Passive alignment of optical components using optical fiber stubs

Embodiments herein include an optical system that passively aligns an optical component (e.g., a fiber array connector, lens array, lens body, etc.) with a semiconductor substrate using trenches that mate with optical fiber stubs. In one embodiment, the trenches are etched into the semiconductor substrate which provides support to optical devices (e.g., lasers, lens arrays, photodetectors, etc.) that transmit optical signals to, or receive optical signals from, the optical component. An underside of the optical component is etched to include at least two grooves (e.g., V-grooves) for receiving optical fiber stubs. In one embodiment, the optical fiber stubs are a portion of optical fiber that includes the core and cladding but not the insulative jacket. Once the fiber stubs are attached to the grooves, the fiber stubs are disposed into the trenches in the semiconductor substrate thereby passively aligning the optical component to the optical device on the substrate.

TECHNICAL FIELD

Embodiments presented in this disclosure generally relate to disposing optical components onto a semiconductor substrate. More specifically, the embodiments disclosed herein use fiber stubs to passively align an optical component to an optical device on the substrate.

BACKGROUND

Alignment of optical components to waveguides such as optical fibers with high coupling efficiency continues to be a challenge in the photonics industry. To align the optical components actively, dedicated equipment is required which uses a sub-micron resolution multi-stage axis system with integrated cameras to align the components. Not only is this equipment expensive, active alignment slows down the fabrication process and limits throughput.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Overview

One embodiment presented in this disclosure is an optical system that includes a semiconductor substrate comprising a plurality of trenches and an optical component comprising at least one lens and a plurality of grooves where the plurality of grooves are formed on a same surface of the optical component. The optical system includes a plurality of optical fiber stubs where each of the optical fiber stubs is at least partially disposed in one of the plurality of grooves and one of the plurality of trenches, whereby the optical fiber stubs establish optical alignment between the at least one lens and an optical device disposed on the semiconductor substrate.

Another embodiment of the present disclosure is a method of aligning an optical component comprising at least one lens and a plurality of grooves each containing an optical fiber stub. The method includes etching a plurality of trenches into a semiconductor substrate and disposing, at least partially, each of the optical fiber stubs into a respective one of the plurality of trenches thereby passively aligning the at least one lens to an optical device disposed on the semiconductor substrate in at least one direction.

Another embodiment of the present disclosure is an optical component that includes a body comprising a plurality of grooves formed in a same surface of the body and at least one lens. The optical component includes a plurality of optical fiber stubs, wherein each of the optical fiber stubs is at least partially disposed in one of the plurality of grooves, whereby the optical fiber stubs establish optical alignment between the at least one lens and an optical device external to the optical component. Moreover, the optical fiber stubs are not configured to transmit any optical signal.

Example Embodiments

Embodiments herein include an optical system that passively aligns an optical component (e.g., a fiber array connector, lens array, lens body, etc.) with a semiconductor substrate by mating trenches etched into the substrate with optical fiber stubs. In one embodiment, the semiconductor substrate is an interposer which provides support to optical components that transmit optical signals to, or receive optical signals from, a fiber array connector (FAC). An underside of the FAC is etched to include at least two grooves (e.g., V-grooves) for receiving the optical fiber stubs. In one embodiment, the optical fiber stubs are a portion of optical fiber cable that includes the core and cladding but not the insulative jacket. Once the fiber stubs are attached to the grooves, the fiber stubs are disposed into the trenches in the interposer, thereby passively aligning the FAC to an optical device (e.g., lens array, waveguide, photodetectors, etc.) mounted on the interposer. One advantage of using fiber stubs is that many manufactures can make optical fiber cable within tight tolerances—e.g., the total diameter of the core and cladding is within +/−0.7 microns. Placing the fiber stubs in the trenches passively aligns the FAC in at least two alignment directions while minimizing tilt relative to the interposer.

