
     Also shown in  FIG. 7 , PIC package  100  may include a plurality of optical fibers  120 A,  120 B. Each of the plurality of optical fibers  120 A,  120 B may be operatively coupled to one of the corresponding waveguides  104 A,  104 B of PIC die  102 , and/or may be positioned in one of the corresponding plurality of grooves  108 . For example, first optical fiber  120 A may be operatively and/or optically coupled to first wave guide  104 A, and may be positioned within first groove  108 A. Additionally, second optical fiber  120 B may be operatively and/or optically coupled to second wave guide  104 B, and may be positioned within second groove  108 B. In the non-limiting example, each of the plurality of optical fibers  120 A,  120 B may include ends  126 A,  126 B positioned within grooves  108 A,  108 B and separated from and/or positioned a distance away (e.g., gap (G)) from corresponding waveguides  104 A,  104 B. 
     In the non-limiting example, a single plate  128  may be positioned over both optical fibers  120 A,  120 B. More specifically, and as shown in  FIG. 7 , plate  128  may extend or be positioned over respective sections  130 A,  130 B of the plurality of optical fibers  120 A,  120 B. Section  130 A,  130 B of optical fibers  120 A,  120 B positioned under and/or covered by plate  128  may not include respective first ends  126 A,  126 B of optical fibers  120 A,  120 B or a part of optical fibers  120 A,  120 B that are positioned directly adjacent to and/or extend over side  110  of PIC die  102 . 
     As shown in  FIG. 7 , First adhesive  138  may be disposed along second edge  134  of plate  128 . That is, and as discussed herein, first adhesive  138  may be disposed over PIC die  102 , linearly along and/or across second edge  134  of plate  128 . In addition to being disposed along second edge  134 , first adhesive  138  may flow, be dispensed, be disposed, and/or may be positioned over distinct first portions  140 A,  140 B of optical fibers  120 A,  120 B, as well as a portion of PIC die  102  formed between first portions  140 A,  140 B. In the non-limiting example, first portions  140 A,  140 B of optical fibers  120 A,  120 B may include areas which are covered by plate  128  and distinct areas which are uncovered and/or exposed, prior to the dispensing of first adhesive  138 . At least some (e.g., uncovered area) of first portions  140 A,  140 B of optical fibers  120 A,  120 B may be positioned directly adjacent side  110  of PIC die  102 , while the remaining first portions  140 A,  140 B of optical fibers  120 A,  120 B may be covered by plate  128 . Additionally, first adhesive  138  may be disposed and/or positioned between plate  128  and surface  106  of PIC die  102 , as well as between and/or adjacent to optical fibers  120 A,  120 B. 
     Additionally, second adhesive  144  may be disposed along first edge  132  of plate  128 . That is, and as discussed herein, second adhesive  144  may be disposed over PIC die  102 , linearly along and/or across first edge  132  of plate  128 . In addition to being disposed along first edge  132 , second adhesive  144  may flow, be dispensed, be disposed, and/or may be positioned over second portions  146 A,  146 B of optical fibers  120 A,  120 B, including ends  126 A,  126 B, as well as portions  148 A,  148 B of respective waveguides  104 A,  140 B. In the non-limiting example, second portions  146 A,  146 B of optical fibers  120 A,  120 B may include areas which are covered by plate  128  and distinct areas which are uncovered and/or exposed, prior to the dispensing of second adhesive  144 . At least some (e.g., uncovered area) of second portions  146 A,  146 B of optical fibers  120 A,  120 B may be positioned directly adjacent waveguides  104 A,  104 B of PIC die  102 , while the remaining second portions  146 A,  146 B of optical fibers  120 A,  120 B may be covered by plate  128 . In this non-limiting example, second adhesive  144  may be disposed over and/or may cover ends  126 A,  126 B of optical fibers  120 A,  120 B included in second portions  146 A,  146 B. As a result, second adhesive  144 , like first adhesive  138 , may be disposed and/or positioned between plate  128  and surface  106  of PIC die  102 , as well as between and/or adjacent to optical fibers  120 A,  120 B. 
