Patent Publication Number: US-11378751-B2

Title: Laser patterned adapters with waveguides and etched connectors for low cost alignment of optics to chips

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 16/058,608 entitled LASER PATTERNED ADAPTERS WITH WAVEGUIDES AND ETCHED CONNECTORS FOR LOW COST ALIGNMENT OF OPTICS TO CHIPS filed Aug. 8, 2018, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     Embodiments presented in this disclosure generally relate to fabricating features in optoelectronic devices. More specifically, embodiments disclosed herein provide for the use of lasers to improve the etching of physical features in addition to optical features in photonic elements. 
     BACKGROUND 
     The discrete optical and electronic components of optoelectronic devices are fabricated separately and later joined together to produce an assembled device. Various epoxies and engagement features may be used to ensure that the optical and electronic components maintain proper joints once assembled, but due to the tolerances of these devices, the relative locations of the features present in the optical and electronic components is typically verified before finalizing assembly (e.g. curing the epoxy). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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. 
         FIG. 1  illustrates an example optoelectronic device according to aspects of the present disclosure. 
         FIGS. 2A-D  illustrate various views of an example optoelectronic device with an optical adapter configured to optically couple for linear transmission according to aspects of the present disclosure. 
         FIGS. 3A-D  illustrate various views of an example optoelectronic device with an optical adapter configured to optically couple for evanescent transmission according to aspects of the present disclosure. 
         FIGS. 4A-D  illustrate various views of the photonic elements of an optical adapter constructed as a multi-piece unit according to aspects of the present disclosure. 
         FIGS. 5A-E  illustrate various views of an example optoelectronic device with an optical adapter configured with open cable connectors according to aspects of the present disclosure. 
         FIGS. 6A-G  illustrate various planar arrangements of waveguides within an optical adapter according to aspects of the present disclosure. 
         FIG. 7  illustrates an example substrate layout according to aspects of the present disclosure. 
         FIGS. 8A-D  illustrate detailed views of engaging engagement features and mating features of the optoelectronic assembly according to aspects of the present disclosure. 
         FIG. 9A  illustrates mating the engagement feature with the mating feature according to aspects of the present disclosure. 
         FIG. 9B  illustrates engaging the engagement feature with the mating feature according to aspects of the present disclosure. 
         FIG. 9C  illustrates engagement the engagement feature with the mating feature according to aspects of the present disclosure. 
         FIG. 10  is a flowchart illustrating high level operations of an example method for the use of laser patterning in optical components according to aspects of the present disclosure. 
     
    
    
     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. 
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Overview 
     One embodiment presented in this disclosure provides a substrate fabricated with laser patterned adapters with waveguides and etched connectors for low cost alignment of optics to chips, the substrate comprising: a light-transmissive material having a first side and a second side opposite to the first side; a plurality of dies defined in the light-transmissive material, each die of the plurality of dies including: a first pattern imparted on the light-transmissive material by a laser, wherein the first pattern extends into the light-transmissive material from the first side, the first pattern defining a patterned region of the light-transmissive material and an un-patterned region of the light-transmissive material, wherein a chemical structure of the patterned region has an increased reactivity to an etchant relative to the un-patterned region, and wherein the patterned region defines an engagement feature in the un-patterned region that is configured to engage with a mating feature on a Photonic Integrated Circuit (PIC); and a second pattern imparted on the light-transmissive material by the laser, wherein the second pattern extends to neither the first side nor the second side, the second pattern defining a permanent waveguide within the light-transmissive material resulting from a laser induced change in the material/crystal structure, wherein the waveguide is aligned relative to the engagement feature to optically couple with an integrated waveguide of the PIC. 
     Another embodiment presented in this disclosure provides a method for fabricating laser patterned adapters with waveguides and etched connectors for low cost alignment of optics to chips, the method comprising: determining an alignment point for a photonic element in a substrate of a given material; applying, via a laser aligned with the photonic element according to the alignment point, an etching pattern to the photonic element to produce a patterned region and an un-patterned region in the photonic element, wherein applying the etching pattern alters a chemical bond in the given material for the patterned region of the photonic element that increases a reactivity of the given material to an etchant relative to a reactivity of the un-patterned region, and wherein the patterned region defines an engagement feature in the un-patterned region that is configured to engage with a mating feature on a Photonic Integrated Circuit (PIC); and removing the patterned region from the photonic element via the etchant. 
     A further embodiment presented in this disclosure provide a method for fabricating laser patterned adapters with waveguides and etched connectors for low cost alignment of optics to chips, the method comprising: imparting a first pattern on a light-transmissive material by a laser, wherein the first pattern extends into the light-transmissive material from a first side to a second side that is opposite to the first side, wherein the first pattern defines an un-patterned region of the light-transmissive material and a patterned region of the light-transmissive material that has an increased reactivity to an etchant relative to the un-patterned region, and wherein the patterned region defines an engagement feature in the un-patterned region that is configured to engage with a mating feature on a Photonic Integrated Circuit (PIC); and imparting a second pattern on the light-transmissive material by the laser, wherein second pattern extends to neither the first side nor the second side, the second pattern defining a waveguide within the light-transmissive material aligned relative to the engagement feature to optically couple with an integrated waveguide of the PIC. 
     EXAMPLE EMBODIMENTS 
     The present disclosure provides systems and methods for the use of laser patterning in optical components to affect the etch rate of the optical components and the optical components produced according to such systems and methods. By applying laser light to an optical component, not only can the laser construct waveguides within the material matrix of the optical component, but the laser may also change the material&#39;s susceptibility to chemical etching. The laser precisely imparts a three-dimensional pattern into the material to control what portions of the material have higher etching rates than the surrounding un-patterned material, and may also impart three dimensional patterns that affect the refractive indices of the material to form waveguides. Once the etchant is applied, the patterned regions are removed at a faster rate than the un-patterned regions, and the optical component exhibits physical features that are co-aligned with the optical features (e.g., waveguides). By co-aligning the optical and physical components and employing the high degree of precision of laser patterning, the optical components avoid the need for active alignment and testing before integration into an optoelectronic assembly, thus improving yields, improving speed of assembly, and reducing overlapping/stacking tolerances by providing more precisely toleranced components. Laser patterning and chemical etching provides a higher degree of precision in tolerancing the defined components than physical etching (e.g., ± hundreds of nanometers versus ±tens of micrometers (also referred to as microns)), and allow for components to be co-fabricated with fewer and less labor-intensive verification tests. 
