WO2017127455A1

WO2017127455A1 - Precision mounting of laser diodes and other optical component

Info

Publication number: WO2017127455A1
Application number: PCT/US2017/013986
Authority: WO
Inventors: James Thomas Triplett; Gregory David Miller; John Frederick ARNTSEN; Gennady Imeshev; Dzhakhangir V. Khaydarov
Original assignee: Dolby Laboratories Licensing Corporation
Priority date: 2016-01-21
Filing date: 2017-01-18
Publication date: 2017-07-27

Abstract

A material removal process is applied to remove substrate material portions from a substrate to create a recessed pocket in the substrate. The substrate comprises substrate materials with an unprocessed surface before the material removal process. The recessed pocket represents a spatial cavity cut into the substrate, and has a top surface corresponding to a portion of the unprocessed surface and a bottom surface below the portion of the unprocessed surface. A bonding material is deposited in the recessed pocket. Relief channels are created in the recessed pocket. A bonding process is applied to place an optical component into direct surface contact with hard stop portions among remaining portions of unprocessed surface of the substrate. In particular, the bottom surface of the recessed pocket is a tapered bottom surface relative to the unprocessed surface of the substrate, and the tapered bottom surface having a depth of the recessed pocket increasing along a longitudinal direction of the recessed pocket.

Description

PRECISION MOUNTING OF LASER DIODES AND

OTHER OPTICAL COMPONENT

CROSS-REFERENCE TO RELATED APPLICATIONS

[001] This application claims priority to United States Provisional Patent Application No. 62/281,594, filed on January 21, 2016 and European Patent Application No. 16157876.0, filed on February 29, 2016, each of which is incorporated herein by reference in its entirety. TECHNOLOGY

[002] The present invention relates generally to precise positioning of components. More particularly, embodiments of the present invention relates to precise positioning of optical components in a height dimension relative to substrates.

BACKGROUND

[003] Light emitters such as laser diodes may act as light sources for other optical components. However, the other optical components to which the laser diodes are to be commonly aligned may have very different bonding requirements than the laser diodes. For example, the other optical components and the laser diodes may specify uses of different metallized layers, different bonding materials, different thickness of bonding materials, etc.

[004] The laser diodes may be soldered to a substrate, whereas one or more of the other components may be bonded to the same substrate or other substrates with adhesive materials. Solder materials, adhesive materials, and other intervening layers, which are involved in bonding the laser diodes and the other optical components to the substrate(s), produce variable tolerance stack-ups on the finished heights of optical axes of the laser diodes and the other optical components relative to the substrate(s).

[005] As a result, the other optical components and the laser diodes likely experience mismatched tolerance stack-ups between the optical components and the laser diodes. This can prevent the laser diodes and the other optical components from being vertically aligned to form high quality optical coupling, even on the same substrate. Compensation by using lenses, mirrors, and vertical height adjustment operations, may be used to correct

misalignments of the optical axes. However, these additional compensatory components and operations significantly add to cost and time in manufacturing optical modules/devices, and reduce overall optical and system efficiencies and reliabilities in these optical

modules/devices .

[006] The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. Similarly, issues identified with respect to one or more approaches should not assume to have been recognized in any prior art on the basis of this section, unless otherwise indicated.

BRIEF DESCRIPTION OF DRAWINGS

[007] Drawings accompanying this specification are for illustration purposes only, and do not necessarily represent scaled drawings. Further, the present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

[008] FIG. 1A illustrates a sideview of an example substrate;

[009] FIG. IB illustrates a sideview of an example recessed pocket;

[0010] FIG. 1C and FIG. ID illustrate an example optical component placed over a recessed pocket formed in a substrate;

[0011] FIG. 2A and FIG. 2B illustrate an example substrate on which multiple optical components can be bonded with precise height positions;

[0012] FIG. 3A through FIG. 3C illustrate example recessed pockets formed on a substrate;

[0013] FIG. 4 illustrates an example recessed pocket with a tapered bottom;

[0014] FIG. 5A, FIG. 5B, FIG. 6A and FIG. 6B illustrate example laser diode bars bonded to solder layers deposited in recessed pockets formed in substrates;

[0015] FIG. 7A and FIG. 7B illustrate an example material removal process used to produce one or more recessed pockets on a substrate; and

[0016] FIG. 8A and FIG. 8B illustrate example process flows.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[0017] Example embodiments, which relate to precise positioning of components, are described herein. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, that the present invention may be practiced without these specific details. In other instances, well-known structures and devices are not described in exhaustive detail, in order to avoid unnecessarily occluding, obscuring, or obfuscating the present invention. [0018] Example embodiments are described herein according to the following outline:

1. GENERAL OVERVIEW

2. RECESSED POCKET(S)

3. ALIGNING OPTICAL AXES OF MULTIPLE OPTICAL

COMPONENTS

4. RELIEF CHANNELS, OVERFLOW SECTIONS AND SUPPLY

WELLS

5. DUAL FUNCTIONALITY OF LASER SUBSTRATE AND

LASER BASEPLATE

6. RECESSED POCKET WITH TAPERED BOTTOM

7. LASER MICROMACHINING IN BONDING MATERIAL AND

SUBSTRATE

8. LASER MICROMACHINED GROOVES IN SUBSTRATE

9. EXAMPLE EMBODIMENTS

10. EQUIVALENTS, EXTENSIONS, ALTERNATIVES AND

MISCELLANEOUS

1. GENERAL OVERVIEW

[0019] This overview presents a basic description of some aspects of an example embodiment of the present invention. It should be noted that this overview is not an extensive or exhaustive summary of aspects of the example embodiment. Moreover, it should be noted that this overview is not intended to be understood as identifying any particularly significant aspects or elements of the example embodiment, nor as delineating any scope of the example embodiment in particular, nor the invention in general. This overview merely presents some concepts that relate to the example embodiment in a condensed and simplified format, and should be understood as merely a conceptual prelude to a more detailed description of example embodiments that follows below.

[0020] Techniques as described herein can be used to bond optical components to a substrate such that these optical components are placed at precise post-bond heights (e.g., a common height) in relation to a reference plane associated with the substrate and/or in relation to one another of the optical components.

[0021] An optical component (e.g., a laser diode bar, etc.) may refer to a discrete or unitary optical component, which may further comprise one, two or more optical subcomponents (e.g., laser diodes in the laser diode bar, etc.). Examples of optical components (and/or optical sub-components) include, but are not limited to only, any of: laser diodes, laser diode bars, light emitting diodes, optical waveguides, optical waveguide bars, microlens, diffraction gratings, prisms, mirrors, planar lightwave circuits, or waveguides, optoelectric components, combinations of the foregoing, etc. A laser diode may comprise a structure having a p-n junction, an active region that converts electric energy into laser light, a waveguide such as a ridge waveguide, a cladding layer, a physical edge surface possibly metallically coated for electric and/or heat conduction, etc. Laser diodes or laser diode bars containing laser diodes are some example light emitters that can be bonded to substrates using techniques as described herein.

[0022] As used herein, the term "post-bond height" of an optical component may refer to a height of the optical component in a height dimension (e.g., a z dimension, etc.) relative to a substrate after a bonding process used to bond the optical component to the substrate has been completed. The bonding process may cause the optical component to be bonded to the substrate based on a solder-based physical bonding, an adhesive-based physical bonding, etc. The height of the optical component can be represented by a height of one or more optical axes of the optical component. Additionally, optionally, or alternatively, the height of the optical component can be represented by a height of one or more specific points on one or more optical axes of the optical component.

[0023] Techniques as described herein may be used to spatially align optical axes of two or more optical components (e.g., a laser diode and a corresponding optical waveguide, etc.) into a single post-bond common optical axis. In some embodiments, the optical axes of the two or more optical components can be aligned around the post-bond common optical axis within a specific tolerance such as 1 milliradian, 0.1 angular degree, 0.2 angular degree, etc. For example, an optical axis of a laser diode in a laser diode bar can be aligned with an optical axis of a corresponding optical waveguide in an optical waveguide bar into a single post-bond common optical axis or around the single post-bond common optical axis within a specific tolerance such as 1 milliradian, 0.1 angular degree, 0.2 angular degree, etc.

[0024] Techniques as described herein may also be used to spatially align a first spatial point of a first optical component and a second spatial point of a second optical component into a single post-bond common height. For example, these techniques can be applied to align a laser beam egress point on an endface of a laser diode in a laser diode bar to a single post- bond common height with a laser beam ingress point on an endface of an optical core of an optical waveguide in a laser waveguide bar. Here, the laser beam egress point of the laser diode may be a central point at an emitting edge of the laser diode on an optical axis of the laser diode. The laser beam ingress point of the optical core of the optical waveguide may be a central point at a light receiving edge of the optical core of the optical waveguide on an optical axis of the optical waveguide.

[0025] In some optical applications, strict collimation of optical axes of a light output optical component and a light input optical component is not necessary. If an endface of a light emission area of the light output optical component is positioned close enough (e.g., within a micometer, within 0.5 micrometer, within 0.3 micrometer, etc.) to an endface of a light ingress area of the light input optical component, high quality optical coupling can still be achieved, without necessarily collimating optical axes of the two optical components. For example, light emitted out of the light emission area can still be effectively (e.g., 99%, 98%, 95%, 90%, etc.) injected into the light ingress area as the light emission area is positioned close to the light ingress area, even if the optical axes of the two optical components have a collimation error of less than 1 milliradian, less than one (1) angular degree, less than one half (1/2) angular degree, etc.

[0026] In a non-limiting example, the common height to which the optical components are precisely positioned under techniques as described herein may be the distance (e.g., 1.2 micrometers, 1.5 micrometers, 1.8 micrometers, etc.) between a central point of a light emissive area on an endface of the laser diode and a bottom ege (which, for example, may be perpendicular to the endface of the laser diode) of a corresponding ridge waveguide (e.g., as a part of the laser diode, etc.) located next to, or surrounds in part or in whole, an active region of the laser diode. The active region of the laser diode refers to an interior region of the laser diode where lasing occurs or where energy of an electric current flowing through a p-n junction is at least partly converted into laser light. Under techniques as described herein, in some embodiments, the bottom edge of the ridge waveguide of the laser diode may be placed, or hard stop, against hard stop points/surfaces on a substrate to which the laser diode, or a laser diode bar that includes the laser diode, is to be bonded.

[0027] Under other approaches that do not implement techniques as described herein, bonding of optical components to substrates (or baseplates) suffers from imprecise post-bond heights of optical axes due to variability of solder or adhesive thickness under the optical components. In contrast, under the techniques as described herein, variability of optical component positioning (e.g., height positioning of optical axes, etc.) caused by variable solder or adhesive bond joint thickness under optical components is eliminated.

[0028] More specifically, under the techniques as described herein, variable thickness of a bonding material used to bond an optical component with a substrate is excluded from becoming any factor in determining a specific post-bond spatial location (e.g., height, etc.) of the optical component in relation to a spatial reference such as a surface of the substrate.