In another embodiment, the trenches are etched into a photonic chip or a laser module while the fiber stubs are disposed into grooves in a lens array or single lens structure. As above, disposing the fiber stubs in the trenches aligns the lenses to optical devices in the photonic chip or laser module (e.g., waveguides, optical adapters, lasers, etc.), thereby eliminating or reducing the amount of active alignment that must be performed. Although the optical components may be passively aligned in all directions, in some embodiments, placing the fiber stubs in the trench may align the optical components in two directions while active alignment is used to align the components in a third direction.

FIG. 1illustrates an optical system100including a FAC110passively aligned on a semiconductor interposer105, according to one embodiment described herein. In one embodiment, the interposer105is made from silicon, but could also be made from any material that permits precision etching to form the trenches described below. The interposer105forms a substrate on which various optical components are mounted. In this example, the interposer105provides support for the FAC110, an electrical integrated circuit (IC)120, a photonic chip130, a laser module140, and a receiver145.

The FAC110includes an upper portion160, a lower portion155, a collimator array150, and a plurality of optical fiber cables115. For clarity, the lower portion155and the upper portion160of the FAC110are transparent inFIG. 1so that the features inside and below the FAC110are visible. One or both of the upper portion160and lower portion155include grooves (e.g., U-grooves or V-grooves) that extend along the length of the FAC110which provide support to the optical fiber cables115. In one embodiment, the lower portion155is made from a semiconductor material (e.g., silicon) and includes the grooves. Many fabrication techniques are known for forming V- or U-shaped grooves in a semiconductor material and these techniques will not be described in detail herein. In another embodiment, the lower portion155may be a glass substrate with machines V- or U-shaped grooves. Moreover, in addition to grooves on the underside, the lower portion155may also have grooves along its side or top surfaces.

The upper and lower portions155,160are pressed together and attached (e.g., epoxied) to secure the optic cables115into place. In one embodiment, the upper portion160may be made from glass or other material suitable for mating with the lower portion155to hold the fiber optic cables115in place. Moreover, the optical cables115inside the FAC110may have been stripped of the insulative jackets such that these cables115only include the core and cladding. Outside of the FAC110—i.e., the portion of the cables extending away from the interposer105—the optical cables115may still include the jacket.

The optical fibers115(and the grooves in the lower portion155) are aligned to the collimator array150which includes multiple lenses that each corresponds to one of the optical cables115. The collimator array150collimates the lights outputted from the optic fibers115to generate collimated beams185that are received by optical components on the interposer105. For example, the portion of the optical fibers115in the FAC115tasked with transmitting optical signals to the interposer105are aligned with the receiver145. The receiver145may include a lens array and photodiodes for converting the received optical signals into corresponding electrical signals. In one example, the lens in the receiver145reflect the collimated beams185received from the FAC115down towards photodiodes that are parallel with the upper surface of the interposer105. As discussed in greater detail below, the interposer105may have one or more through vias which transmit the electrical signals derived from the received optical signals to the lower surface of the interposer105.

To transmit optical signals from the interposer105to the FAC110, the laser module140generates a continuous wave (CW) optical signal190which strikes a lens array135mounted on the photonic chip130. The lens array135focuses the CW signal190into a waveguide in the photonic chip130(e.g., a silicon photonic chip). The photonic chip130may include one or more optical modulators (e.g., Mach-Zehnder interferometers, ring resonators, Fabry-Perot cavities, etc.), sub-micron optical waveguides, CMOS circuitry, and the like. As shown inFIG. 1, the photonic chip130includes wire bonds to the electrical IC120which permit electrical data signals provided by the IC120to control the components in the photonic chip130. For example, the photonic chip130may use the data signal to modulate the CW signal190using a modulation technique (e.g., quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM)). Once modified, the photonic chip130transmits a modulated optical signal via the lens array135to the FAC195. In one embodiment, the lens array135collimates the light to form collimated beams195which align with respective lens in the collimator array150in the FAC110. The collimator array150focuses the collimated beams195into respective optical fibers115. In this example, the interposer105and the FAC110include optical components for both transmitting optical signals to, and receiving optical signals from, each other.