     Also shown in the non-limiting example PIC package  100  may include an optical loopback  152 . Optical loopback  152  may be optically and/or operatively coupled to at least two of the plurality of waveguides  104 A,  104 B included on PIC die  102 . As shown in  FIG. 7 , optical loopback  152  may be positioned opposite optical fibers  120 A,  120 B, and may be formed and/or positioned on surface  106  of PIC die  102 . In the non-limiting example where PIC package  100  includes optical loopback  152 , waveguide  104 A,  104 B and optical fibers  120 A,  120 B may form one optical information signal in-line, and one optical information signal out-line. In this non-limiting example, optical loopback  152  may allow distinct waveguides  104 A,  104 B to transmit data and/or signals between one another. 
     Although two waveguides, grooves, and optical fibers are shown in  FIG. 7 , it is understood that the number of waveguides, grooves, and optical fibers for the PIC package is merely illustrative. As such, PIC package may include more than two waveguides, grooves, and optical fibers, where optical fibers are arranged as an array assembly. For example, the PIC package may include an array of 12 optical fibers that may all be secured, aligned, and/or optically coupled simultaneously using the process discussed herein. 
     Additionally during the installation process, when a first or single optical fiber is positioned within the PIC die, the entire die and/or package may move, rotate, and/or “rock” based on the force of positioning the optical fiber in the groove. To aid in the stabilization during installation and/or positioning of the optical fiber in the grooves formed in the PIC die, as discussed herein in detail, the PIC die may include auxiliary or “inactive” grooves and corresponding auxiliary or “inactive” fibers. The inactive grooves and inactive fibers may provide additional support for the single optical fiber, and/or may spread the force applied to the PIC die across multiple locations to avoid the movement of the die during installation. These inactive grooves and/or inactive fibers may not be configured to transmit and/or receive optical signals, and may be provided purely for mechanical support in embodiments that include a single, (active) optical fiber. 
       FIG. 8  depicts a flow chart illustrating a process for forming PIC packages as discussed herein. Specifically,  FIG. 8  shows a non-limiting example process for aligning and securing optical fiber(s) to PIC dies using various adhesives. 
     In process P 1  one or more optical fibers may be positioned within a groove formed in a PIC die of the PIC package. More specifically, optical fiber(s) may be positioned in a groove formed in a surface of the PIC die. The groove may correspond to and be positioned directly adjacent a corresponding waveguide positioned and/or formed on the surface of the PIC die. Positioning the optical fiber within the groove may also include positioning an end of the optical fiber within the groove directly adjacent the waveguide. In a non-limiting example, the end of the optical fiber may be separated from and/or may not directly contact the waveguide, but rather may be positioned such that a gap (G) exists between the end of the optical fiber and the waveguide. 
     In process P 2 , a plate may be positioned over a section of the optical fibers. The plate may include a first edge positioned adjacent, but separated from, the waveguide formed in the surface of the PIC die, and a second edge positioned opposite the first edge. The second send may be positioned adjacent and distanced from a side of the PIC die in which the optical fibers extend beyond. Positioning the plate in process P 2  may also include positioning the first edge of the plate adjacent the end of the optical fiber, but not covering the end of the optical fiber. As a result, the end of the optical fibers may be exposed and/or remain uncovered by the plate during the formation process discussed herein. 
     In process P 3  (shown in phantom as optional), a force may be applied to a top surface of the plate. More specifically, a force may be applied to a top, exposed surface of the plate that extends between the first edge and the second edge of the plate to press the optical fiber into the groove of the PIC die. The force applied to the plate may ensure that the optical fiber is positioned and/or aligned within the groove and temporarily secured to PIC die before being adhered, as discussed in detail below. In a non-limiting example, a force may be applied to the plate using a pin attached to a gimbal assembly for ensuring even distribution of the force. The pin may be a straight pin applying a downward force on the plate, or alternatively, may be an angled pin to minimize the space required by the pin-gimbal assembly to apply the force, and/or to reduce the blockage of an ultraviolet light during a curing process, as discussed herein. 
     In process P 4  a first adhesive may be dispensed on the PIC die. More specifically, a first adhesive may be dispensed linearly along the second edge of the plate, adjacent the side of the PIC die. The dispensed first adhesive may be disposed and/or may cover a first portion of the optical fiber. Additionally, the dispensed first adhesive may be disposed, may cover, and/or may flow into a first portion of the groove that may receive the first portion of the optical fiber. Additionally, the dispensed first adhesive may be flowed between the plate and the surface of the PIC die, adjacent the first portion of the optical fiber. The first adhesive may be formed as a UV curable adhesive material. 