[0029] A recessed pocket is formed on a substrate by cutting or ablating materials away from a designated portion of the substrate at or below an unprocessed surface. In an example, the recessed pocket can be created by cutting away (e.g., ablating, etc.) one or more portions of materials from the substrate through laser micromachining (e.g. through a laser beam such as a continuous-wave or pulsed laser beam), without adding pedestals, pillars, standoff structures to a substrate. In particular, the thickness of the recessed pocket may vary along a longitudinal direction of the recessed pocket. In other words, the recessed pocket may have a tapered bottom surface which is relative to the unprocessed surface of the substrate. In some embodiments, a laser beam for cutting/ablating one or more portions of materials from the substrate (i.e. to perform a material removal process) may be adjusted based on a location along a longitudinal direction of the recessed pocket. For example, parameters such as light intensity and/or duty cycle of a laser beam may be adjusted to vary in different locations of the recessed pocket. The light intensity of a laser beam applied at one side of the recessed pocket may be lower than that applied at the other side of the recessed pocket, so that the thickness at the other side of the recessed pocket is larger than the thickness at the one side of the recessed pocket. By this way, the recessed pocket can have a depth which is varied increasingly or decreasingly along the longitudinal direction, so as to create a tapered bottom surface for the recessed pocket.

[0030] A bonding material such as solder, adhesive, etc., can be deposited in the recessed pocket. Through a bonding process (e.g., a reflow process, a welding process, an adhesive bonding process, a contact bonding process, etc.), an optical component that is placed on top of the bonding materials in the recessed pocket can establish a physical bonding with the substrate. The depth of the recessed pocket can be made not only to attain sufficient thickness (which may vary with a height tolerance and/or reach a height above the unprocessed surface of the substrate at the beginning of the bonding process) of the bonding material to achieve a designated bonding strength between the optical component and the substrate, but also to allow the bonding material to be contained in the recessed pocket with no or little

overflowing out of the recessed pocket during or in the aftermath of the bonding process. For example, with a tapered bottom surface of the recessed pocket as described above, a bonding material deposited in the recessed pocket (e.g. a solder layer) may have a shallow end portion at one side of the recessed pocket having a smaller thickness, and the shallow end portion may be at least partially above a reference plane (e.g. a surface of the substrate). This ensures a relatively high quality contact between the bonding material and an optical component to be bounded to the substrate over the bonding material. Furthermore, the bonding material may have a deep end portion at the other side of the recessed pocket having a larger thickness, and the deep end portion may be below the reference plane, which allows excess bonding material portions to be displaced toward the deep end to prevent the optical component from floating on top of the bonding material. Accordingly, by optimizing distribution of the bonding material within the recessed pocket using such tapered bottom surface of the recessed pocket, high quality contact between the bonding material and the optical component as well as stable positioning of the optical component over the bonding material on the substrate can be provided, which ensures precise placement of optical axes of the optical component. Correspondingly, techniques as described herein may be also directed to a mounting device for an optical component which includes a substrate comprising an unprocessed surface and a recessed pocket deposited in the substrate. The recessed pocket may represent a spatial cavity cut into the substrate caused by a material removal process. Further, the spatial cavity may have a top surface corresponding to a portion of the unprocessed surface and a bottom surface below the portion of the unprocessed surface. In particular, the bottom surface of the recessed pocket may be a tapered bottom surface relative to the unprocessed surface of the substrate, and the tapered bottom surface may have a depth of the recessed pocket increasing along a longitudinal direction of the recessed pocket. The mounting device also comprises a bonding material in the recessed pocket and one or more relief channels in the recessed pocket. The mounting device further comprises one or more hard stop portions among remaining portions of unprocessed surface of the substrate that remain after the material removal process.

[0031] For example, a laser diode bar that comprise one or more laser diodes can be bonded as a (e.g., unitary, discrete, etc.) optical component with a metalized substrate through a solder material deposited in a recessed pocket formed on the metalized substrate. Optical axes of laser diodes in the laser diode bar can be precisely placed at a specific post- bond height above a heigh reference surface on the metalized substrate such that any spatial dimension (e.g., thickness, etc.) of solder used in the solder-based physical bonding is excluded from becoming a factor in detrmining the specific post-bond height of the optical axes of the laser diodes.

[0032] In some embodiments, other optical components such as optical waveguides in an optical waveguide bar, etc., can be bonded with the same substrate through an adhesive material deposited in another recessed pocket formed on the metalized substrate. While thicknesses of the adhesive material and the solder material and/or depths of the recessed pockets may vary, optical axes of optical waveguides in the optical waveguide bar can be precisely placed at the same specific post-bond height as the laser diodes in the laser diode bar in relation to (e.g., above, etc.) the heigh reference surface such that any thickness of the adhesive or solder materials used in any of these physical bondings is excluded from becoming a factor in detrmining the specific post-bond height of the optical axes of the optical waveguides and the (e.g., same) specific post-bond height of the optical axes of the laser diodes.

[0033] As used herein, a hard stop reference plane may be a specific surface of a substrate. For example, the hard stop reference plane may be an unprocessed surface of the substrate before a recessed pocket is created or formed on the substrate to hold a bonding material such as solder, adhesive, etc., for the purpose of bonding optical components to the substrate. The recessed pocket comprises a bonded top surface that corresponds to a surface portion on the unprocessed surface of the metalized substrate.

[0034] In some embodiments, x and y dimensions of (e.g., a main section of, etc.) a recessed pocket are made (e.g., slightly, 5%, 10%, etc.) smaller than x and y dimensions of an optical component that is to be bonded with a bonding material deposited in the recessed pocket to the substrate. The x and y dimensions refer to spatial dimensions that are orthogonal to the height dimension or the z dimension. The optical component can be placed over (e.g., the main section of, etc.) the recessed pocket during the bonding process in such a way that the optical component "hard stops" against the substrate at substrate surface portions (or one or more hard stop portions) beyond and adjacent to the edges or perimeters of the recessed pocket.

[0035] As used herein, the phrase "an optical component hard stops against (hard stop points or surfaces of) a substrate" means that designated hard stop contact portions (e.g., edges, ridge waveguides, bottom surface portions, etc.) of the optical component are pressed along the z dimension in a bonding process onto direct surface contact (without any intervening layer or gap in between) with (the hard stop points or surfaces of) the substrate. The hard stop portions (hard stop points and/or surfaces) may, but is not required to, be covered by bonding material portions (e.g., solder, adhesive, etc.) at the beginning of the bonding process. The bonding material portions if existing on the hard stop portions may be expelled or pushed off during the bonding process from the hard stop portions and the hard stop contact portions of the optical component such that there is no or little bonding material thickness between the hard stop portions of the substrate and the designated hard stop contact portions of the optical component at the end of the bonding process.

[0036] The direct surface contact between the optical component and the substrate at the substrate surfaces ensures that a post-bond height of an optical axis of the optical component is not affected by any variable height of solder or adhesive used to bond the optical component with the substrate.

[0037] By way of example but not limitation, consider a scenario in which output light emission of an optical component such as a laser diode bar is to be optically coupled to subsequent optical components such as optical waveguides, fiber optics or other optical components. Heights of optical axes of optical components subsequent to the laser diode bar in the optical path can be engineered to be equal to a height of the optical axes of the laser diode bar within a spatial range (or a spatial tolerance) that supports efficient optical coupling. All of the optical components with the equal (optical axis) height can be placed on hard stop points or surfaces of a substrate, where the hard stop points or surfaces may be adjacent to recessed pockets formed on the substrate to bond the optical components to the substrate. The hard stop points or surfaces of the substrate may be parts of an unprocessed surface of the substrate and may be of the equal height (which may lie on the same hard stop reference plane). Being of the equal (optical axis) height and being placed on the hard stop points or surfaces of the equal heigh, these optical components can be (e.g., inherently, precisely, etc.) aligned without being affected by variable thicknesses of bonding material layers in the vertical dimension or the height dimension.

[0038] In some embodiments, a height or heights of optical axes of laser diodes in a laser diode bar can be precisely known or pre-engineered with respect to physical (e.g., bottom, etc.) edges of ridge waveguides of the laser diodes. In some embodiments, during a bonding process that bonds the laser diode bar to a substrate, the top edges of the ridge waveguides of the laser diodes (e.g., p-side down when bonded to the substrate, etc.) hard stop against (e.g., the unprocessed surface of, etc.) the substrate. The post-bond height from the substrate to the optical axes of the laser diodes in the laser diode bar is therefore only a function of the inherent height of the optical axes of the laser diodes in the laser diode bar relative to the top edges of the ridge waveguides of the laser diodes in the laser diode bar, and is invariant with respect to solder or adhesive thickness variability. The height of optical axes of optical waveguides, fiber optics or other optical components can also be precisely known or pre- engineered. A post-bond height of optical axes of the optical waveguides, fiber optics or other optical components is likewise only a function of the inherent height of the optical axis, and is invariant to variable solder or adhesive thickness.

[0039] As a result, under techniques as describe herein, efficient optical coupling can be formed (e.g., with possibly additional horizontal adjustments automatically and/or efficiently performed, etc.) among the optical components bonded to the substrate, as the optical axes of these optical components can be aligned to a common height.

[0040] Highly accurate height precision achieved under techniques as described herein makes it feasible to align optical components with little or no active vertical alignment adjustments in the bonding process and/or with little or no post-bond vertical alignment adjustments. Thus, automated, mass production of optical modules, optical devices, complex laser systems, etc., becomes feasible under techniques as described herein.

[0041] Various modifications to the preferred embodiments and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the disclosure is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein.

2. RECESSED POCKET(S)

[0042] FIG. 1A illustrates a sideview (or a cross sectional view) of an example substrate 100 on which one or more optical components can be bonded. Example substrates include but are not limited to only, any of: a metallic layer alone, a non-metallic layer alone, a

combination of one or more metallic layers and one or more non-metallic layers, etc. As illustrated in FIG. 1A, the substrate (100) comprises a ceramic substrate 104 and a metalized layer 106. In some embodiments, the matalized layer can serve an electric conductor (e.g., anode, cathode, an electrode for p- or n-side of a p-n junction of a laser diode, etc.) for electric current. Additionally, optionally, or alternatively, the metalized layer can also serve as a heat conductor for (e.g., rapid, efficient, etc.) heat removal/transportation/dissipation.