Aligning the FAC110to the optical devices on the interposer105, presents many challenges. As shown, lenses in the collimator array150are aligned with lenses in both the receiver145and the lens array135for receiving and transmitting optical signals. To permit this transfer of optical signals, the FAC110is aligned onto the interposer105in the x, y, and z directions. Moreover, any tilt in the FAC110along the x, y, or z directions can also misalign the optical paths between the FAC110and the receiver145/lens array135. For example, if the FAC110is tilted in the x-axis such that leftmost portion of the FAC110is slightly higher than the rightmost portion, the optical paths transmitting the collimated beams195may be aligned while the optical paths transmitting the collimated beams185are not.

Although active alignment may be used to align the FAC110with the components on the interposer105, this requires expensive equipment and time to transmit test optical signals, measure the signal power, and adjust the location of the FAC110on the interposer105until the test signals achieve a desired threshold. Instead, the embodiments herein disclose an alignment structure that passively aligns the FAC110and the interposer105. As used herein, “passively aligning” means that at least two components can be aligned optically in one or more directions without requiring the transmission and detection of optical test signals.

To passively align the FAC110, the interposer105includes a trench175and a reservoir180. The details of these features are provided in the blowout portion ofFIG. 1. As shown there, the trench175and reservoir180are etched into the upper surface of the interposer105. In one embodiment, a deep reactive ion etch (RIE) is used to generate the trench175and reservoir180. AlthoughFIG. 1illustrates that these features have the same depth and could be formed during the same etching step, in other embodiments, the trench175may have a different depth than the reservoir180.

A fiber stub170is placed into the trench175and the V-groove165of the lower portion155of the FAC110. In one example, the fiber stub170is epoxied to the V-groove165before the FAC110is placed onto the interposer105. As explained in more detail below, moving the FAC110and the interposer105relative to each other until the fiber stub170is located within the trench175passively aligns the FAC110. Although only one trench175and reservoir180are shown inFIG. 1, the interposer105may include multiple trenches and reservoirs which align to a corresponding fiber stubs and V-grooves in the FAC110.

In one embodiment, the features of the reservoir180may be used to passively align the FAC110. For example, the edge of the reservoir180closest to the FAC110may be used to passively align the FAC110in the z-direction. For example, once the fiber stub170is deposited within the trench175, a technician may move the FAC110in the z-direction using the trench175as a guide until the front side of the FAC110that includes the collimator array150is parallel with the edge of the reservoir180closest to the FAC110. Stated differently, the trench170establishes a guide for sliding the fiber stub170(and the entire FAC110) in the z-direction. Once aligned, epoxy is deposited into the reservoir180which uses a capillary action to draw the epoxy into the V-groove165thereby attaching the FAC110to the interposer105.

FIG. 2illustrates an optical system200including the FAC110which is passively aligned on the semiconductor interposer105, according to one embodiment described herein. The interposer105is etched to include two reservoirs280A and280B along with two trenches (not shown). The FAC110includes two V-grooves265A and265B which receive respective fiber stubs deposited into the two trenches as shown inFIG. 1. For clarity, the various other electrical and optical components on the interposer105have been removed—i.e., IC, photonic chip, laser, receiver, etc.

