Abstract:
An optical communications module includes a housing that accommodates at least one optical receptacle having a cylindrical connector portion. The module further includes at least one deformable constraining member made of a material having a Young&#39;s modulus that allows the deformable constraining member to take on an initial deformity upon application of a compression force, but permits only a partial reversal of the deformity upon reduction or removal of the compression force. The initial deformity is created when the deformable constraining member is pressed against the cylindrical connector portion during assembly of the module. The initial deformity includes a deformed contour portion that conforms to at least a part of the cylindrical connector portion of the optical receptacle and prevents wiggling of the cylindrical connector portion after the cylindrical connector portion is pushed during assembly into an alignment notch provided in a lower housing portion of the module.

Description:
FIELD OF THE INVENTION 
     The invention relates to an optical communications module, and more particularly, to an optical communications module having one or more elements for holding an optical receptacle in place. 
     BACKGROUND 
     In an optical communication system, it is generally desirable to connect a fiber optic cable to an optoelectronic device such as an optoelectronic transmitter, an optoelectronic receiver, or an optoelectronic transceiver device; and in turn, to connect the optoelectronic device to an electronic system such as a switching system. Such operations can be facilitated by modularizing the optoelectronic device so as to enclose various optical components and electronic components into an optical communications module. While enclosing the electronic components into an optical communications module is a fairly straightforward process, several special precautions need to be taken with respect to optical components. For example, it is important to ensure that minimal optical path loss occurs between an optical component (such as a laser device or a photodetector) and an optical connector that provides external connectivity to the optical component. It is also important to ensure that minimal optical path loss occurs between the optical connector of the optical communications module and a connector portion of a fiber optic cable when the fiber optic cable is coupled to the optical connector. 
     Optical path loss can occur due to a variety of reasons, such as, for example, attenuation inside an optical element or attenuation as a result of misalignment between two optical components. Among the various types of misalignments that can occur, one type pertains to an optical misalignment between an optical connector of a fiber optic cable and a connector of the optical communications module when the fiber optic cable is connected to the optical communications module. Such misalignment can occur due to various reasons such as, for example, due to manufacturing problems or due to excessive and undesirable play when either the fiber optic cable or the optical communications module is moved after the fiber optic cable is connected to the optical communications module. It is very desirable to minimize optical misalignment and obtain tolerances of the order of +/−0.050 mm or better. 
     Traditional solutions for addressing some misalignment issues includes the use of various retainers such as clips and springs that use a resilient action to apply pressure against the optical connector and prevent movement of the optical connector inside the optical communications module. However, the resilient action of such elements fails to prevent counteractive forces that can occur during the process of inserting a fiber optic cable into the optical connector or when inadvertently flexing the fiber optic cable after coupling to the optical connector. Consequently, an alternative approach uses an epoxy to bind the optical connector to a housing portion of the optical communications module. While the epoxy based approach can feasibly provide good anchoring and alignment of the optical connector, the nature of such adhesives prevents, or hampers, removal and reinstalling of the optical connector if such operations are needed later on, such as, for example, when carrying out an active optical alignment procedure of the optical connector after manufacture or when carrying out repairs on a defective optical communications module. 
     It is therefore desirable to address at least some of the traditional shortcomings described above. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Many aspects of the invention can be better understood by referring to the following description in conjunction with the accompanying claims and figures. Like numerals indicate like structural elements and features in the various figures. For clarity, not every element may be labeled with numerals in every figure. The drawings are not necessarily drawn to scale, emphasis instead being placed upon illustrating the principles of the invention. The drawings should not be interpreted as limiting the scope of the invention to the example embodiments shown herein. 
         FIG. 1  shows an exemplary embodiment of an optical communications module in accordance with the disclosure, the optical communications module configured to accommodate a pair of connectors that are provided at an end of a fiber optic cable. 
         FIG. 2  shows a perspective external view of the optical communications module shown in  FIG. 1 . 
         FIG. 3  shows a frontal view of a portion of an optical communications module, the frontal view showing a pair of deformable constraining members placed upon a pair of optical receptacles in accordance with one exemplary embodiment of the disclosure. 