[0043] Under techniques as described herein, an optical component can be bonded to the substrate (100) at a precise spatial location along a specific spatial dimension that is free from any variable bonding layer. For the purpose of illustration only, a spatial location along the specific spatial dimension is denoted as a height. For example, the precise spatial location may be a height in relation to a hard stop reference plane 102 that is stationary to the substrate (100). In some embodiments, the hard stop reference plane (102) may represent an unprocessed upper surface 150 of the substrate (100) as illustrated in FIG. 1A before substrate materials are removed from the substrate (100) to create a recessed pocket as described herein. [0044] FIG. IB illustrates a sideview (or a cross sectional view) of an example recessed pocket 108 that is formed or made in the substrate (100) by removing substrate materials from the substrate (100) underneath a portion of the unprocessed upper surface (150 of FIG. 1A) of the substrate (100). The portion of the unprocessed upper surface (150 of FIG. 1 A) of the substrate (100) represents a top surface of the recessed pocket (108). A bonding material such as solder, adhesive, etc., can be deposited in the recessed pocket (108). An optical component can be placed on top of the recessed pocket (108) to form a physical bonding with the substrate (100) through the bonding material in the recessed pocket (108).

[0045] The recessed pocket (108) on the substrate (100) can be designed with

mechanisms (e.g., relief channels, supply wells, overflow regions, additional recessed pocket portions, etc.) to compensate for any variable thickness or height of the bonding material and effectively decouple the hard stop reference plane (102) from a variable height - at which the optical component is placed against the bonding material in the beginning of a bonding process - of the bonding material deposited in the recessed pocket (108).

[0046] The recessed pocket (108) can be precisely laser micromachined (or laser machined) or etched. In some embodiments, recessed pockets as described herein can be cut or etched directly into the metalized layer (106) which is on top of the ceramic substrate (104). Additionally, alternately, or optionally, recessed pockets can be cut or etched into the ceramic substrate (104) commonly used for laser diodes in preparation for the metallization step. Pillars or pads (denoted as hard stop 110 in FIG. IB) formed by substrate materials that have not been cut away can be left behind from the laser micromachining or etching process to provide (intermediate or perimeter) hard stop points, hard stop surfaces, etc., to support the optical component via direct surface contacts between the optical component and the substrate (100).

[0047] FIG. 1C and FIG. ID illustrate cross sectional and perspective views of an example optical component (e.g., a laser diode bar 130, etc.) placed over a bonding material (e.g., a solder layer 112, etc.) deposited in a recessed pocket (e.g., 108, etc.) formed in a substrate (e.g., 100, etc.) and hard stop against the substrate (100) to form a physical bonding with the substrate (100). In some embodiments, the laser diode bar (130) may comprise an array of laser diodes. Optical axes 116 of the diodes may represent central directions/points of laser emission outputted from the laser diodes in the laser diode bar (130). In some embodiments, the optical axes (116) are made to a precise common height 118 from (e.g., in reference to, relative to, etc.) an edge 114 of the laser diode bar (130). In some embodiments, the edge (114) of the laser diode bar (130) represents lower edges (e.g., of cladding layers, etc.) of ridge waveguides of the laser diodes in the laser diode bar (130). In some embodiments, the edge (114) of the laser diode bar (130) represents lower edges of interstitial surfaces between adjacent ridge waveguides of the laser diodes in the laser diode bar (130).

[0048] As illustrated in FIG. 1C, the solder layer (108) may have a height above a hard stop reference plane (e.g., 102, etc.) representing the height of hard stop points and/or surfaces onto which the optical component (or the laser diode bar (130)) is placed.

[0049] A thickness of the solder layer (108) may vary in different scenarios/applications. In some embodiments, the thickness of the solder layer (108) can be selected depending on a number of factors including but not limited to, the designated bonding force to be achieved after the bonding process is completed, the type of solder used to bond the optical component to the substrate (100), the volume or depth (e.g., 0.3 micrometer, 0.5 micrometer, 0.8 micrometer, etc.) of relief channels (as will be explained in more detail later) in the recessed pocket (108), the geometry of the optical component, the depth (e.g., 1 micrometer, 1.5 micrometers, 2 micrometers, etc.) of the recessed pocket (108), etc.

[0050] One or more of a wide variety of placement techniques, surface preparation methods, etc., can be used to cause an optical component to have a strong post-bond physical bonding with a substrate (e.g., 100, etc.) as described herein and a direct surface contact with hard stop surfaces and/or hard stop points on the substrate (100) after solder shrinks during cool down of the solder or after adhesive shrinks during curing of the adhesive. A thickness of solder or adhesive used to bond the optical component to the substrate (100) may be, but is not limited to only, any of less than 10 micrometers, less than the thickness of a metalized layer (e.g., 106), etc. In some embodiments, laser micromachining (or laser machining) may be confined within or made into a part of the substrate (100) such as a metalized layer (e.g., 106, etc.) before reaching down to other parts of the substrate (100) such as a ceramic substrate (e.g., 104, etc.). In scenarios/applications in which the ceramic substrate (104) is made of beryllium oxide (BeO), laser micromachining can be confined within the metalized layer (106) so that air born particulates generated by the laser micromachining may be free of BeO (hazardous to human health).

3. ALIGNING OPTICAL AXES OF MULTIPLE OPTICAL COMPONENTS

[0051] FIG. 2A and FIG. 2B illustrate cross sectional and perspective views of an example substrate (e.g., 100, etc.) on which multiple optical components can be bonded with precise height positions. As illustrated in FIG. 1A, the substrate (100) comprises a ceramic substrate (e.g., 104, etc.) and a metalized layer (e.g., 106, etc.). The optical components may include, but are not limited to only, a laser diode bar (e.g., 130 of FIG. 1C, etc.), an optical component 130-1, etc.

[0052] Under techniques as described herein, some or all of the multiple components (e.g., 130, 130-1, etc.) can be bonded to the substrate (100) at a specific precise spatial location along a specific spatial dimension, where the specific precise spatial location along the specific spatial dimension is free from any variable bonding layer. In some embodiments, the specific precise spatial location may be a precise height in relation to a hard stop reference plane 102 that is stationary to the substrate (100). In some embodiments, the hard stop reference plane (102) may be selected as an unprocessed upper surface (e.g., 150 of FIG. 1A, etc.) of the substrate (100).

[0053] In some embodiments, multiple recessed pockets (e.g., 108, 108-1, etc.) are formed or made in the substrate (100) by cutting or ablating away substrate materials from the substrate (100). Each of the multiple recessed pockets (e.g., 108, 108-1, etc.) may be formed underneath a respective portion of the unprocessed surface (e.g., 150 of FIG. 1A, etc.) of the substrate (100) of FIG. 1A to bond a respective optical component (e.g., 130, 130-1, etc.) onto the substrate (100). A bonding material such as a solder layer (e.g., 112, etc.), an adhesive layer (e.g., 112-1, etc.), etc., can be deposited in each of the recessed pockets (e.g., 108, 108-1, etc.). An optical component (e.g., the laser diode bar (130)) of the multiple optical components (e.g., 130, 130-1, etc.) can be placed on top of a corresponding recessed pocket (e.g., 108) of the multiple recessed pockets (e.g., 108, 108-1, etc.) to form a physical bonding with the substrate (100) through a bonding material (e.g., the solder layer (112)) in the corresponding recessed pocket (e.g., 108).

[0054] Each of the multiple recessed pockets (e.g., 108, 108-1, etc.) on the substrate (100) can be designed to compensate for any variable thickness or height of the bonding material and effectively decouple the hard stop reference plane (102) from a height - at which an optical component of the multiple optical components (e.g., 130, 130-1, etc.) is placed in contact with the bonding material in the beginning of a bonding process - of the bonding material.

[0055] Each of the multiple recessed pockets (e.g., 108, 108-1, etc.) on the substrate (100) can be precisely laser micromachined (or laser machined) or etched. In some embodiments, one or more of the multiple recessed pockets (e.g., 108, 108-1, etc.) can be cut or etched directly into the metalized layer (106) which is on top of the ceramic substrate (104). Additionally, alternately, or optionally, one or more of the multiple recessed pockets (e.g., 108, 108-1, etc.) can be cut or etched into the ceramic substrate (104) commonly used for laser diodes in preparation for the metallization step. Pillars or pads (denoted as hard stop 110 in FIG. IB) formed by uncut substrate materials can be left behind from the laser micromachining or etching process to provide (intermediate or perimeter) hard stop points, hard stop surfaces, etc., to support the multiple optical components (e.g., 130, 130-1, etc.) via direct surface contacts between the multiple optical components (e.g., 130, 130-1, etc.) and the substrate (100).

[0056] In some embodiments, the laser diode bar (130) may comprise an array of laser diodes with optical axes 116 that represent central directiosn of laser emission outputted from the laser diodes in the laser diode bar (130). In some embodiments, the optical

component(130-l) may comprise an array of optical cores (e.g., 160 of FIG. 2B, of optical waveguides, etc.) that have optical axes 116-1 (or axes of symmetry) and claddings that surround the optical cores.

[0057] A thickness of a bonding material such as the solder layer (108), the adhesive layer (118-1) can be selected depending on a number of factors including but not limited to, the designated bonding force to be achieved after the bonding process is completed, the type of solder or adhesive used to bond an optical component to the substrate (100), the volume of relief channels in a recessed pocket, the geometry of an optical component, the depth of a recessed pocket, etc. In som embodiments, the thickness of the solder layer (108) may be different from the thickness of the adhesive layer (108-1).

[0058] In some embodiments, both of the optical axes (116) of the laser diode bar (130) and the optical axes (116-1) of the optical component (130-1) are completely aligned (or coincide), and are positioned to a precise common height from (e.g., in reference to, relative to, etc.) the hard stop (102) when both the laser diode bar (130) and the optical component (130-1) hard stop against hard stop points and/or hard stop surfaces left on the unprocessed surface (e.g., 150 of FIG. 1A, etc.) of the substrate (100). In some embodiments, both of the optical axes (116) of the laser diode bar (130) and the optical axes (116-1) of the optical component (130-1) are aligned within a small tolerance (e.g., within 0.5 angular degree, within 1 angular degree, etc.).

[0059] Additionally, alternatively, or optionally, specific points on the optical axes (116) of the laser diode bar (130) are completely aligned with specific points on the optical axes (116-1) of the optical component (130-1), or within a small tolerance (e.g., within 0.1 micrometer, within 0.2 micrometer, within 1 micrometer, etc.). Examples of a specific point on an optical axis may include, but are not limited to only, any of: a central point of a light emissive area on an endface of a laser diode (which may be a part of a laser diode bar), a central point of a light ingress area on an endface of an optical core of an optical waveguide (which may be a part of an array of optical waveguides in an optical component), etc.

[0060] A laser diode bar (or laser diodes) may be soldered to a metalized ceramic substrate (e.g., 100, etc.). Metalization (or a metalized layer) of the ceramic substrate provides a wetting surface for the solder used to bond the lasser diode bar to the substrate. In addition, the metalized layer of the substrate may serve as an electrical conductor for the p- side or n-side to p-n junctions of laser diodes in the laser diode bar. The output of the laser diodes may be aligned to optical cores of optical waveguides in an optical component (e.g., an optical waveguide bar), which may have bonding requirements much different than those of the laser diode bar. These bonding requirements may specify different metalization or adhesive layers as compared with those of the laser diode bar in order to optimize placement and bonding of the optical component or circuit to the substrate.