     In process P 5  (shown in phantom as optional), the first adhesive may be cured. More specifically, after dispensing the first adhesive and allowing time for the first adhesive to flow over the first portion of the optical fiber, the first adhesive may be cured. The first adhesive may be cured using any suitable curing technique or process. For example, where the first adhesive is formed as a UV curable adhesive material, the PIC die include the first adhesive may be exposed to a UV light (e.g., 1-2 minutes) to cure the first adhesive. Curing the first adhesive may arrest and/or stop the flow of the first adhesive as it is disposed and/or covers portions of the PIC die. Curing the first adhesive may also ensure that the first adhesive does not flow over and/or cover the (exposed) end of the optical fiber and/or a portion of the waveguide. Curing the first adhesive may take place prior to dispensing the second adhesive in process P 6 . In response to performing process P 5  and curing the first adhesive dispensed on the PIC die, the force applied to the plate may be removed and/or discontinued. That is, curing the first adhesive in process P 5  may ensure that the optical fibers are secured within the grooves of the PIC die enough to continue performing processes for securing and/or aligning the optical fibers on the PIC package without the need of the applied force (e.g., process P 3 ). As such, the pin applying the force may be removed, and additional processes may be performed on the PIC package. 
     In process P 6  a second adhesive may be dispensed on the PIC die. More specifically, a second adhesive may be dispensed linearly along the first edge of the plate, adjacent the waveguide included in the PIC die. The dispensed second adhesive may be disposed and/or may cover a second portion of the optical fiber and a portion of the waveguide. The second portion of the optical fiber may include the end of the optical fiber positioned directly adjacent to, but separated from the waveguide. Additionally, the dispensed second adhesive may be disposed, may cover, and/or may flow into a second portion of the groove that may receive the second portion of the optical fiber. Additionally, the dispensed second adhesive may be flowed between the plate and the surface of the PIC die, adjacent the second portion of the optical fiber. In a non-limiting example, the second adhesive may be dispensed and/or may flow to be separate and/or distant from the (cured) first adhesive. In another non-limiting example, the second adhesive may be dispensed and/or may flow to contact the first adhesive and/or prevent the first adhesive from being disposed over and/or covering the end of the optical fiber and/or the waveguide. The second adhesive may be formed as an optical adhesive material that may be configured to optically couple the optical fiber and the waveguide for which the first adhesive is dispensed and/or disposed over. 
     In process P 7  the adhesives are cured. More specifically, and dependent on whether the curing process of P 5  is performed, at least one of the first adhesive or the second adhesive dispensed on the PIC die is cured. In non-limiting examples, the first adhesive and/or the second adhesive may be thermally cured using any suitable curing process and/or technique. Where process P 5  is not performed, the first adhesive and the second adhesive may be (thermally) cured simultaneously to form the desired PIC package. Alternatively where process P 5  is performed, and the first adhesive is cured, process P 7  may include (thermally) curing the second adhesive dispensed and/or disposed on the identified portions of the PIC die. 
     The adhesives discussed herein may be dispensed using any suitable dispense system, such as a micro fluid dispense system marketed by Nordson (East Providence, R.I.). An example dispense system may include portable or bench-top dispense system that is operable to pressurize and deliver through a dispensing tip an effective amount of the adhesives to a desired location on the PIC package, e.g., the linearly along the first edge or the second edge of the plate. 
     It will be recognized that the teachings of the disclosure are also applicable for alternate applications in which optical fibers to polymer waveguides, laser dies in PIC die cavities, individual optical fibers and fiber ribbons in groove fiber optic receptacles, etc. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not. 
     Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred. Any recited single or multiple feature or aspect in any one claim can be combined or permuted with any other recited feature or aspect in any other claim or claims. 
     It will be understood that when an element such as a layer, region or substrate is referred to as being formed on, deposited on, or disposed “on” or “over” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or “directly over” another element, no intervening elements are present. 
     Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. “Approximately” as applied to a particular value of a range applies to both values, and unless otherwise dependent on the precision of the instrument measuring the value, may indicate +/−10% of the stated value(s). 
     The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The embodiment was chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.