The interposer105is placed on a ceramic substrate205and a printed circuit board (PCB)210. In one embodiment, the interposer105includes multiple through vias which provide electrical connections between the components on its top surface (i.e., the surface coupled to the FAC110) and its bottom surface (i.e., the surface coupled to the ceramic substrate205). The optical system200may include bond pads and/or solder bumps for electrically connecting the through vias in the interposer105to electrical connections in the ceramic substrate205. Moreover, the ceramic substrate205may include multiple electrical connections to the PCB210. For example, the ceramic substrate205may include through vias or wire bonds that couple to the top surface of the PCB210. Using the electrical connections in the ceramic substrate and the through vias in the interposer105, the PCB210can transmit and/or receive electrical data signals from the components deposited on the top surface of the interposer105. For example, the PCB210may serve as an interface to a computing device which provides electrical signals for modulating and generating an optical signal using the components on the interposer105. Similarly, the components on the interposer105may receive optical signals from the FAC110and convert these signals into electrical signals that are transmitted to the computing device through the interposer105, ceramic substrate205and PCB210.

FIG. 3illustrates an optical system300with the FAC110aligned to the interposer105using fiber stubs170, according to one embodiment described herein.FIG. 3illustrates a close up side view of the interface between the FAC110and the interposer105shown inFIG. 1. The other components on the interposer105are removed for clarity. Moreover, the lower and upper portions155,160of the FAC110are shown as being made from a transparent material so that the V-grooves165and fiber stubs170are visible. However, in other embodiments, the lower and upper portions155,160may be made from opaque materials.

As shown, the fiber stubs170are positioned within the V-grooves165such that the each fiber stub170contacts both walls of the respective V-groove105. Moreover, the fiber stubs170contact the bottom surface and/or side surfaces of the trenches etched into the interposer105. Placing the fiber stubs170into the trenches establish the orientation of the FAC110onto the interposer105in the x and y directions. As discussed above, the orientation of the FAC110along the z direction may be established by using an edge of the reservoir180or by using some other alignment marker. Moreover, by including two trenches in the interposer105and two fiber stub/V-groove combinations in the FAC110, the fiber stubs170also set the tilt of the FAC110relative to the interposer105along the x, y, and z directions.

In one embodiment, the fiber stubs170include the core and cladding (but not the jacket) of an optical fiber cable. One reason for using optical fiber cable for the fiber stubs170is because optical fibers are manufactured within tight tolerances which means the FAC110can be aligned precisely on the interposer105. For example, the diameter of the fiber stubs170may range between +/−0.7 microns. The type of optical fiber used to form the fiber stubs170does not matter so long as the diameter of the optical fiber is manufactured with tolerances less than 1.5 microns. For example, the fiber stubs170may made from single mode or multi-mode optical fibers. As shown, the fiber stubs170are not used to carry light or an optical signal (i.e., the stubs170are not coupled to any light source), but rather to align the FAC110and the interposer105. The length of the fiber stubs170(i.e., the amount of optical fiber cable cut off to form the fiber stubs170) may vary according to the length of the trenches etched into the interposer105and the FAC110.

FIG. 4illustrates different sized trenches175in the interposer105for receiving fiber stubs170, according to one embodiment described herein. For example,FIG. 4may be a cross sectional view of the optical system shown inFIG. 3where the FAC is disposed over the interposer105. InFIG. 4, only the lower portion155of the FAC is shown.

The left trench175A has a depth D1and width W1that is different from the depth D2and width W2of the right trench175B. In this example, the depth D1of trench175A is less than the depth D2of trench175B, while the width W1of trench175A is greater than the width W2of trench175B. In one embodiment, the width W1is greater than the diameter of the fiber stubs170, while the width W2is less than the diameter of the fiber stubs170. As such, the fiber stub170A contacts the bottom surface of trench175A, but the fiber stub170B does not contact the bottom surface of trench175B. Instead, the fiber stub170B rests on the sides of the trench175B. As such, the width W2determines how far the fiber stub170B extends into the trench175B, thereby establishing the distance between the interposer105and the bottom portion155of the FAC in the y direction. In contrast, the depth D1determines how far the fiber stub170A extends into the trench175A, thereby establishing the distance between the interposer105and the bottom portion155in the y direction. In sum, the separation distance between the FAC and interposer105is established in the right trench175B by controlling the width W2but this distance is established in the left trench175A by controlling the depth D1. In one embodiment, the width W2and depth D1are set such that the heights H1and H2are the same, and as such, there is no (or a very small) tilt of the FAC along the x direction.