     The laser used in laser patterning shines a high intensity light into the material of the optical component (e.g., a SiO 2  based material) to break chemical bonds within the material to alter the light-transmission properties of the material and/or affect how readily the material reacts with an etchant. The etchant may include various acids (e.g., HCl, HNO 3 , H 2 SO 4 ) or other caustic compounds that bond with the patterned material more readily than the un-patterned material and that may be washed away to remove material from the optical component. In some embodiments, laser patterning increases the reactivity of the material up to around 5000 times the reactivity of the un-patterned material. 
     When patterning an optical component, the laser maintains a reference point (e.g., an edge of the optical component of a substrate containing several optical components) so that the beam precisely defines the portions of the material that are to become waveguides, and what portions are to be removed during chemical etching. In some embodiments, establishing the waveguides using laser patterning is performed simultaneously with defining the portions of material to remove. In additional embodiments, laser patterning is done prior to and the chemical etching is done after physical etching to allow a rough physical removal of material followed by a more precise chemical removal of material, or to establish flow guides for the etchant prior to chemical etching. 
       FIG. 1  illustrates an example optoelectronic device  100  that includes an optical adapter  110  and a Photonic Integrated Circuit (PIC)  120  in an example arrangement. Each of the optical adapter  110  and the PIC  120  are examples of optical elements that may be laser patterned according to embodiments of the present disclosure. The optical adapter  110  and the PIC  120  are each made of a glass material (such as SiO 2 , which may be doped with various dopants) or other light-transmissive material to which a laser may be applied to selectively break or alter the chemical bonds of that material to affect the reactivity of that material to a chemical etchant; affecting the material or crystal structure of the substrate (i.e., the chemical structure). Various waveguides  115  in the Optical Adapter  110  and integrated waveguides  125  in the PIC  120  are defined in the respective materials to establish distinct pathways over which beams of light may be propagated. In some embodiments, a photo-receiver (e.g., a light-activated diode) connected to a waveguide  115  receives a beam of light propagated from an external source, and in other embodiments a light source (e.g., a fiber optic cable or laser) connected to a waveguide  115  transmits a beam of light through the material. 
     The optical adapter  110  is a passive device that connects the optoelectronic device  100  to various other devices or cabling. For example, the optical adapter  110  may be a Fiber Array Unit (FAU) to connect the optoelectronic device  100  with various fiber optic cabling via several individual light paths arranged in an array. In various embodiments, the optical adapter  110  conforms to various standard shapes and sizes for optical connectors, including, but not limited to: Media Interface Connector (MIC), Aviation Intermediate Maintenance (Avio), Diamond Micro Interface (DIM), IEC 61754 (and variants/offshoots thereof, such as Multiple-Fiber Push-On/Pull-Off), Enterprise Systems Connection (ESCON), and the like. As such, the number of waveguides  115 , the spacing and arrangement of waveguides  115 , and various connection points on the optical adapter  110  may vary based on the standard and how the PIC  120  is arranged. 
     The PIC  120  is a photonic element that may operate to amplify, dim, extinguish, phase shift, switch, modulate, direct optical signals, and convert optical signals to an electrical signal for use by an Electrical Integrated Circuit (EIC) integrated with or connected to the PIC  120 . The EIC is an electrical circuit that operates with the PIC  120  to send or receive and process optical signals. The EIC may include a processor, memory storage devices, communications interfaces to other electrical circuits or equipment, and components to drive or receive optical signals via the PIC  120 . The optical adapter  110  optically interfaces with the PIC  120  to carry optical signals from the PIC  120  to external devices or to the PIC  120  from external devices. The optical adapter  110  may physically interface with one or more of the EIC and the PIC  120  via various connectors and/or epoxies. 
       FIGS. 2A-D  illustrate various views of an example optoelectronic device  100  with an optical adapter  110  configured to optically couple with a PIC  120  for direct transmission. As will be appreciated, in a given view, a given feature may be occluded or obscured by another feature, and a better understanding of how the features of an optoelectronic device interact may be gained by considering  FIGS. 2A-D  in aggregate than individually. 
       FIG. 2A  illustrates an isometric view of a translucent optical adapter  110  that is affixed to and optically coupled with the PIC  120 . As shown, engagement features  111  of the optical adapter  110  are engaged with mating features  121  of the PIC  120 , and epoxy joints  130  are formed between the optical adapter  110  and the PIC  120 . Epoxy joints  130  are formed via a deposited epoxy (e.g., in an epoxy well) being cured to bond one component to another. The optical adapter  110  shows cable connectors  112  extending from a free surface  117 , and a set of waveguides  115  that run from the free surface  117  of the optical adapter  110  to an optical coupling interface  118  of the optical adapter  110  that is held in contact with integrated waveguides  125  in the PIC  120 . A mating interface  116  and an optical coupling interface  118  of the optical adapter  110  may be collectively referred to as a connecting surface, and although illustrated as being disposed on two orthogonal planes in  FIGS. 2A-D , may be disposed on a curved surface or more than two planes in other embodiments. 
     An external fiber optic plug  210  is illustrated in relation to the optoelectronic device  100 , which may be coupled with the optoelectronic device  100  via the optical adapter  110 . As illustrated, the external fiber optic plug  210  includes securing features  212  that secure the external fiber optic plug  210  to the optical adapter  110 , and fiber waveguides  215  that extend from a plug surface  217  to fiber cables  218 . In the illustrated example, the securing features  212  are male prongs that the cable connectors  112  are configured to receive to secure the plug surface  217  of the external fiber optic plug  210  against the free surface  117  of the optical adapter  110 . In other embodiments, in which the securing features  212  are female connectors, the cable connectors  112  are male connectors configured for insertion into the securing features  212  to secure the plug surface  217  against the free surface  117 . When secured against the free surface  117 , a fiber waveguide  215  is optically coupled with a waveguide  115  in the optical adapter  110 . In various embodiments, some or all of the fiber waveguides  215  may optically couple with some or all of the waveguides  115 . For example, an external fiber optic plug  200  may include N fiber waveguides  215  and the optical adapter  110  may include N waveguides  115  to allow each fiber waveguide  215  to optically couple with one waveguide  115 . In another example, an external fiber optic plug  200  may include N fiber waveguides  215  and the optical adapter  110  may include N+M waveguides  115  (e.g., to work with multiple standards of external fiber optic plug  200 ), and M of the waveguides  115  may remain uncoupled when N of the waveguides  115  are optically coupled with the N fiber waveguides  215 . 