[0061] Under other approaches, a metalized layer and solder both contribute to a tolerance stack-up on a finished height of optical axes of laser diodes in a laser diode bar. Since the laser and the optical component have different metalization or adhesive layers, such tolerance stack-up prevents these two components from being vertically aligned on the same substrate. Thus, under these other approaches, compensation by lenses, mirrors or vertical height adjustment may be necessary for correcting misalignment generated in bonding processes. These additional optical components and adjustments/operations can add significant cost and time in manufacturing optical devices/modules and reduce overall optical and/or system efficiencies and reliabilities.

[0062] In contrast, under techniques as described herein, two or more optical components (e.g., of the same laser system, etc.) such as a laser diode bar (e.g., 130, etc.), an optical waveguide bar (e.g., an optical component 130-1, etc.), etc., can be made with the same height from respective optical axes of the two or more optical components to respective edges of the two or more optical components. Further, the respective edges of the two or more optical components can be placed against respective hard stop points and/or hard stop surfaces on the same reference plane, which represents an unprocessed surface (e.g., 150 of FIG. 1A, etc.) of a substrate (e.g., 100, etc.) before recessed pockets are formed. Since the heights of the optical axes to the edges are the same, and since the edges are placed on the same reference plane, these optical axes and/or specific points thereon can be aligned completely, or within a small tolerance.

[0063] For example, the optical axes of the laser diode bar (130) may have a specific height to the edges of the laser diode bar that are to be placed against hard stop points and/or hard stop surfaces on a substrate, and the optical axes of the optical waveguide bar (e.g., the optical component 130-1, etc.) may have the same specific height to the edges of the optical waveguide bar that are to be placed against hard stop points and/or hard stop surfaces on a substrate. When the laser diode bar (130) and the optical waveguide bar (130-1) are placed on the same hard stop surface (e.g., 102) of a substrate (e.g., 100, etc.), the optical axes of the laser diode bar (130) and the optical waveguide bar (130-1) are aligned completely, or within a small tolerance (e.g., an angular tolerance, a positional tolerance, etc.).

[0064] Techniques as described herein can be used to place optical axes and/or specific points on the optical axes multiple optical components at precise height positions with a minimal placement error such as 0.3 micrometer, 0.5 micrometer, 0.8 micrometer, etc. As a result, active alignment for differing heights of optical components using time consuming vertical height adjustments, compensation by using lenses, mirrors, etc., can be partly or completely avoided. Spacings, distances, displacements and angles in x and y dimensions (perpendicular to the z height dimension) are little or not affected by bonding processes that place optical axes to precise height(s). Furthermore, it is relatively simple to perform positional alignments and angular alignments in the x and y dimensions for the multiple optical components. After accurate height placement under techniques as described herein, additional adjustments in the x and y dimensions can be performed automatically and efficiently by machine with little or no manual intervention.

[0065] Additionally, alternatively, or optionally, under techniques as described herein, two or more optical components (e.g., of the same laser system, etc.) such as a laser diode bar (e.g., 130, etc.), an optical waveguide bar (e.g., 130-1, etc.), etc., can be made with differing heights from respective optical axes of the two or more optical components to respective edges of the two or more optical components. The respective edges of the two or more optical components can be placed against respective hard stop points and/or hard stop surfaces on different reference planes of the same substrate. The different reference planes of the substrate may be different unprocessed surfaces (e.g., before recessed pockets are formed, etc.) of the same substrate. These different reference planes may have the height difference(s) that accounts for or compensate the height difference(s) among the optical axes of the two or more optical components. When the respective edges of the two or more optical components are placed on (or hard stop against) the respective reference planes of the substrate (100), the height differences among the optical axes of the two or more optical components are canceled by the height differences among the respective reference planes. As a result, these optical axes and/or specific points thereon can be aligned completely, or within a small tolerance. [0066] In some embodiments, two or more recessed pockets as described herein can be made in the same substrate material removal process. In an example, two or more laser pulse beams that can be operated in parallel may be used to create the two or more recessed pockets at the same time in the same laser micromachining process. In another example, a laser pulse beam may be used in series to create the two or more recessed pockets sequentially within a relatively short time interval in the same laser micromachining process. Examples of laser pulse beams may include, but are not limited to, any of: tightly focused femtosecond pulses, picosecond pulses, nanosecond pulses, a laser pulse beam of a specific spectral range, a laser pulse beam of multiple spectral ranges, etc.

[0067] By using the same substrate material removal process on the same substrate, accuracies of the two or more recessed pockets and/or uniformity of heights of hard stop portions (points and/or surface portions) can be achieved on the same substrate without needing to perform elaborate and error prone realignment of multiple masks in other etching or spatial feature creation processes that do not implement techniques as described herein. 4. RELIEF CHANNELS, OVERFLOW SECTIONS AND SUPPLY WELLS

[0068] FIG. 3A illustrates an example topview (e.g., as viewed from the top in FIG. IB, etc.) of a recessed pocket (e.g., 108, etc.) formed on a metalized layer (e.g., 106, etc.) of a substrate (e.g., 100, etc.). In some embodiments, the recessed pocket (108) comprises a main section 124, and zero, one or more finger sections (e.g., 122-1 through 122-5, etc.). An optical component such as the laser diode bar (130) of FIG. 1C, etc., can be bonded to the metalized layer (106) of the substrate (100) through at least a main portion of a solder layer (e.g., 112, represented by a hatch fill pattern in FIG. 3A, etc.) deposited in the recessed pocket (108). A main section of a recessed pocket can be in any of a wide variety of planar shapes such as square, rectangles, polygon, ellipse, regular shape, irregular shape, etc. In some embodiments, edges or perimeters of the main section form a shape geometrically similar to a shape formed by bottom edges of an optical component that is to be bonded with the substrate (100) through the bonding material deposited in the recessed pocket (108).

[0069] The optical component can hard stop against pillars or pads (denoted as hard stop 110 in FIG. IB) near and/or outside a perimeter 120. These pillars or pads constitute hard stop points, hard stop surfaces, etc., that support the optical component via direct surface contacts between the optical component and the metalized layer (106). In some embodiments, one or more portions of the perimeter (120) may coincide with one or more portions of edges of the main section (124) of the recessed pocket (108). In some embodiments, one or more portions of the perimeter (120) may be slightly (e.g., 1 micrometer, 10 micrometer, 100 micrometer, 1 mm, etc.) outside of the edges of the main section (124) of the recessed pocket (108). For example, the perimeter (120) may be slightly (e.g., 1 micrometer, 10 micrometer, 100 micrometer, 1 mm, etc.) larger than x and y dimensions of the main section (124) of the recessed pocket (108).

[0070] The solder layer (112) comprises a main solder portion in the main section (124) of the recessed pocket (108), and zero, one or more additional portions in the finger sections (e.g., 122-1 through 122-5, etc.). Relief channels (e.g., 128, etc.) of various shapes and sizes and/or finger sections (e.g., 122-1 through 122-5, etc.) of various shapes and sizes can be incorporated into the resessed pocket (108) to allow excess solder or adhesive to flow out during a bonding process. The relief channels can be placed anywhere in the recessed pocket (108). As illustrated in FIG. 3A, the relief channels (128) may comprise those engineered around the edges of the recessed pocket (108). Additionally, optionally, or alternatively, the relief channels (128) may comprise those engineered in one or more interior regions of the recessed pocket (108) away from the edges of the recessed pocket (108).

[0071] In some embodiments, the relief channels (128) may comprise additional recessed pockets cut out from the substrate (100) in and below areas of the unprocessed surface that are designated to be under endfaces of light emitters such as endfaces of light diodes post the bonding process. These additional recessed pockets on the substrate (100) may be used to prevent endface portions of the light emitters from being in direct surface contact with the substrate (100).

[0072] A finger section as described herein may be used as a supply well for storing additional bonding material portions before the bonding process, may be used as an overflow section for receiving overflow bonding material portions during the bonding process, may be used as both a supply well and an overflow section, etc. For example, the additional bonding material portions (e.g., 126, etc.) such as solder, adhesive, etc., can be deposited in supply wells as represented by the finger sections (e.g., 122-1 through 122-5, etc.). The additional bonding material in the finger sections (e.g., 122-1 through 122-5, etc.) can be wicked in during the bonding process if there is an inadequate volume of the bonding materisl in the main section (124) of the recessed pocket (108).

[0073] FIG. 3B and FIG. 3C illustrates example top and perspective views (e.g., as viewed from the top in FIG. IB, etc.) of a recessed pocket (e.g., 108, etc.) formed on a metalized layer (e.g., 106, etc.) of a substrate (e.g., 100, etc.) in a different configuration from that represented in FIG. 3A. In some embodiments, one or more finger sections (e.g., 122-6, etc.) is provisioned in the recessed pocket. An optical component such as the laser diode bar (130) of FIG. 1C, etc., can be bonded to the metalized layer (106) of the substrate (100) through at least a main portion of a solder layer (e.g., 112, represented by a hatch fill pattern in FIG. 3B, etc.) deposited in the recessed pocket (108).

[0074] The solder layer (112) comprises a main solder portion in the main section (124) of the recessed pocket (108), and zero, one or more additional portions in the finger sections (e.g., 122-6, 122-7, 122-8, etc.). Finger sections (e.g., 122-6, 122-7, 122-8, etc.) of various shapes and sizes can be incorporated into the resessed pocket (108) to allow excess solder or adhesive to flow out during a bonding process.

[0075] In some embodiments, finger sections (e.g., 122-7, 122-8, etc.) used to allow solder or adhesive to flow out may be arranged away from spatial areas that are close to an endface where light emitting areas are located. For example, such finger sections may be arranged on a side of a laser diode bar that is opposite from where laser light is emitted so that overflowed solder or adhesive does not affect the light transmission and/or does not tilt the endface where the laser light is emitted.

[0076] Additionally, optionally, or alternatively, relief channels (128) may be engineered around the edges of the main section of the recessed pocket (108), or in one or more interior regions of the recessed pocket (108) away from the edges of the recessed pocket (108).

[0077] In some embodiments, additional bonding material (e.g., 126, etc.) such as solder, adhesive, etc., can be deposited in the finger sections (e.g., 122-6, etc.). The additional bonding material in the supply wells (e.g., 122-6, etc.) can be wicked in during the bonding process if there is an inadequate volume of the bonding materisl in the main section of the recessed pocket (108).

5. DUAL FUNCTIONALITY OF LASER SUBSTRATE AND LASER BASEPLATE

[0078] A laser diode may comprise an active region (which converts electricity to light), an optical waveguide such as a ridge waveguide with a layer of cladding, etc. The layer of cladding may be used to prvent light leakage from the ridge waveguide as well as to prevent mechanical stress from damaging the ridge waveguide, the active region, the spatial integrity of an light emissive area, interior layers, the inner structural components, etc.