One advantage of using the width W2to control the height H2and the depth D1to control the height H1is that the separation distance between the V-grooves165A and165B may vary. That is, the bottom portion155may be manufactured such that the distance between the V-grooves165A and165B can vary by +/−3 microns. Such a large variation means that the V-grooves165A and165B may not be spaced the same distance as the spacing between the trenches175A and175B in the interposer105. These disparate distances may prevent the FAC from aligning properly with the interposer105. For example, if both trenches used the width to set the height between the FAC and interposer105as shown by right trench175B and the distance between the trenches175and the V-grooves165did not match, one of the fiber stubs170would not align with a trench. Put differently, one of the fiber stubs would be disposed in a trench but the other stub would not. Instead, having one trench with a width greater than the diameter of the fiber stub170enables the interposer105to accommodate the tolerance variation in the distance between the V-grooves165A and165B. For example, even if the distance between the V-grooves165A and165B increases, the left fiber stub170A would be moved over to the left in the trench175A but the right fiber stub170B would still register with the sides of the right trench175B. Thus, even as the distance between the V-grooves165A and165B varies, the trenches175A and175B can still set the heights H1and H2to the same value.

Alternatively, if both trenches used the depths D1and D2to set the height between the FAC and interposer105as shown by the left trench175A, the trenches175could no longer passively align the FAC110in the x direction. That is, the FAC110could still be aligned in the y direction because the depths of the trenches175are controlled, but the sides of the trench175B are what align the FAC in the x direction. If the widths of both trenches were greater than the diameter of the fiber stubs170, then the fiber stubs170could slide within the trenches and may need to be actively aligned in the x direction. Instead, once the fiber stub170B registers with the side walls of the right trench175B, then the technician knows the FAC is aligned in the x direction. Furthermore, the variable distance between the V-grooves165can be accommodated by the left trench175A which permits the fiber stub170A to move to the left or right and still rest on the bottom surface of the trench175A thereby establishing the desired height H1.

The values of the widths W1and W2and depths D1and D2will vary according to the dimensions of the fiber stubs170and the arrangement of the components in the FAC and interposer105. For example, the width W2may be smaller when a fiber stub170with a diameter of 120 microns is used instead of a fiber stub170with a diameter of 150 microns. Thus, the dimensions of the trenches175can be adjusted to accommodate different types of fibers stubs (e.g., fiber stubs made using multi-modal and single mode optical fibers) and optical arrangements of the components in the FAC and interposer105.

In an embodiment where the distance between the V-grooves165in the lower portion155has tighter tolerances—e.g., less than +/−1 micron—the interposer105may include two trenches with widths that are less than the diameter of the fiber stubs170. As such, the stubs170will register with the side of the trenches but not the bottom of the trenches as shown by trench175B. Put differently, if the distance between V-grooves165A and165B does not vary substantively, the interposer105may include two trenches like the right trench175B rather than one of each kind as shown inFIG. 4.

FIG. 5is a flow chart for a method500of passively aligning a FAC to an interposer, according to one embodiment described herein. At block505, trenches are etched for optical fiber stubs into the interposer of an optical system. In one embodiment, the interposer may be located on a semiconductor wafer that includes multiple interposers. In this example, the trenches may be etched onto the interposers in the wafer using the same processing steps. Using the trenches shown inFIG. 4as an example, at Time A, all the interposers in the wafer may be etched using deep RIE to form a trench like the left trench175A where the width of the trench is wider than the diameter of the fiber stub170A. At Time B, all the interposers may be etched to form a trench like the right trench175B where the width of the trench is smaller than the diameter of the fiber stub170B. In this manner, the trenches may be formed using a wafer-level processing technique. Moreover, before etching the trenches, the interposer may have already been processed to include other features such as electrical connections for the IC or the through vias that electrical connect a top surface of the interposer to a bottom surface.