       FIG. 2B  illustrates a cross-section of the example optoelectronic device  100 , showing details of the installed optical adapter  110  and PIC  120 . Although  FIG. 2B  shows one planar view with various features, other planar views may show more or fewer features, such as the cable connectors  112  (not shown in  FIG. 2B ) that extend through various other planes. The waveguide  115  is fabricated within the optical adapter  110  and is optically exposed on a free surface  117  of the optical adapter  110  and mated at the optical coupling interface  118  of the optical adapter  110  with the integrated waveguide  125  of the PIC  120 . As used herein, optical exposure does not require physical exposure; a waveguide  115 ,  125  may be encased in a substrate and receive and transmit light through that substrate. Accordingly, a waveguide  115 ,  125  may be optically exposed when a given end of the waveguide  115 ,  125  is within a predefined distance (e.g., about 5 micrometers) of a given surface of the optical adapter  110  or PIC  120  so as to be able to transmit or receive light from one side of the given surface to the other side. Various lenses and filters (not illustrated) may be used in some embodiments at one or more of a first end or a second end of a waveguide  115  to aid in gathering or transmitting light to a fiber waveguide  215  or an integrated waveguide  125 . 
       FIG. 2C  illustrates a cross-section of a substrate, such as a glass or optical resin, from which the optical adapter  110  may be fabricated that defines male connector engagement features  111 .  FIG. 2D  illustrates an alternative cross-section of a substrate from which the optical adapter  110  may be fabricated that defines female connector engagement features  111 . In either embodiment, a laser is used to impart an etching pattern in the material of the substrate to define a patterned region  113  and an un-patterned region  114 . The patterned region  113  has a higher reactivity to a chemical etchant than the un-patterned region  114 , and the borders between the regions define various faces and features of the optical adapter  110 . The laser may also (simultaneously or at a different time) impart a waveguide pattern to define one or more waveguides  115  in the material of the substrate. The waveguide pattern imparts a different refractive index to portions of the material to guide light from one surface to another. In various embodiments, the waveguides  115  may be optically exposed in the material of the substrate via physical etching, polishing, or chemical etching. 
     The laser forms the patterned region  113  by imparting energy to the material of the substrate, thereby affecting chemical bonds in the material and increasing the reactivity of the material in the patterned region  113  (relative to the reactivity of the material in the un-patterned region  114 ) to an etchant. The etchant is then applied to an etching surface  119  of the substrate to remove the patterned region  113  and leave behind the un-patterned region  114 . Because the borders between the patterned region  113  and the un-patterned region  114  define the various contacting surfaces (e.g., a mating interface  116 , an optical coupling interface  118 ), engagement features  111 , and cable connectors  112  in the optical adapter  110 , once the patterned region  113  is removed, the optical adapter  110  includes the engagement features  111  and the cable connectors  112 . The patterned region  113  may define the various engagement features  111  and cable connectors  112  as male connectors (e.g., extending outward from a face of the optical adapter  110 ) or as female connectors (e.g., extending inward from a face of the optical adapter  110 ). 
     The engagement features  111  are defined on the mating interface  116  in relation to the waveguides  115  of the optical adapter  110  so that when the optical adapter  110  is affixed to the PIC  120 , the waveguides  115  are aligned to optically couple with the integrated waveguides  125  of the PIC  120 . Similarly, the cable connectors  112  are defined in the free surface  117  of the optical adapter  110  in relation to where the waveguides  115  are located on the free surface  117 . In some embodiments, the relative locations of the cable connectors  112  and the waveguides  115  are set according to various standards used for the cabling intended for connection to the optoelectronic device  100  (e.g., the fiber optic plug  210 ). 
       FIGS. 3A-D  illustrate various views of an example optoelectronic device  100  with an optical adapter  110  configured to optically couple with a PIC  120  for evanescent transmission. As will be appreciated, in a given view, a given feature may be occluded or obscured by another feature, and a better understanding of how the features of an optoelectronic device interact may be gained by considering  FIGS. 3A-D  in aggregate than individually. 
       FIG. 3A  illustrates an isometric view of a translucent optical adapter  110  that is affixed to and optically coupled with the PIC  120 . As shown, engagement features  111  of the optical adapter  110  are engaged with mating features  121  of the PIC  120 , and epoxy joints  130  are formed between the optical adapter  110  and the PIC  120 . Epoxy joints  130  are formed via a deposited epoxy (e.g., in an epoxy well) being cured to bond one component to another. The optical adapter  110  shows cable connectors  112  extending inward from a free surface  117 , and a set of waveguides  115  that run from the free surface  117  of the optical adapter  110  to an optical coupling interface  118  of the optical adapter  110  that is held in contact with integrated waveguides  125  in the PIC  120  that extend to the mating surface  126  of the PIC  120 . A mating interface  116  and an optical coupling interface  118  of the optical adapter  110  may be collectively referred to as a connecting surface. In some embodiments that use evanescent transmission, the mating interface  116  and the optical coupling interface  118  of the optical adapter  110  may be coplanar, but in other embodiments may be located on separate parallel planes. 
     An external fiber optic plug  210  is illustrated in relation to the optoelectronic device  100 , which may be coupled with the optoelectronic device  100  via the optical adapter  110 . As illustrated, the external fiber optic plug  210  includes securing features  212  that secure the external fiber optic plug  210  to the optical adapter  110 , and fiber waveguides  215  that extend from a plug surface  217  to fiber cables  218 . In the illustrated example, the securing features  212  are male prongs that the cable connectors  112  are configured to receive to secure the plug surface  217  of the external fiber optic plug  210  against the free surface  117  of the optical adapter  110 . In other embodiments, in which the securing features  212  are female connectors, the cable connectors  112  are male connectors configured for insertion into the securing features  212  to secure the plug surface  217  against the free surface  117 . When secured against the free surface  117 , a fiber waveguide  215  is optically coupled with a waveguide  115  in the optical adapter  110 . In various embodiments, some or all of the fiber waveguides  215  may optically couple with some or all of the waveguides  115 . For example, an external fiber optic plug  200  may include N fiber waveguides  215  and the optical adapter  110  may include N waveguides  115  to allow each fiber waveguide  215  to optically couple with one waveguide  115 . In another example, an external fiber optic plug  200  may include N fiber waveguides  215  and the optical adapter  110  may include N+M waveguides  115  (e.g., to work with multiple standards of external fiber optic plug  200 ), and M of the waveguides  115  may remain uncoupled when N of the waveguides  115  are optically coupled with the N fiber waveguides  215 . 