[0079] Under some approaches, to package a laser diode into a laser module or a laser system, the laser diode may first be mounted to a laser substrate such as a ceramic substrate with a similar thermal expansion rate as that of the laser diode. The laser diode and the laser substrate may then be mounted to a submount that is capable of transferring heat at a fast heat transfer/spread speed. The laser diode with the laser substrate and the submount may further be mounted to a laser baseplate that can be cooled with fluid or air flows. In operation, the laser diode may be conduction cooled through the laser substrate, submount and laser baseplate. However, the stack up of multiple layers such as layer substrate, submount, laser baseplate, etc., may result in poor thermal conduction performance.

[0080] In contrast, techniques as described herein can be used to simplify structures of laser modules/systems. These techniques may be used to provide a thermal conduction architecture in which a laser substrate also functions as a laser baseplate. For example, a laser diode bar may comprise one or more laser diodes each of which comprises an active region, an optical waveguide such as a ridge waveguide, etc. An edges of a ridge waveguide of such a laser diode can be directly placed on top of hard stop points/surfaces of a metalized substrate (e.g., a metalized ceramic substrate, etc.), when the laser diode bar is bonded with the substrate over a solder layer in a recessed pocket formed on the metalized substrate.

[0081] Metalization (or a metalized layer) of the metalized substrate can be used as an electricity conductor for one of a p-type and n-type layer in the laser diode. As a result, the metalized substrate can play a dual role of a laser substrate and a laser baseplate, resulting in reducing the number of thermal conduction layers, as compared with other approaches that do not implement the techniques as described herein. Dual functionality and consolidation of the laser substrate and laser baseplate in this architecture provides significant improvement in thermal performance of a laser module/system, as the number of thermal layers for thermal conduction is reduced as compared with other approaches.

[0082] Additionally, optionally, or alternatively, in the efficient thermal and electric conduction architecture implemented under techniques as described herein, an optical axis of a laser diode is positioned at a precise height in relation to a reference plane (e.g., an unprocessed surface of the metalized substrate, a lower surface of the ceramic substrate, etc.), which helps align the laser diode to other optical components bonded to the same substrate or even other components bonded to adjacent substrates.

6. RECESSED POCKET WITH TAPERED BOTTOM

[0083] A recessed pocket (e.g., 108, 108-1, etc.) may be cut into a substrate (e.g., 100, etc.) with a certain error or tolerance in the depth of the recessed pocket. In addition, a bonding material such as a solder layer (e.g., 112, etc.), an adhesive layer (e.g., 112-1, etc.), etc., may be deposited in the recessed pocket with a certain error or tolerance in the thickness of the bonding material such as the solder layer (112), the adhesive layer (112-1), etc.

[0084] The errors or tolerances in the depth and thickness of the recessed pocket and the bonding material may result in an optical component such as a laser diode bar (e.g., 130, etc.), a lightwave guide (e.g., 130-1, etc.), etc., not coming into physical contact with the bonding material after the optical component lands on hard stop points/surfaces (e.g., 110, etc.) of the substrate during or after a bonding process that bonds the optical component to the substrate. This could result in no or poor wetting and a poor bond forming. The errors or tolerances in the depth and thickness of the recessed pocket and the bonding material could also result in the optical component coming into contact with the bonding material long before the optical component lands on the hard stop reference plane. This could result in excess bonding material portions failing to be displaced from physical contact between the optical component and the hard stop points/surfaces. The optical component might be floating on top of the bonding material with no or incomplete physical contact with hard stop points/surfaces (e.g., 110, etc.) of the substrate. Consequently, an optical axis or optical axes of the optical component, or specific points on an optical axis or optical axes of the optical component, may not be placed precisely at a specific height in relation to a height reference plane.

[0085] FIG. 4 illustrates an example recessed pocket 108-2 that is cut into a substrate (e.g., 100, etc.) with a tapered bottom 132. The tapered bottom (132) is of a tapered slope relative to a hard stop reference plane 102 (e.g., representing an unprocessed surface (e.g., 150 of FIG. 1 A, etc.) of the substrate (100), etc.), and can be used to prevent or ameliorate the above-mentioned problems (e.g., no or little wetting, no or little physical contact with hard stop, excessive bonding materials failing to be expelled under relatively important points, etc.) and to produce a relatively high quality wetting of surfaces of an optical component and a bonding material deposited in the recessed pocket (108-2).

[0086] The recessed pocket (108-2) with the tapered bottom (132) comprises a transition from a deep end 136 to a shallow end 134 along a longitudinal direction (from right to left in FIG. 4) of the recessed pocket (108-2). In other words, the thickness of the recessed pocket may vary along a longitudinal direction of the recessed pocket, so as to create the tapered bottom of the recessed pocket which is relative to the hard stop reference plane 102 (e.g. the unprocessed surface of the substrate). By means of creating recessed pocket having a tapered bottom surface as described above, a bonding material deposited in the recessed pocket (e.g. a solder layer) may have a shallow end portion of a smaller thickness at one side of the recessed pocket, and the bonding material may have a deep end portion of a larger thickness at the other side of the recessed pocket. It is noted that the shallow end portion may be at least partially above the reference plane 102 (e.g. a surface of the substrate), and that the deep end portion may be below the reference plane. Such tapered bottom of the recessed pocket ensures a relatively high quality contact between the bonding material and an optical component to be bounded to the substrate over the bonding material as well as allows excess bonding material portions to be displaced toward the deep end to prevent the optical component from floating on top of the bonding material. Accordingly, the bonding material can be optimally distributed within the recessed pocket to provide high quality contact between the bonding material and the optical component as well as stable positioning of the optical component over the bonding material on the substrate can be provided. By this way, precise placement of optical axes of the optical component can be ensured.

[0087] In some embodiments, the tapered bottom (132) can be laser micromachined into the bottom of the recessed pocket cut with relatively high efficiency and low cost. In detail, a laser beam for cutting/ablating one or more portions of materials from the substrate (i.e. to perform a material removal process) may be adjusted based on a location along a longitudinal direction of the recessed pocket. For example, one or both of light intensity and duty cycle of a laser pulse beam used to remove materials from the substrate (100) for the purpose of creating the recessed pocket (108-2) can be adjusted to vary in different locations of the recessed pocket (108-2) to create different depths at these different locations. More specifically, the light intensity of a laser beam may be increased or decreased along the longitudinal direction to increase or decrease the thickness of the recessed pocket

accordingly. That is, the laser beam may have lower intensity being applied at one side of the recessed pocket, while the laser beam may have higher intensity being applied at the other side of the recessed pocket, which creates larger depth at the other side of the recessed pocket and smaller depth at the one side of the recessed pocket. By this way, a tapered bottom surface for the recessed pocket having a depth varying increasingly or decreasingly along the longitudinal direction is formed.

[0088] A bonding material such as a solder layer 112-2, as deposited in the recessed pocket (108-2), may have a (e.g., relatively uniform, etc.) height relative to the tapered bottom (132) with an error or tolerance. Carefully selected dimensions of the recessed pocket cut and a relatively uniform thickness of the solder layer (112-2) can be used to guarantee that the solder layer (112-2) has a shallow end solder layer portion 138 at least partly above the hard stop reference plane (102). This ensures that an optical component bonded to the substrate (100) over the solder layer (112-2) can have a relatively high quality contact with the solder layer (112-2) for wetting purposes, etc., at least starting from the shallow end of the recessed pocket (108-2).

[0089] Additionally, optionally, or alternatively, the solder layer (112-2) may have a deep end solder portion 140 that is below the hard stop reference plane (102). This allows excess bonding material portions to be displaced toward the deep end (136) to prevent the optical component from floating on top of the bonding material with no or incomplete physical contact with hard stop points/surfaces (e.g., 110, etc.) of the substrate (100). Consequently, an optical axis or optical axes of the optical component, or specific points on an optical axis or optical axes of the optical component, may be placed precisely at a specific height in relation to a height reference plane such as the hard stop reference plane (102).

[0090] For example, a laser diode in the laser diode bar (130) may have an output facet end 142 from which laser light can be outputted and a high reflector facet end 144 from which light in the active region of the laser diode is internally reflected. The output facet end (142) represents a relatively important specific point or( a critical end) for vertical or height location of an optical axis for the laser diode. In some embodiments, the output facet end (142) is placed above first hard stop points/surfaces near or beyond the deep end (136) of the tapered bottom (132) of the recessed pocket (108-2), whereas the high reflector facet end (144) is placed above second hard stop points/surfaces near or beyond the shallow end (134) of the tapered bottom (132) of the recessed pocket (108-2).

[0091] In some embodiments, the errors or tolerances of the depths of the solder layer (112-2) and the recessed pocket (108-2) are relatively small and do not prevent the optical component such as the laser diode bar (130), etc., from making hard stop contacts below both the output facet end (142) and the high reflector facet end (144).

[0092] In some embodiments, the errors or tolerances of the depths of the solder layer (112-2) and the recessed pocket (108-2) are relatively large and prevent the optical component such as the laser diode bar (130), etc., from making hard stop contacts below the high reflector facet end (144). However, since the solder layer (112-2) is lower at the deep end (136) relative to the hard stop reference plane (102), in the bonding process, the laser diode bar (130) still makes physical contact (or surface contact) above the first hard stop points/surfaces near or beyond the deep end (136) of the tapered bottom (132) of the recessed pocket (108-2), even though the high reflector facet end (144) protrudes above and makes no physical contact (or surface contact) with the second hard stop points/surfaces near or beyond the shallow end (134) of the tapered bottom (132) of the recessed pocket (108-2). This at minimum guarantees that the laser diode contacts the solder layer (112-2) at least at the back end or the high reflector facet end (144) of the laser diode bar (130), while the laser diode bar (130) lands on the first hard stop points/surfaces at the front end or the output facet end (142) of the laser diode bar (130). Consequently, output facet ends of laser diodes in the laser diode bar (130) ends up at a precise height above the hard stop reference plane (102). While optical axes of the laser diodes in the diode bar (130) may be inclined relative to the hard stop reference plane (102), angular deviations (e.g., < 1 milli-radian, < .5 angular degree; etc.) caused by inclined optical axes can be still acceptable (or sufficiently accurate) to a wide variety of optical applications in which laser light is outputted to (e.g., optical cores of optical waveguides in, etc.) other optical components, since vertical positioning at front ends or output facet ends of the laser diodes in the laser diode bar (130) is sufficiently precise to efficiently inject light from the laser diodes into the optical waveguides and thus effectuate relatively high quality optical coupling between the laser diodes in the laser diode bar (130) and the other optical components.