At block510, optical components are disposed onto the interposer for receiving optical signals from, or transmitting optical signals to, the FAC. In one embodiment, the interposer includes only components for receiving optical signals from the FAC. In another embodiment, the interposer includes only components or transmitting optical signals to the FAC. Alternatively, as shown inFIG. 1, the interposer may include components for both transmitting and receiving optical signals.

The optical devices on the interposer may be aligned before being fixed onto the interposer. As shown inFIG. 1, the laser module140and photonic chip130may be aligned to the lens array135to ensure that the CW generated by the laser module140is properly introduced into the photonic chip130and that the modulated wave generated by the photonic chip130is collimated by one of the lenses in the lens array135. Moreover, the lens array and photodetectors in the receiver145may be aligned to ensure light received from the FAC110is reflected by the lens array onto the detectors. These alignments may be performed using passive alignment techniques and/or active alignment techniques.

At block515, the fiber stubs are coupled into grooves in the same surface or plane of the FAC. As described above, the bottom surface of the FAC which faces the interposer may include two V-grooves that are at least as long as the fiber stubs. Because the fiber stubs are used to align the FAC to the interposer rather than being used to carry an optical signal, the fiber stubs may contact both sides of the V-grooves to ensure proper alignment. An epoxy material may be used to fix the fiber stubs into the V-grooves.

At block520, the optical components on the interposer are passively aligned to the FAC by disposing the fiber stubs into the trenches etched at block505. Put differently, placing the fiber stubs into the trenches passively aligns the FAC to the interposer in at least one alignment axis or direction. In the embodiment shown inFIG. 4, by using different types of trenches175, the FAC is passively aligned in two alignment axis (e.g., the x and y directions) when the fiber stubs are disposed in the trenches175. Moreover, to align in the z direction, the upper surface of the interposer may include an alignment mark that aligns with a leading edge of FAC on which the collimator array is exposed. For example, a side of the reservoir180shown inFIG. 3may be used by a technician to align the FAC in the z direction.

Once aligned, an adhesive may be used to secure the fiber stubs (which were previously secured to the FAC) to the interposer. In one embodiment, epoxy is deposited into the reservoir after the FAC is aligned on the interposer. A capillary action pulls the epoxy into the V-groove and the trench thereby fixing the FAC to the interposer. However, in other embodiments, the epoxy may be injected into the trench, or the epoxy may be place in the trench before the fiber stub is disposed into the trench so long as the epoxy does not interfere with aligning the FAC.

FIGS. 6A-6Dillustrate passively aligning the lens array135to the photonic chip130using fiber stubs, according to one embodiment described herein. In one example, the process shown byFIGS. 6A-6Dmay be performed when arranging and aligning the optical devices on the interposer. This process may occur before the FAC is disposed on the interposer using the fiber stubs as described in method500.

FIG. 6Aillustrates the bottom surfaces of the lens array135which includes a body that encapsulates lenses used to collimate optical signals received from the photonic chip130or focus a CW received from the laser module (not shown). The body and lenses of the lens array135may be made from a semiconductor material such as silicon. In another example, the body may be made from a semiconductor material while the lenses are made from glass. As shown, the lens array135includes two V-grooves605adapted to receive fiber stubs. The V-grooves605may have similar dimensions as the V-grooves formed in the FAC discussed above except the length of the V-grooves605may be shorter since the lens array135is typically shorter than the FAC.

FIG. 6Billustrates disposing fiber stubs610into the V-grooves of the lens array135. Epoxy may be used to attach the fiber stubs610to the lens array135. The epoxy may be applied either before the fiber stubs610are disposed in the V-grooves (e.g., a small amount of epoxy may be disposed in the grooves) or after the fiber stubs610have been placed in the grooves.