       FIG. 3B  illustrates a cross-section of the example optoelectronic device  100 , showing details of the installed optical adapter  110  and PIC  120 . Although  FIG. 3B  shows one planar view with various features, other planar views may show more or fewer features, such as cable connectors  112  (not shown in  FIG. 3B ) that extend through various other planes. The waveguide  115  is fabricated within the optical adapter  110  and is optically exposed on a free surface  117  of the optical adapter  110  and mated at the optical coupling interface  118  of the optical adapter  110  with the integrated waveguide  125  of the PIC  120 . 
       FIG. 3C  illustrates a cross-section of a substrate, such as a glass or optical resin, from which the optical adapter  110  may be fabricated that defines male connector engagement features  111 . A laser is used to impart an etching pattern in the material of the substrate to define a patterned region  113  and an un-patterned region  114 . The patterned region  113  has a higher reactivity to a chemical etchant than the un-patterned region  114 , and the borders between the regions define various faces and features of the optical adapter  110 . The etching pattern is applied to an etching surface  119  of the substrate, to which the chemical etchant is applied to remove the patterned region  113  during a chemical etch process. The laser may also (simultaneously or at a different time) impart a waveguide pattern to define one or more waveguides  115  in the material of the substrate in the un-patterned region  114 . The waveguide pattern imparts a different refractive index to portions of the material to guide light from one surface to another. In various embodiments, the waveguides  115  may be optically exposed in the material of the substrate via physical etching, polishing, or chemical etching. 
       FIG. 3D  illustrates an underside of an optical adapter  110  configured for evanescent transmission that shows various features present on the mating interface  116  of the optical adapter  110 . Four engagement features  111  with various shapes and orientations on the mating interface  116  are present, and are oriented for engagement with mating features  121  on the PIC  120 . Although the example engagement features  111  are shown as having quadrilateral and circular cross sections, other shapes and sizes of engagement features  111  are possible. Similarly, more or fewer than four engagement features  111  may be present on the mating interface  116 , and the engagements features  111  may be male connectors, female connectors, or a combination of male and female connectors. The shapes, sizes, and positions of the engagements features  111  on the mating interface  116  relative to one another may be such that the optical adapter  110  has only one orientation that matches with the mating features  121  of the PIC  120 . 
     The engagement features  111  are defined on the mating interface  116  in relation to the waveguides  115  of the optical adapter  110  so that when the optical adapter  110  is affixed to the PIC  120 , the waveguides  115  are aligned to optically couple with the integrated waveguides  125  of the PIC  120 . Similarly, the cable connectors  112  are defined in the free surface  117  of the optical adapter  110  in relation to where the waveguides  115  are located on the free surface  117 . In some embodiments, the relative locations of the cable connectors  112  and the waveguides  115  are set according to various standards used for cabling intended for connection to the optoelectronic device  100  (e.g., a fiber optic plug  210 ). 
       FIGS. 4A-D  illustrate various views of the photonic elements of an optical adapter  110  constructed as a multi-piece unit. As will be appreciated, in a given view, a given feature may be occluded or obscured by another feature, and a better understanding of how the features of an optoelectronic device interact may be gained by considering  FIGS. 4A-D  in aggregate than individually. 
       FIG. 4A  is an isometric view of a first photonic element  410  and a second photonic element  420  that are configured to connect together to form an optical adapter  110 . The illustrated first photonic element  410  includes the engagement features  111 , a first portion of the cable connectors  112 , and the waveguides  115 . The illustrated second photonic element  420  includes a second portion of the cable connectors  112 , so that when the first photonic element  410  is connected with the second photonic element  420 , the first and second portions define the cable connectors  112 . 
       FIG. 4B  is an isometric view of a first photonic element  410  and a second photonic element  420  in which the first photonic element  410  and the second photonic element  420  are connected to form an optical adapter  110 . Also illustrated in  FIG. 4B  are several through-holes  430  in the optical adapter  110  running through the cable connectors  112  in the first photonic element  410  and the second photonic element  420 . In various embodiments, the through-holes  430  are defined via physical etching or chemical etching of the patterned region  113  to provide a fluid outlet (e.g., the etchant during etching or air when a male connector is inserted into the cable connectors  112 ). Although illustrated as vertical elements, in other embodiments, the through-holes  430  may be provided in other orientations. 
       FIG. 4C  is a first cross-sectional view of a substrate in which a first photonic element  410  and a second photonic element  420  are defined. The present example shows the first photonic element  410  and the second photonic element  420  defined in a combined die on one substrate for purposes of explanation. In other embodiments, dies for a first photonic element  410  are defined in a separate substrate from the dies for a second photonic element  420 .  FIG. 4D  is a second cross-sectional view of the substrate illustrated in  FIG. 4C  showing different details of the first photonic element  410  and the second photonic element  420  defined therein. 
       FIG. 4C  illustrates several through-holes  430 , including through-holes  430  positioned in the regions corresponding to the portions of patterned region  113  that will be removed to form the cable connectors  112  and a through-hole  430  in a central region of the substrate (between the portions of the un-patterned regions  114  that will form the first photonic element  410  and the second photonic element  420 ) to channel the etchant from a first surface  440  of the substrate to a second surface  450  of the substrate. For example, a central through-hole  430  may be physical etched to prior to chemical etching to channel the etchant from the first surface  440  on the top side of the substrate to a second surface  450  opposite the first surface  440  to define an engagement feature  111  thereon.  FIG. 4C  also illustrates a first pair on internal alignment features  460  of matched male and female interconnects that may position and align the first photonic element  410  with the second photonic element  420  when assembled. 
       FIG. 4D  illustrates a second plane of the substrate in which through-holes  430  are absent, but partial channels  470  are present. The partial channels  470  define regions in the substrate that may be physically etched (e.g., to direct the flow of a chemical etchant), but do not run completely from the first surface  440  to the second surface  450  of the substrate. In some embodiments, the partial channels  470  interface with the through-holes  430  to direct an etchant to particular portions of the substrate. For example, the partial channel  470  illustrated in  FIG. 4D  may flow into the central through-hole  430  illustrated in  FIG. 4C  to direct an etchant to the patterned region  113  on the second surface  450  of the substrate. In some embodiments, a channel  480  of an un-patterned region  114  may physically link one or more dies on the substrate for the duration of the etching process, and may be removed by a physical processing or dicing process once chemical etching has concluded. 