7. LASER MICROMACHINING IN BONDING MATERIAL AND SUBSTRATE

[0093] The depth of a recessed pocket (e.g., as laser micromachined, etc.) and the height/thickness of a bonding materials such as a solder layer, an adhesive layer, etc., can be chosen such that the bonding material is guaranteed to be above a hard stop reference plane at all ranges of tolerances. In this condition, excess bonding material portions may likely be present and will be displaced during a bonding process such as solder reflow, etc., as an optical component such as a laser diode bar, an optical waveguide bar, etc., is placed against hard stop points/surfaces on the hard stop reference plane and bonded with the bonding material in the recessed pocket.

[0094] FIG. 5A and FIG. 5B illustrate cross sectional and perspective views of an example laser diode bar (e.g., 130, etc.) bonded in a bonding process (e.g., reflow, etc.) to a solder layer (e.g., 112, etc.) deposited in a recessed pocket formed in a substrate (e.g., 100, etc.). Prior to the bonding, a part of the solder layer (112) may be located above a hard stop reference plane (e.g., 102, etc.), whereas the remaining part (not shown) of the solder layer (112) may be located underneath and up to the hardstop reference plane (102). In some embodiments, relief channels (e.g., 148-1 through 148-4, etc.) in the solder layer (112) can be laser micromachined parallel to and in between solder portions, which in turn are to be placed against ridges (e.g., 152-1 through 152-5, etc.) on the bottom of the laser diode bar (130). The relief channels (e.g., 148-1 through 148-4, etc.) in the solder layer (112) can serve as spatial voids where the excess bonding material portion of the solder portions can flow. In some embodiments, the ridges (e.g., 152-1 through 152-5, etc.) on the bottom of the laser diode bar (130) may be ridge waveguides of laser diodes (e.g., 146-1 through 146-5, etc.) in the laser diode bar (130). The relief channels (e.g., 148-1 through 148-4, etc.) can be laser

micromachined with high efficiency and low cost in the solder layer (112) deposited in the recessed pocket. The dimensions and shape of the relief channels (e.g., 148-1 through 148-4, etc.) can be chosen such that (a) the relief channels will be substantially (e.g., completely, 100%, 99%, 98%, etc.) filled post the bonding processre when the tolerances in the depth of the recessed pocket and the height/thickness of the solder layer (112) stack or accumulate into a maximum bonding material height, and (b) the relief channels (e.g., 148-1 through 148-4, etc.) will be partly (e.g., 0%, 50%, etc.) filled post the bonding process when the tolerances in the depth of the recessed pocket and the height of the bonding materiathe stack or accumulate into the minimum bonding material height.

[0095] In some embodiments, below each laser diode in a plurality of laser diodes in the laser diode bar (130) is a corresponding edge portion (or bottom portion) - of the laser diode bar (130) - that is a designated hard stop contact portion. For example, the designated hard stop contact portion of the laser diode bar (130) may comprise bottom surfaces/edges of ridge waveguides of laser diodes in the laser diode bar (130). A height (or distance) between an optical axis of a laser diode and a corresponding surface/edge of a ridge waveguide of the laser diode can be precisely engineered in the process of creating the laser diode in the laser diode bar (130). When the laser diode bar (130) hard stops against the substrate (100), each such designated hard stop contact portion of a laser diode in the laser diode bar (130) hard stops against a corresponding hard stop portion (e.g., a hard stop point, a hard stop surface, etc.) of the substrate (100). Any existing bonding material portion that covers the

corresponding hard stop portion of the substrate (100) before th bonding process is expelled or pushed off during the bonding process from the corresponding hard stop portion of the substrate (100) such that there is no or little bonding material thickness between the corresponding hard stop portion of the substrate and the designated hard stop contact portion of the optical component.

[0096] In some embodiments, relatively small post-bond voids that may still be formed in the relief channels (e.g., 148-1 through 148-4, etc.) parallel to and in between the ridges (e.g., 152-1 through 152-5, etc.) as a result of these relief channels (e.g., 148-1 through 148-4, etc.) not being completely filled. However, these post-bond voids may not adversely affect heat transfer/conduction performance as the excess bonding material portions are laterally displaced from the ridges (e.g., 152-1 through 152-5, etc.); most heat transfer/conduction can still occur in the downward direction towards the substrate (or heatsink therein) through relatively high quality surface contact or wetting between the ridges (e.g., 152-1 through 152- 5, etc.) and the solder layer (112).

8. LASER MICROMACHINED GROOVES IN SUBSTRATE [0097] FIG. 6A and FIG. 6B illustrate cross sectional and perspective views of an example laser diode bar (e.g., 130, etc.) bonded in a bonding process (e.g., reflow, etc.) to a solder layer (e.g., 112, etc.) deposited in a recessed pocket formed in a substrate (e.g., 100, etc.). Prior to the bonding, a part of the solder layer (112) may be located above a hard stop reference plane (e.g., 102, etc.), whereas the remaning part (not shown) of the solder layer (112) may be located underneath and up to the hardstop reference plane (102).

[0098] In some embodiments, relief channels (e.g., 154-1 through 154-5, etc.) or additional recessed pockets can be cut or laser micromachined onto the substrate (100) below the hard stop reference plane (102), for example, under output facet ends of laser diodes (e.g., 146-1 through 146-5, etc.) of the laser diode bar (130), in order to prevent ridge waveguides (as represented by ridges 152-1 through 152-5, etc.) surrounding or below the laser diodes (e.g., 146-1 through 146-5, etc.) from colliding onto hard stop points/surfaces of the substrate (100) (consequently damaging the laser diodes or the ridge waveguides) during placement of the laser diode bar (130) onto these hard stop points/surfaces. A relief channel (e.g., 154-1, etc.) or an additional recessed pocket cut under an unprocessed surface corresponding to an output facet end of a laser diode (e.g., 146-1, etc.) of the laser diode bar (130) may have a relatively shallow depth as compared with the recessed pocket (108) such as a fraction of the depth of the recessed pocket (108), 1 micrometer, 0.5 micrometer, etc.

[0099] In this example configuration, the hard stop points/surfaces as formed on the upper surface of the substrate (100) can be placed in physical contact (or surface contact) with grooves in between the ridge waveguides (e.g., on the p-sides of the laser diodes, etc.), instead of being placed in physical contact with the ridge waveguides as illustrated in FIG. 5A and FIG. 5B. More specifically, below each interstitial space (e.g., 100 micrometers between two adjacent laser diodes, a 150-micrometer pitch in diode spacings, etc.) between two adjacent laser diodes in a plurality of laser diodes in the laser diode bar (130) is a corresponding edge portion (or bottom portion) - of the laser diode bar (130) - that is a designated hard stop contact portion. For example, the designated hard stop contact portion of the laser diode bar (130) may be a bottom surface of the laser diode bar (130) in between two ridges or two ridge waveguide of the two adjacent laser diodes. A height (or distance) between an optical axis of that laser diode and the corresponding edge portion can be precisely engineered in the process of creating the laser diode bar (130). When the laser diode bar (130) hard stops against the substrate (100), each such designated hard stop contact portion below a corresponding laser diode in the laser diode bar (130) hard stops against a corresponding hard stop portion (e.g., a hard stop point, a hard stop surface, etc.) of the substrate (100). Any existing bonding material portion that covers the corresponding hard stop portion of the substrate (100) before th bonding process is dispelled (or expelled) or pushed off during the bonding process from the corresponding hard stop portion of the substrate (100) such that there is no or little bonding material thickness between the correspolnding hard stop portion of the substrate and the designated hard stop contact portion of the optical component. Additionally, optionally, or alternatively, bonding materials deposited or transferred into the relief channels or the additional recessed pockets allow the laser diodes in the laser diode bar (130) to have high quality wetting surfaces for effective heat removal from the laser diodes.

8. LASER MICROMACHINED RESIST

[0100] FIG. 7A and FIG. 7B illustrate an example material removal process that can be used to produce a recessed pocket (e.g., 108 of FIG. IB and FIG. 1C, 108-1 of FIG. 2A, 108- 2 of FIG. 4, etc.) on a substrate. The substrate can be in any of a wide variety of sizes such as sub-centimeter by centimeter, centimeter by centimeter, 2 inches by 2 inches, etc. The substrate can also be in any of a wide variety of planar shapes such as square, rectangles, polygon, ellipse, regular shape, irregular shape, etc. A bonding material such as a solder layer (e.g., 112 of FIG. IB and FIG. 1C, 112-1 of FIG. 2A, 112-2 of FIG. 4, etc.), etc., can later be deposited in the recessed pocket. In some embodiments, the substrate may consist of a homogeneous material layer such as a homogeneous metallic layer, a homogeneous non- metallic layer, etc. In some embodiments, the substrate may comprise more than one homogeneous material layer. For the purpose of illustration only, as shown in FIG. 7A and FIG. 7B, the substrate may comprise a ceramic substrate (e.g., 104, etc.) covered by a metalized layer (e.g., 106, etc.). The metalized layer may be relatively thin (e.g., several micrometers, several tens of micrometers, etc.) as compared with the ceramic substrate. The metalized layer may be any metallic material such as copper, aluminum, zinc, gold, metallic alloy, etc.

[0101] Initially, an unprocessed surface (e.g., 150 of FIG. 1A, etc.) such as an upper surface of a substrate (e.g., 100 of FIG. 1 A, etc.) may be covered with a resist layer prior 708 to any laser micromaching for recessed pockets. The unprocessed surface (e.g., 150 of FIG. 1A, etc.) of the substrate may be made sufficiently flat, smooth, and/or planar, to provide a height reference surface (or a hard stop reference plane).

[0102] In step (a), a resist layer portion 704 above a designated unprocessed surface portion (of the substrate) from which the recessed pocket is to be generated may be removed by a laser pulse beam 702 with a first pulse energy level (or first duty cycles) that is configured to remove the resist layer portion (704) in the resist layer (708). Precise laser removal of resist eliminates or lessens needs for patterning and alignment of multiple patterns comprising micro or nano features that may be difficult or impossible under some other approaches. The first pulse energy level for resist removal may be chosen such that the underlying metalized layer (106) remains unmodified or unablated by the laser pulse beam (702) during resist removal. That way, the uniformity and flatness of the metalized layer (106) is preserved for subsequent laser micromachining of the recessed pockets.

[0103] In step (b), once the resist layer portion (704) in the resist layer (708) is removed from the designated unprocessed surface portion of the substrate, the laser pulse beam (702) may be set to a second pulse energy level (e.g., second duty cycles, higher than the first pulse energy level, etc.) to ablate a metalized layer portion 706 below the designated unprocessed surface portion to form a recessed pocket of a designated shape in the metalized layer (106). In some embodiments, the recessed pocket may be entirely in a homogeneous material layer, as illustrated in FIG. 7A and FIG. 7B. In some embodiments, the recessed pocket may be partly in more than one homogeneous material layers (e.g., passing through the metalized layer (106) and into the ceramic layer (104), etc.).