FIG. 6Cillustrates the photonic chip130before the lens array135is placed onto the chip130. The photonic chip130includes a platform620which is recessed relative to the upper surface of the photonic chip130to provide room for the lens array130to extend down towards the bottom surface of the photonic chip130. Although not shown, one or more waveguides may terminate at or near the upper surface of the photonic chip130. These waveguides either receive an optical signal from, or transmit an optical signal to, a lens in the lens array135.

Moreover, the photonic chip130includes trenches615which correspond to the V-grooves605shown inFIG. 6A. In one embodiment, the trenches may have different depths and widths as shown inFIG. 4, although this is not a requirement. For example, the width of the right trench615may be smaller than the diameter of the fiber stubs610such that the fiber stub registers with the side walls of the trench. Moreover, the depth of the right trench615may be deep enough such that the fiber stub610does not contact its bottom surface. The left trench615, in contrast, may have a width greater than the diameter of the fiber stub610which accommodates differences between the distances between the V-grooves605and the trenches615.

FIG. 6Dillustrates passively aligning the lens array135to the photonic chip130using the fiber stubs610. Relative to the view shown inFIG. 6A, the lens array135is rotated so the bottom surface (which is facing up inFIG. 6A) now faces the platform620and the extension of the lens array135between the grooves605extends down into the recess of the photonic chip130. Moreover, the fiber stubs610are disposed within the trenches615thereby passively aligning the lens array135in one or more alignment axes. In one embodiment, active alignment may also be used to align the lens array135and photonic chip130. For example, the fiber stubs610may passively align the lens array135in the x and y directions, while the lens array135is actively aligned in the z direction.

FIGS. 7A-7Dillustrate passively aligning a silicon lens body700to the laser module140using fiber stubs710, according to one embodiment described herein. In one example, the process shown byFIGS. 7A-7Dmay be performed when arranging and aligning the optical devices on the interposer. This process may occur before the FAC is disposed on the interposer using the fiber stubs as described in method500.

FIG. 7Aillustrates the bottom surfaces of the silicon lens body700which includes two V-grooves705. Like the lens array135, the lens body700has an extension between the grooves705that provides room for the silicon lens. In one example, both the body700and the lens are made out of a semiconductor material such as silicon. The V-grooves705are adapted to receiver fiber stubs and may have similar dimension as the V-grooves formed in the FAC except the length of the V-grooves705may be shorter since the lens body700is typically shorter than the FAC.

FIG. 7Billustrate disposing the fiber stubs710into the V-grooves705. Epoxy may be used to attach the fiber stubs710to the body700. The epoxy may be applied either before the fiber stubs710are disposed in the V-grooves705(e.g., a small amount of epoxy may be disposed in the grooves) or after the fiber stubs710have been placed in the grooves705.

FIG. 7Cillustrates the laser module140before the silicon lens body700is placed onto the module140. The laser module140includes a laser720which generates a CW optical signal that is then collimated by the silicon lens. The laser module140also includes two trenches725and a recess730. The trenches725correspond to the V-grooves705in the lens body700. In one embodiment, the trenches725may have different depths and widths as shown inFIG. 4, but in other embodiments, the dimensions of the trenches725may be the same.

FIG. 7Dillustrates aligning the silicon lens body700to the laser module140using the fiber stubs710and trenches725as guides. Relative to the view shown inFIG. 7A, the body700is rotated so the bottom surface (which is facing up inFIG. 7A) and the extension of the body700are within the recess730in the laser module140. Moreover, the fiber stubs710are disposed within the trenches725thereby passively aligning the lens body700in one or more alignment axes to the laser720. In one embodiment, active alignment may also be used to align the lens body700and laser module140. For example, the fiber stubs710may passively align the lens body700in the x and y directions, while the lens body700is actively aligned in the z direction.

The flowchart and block diagrams in the Figures illustrate the architecture, functionality and operation of possible implementations of systems or methods according to various embodiments. It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.