       FIG. 4D  also illustrates a waveguide  115 , and a second pair of internal alignment features  460  of matched male and female interconnects that may position and align the first photonic element  420  with the second photonic element  420  when assembled. Although the illustrated waveguide  115  is configured for direct transmission, waveguides  115  configured for evanescent transmission may also be defined in multi-piece constructions for an optical adapter  110 . 
       FIGS. 5A-E  illustrate various views of an example optoelectronic device  100  with an optical adapter  110  configured with open cable connectors  112 . As will be appreciated, in a given view, a given feature may be occluded or obscured by another feature, and a better understanding of how the features of an optoelectronic device interact may be gained by considering  FIGS. 5A-E  in aggregate than individually. 
       FIG. 5A  illustrates an isometric view of a translucent optical adapter  110  that is affixed to and optically coupled with the PIC  120 . As shown, engagement features  111  of the optical adapter  110  are engaged with mating features  121  of the PIC  120 , and epoxy joints  130  are formed between the optical adapter  110  and the PIC  120 . Epoxy joints  130  are formed via a deposited epoxy (e.g., in an epoxy well) being cured to bond one component to another. The optical adapter  110  shows cable connectors  112  extending from a free surface  117 , and a set of waveguides  115  that run from the free surface  117  of the optical adapter  110  to an optical coupling interface  118  of the optical adapter  110  that is held in contact with integrated waveguides  125  in the PIC  120 . A mating interface  116  and an optical coupling interface  118  of the optical adapter  110  may be collectively referred to as a connecting surface, and although illustrated as being disposed on two orthogonal planes in  FIGS. 5A-E , may be disposed on a curved surface or more than two planes in other embodiments. 
     An external fiber optic plug  210  is illustrated in relation to the optoelectronic device  100 , which may be coupled with the optoelectronic device  100  via the optical adapter  110 . As illustrated, the external fiber optic plug  210  includes securing features  212  that secure the external fiber optic plug  210  to the optical adapter  110 , and fiber waveguides  215  that extend from a plug surface  217  to fiber cables  218 . In the illustrated example, the securing features  212  are male prongs that the cable connectors  112  are configured to receive to secure the plug surface  217  of the external fiber optic plug  210  against the free surface  117  of the optical adapter  110 . In other embodiments, in which the securing features  212  are female connectors, the cable connectors  112  are male connectors configured for insertion into the securing features  212  to secure the plug surface  217  against the free surface  117 . When secured against the free surface  117 , a fiber waveguide  215  is optically coupled with a waveguide  115  in the optical adapter  110 . In various embodiments, some or all of the fiber waveguides  215  may optically couple with some or all of the waveguides  115 . For example, an external fiber optic plug  200  may include N fiber waveguides  215  and the optical adapter  110  may include N waveguides  115  to allow each fiber waveguide  215  to optically couple with one waveguide  115 . In another example, an external fiber optic plug  200  may include N fiber waveguides  215  and the optical adapter  110  may include N+M waveguides  115  (e.g., to work with multiple standards of external fiber optic plug  200 ), and M of the waveguides  115  may remain uncoupled when N of the waveguides  115  are optically coupled with the N fiber waveguides  215 . 
     In contrast to the closed cable connectors  112  illustrated in  FIGS. 2A and 3A , the cable connectors  112  illustrated in  FIG. 5A  are open. Open cable connectors  112  are exposed on the free surface  117  (to allow insertion of the securing features  212 ), and are also exposed on a surface orthogonal to the free surface  117 . During the manufacturing process, a patterned region  113  is defined in the substrate of the optical adapter  110  such that the patterned region  113  runs from the etching surface  119  to the free surface  117  and a surface orthogonal to the free surface  117 . The portion of the patterned region  113  that runs to the orthogonal surface defines a channel opening by which a chemical etchant applied to the substrate may carry away material removed from the substrate, and allowing the chemical etchant to etch from the etching surface  119  to the free surface  117 . Although the orthogonal surface in which the channel opening is defined is shown on the “side” of the example optical adapter  110  in  FIGS. 5A-E , in other embodiments the “top” or the “bottom” side may include the channel opening. Similarly, the size of the channel opening may vary in different embodiments from the examples illustrated in  FIGS. 5A-E . 
       FIG. 5B  illustrates a cross-sectional side view of an optical adapter  110  with open cable connectors  112 , and  FIG. 5C  illustrates an isometric view of an optical adapter with open cable connectors  112  as may be positioned during chemical etching. The open cable connectors  112  are defined by a pattern imparted by a laser in the substrate from which the optical adapter  110  is formed. The pattern alters the chemical bonds of the substrate material to increase the material&#39;s reactivity to a chemical etchant. In the illustrated embodiment, the pattern extends from an etching surface  119  to the free surface  117 , and defines a channel opening in a plan orthogonal to the free surface  117 , which allow a chemical etchant applied to the etching surface  119  to run off and away from the optical adapter  110  once the chemical etchant has reacted with the substrate in the patterned region; allowing fresh etchant to come into contact with the remaining patterned region and allowing spent etchant to carry material away from the optical adapter  110 . The free surface  117  may be mounted below the etching surface  119  during a chemical etch process to allow gravity to assist the flow of etchant through the patterned region. The patterned region that defines the open cable connectors  112  may be in fluid communication and part of the patterned region that defines the mounting surfaces or may be separate from the other patterned regions defined in the substrate of the optical adapter  110 . For example, un-patterned regions may separate the patterned regions that define the waveguides  115  from the patterned regions that define the open cable connectors  112 . 
       FIG. 5D  is an isometric view of a first photonic element  410  and a second photonic element  420  that are configured to connect together to form an optical adapter  110 . The illustrated first photonic element  410  includes a first portion of the cable connectors  112  and the waveguides  115 . The illustrated second photonic element  420  includes a second portion of the cable connectors  112 , so that when the first photonic element  410  is connected with the second photonic element  420 , the first and second portions define the open cable connectors  112 . The relative amounts of patterning applied to the first photonic element  410  and the second photonic element  420  may be varied to account for a greater or lesser portion of the cable connectors  112  to be defined by one of the first photonic element  410  or the second photonic element  420 . In some embodiments, the open cable connector  112  is defined solely by etching on one of first photonic element  410  or second photonic element  420 , with the other of flat first photonic element  410  or second photonic element  420  providing a flat un-etched surface to define a surface of the open cable connector  112 . 