[0104] In step (c), a bonding material may be deposited into the recessed pocket corresponding to the removed/ablated metalized layer portion (706). For example, a solder layer (e.g., gold-tin or AuSn solder, etc.) may be electroplated into the recessed pocket. In some embodiments, relief channels, supply wells, grooves, etc., may be further created by the laser pulse beam (702) at designated areas.

[0105] In step (d), the remaining resist layer portions in the resist layer (708) may be removed from the substrate, for example, in a chemical process.

9. EXAMPLE EMBODIMENTS

[0106] FIG. 8A illustrates an example process flow according to an example embodiment of the present invention. In some example embodiments, this process flow is implemented as a part of a manufacturing process used to produce a substrate with recessed pockets, an optical component/module/device, an electro-optic component/module/device, etc. In block 802, a material removal process (e.g., laser micromachining, etching, etc.) is applied to remove one or more substrate material portions from a substrate to create a recessed pocket in the substrate. The substrate comprising one or more substrate materials with an unprocessed surface before the material removal process. The recessed pocket represents a spatial cavity cut into the substrate. The spatial cavity has a top surface corresponding to a portion of the unprocessed surface and a bottom surface below the portion of the unprocessed surface. [0107] In block 804, a bonding material is deposited (e.g., using an electroplating process, using a robotic injector, etc.) in the recessed pocket.

[0108] In block 806, one or more relief channels are created (e.g., in a material removal processing, etching, laser micromachining, etc.) in the recessed pocket.

[0109] In block 808, a bonding process is applied to place an optical component into direct surface contact with one or more hard stop portions among remaining portions of unprocessed surface of the substrate that remain after the material removal process.

[0110] In an embodiment, the one or more relief channels comprise one or more of relief channels around a perimeter of the recessed pocket, relief channels inside a perimeter of the recessed pocket, etc.

[0111] In an embodiment, the one or more relief channels comprise at least one relief channel that is formed by removing one or more bonding material portions from the bonding material as deposited in the recessed pocket.

[0112] In an embodiment, the one or more hard stop portions comprises one or more of portions of the unprocessed surface outside a perimeter of the recessed pocket, portions of the unprocessed surface adjacent to a perimeter of the recessed pocket, portions of the unprocessed surface inside a permimeter of the recessed pocket, etc.

[0113] In an embodiment, in the bonding process, the unprocessed surface of the substrate is established as a height reference plane in a height direction for positioning one or more optical axes of the optical component at a specific height, the height direction being perpendicular to the height reference plane.

[0114] In an embodiment, the optical component and the substrate are parts of one of an optical module, an optical device, an electro-optic module, an electro-optic device, etc.

[0115] In an embodiment, the substrate is composed of a metallic layer alone, a non- metallic layer alone, a combination of one or more metallic layers and one or more non- metallic layers, etc.

[0116] In an embodiment, the one or more substrate materials are composed of a homogeneous material alone, a non-homogeneous material alone, a combination of one or more homogeneous materials and one or more non-homogeneous materials, etc.

[0117] In an embodiment, the one or more substrate material portions are composed of a homogeneous material portion alone, a non-homogeneous material portion alone, a combination of zero, one or more homogeneous material portions and zero, one or more non- homogeneous material portions, etc. [0118] In an embodiment, the recessed pocket comprises a main section over which the optical component comes into contact with the bonding material and one or more finger sections without direct contact with the optical component.

[0119] In an embodiment, at least one portion of the bonding material is located in the one or more finger sections, and the one or more finger sections are specifically shaped to allow the at least one portion of the bonding material located in the one ore more finger sections to be capillarily wicked into the main section in the bonding process.

[0120] In an embodiment, in the bonding process, the unprocessed surface of the substrate is established as a height reference plane in a height direction for positioning a specific point on an optical interface of the optical component at a specific height in relation to the height reference plane, the height direction being perpendicular to the height reference plane. In an embodiment, the optical interface is one of a light output endface of a light emitter, a light ingress endface of an optical waveguide, etc.

[0121] In an embodiment, the bottom surface of the recessed pocket is slanted relative to the unprocessed surface of the substrate.

[0122] In an embodiment, the optical component represents one or more of discrete optical components, unitary optical components, laser micromachined optical components, laser diode bars, light emitters, laser diodes, optical waveguide bars, optical waveguides, microlens, diffraction gratings, prisms, mirrors, planar lightwave circuits, etc.

[0123] In an embodiment, an optical module/device manufacture process as described herein further performs: applying the material removal process to remove one or more second substrate material portions from the substrate to create a second recessed pocket in the substrate, the second recessed pocket representing a second spatial cavity cut into the substrate, the spatial cavity having a second top surface corresponding to a second portion of the unprocessed surface and a second bottom surface below the second portion of the unprocessed surface; depositing a second bonding material in the second recessed pocket; creating one or more second relief channels in the second recessed pocket; applying a second bonding process to place a second optical component into direct surface contact with one or more second hard stop portions among the remaining portions of unprocessed surface of the substrate; etc. In an embodiment, the first portion of the unprocessed surface of the substrate and the second portion of the unprocessed surface of the substrate layer are co-planar. In an embodiment, the first portion of the unprocessed surface of the substrate and the second portion of the unprocessed surface of the substrate layer are not co-planar. In an embodiment, the optical component and the second optical component are parts of a single optical module; the optical component is optically coupled to the second optical component in the single optical module.

[0124] In an embodiment, the bonding material are of a protruding height above the unprocessed surface of the substrate before the material removal process.

[0125] In an embodiment, the substrate is a metalized ceramic layer comprising a ceramic layer and a metallic coating layer of the ceramic layer. In an embodiment, the recessed pocket is within the metalized coating layer of the ceramic layer. In an embodiment, the recessed pocket comprises portions in both of the ceramic layer and the metalized coating layer of the ceramic layer.

[0126] In an embodiment, the bonding material represents one or more of: adhersive materials, welding materials, solder materials, etc.

[0127] In an embodiment, the direct surface contact with the one or more hard stop portions on the unprocessed surface of the substrate is made through a bottom surface of the optical component. In an embodiment, the bottom surface of the optical component is flat. In an embodiment, the bottom surface of the optical component is not flat; the bottom surface of the optical component comprises a plurality of ridge surface portions that are placed against the one or more hard stop portions. In an embodiment, the bottom surface of the optical component is not flat; the bottom surface of the optical component comprises a plurality of groove surface portions in between a plurality of ridge surface portions; the plurality of groove surface portions are placed against the one or more hard stop portions.

[0128] FIG. 8B illustrates an example process flow according to an example embodiment of the present invention. In some example embodiments, this process flow is implemented as a part of a manufacturing process used to produce a substrate with recessed pockets, an optical component/module/device, an electro-optic component/module/device, etc. In block 852, a laser pulse beam is set to a first energy level and directed to remove a designated portion of a resist layer disposed on top of a substrate, the substrate comprising one or more substrate materials.

[0129] In block 854, the laser pulse beam is set to a second energy level and directed to remove one or more designated substrate material portions from the substrate to create a recessed pocket in the substrate below the removed designated portion of the resist layer.

[0130] In block 856, a bonding material is deposited into the recessed pocket in the substrate. [0131] In block 858, the laser pulse beam is set to a third energy level and directed to remove one or more bonding material portions from the bonding material deposited in the recessed pocket to form one or more relief channels in the recessed pocket.

[0132] In some embodiments, remaining portions of the resist layer are removed from the substrate.

[0133] In some embodiments, an optical module or an optical device comprises: a substrate from which a material removal process is applied to remove one or more substrate material portions to create a recessed pocket in the substrate, the substrate comprising one or more substrate materials with an unprocessed surface before the material removal process, the recessed pocket representing a spatial cavity cut into the substrate, the spatial cavity having a top surface corresponding to a portion of the unprocessed surface and a bottom surface below the portion of the unprocessed surface; a bonding material in the recessed pocket; one or more relief channels in the recessed pocket; an optical component which is placed through a bonding process into direct surface contact with one or more hard stop portions among remaining portions of unprocessed surface of the substrate that remain after the material removal process; etc.

[0134] In some embodiments, an optical module or an optical device is produced in part based on a method as described herein.

[0135] In various example embodiments, a system, an apparatus, or one or more other devices may be used to implement at least some of the techniques as described including but not limited to a method, a control, a function, a feature, etc., as described herein. In an embodiment, a non-transitory computer readable storage medium stores software

instructions, which when executed by one or more processors cause performance of a method, a control, a function, a feature, etc., as described herein.

[0136] Note that, although separate embodiments are discussed herein, any combination of embodiments and/or partial embodiments discussed herein may be combined to form further embodiments.

10. EQUIVALENTS, EXTENSIONS, ALTERNATIVES AND MISCELLANEOUS

[0137] In the foregoing specification, example embodiments of the invention have been described with reference to numerous specific details that may vary from implementation to implementation. Thus, the sole and exclusive indicator of what is the invention, and is intended by the applicants to be the invention, is the set of claims that issue from this application, in the specific form in which such claims issue, including any subsequent correction. Any definitions expressly set forth herein for terms contained in such claims shall govern the meaning of such terms as used in the claims. Hence, no limitation, element, property, feature, advantage or attribute that is not expressly recited in a claim should limit the scope of such claim in any way. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

[0138] Various aspects of the present invention may be appreciated from the following enumerated example embodiments (EEEs):

EEE 1. A method comprising:

applying a material removal process to remove one or more substrate material

portions from a substrate to create a recessed pocket in the substrate, the substrate comprising one or more substrate materials with an unprocessed surface before the material removal process, the recessed pocket representing a spatial cavity cut into the substrate, the spatial cavity having a top surface corresponding to a portion of the unprocessed surface and a bottom surface below the portion of the unprocessed surface;

depositing a bonding material in the recessed pocket;

creating one or more relief channels in the recessed pocket;

applying a bonding process to place an optical component into direct surface contact with one or more hard stop portions among remaining portions of unprocessed surface of the substrate that remain after the material removal process.

EEE 2. The method of EEE 1, wherein the one or more relief channels comprise one or more of relief channels around a perimeter of the recessed pocket, or relief channels inside a perimeter of the recessed pocket.

EEE 3. The method of EEE 1, wherein the one or more relief channels comprise at least one relief channel that is formed by removing one or more bonding material portions from the bonding material as deposited in the recessed pocket.

EEE 4. The method of EEE 1, wherein the one or more hard stop portions comprises one or more of portions of the unprocessed surface outside a perimeter of the recessed pocket, portions of the unprocessed surface adjacent to a perimeter of the recessed pocket, or portions of the unprocessed surface inside a permimeter of the recessed pocket. EEE 5. The method of EEE 1, further comprising establishing the unprocessed surface of the substrate as a height reference plane in a height direction for positioning one or more optical axes of the optical component at a specific height, the height direction being perpendicular to the height reference plane.