     In some embodiments, the second photonic element  420  may be constructed to be longer than the first photonic element  410  (along the Y axis) to define the mating interface  116  (and may include engagement features  111  and epoxy joints  130  defined thereon). Additionally, various alignment features and male/feature interconnects may be defined on the mating surfaces of the first photonic element  410  and the second photonic element  420  to ensure that the free surfaces  117  of the respective photonic elements are aligned into a single surface when the first photonic element  410  and the second photonic element  420  are joined together. 
     In various embodiments, dies for a first photonic element  410  may be defined on the same or a separate substrate from the dies for a second photonic element  420 . In some embodiments, the etching surfaces  119  for each of the first photonic element  410  and the second photonic element  420  may be the surfaces by which the two elements are mated together. In other embodiments, the free surface  117  (or the opposite surface) for each of the first photonic element  410  may be the etching surface for the respective photonic element. 
       FIG. 5E  is an isometric view of an optical adapter  110  that is configured to mount with the PIC  12  to form cable connectors  112 . The illustrated optical adapter  110  includes a first portion of the cable connectors  112  and the waveguides  115 , and uses the mating surface  126  of the PIC  120  to form additional surfaces/portions of the cable connectors  112 . The mating interface  116  of the optical adapter  110  may include various engagement features  111  (not illustrated) to interface with the mating features  121  (not illustrated) of the PIC  120  to align the waveguides  115  with the integrated waveguides  125  for evanescent coupling. In various embodiments, the optical adapter  110  of  FIG. 5E  may be constructed such that the etching surface  119  and the mating interface  116  are the same surface or parallel surfaces (e.g., the etching surface  119  may be removed to reveal the mating interface  116 ). 
       FIGS. 6A-G  illustrate various coupling arrangements of waveguides  115  within an optical adapter  110 . The individual paths of waveguides  115  within an optical adapter  110  may vary in different embodiments in the number of waveguides  115 , the arrangement of waveguides  115 , the three-dimensional path that each waveguide  115  runs in the optical adapter  110 , etc., and the example coupling arrangements shown in  FIGS. 6A-G  are illustrative of but a few arrangements. It will be appreciated that the coupling arrangements may be applied in embodiments that use evanescent or direct transmission of light. A given embodiment of an optical adapter  110  may use one or more of the example coupling arrangements in combination with one another. 
       FIG. 6A  illustrates several waveguides  115  arranged for straight coupling, in which the number, spacing, and order of the waveguides  115  remain consistent from the free surface  117  to the optical coupling interface  118 .  FIG. 6B  illustrates several waveguides  115  arranged for condensed coupling, in which the number and order of the waveguides  115  remain consistent, but the spacing decreases from the free surface  117  to the optical coupling interface  118 .  FIG. 6C  illustrates several waveguides  115  arranged for expanded coupling, in which the number and order of the waveguides  115  remain consistent, but the spacing increases from the free surface  117  to the optical coupling interface  118 .  FIG. 6D  illustrates several waveguides  115  arranged with swapped ordering, in which the number of waveguides  115  remain consistent, the relative order of the waveguides  115  at the free surface  117  is different than at the optical coupling interface  118 . The spacing and order of the various waveguides  115  may be adjusted to account for various standards used on the connector side and the PIC side of an assembly, to allow a PIC  120  to use a different standard than the external fiber optic plug  210 . 
       FIG. 6E  illustrates several waveguides  115  arranged for combined coupling, in which several waveguides  115  defined at the free surface  117  combine into one waveguide  115  at the optical coupling interface.  FIG. 6F  illustrates several waveguides  115  arranged for split coupling, in which one waveguides  115  defined at the free surface  117  splits into multiple waveguides  115  at the optical coupling interface. Waveguides  115  may split/combine signals for various purposes in signal processing, such as for amplifying, extinguishing, or accepting multiple signals for a single output. 
       FIG. 6G  illustrates several waveguides  115  arranged with several unused pathways. In some embodiments, the unused pathways have no waveguide  115  defined between the free surface  117  and the optical coupling interface  118 . In other embodiments, waveguides  115  are defined between the free surface  117  and the optical coupling interface  118 , but a corresponding integrated waveguide  125  or fiber waveguide  215  is not present or couple with the waveguide  115  on the unused path. 
       FIG. 7  illustrates an example substrate layout  700 . The example layout  700  shows four dies  710  for various photonic elements, although more or fewer dies  710  may be present on other substrates with different layouts  700 . Each of the dies  710  is shown with a first surface on which several features have been produced via etching. These features may include features that protrude from the first surface of the die  710  as well as features that extend into the die  710  from the first surface based on the patterned region  113  applied to the material of the substrate. Several dice-lines  720  are illustrated between the dies  710  that indicate where a physical etching operation may be performed to separate the dies  710  from the substrate and one another. 
       FIGS. 8A-D  illustrate detailed views of engaging engagement features  111  and mating features  121  of the PIC  120 . Each of the detailed views is illustrated relative to a thickness (T) of the features and a width (W) of the features, which may correspond to various planes in the optoelectronic device  100  depending on the orientation of the engagement feature  111  and the mating feature  121 . 
       FIG. 8A  illustrates engaging an engagement feature  111  with a mating feature  121 , according to one embodiment disclosed herein. Specifically,  FIG. 8A  illustrates a cross section of a male engagement feature  111  and a female mating feature  121 , but other embodiments may switch which of the engagement feature  111  and the mating feature  121  is male/female. In one embodiment, these features may form a frustum and a rectangular trench, respectively. 
       FIG. 8A  illustrates a desired target location  810  where a middle of the engagement feature  111  aligns with a middle of the mating feature  121 . That is, for optimal alignment, the middle of the engagement feature  111  contacts the middle of a bottom surface  830  of the mating feature  121 . In this example, the mating feature  121  includes a trench or cutout in an Inter-Layer Dielectric (ILD) on the top of the PIC  120 . The ILD may be formed on a substrate of the PIC  120 , which may be a semiconductor substrate such as crystalline silicon. 
     In this example, a bottom surface  850  of the engagement feature  111  contacts the bottom surface  830  of the mating feature  121 . Moreover, as discussed in more detail below, the engagement feature  111  includes self-correcting alignment features  820  (e.g., the slanted sides of the engagement feature  111 ) which contact sides  825  of the mating feature  121  for correcting the alignment of the optical adapter  110  and the PIC  120  when the middles of the engagement feature  111  and the mating feature  121  are not aligned. 
       FIGS. 8B-D  illustrate mating a misaligned engagement feature  111  with a mating feature  121 , according to embodiments disclosed herein.  FIG. 8B  illustrates a scenario where the middle of the engagement feature  111  is offset  840  from the desired target location  810 . The difference between the offset  840  and the target location  810  is illustrated as a misalignment  845 . Stated differently, the misalignment  845  is the distance between respective middles of the engagement feature  111  and the mating feature  121 . 
     The misalignment  845  can occur because of tolerances corresponding to the bonding machine or apparatus (e.g., a die bonder) used to place the optical adapter  110  on the PIC  120 . For example, the die bonder may guarantee that the middle of the engagement feature  111  is within ±10 micrometers from the middle of the mating feature  121  (e.g., the desired target location  810 ).  FIG. 8B  illustrates a worst case scenario where the misalignment  845  is the maximum tolerance of the bonding machine. 
     To compensate for the tolerance or accuracy of the bonding machine, the engagement feature  111  is designed such that regardless of the misalignment  845 , the self-correcting alignment feature  820  contacts a side  825  of the mating feature  121 . That is, the width (W) of the engagement feature  111  can be controlled such that the flat, bottom surface  850  of the engagement feature  111  falls within the mating feature  121 , and as a result, at least one of the self-correcting alignment features  820  contacts one of the sides  825 . 
     The accuracy of the alignment in  FIG. 8B , where the bottom surface  850  of the engagement feature  111  contacts the bottom surface  830  of the mating feature  121 , may depend on the amount of control of the flatness of the bottom surface  850  on the engagement feature  111  and the tolerance on the etch depth of the mating feature  121  (which can be around +/−0.5 micrometers for many dielectrics). Moreover, the slope of the self-correcting alignment features  820  can be tightly controlled using an orientation dependent etch, such as a KOH etch, a denser application of the patterned region  113 , and the like. 
     In  FIG. 8B , when the die bonder moves the optical adapter  110  in the vertical direction illustrated by the arrow  860 , the bottom surface  850  is between the sides  825 A and  825 B. Thus, even at maximum misalignment  845 , the bottom surface  830  is within the mating feature  121 . 
     As the optical adapter  110  continues to move in the direction shown by the arrow  860 , the self-correcting alignment feature  820 A contacts the side  825 A which is illustrated in  FIG. 8C . The die bonder continues to apply downward pressure, but the resulting contact between the alignment feature  820 A and the side  825 A creates a horizontal motion as shown by the arrow  865 , which moves the middle of the engagement feature  111  closer to the middle of the mating feature  121 . That is, in one embodiment, the die bonder does not apply the horizontal motion directly (e.g., the die bonder may apply pressure in the vertical direction) for the optical adapter  110  to move horizontally relative to the PIC  120  to correct for the misalignment  845 . The vertical pressure applied by the die bonder is converted into the horizontal motion illustrated by the arrow  865  to align the piece parts. 
       FIG. 8C  illustrates when the die bonder has moved the parts until the bottom surface  850  of the engagement feature  111  contacts the bottom surface  830  of the mating feature  121 . The middles of the engagement feature  111  and the mating feature  121  may both be aligned at the target location  810 , although there may be some remaining misalignment due to the tolerances of the fabrication steps used to form the engagement feature  111  and the mating feature  121 . However, the tolerances for processing the engagement feature  111  and the mating feature  121  may be much smaller or tighter than the tolerances for the die bonder—e.g., within +/−500 nanometers. For example, the engagement feature  111  may be defined via a laser imparting a patterned region  113  in the material of the optical adapter  110 . Similarly, the techniques for defining and etching the mating feature  121  can have much tighter tolerances than the die bonder. 
     Each of the engagement feature  111  and the mating feature  121  are aligned relative to the waveguides  115 ,  125  to ensure optical coupling therebetween without the use of active testing. For example, the engagement feature  111  is defined relative to the waveguide  115  and the mating feature  121  is defined relative to the integrated waveguide  125  with a high enough degree of precision (e.g., with a tolerance within +/−500 nanometers) to ensure that when the optical adapter  110  is affixed to the PIC  120 , that the waveguide  115  is optically aligned with the integrated waveguide  125 . The laser may define the engagement feature  111  and the waveguide  115  simultaneously (or at separate times, using a shared alignment point) to ensure the high degree of precision. Similarly, a laser may define the mating feature  121  and the integrated waveguide  125  simultaneously (or at separate times, using a shared alignment point). The alignment features  820  ensure that the precision in fabrication of the engagement feature  111  is maintained during assembly of the optical adapter  110  with the PIC  120 . 
       FIG. 9A  illustrates mating the engagement feature  111  with the mating feature  121 . Unlike in  FIG. 8D , where the bottom surface  850  of the engagement feature  111  contacts the bottom surface  830  of the mating feature  121 , in this example, there remains a gap between the bottom surface  850  of the engagement feature  111  and the bottom surface  830  of the mating feature  121 . Instead, the thickness of the engagement feature  111  is controlled such that a mating interface  116  of the optical adapter  110  at a base of the frustum formed by the engagement feature  111  contacts a mating surface  126  of the PIC  120 . 
     In one embodiment, given the tolerances associated with the fabrication steps forming the engagement feature  111  and the mating feature  121 , at least one of the self-correcting alignment features  820  may contact one of the sides  825  when aligned, while at least one other of the self-correcting alignment features  820  does not. However, in other embodiments, multiple alignment features  820  may contact respective sides  825  when aligned. 
       FIG. 9B  illustrates engaging the engagement feature  111  with the mating feature  121 . In this example, the width of the engagement feature  111  is again controlled such that the bottom surface  850  fits inside the sides  825  regardless of any misalignment. However, instead of alignment being achieved when a mating interface  116  of the optical adapter  110  contacts a mating surface  126  of the PIC  120 , here the optical adapter  110  is aligned when the self-correcting alignment feature  820  on one side of the engagement feature  111  and the self-correcting alignment feature  820  on the opposite side of the engagement feature  111  both contact respective sides  825  of the mating feature  121 . Although  FIG. 9B  illustrates the self-correcting alignment feature  820 A contacting the side  825 A and the self-correcting alignment feature  820 B contacting the side  825 B, more or fewer self-correcting alignment features  820  (e.g., a circular mating feature  121  may have one continuous edge forming multiple “sides”  825  when viewed in cross-section) in the engagement feature  111  may contact respective sides  825  of the mating feature  121 . Contacting two oppositely disposed self-correcting alignment features  820  to two sides  825  of the receiver provide alignment in a given plane. Moreover, when a third self-correcting alignment feature  820  (which is disposed between the two oppositely disposed alignment features) contacts a side  825  of the mating feature  121 , this can provide alignment in a further direction or plane. 