EEE 6. The method of EEE 1, wherein the optical component and the substrate are parts of one of an optical module, an optical device, an electro-optic module, or an electro- optic device.

EEE 7. The method of EEE 1, wherein the substrate is composed of a metallic layer alone, a non-metallic layer alone, or a combination of one or more metallic layers and one or more non-metallic layers.

EEE 8. The method of EEE 1, wherein the one or more substrate materials are composed of a homogeneous material alone, a non-homogeneous material alone, or a combination of one or more homogeneous materials and one or more non-homogeneous materials.

EEE 9. The method of EEE 1, wherein the one or more substrate material portions are

composed of a homogeneous material portion alone, a non-homogeneous material portion alone, or a combination of zero, one or more homogeneous material portions and zero, one or more non-homogeneous material portions.

EEE 10. The method of EEE 1, wherein the recessed pocket comprises a main section over which the optical component comes into contact with the bonding material and one or more finger sections without direct contact with the optical component.

EEE 11. The method of EEE 10, wherein at least one portion of the bonding material is located in the one or more finger sections, and wherein the one or more finger sections are specifically shaped to allow the at least one portion of the bonding material located in the one ore more finger sections to be capillarily wicked into the main section in the bonding process.

EEE 12. The method of EEE 1, further comprising establishing the unprocessed surface of the substrate as a height reference plane in a height direction for positioning a specific point on an optical interface of the optical component at a specific height in relation to the height reference plane, the height direction being perpendicular to the height reference plane.

EEE 13. The method of EEE 12, wherein the optical interface is one of a light output endface of a light emitter, or a light ingress endface of an optical waveguide.

EEE 14. The method of EEE 1, wherein the bottom surface of the recessed pocket is slanted relative to the unprocessed surface of the substrate.

EEE 15. The method of EEE 1, wherein the optical component represents one or more of discrete optical components, unitary optical components, laser micromachined optical components, laser diode bars, light emitters, laser diodes, optical waveguide bars, optical waveguides, microlens, diffraction gratings, prisms, mirrors, or planar lightwave circuits.

EEE 16. The method of EEE 1, further comprising:

applying the material removal process to remove one or more second substrate

material portions from the substrate to create a second recessed pocket in the substrate, the second recessed pocket representing a second spatial cavity cut into the substrate, the spatial cavity having a second top surface corresponding to a second portion of the unprocessed surface and a second bottom surface below the second portion of the unprocessed surface;

depositing a second bonding material in the second recessed pocket;

creating one or more second relief channels in the second recessed pocket;

applying a second bonding process to place a second optical component into direct surface contact with one or more second hard stop portions among the remaining portions of unprocessed surface of the substrate.

EEE 17. The method of EEE 16, wherein the first portion of the unprocessed surface of the substrate and the second portion of the unprocessed surface of the substrate layer are co-planar.

EEE 18. The method of EEE 16, wherein the first portion of the unprocessed surface of the substrate and the second portion of the unprocessed surface of the substrate layer are not co-planar.

EEE 19. The method of EEE 16, wherein the optical component and the second optical

component are parts of a single optical module; and wherein the optical component is optically coupled to the second optical component in the single optical module.

EEE 20. The method of EEE 1, wherein the bonding material are of a protruding height above the unprocessed surface of the substrate before the material removal process.

EEE 21. The method of EEE 1, wherein the substrate is a metalized ceramic layer

comprising a ceramic layer and a metallic coating layer of the ceramic layer.

EEE 22. The method of EEE 21, wherein the recessed pocket is within the metalized coating layer of the ceramic layer.

EEE 23. The method of EEE 21, wherein the recessed pocket comprises portions in both of the ceramic layer and the metalized coating layer of the ceramic layer.

EEE 24. The method of EEE 1, wherein the bonding material represents one or more of: adhersive materials, welding materials, or solder materials.

EEE 25. The method of EEE 1, wherein the direct surface contact with the one or more hard stop portions on the unprocessed surface of the substrate is made through a bottom surface of the optical component.

EEE 26. The method of EEE 25, wherein the bottom surface of the optical component is flat.

EEE 27. The method of EEE 25, wherein the bottom surface of the optical component is not flat; and wherein the bottom surface of the optical component comprises a plurality of ridge surface portions that are placed against the one or more hard stop portions.

EEE 28. The method of EEE 25, wherein the bottom surface of the optical component is not flat; wherein the bottom surface of the optical component comprises a plurality of groove surface portions in between a plurality of ridge surface portions; and wherein the plurality of groove surface portions are placed against the one or more hard stop portions.

EEE 29. A method comprising:

setting a laser pulse beam to a first energy level and directing the laser pulse beam to remove a designated portion of a resist layer disposed on top of a substrate, the substrate comprising one or more substrate materials;

setting the laser pulse beam to a second energy level and directing the laser pulse beam to remove one or more designated substrate material portions from the substrate to create a recessed pocket in the substrate below the removed designated portion of the resist layer;

depositing a bonding material into the recessed pocket in the substrate;

setting the laser pulse beam to a third energy level and directing the laser pulse beam to remove one or more bonding material portions from the bonding material deposited in the recessed pocket to form one or more relief channels in the recessed pocket;

removing remaining portions of the resist layer from the substrate.

EEE 30. An optical module comprising:

a substrate from which a material removal process is applied to remove one or more substrate material portions to create a recessed pocket in the substrate, the substrate comprising one or more substrate materials with an unprocessed surface before the material removal process, the recessed pocket representing a spatial cavity cut into the substrate, the spatial cavity having a top surface corresponding to a portion of the unprocessed surface and a bottom surface below the portion of the unprocessed surface;

a bonding material in the recessed pocket;

one or more relief channels in the recessed pocket;

an optical component which is placed through a bonding process into direct surface contact with one or more hard stop portions among remaining portions of unprocessed surface of the substrate that remain after the material removal process. EEE 31. An optical device comprising:

a bonding material in the recessed pocket;

one or more relief channels in the recessed pocket;

an optical component which is placed through a bonding process into direct surface contact with one or more hard stop portions among remaining portions of unprocessed surface of the substrate that remain after the material removal process.

EEE 32. An optical module produced in part based on a method as recited in any of EEEs 1- 29.

EEE 33. An optical device produced in part based on a method as recited in any of EEEs 1- 29.

Claims

1. A method comprising:

applying a material removal process to remove one or more substrate material

portions from a substrate to create a recessed pocket in the substrate, the substrate comprising one or more substrate materials with an unprocessed surface before the material removal process, the recessed pocket representing a spatial cavity cut into the substrate, the spatial cavity having a top surface corresponding to a portion of the unprocessed surface and a bottom surface below the portion of the unprocessed surface, wherein the bottom surface of the recessed pocket is a tapered bottom surface relative to the unprocessed surface of the substrate, the tapered bottom surface having a depth of the recessed pocket increasing along a longitudinal direction of the recessed pocket;

depositing a bonding material in the recessed pocket;

creating one or more relief channels in the recessed pocket;

2. The method of claim 1, wherein the one or more relief channels comprise one or more of relief channels around a perimeter of the recessed pocket, or relief channels inside a perimeter of the recessed pocket.

3. The method of any one of the preceding claims, wherein the one or more relief channels comprise at least one relief channel that is formed by removing one or more bonding material portions from the bonding material as deposited in the recessed pocket.

4. The method of any one of the preceding claims, wherein the one or more hard stop

portions comprises one or more of portions of the unprocessed surface outside a perimeter of the recessed pocket, portions of the unprocessed surface adjacent to a perimeter of the recessed pocket, or portions of the unprocessed surface inside a permimeter of the recessed pocket.

5. The method of any one of the preceding claims, further comprising establishing the unprocessed surface of the substrate as a height reference plane in a height direction for positioning one or more optical axes of the optical component at a specific height, the height direction being perpendicular to the height reference plane.

6. The method of any one of the preceding claims, wherein the optical component and the substrate are parts of one of an optical module, an optical device, an electro-optic module, or an electro-optic device.

7. The method of any one of the preceding claims, wherein the substrate is composed of a metallic layer alone, a non-metallic layer alone, or a combination of one or more metallic layers and one or more non-metallic layers.

8. The method of any one of the preceding claims, wherein the one or more substrate

materials are composed of a homogeneous material alone, a non-homogeneous material alone, or a combination of one or more homogeneous materials and one or more non-homogeneous materials.

9. The method of any one of the preceding claims, wherein the one or more substrate

material portions are composed of a homogeneous material portion alone, a non- homogeneous material portion alone, or a combination of zero, one or more homogeneous material portions and zero, one or more non-homogeneous material portions.

10. The method of any one of the preceding claims, wherein the recessed pocket comprises a main section over which the optical component comes into contact with the bonding material and one or more finger sections without direct contact with the optical component., and optionally

wherein at least one portion of the bonding material is located in the one or more finger sections, and wherein the one or more finger sections are specifically shaped to allow the at least one portion of the bonding material located in the one ore more finger sections to be capillarily wicked into the main section in the bonding process.

11. The method of any one of the preceding claims, further comprising establishing the unprocessed surface of the substrate as a height reference plane in a height direction for positioning a specific point on an optical interface of the optical component at a specific height in relation to the height reference plane, the height direction being perpendicular to the height reference plane, and optionally

wherein the optical interface is one of a light output endface of a light emitter, or a light ingress endface of an optical waveguide.

12. The method of any one of the preceding claims, wherein the bottom surface of the

recessed pocket is slanted relative to the unprocessed surface of the substrate.

13. The method of any one of the preceding claims, wherein the optical component

represents one or more of discrete optical components, unitary optical components, laser micromachined optical components, laser diode bars, light emitters, laser diodes, optical waveguide bars, optical waveguides, microlens, diffraction gratings, prisms, mirrors, or planar lightwave circuits.

14. The method of any one of the preceding claims, further comprising:

applying the material removal process to remove one or more second substrate

depositing a second bonding material in the second recessed pocket;

creating one or more second relief channels in the second recessed pocket;

15. The method of claim 14, wherein the first portion of the unprocessed surface of the

substrate and the second portion of the unprocessed surface of the substrate layer are co-planar.

6. A mounting device for an optical component, comprising:

a substrate comprising an unprocessed surface;

a recessed pocket deposited in the substrate, the recessed pocket representing a spatial cavity cut into the substrate caused by a material removal process, the spatial cavity having a top surface corresponding to a portion of the unprocessed surface and a bottom surface below the portion of the unprocessed surface, wherein the bottom surface of the recessed pocket is a tapered bottom surface relative to the unprocessed surface of the substrate, the tapered bottom surface having a depth of the recessed pocket increasing along a longitudinal direction of the recessed pocket;

a bonding material in the recessed pocket;

one or more relief channels in the recessed pocket; and

one or more hard stop portions among remaining portions of unprocessed surface of the substrate that remain after the material removal process.