       FIG. 9C  illustrates engaging the engagement feature  111  with the mating feature  121 .  FIG. 9C  relies on a similar alignment principle in  FIG. 9B  where at least two opposing self-correcting alignment features  820  contact respective sides  925  of a trench—e.g., a deep alignment receiver  905 . However, instead of forming the engagement feature  111  solely within an ILD, in  FIG. 9C , the deep alignment receiver  905  extends into the substrate of the PIC  120 . In one embodiment, the deep alignment receiver  905  may have a depth greater than 15 micrometers. Further, the depth of the deep alignment receiver  905  may permit the engagement feature  111  to have a pyramidal shape rather than a frustum shape as shown in  FIG. 9C . That is, the self-correcting alignment features  820  may intersect at a point rather than forming a flat bottom surface  850  facing the bottom surface  830  of the deep alignment receiver  905 . 
     One advantage of using the alignment technique illustrated in  FIGS. 9B and 9C  is that the spacing between the mating interface  116  of the optical adapter  110  and the mating surface  126  of the PIC  120  can be filled with epoxy for bonding the two components together (e.g., providing an epoxy well produced by physically processing or chemically etching the substrates). However, relying on contact between the self-correcting alignment features  820  and the sides can cause stress which may increase the likelihood of chipping the sides  825 . 
       FIG. 10  is a flowchart illustrating high level operations of an example method  1000  for the use of laser patterning in optical components. Method  1000  begins at block  1010 , where a laser is aligned with a substrate. In various embodiments, a given feature (such as an etched or plated “+” mark, circle or fiducial) in a die  710  of the substrate or the substrate itself is selected as an alignment point. The laser may be aligned in one plane (e.g., a two-dimensional alignment) or in three dimensions relative to the substrate. 
     At block  1020 , the laser applies a pattern to the material of the substrate. The laser applies the pattern relative to the alignment point to define an etching pattern to the substrate. The etching pattern designates portions of the substrate as patterned regions  113 , and the portions to which the etching pattern is not applied as un-patterned regions  114 . By applying the etching pattern, the laser alters a chemical bond in the material of the substrate for the patterned region  113  that increases a reactivity of the material in the patterned region  113  to an etchant relative to a reactivity of the material in the un-patterned regions  114 . The patterned region  113  thus may define the engagement feature  111 , cable connectors  112 , etc., in the un-patterned region  114  that will remain after chemical etching, which are configured to engage with a mating feature  121  on an optoelectronic device  100  or an external cable. 
     In addition to applying the etching pattern at block  1020 , the laser may also apply waveguide patterns to the substrate at block  1020 . The waveguide pattern defines one or more pathways (i.e., waveguides  115 ) through the material of the die  710  with different refractive indices that the surrounding material to direct the propagation of light through the material. The waveguides  115  may have first ends that are co-aligned with the engagement features  111 , to ensure optical coupling with the integrated waveguides  125  of the PIC  120  when mounted. Similarly, the waveguides  115  may have second ends that that are co-aligned with the cable connectors  112 , to ensure optical coupling with an external cable. 
     In some embodiments, the laser defines where the waveguide pattern is located simultaneously with where the etching pattern is applied relative to the alignment point and imparts the patterns simultaneously. In other embodiments, the etching pattern is applied relative to the alignment point, and the waveguide pattern is later applied relative to the etching pattern (e.g., after a chemical etch). In further embodiments, the waveguide pattern is applied relative to the alignment point, and the etching pattern is later applied relative to the waveguide pattern. 
     At block  1030 , optional physical processing may occur. A drill, laser ablator, saw, water jet, or the like may physically etch or processes through-holes  430  or channels  480  in a first surface of the die  710  to direct the flow of a chemical etchant, to remove excess material before a chemical etchant is applied, or to apply features to the die  710  that require less precision than the engagement features  111 , cable connectors  112 , and waveguides  115 . In some embodiments, block  1030  may be performed after block  1040  to separate various dies  710  from one another in a substrate layout  700 , to impart labels, or the like. 
     At block  1040 , a chemical etchant is applied to the die  710 . The etchant reacts with the material of the die  710 , thereby removing material from the physically exposed surfaces of the die  710  and physically exposing the underlying material. The patterned regions  113  (i.e., those portions of the die  710  to which the laser applied the etching pattern) react more vigorously with the etchant, in some cases up to 5000 times more vigorously, and thus lose material faster than the un-patterned regions  114 . The patterned regions  113  thus define what material is left behind in the un-patterned regions  114  once chemical etching concludes, including the engagement features  111 , cable connectors  112 , and various surfaces of the photonic element defined in the die  710 . 
     At block  1050 , after chemical etching (per block  1040 ), the photonic element (waveguides, lenses, and other optical features) is detailed. In various embodiments, detailing the photonic element may include dicing the photonic element from the substrate, polishing at least one surface of the photonic element, or affixing the photonic element to a second photonic element (e.g., in a multi-piece design). 
     At block  1060 , the photonic element is integrated into the optoelectronic device  100 . A die bonder may align the engagement features  111  with the mating features  121  of the PIC  120  and connect the engagement features  111  with the mating features  121 . In various embodiments, the engagement features  111  (or the mating features  121 ) are designed with various self-correcting alignment features  820  that improve the precision at which the die bonder may integrate the engagement features  111  with the mating features  121 . The precision at which the engagement features  111  with the mating features  121  are connected influences where the waveguides  115  and the integrated waveguides  125  are positioned relative to one another. By fabricating the engagement features  111  of an optical adapter  110  with the precision afforded by laser patterning, (e.g., with tolerances with ±500 nanometers) a die bonder may affix the optical adapter  110  with similar precision, and thus passively align the waveguides  115  of the optical adapter  110  with the integrated waveguides  125  of the PIC  120  (i.e., without requiring active alignment and test). As part of affixing the photonic element to optoelectronic device  100 , the die bonder may apply and cure an epoxy to form epoxy joints  130  that secure the separate components together. In other embodiments, the thermocompression or wafer bonding processes may be used in addition to or instead of die or epoxy bonding. 
     After the photonic element is integrated into the optoelectronic device  100 , various tests of the optical coupling, dimensioning, loss ratios, extinction ratios, and the like may be performed, and method  1000  may then conclude. 
     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). 
     In view of the foregoing, the scope of the present disclosure is determined by the claims that follow.