         FIG. 4  shows a profile drawing of a portion of an optical communications module, the profile drawing showing a pair of deformable constraining members placed upon a pair of optical receptacles in accordance with another exemplary embodiment of the disclosure. 
         FIG. 5  shows a perspective view of various exemplary components mounted in a lower housing portion of an optical communications module in accordance with the disclosure. 
         FIG. 6  shows a close-up perspective view of a portion of the optical communications module that incorporates a pair of deformable constraining elements in accordance with the disclosure. 
         FIG. 7  shows an inside view of an exemplary upper housing portion of an optical communications module, the upper housing portion configured to anchor a pair of deformable constraining elements in accordance with the disclosure. 
         FIG. 8  shows an exemplary embodiment of a deformable constraining element incorporating anchoring elements for anchoring the deformable constraining element inside a recess of an upper housing portion of an optical communications module in accordance with the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Throughout this description, embodiments and variations are described for the purpose of illustrating uses and implementations of inventive concepts. The illustrative description should be understood as presenting examples of inventive concepts, rather than as limiting the scope of the concept as disclosed herein. It should also be understood that the word “example” as used herein is intended to be non-exclusionary and non-limiting in nature. More particularly, the word “exemplary” as used herein indicates one among several examples and it must be understood that no undue emphasis or preference is being directed to the particular example being described. It should be further understood that certain words and terms are used herein solely for convenience and such words and terms should be interpreted as referring to various objects and actions that are generally understood in various forms and equivalencies by persons of ordinary skill in the art. For example, it should be understood that words indicative of surfaces, such as “top,” “bottom,” “upper,” and “lower” can be used herein as a matter of convenience for describing certain features and actions. However, one of ordinary skill in the art will recognize that a “bottom” surface when an object is oriented in one way can become a “top” surface when the object is oriented in an opposite way. Also, it should be understood that the phrase “optical receptacle” as used herein generally refers to a connector portion of an optical communications module. The connector portion can be used for mating with various external components such as, for example, an optical connector disposed at the end of a fiber optic cable. Furthermore, the word “receptacle” in the phrase “optical receptacle” should not be interpreted as exclusively indicating a female element because in various embodiments the “optical receptacle” can be a male connector of an optical communications module. It should be further understood that the phrase “optical communications module” can refer to any module that includes one or more optoelectronic sub-assemblies, such as, for example, a receiver optical sub-assembly (ROSA), a transmitter optical sub-assembly (TOSA), or a transceiver optical sub-assembly. 
     When the optical communications module includes a transceiver optical sub-assembly, the transceiver optical sub-assembly can include an optoelectronic light source such as a laser, an optoelectronic light receiver such as a photodiode, and may further include electronic circuitry associated with the light source and the optoelectronic light receiver. For example, driver circuitry can be included for driving the laser, and receiver circuitry can be included for processing electrical signals produced by the photodiode. Optics such as lenses and reflectors may also be included in the sub-assembly in order to direct light emitted by the laser to an output receptacle of the sub-assembly or to direct light that is received at an input receptacle of the sub-assembly towards the photodiode contained inside the sub-assembly. 
     Attention is now drawn to  FIG. 1 , which shows an exemplary embodiment of an optical communications module  100  configured to accommodate a pair of connectors  106  and  107  that are provided at an end of a fiber optic cable  105 . In accordance with this disclosure, the optical communications module  100  can be a small form-factor pluggable (SFP), an enhanced SFP (SFP+) optical communications module, or a Quad SFP (QSFP) optical communications module. However, the invention is not limited to these optical communications modules and can be implemented in various other optical communications modules. Furthermore, in this exemplary embodiment, the optical communications module  100  includes a pair of optical receptacles configured to accept a pair of connectors located at the end of a fiber optic cable. In other embodiments, the optical communications module  100  can include a single optical receptacle in order to provide connectivity to a single fiber optic cable or more than two optical receptacles in order to provide connectivity to more than two fiber optic cables. 
     The fiber optic cable assembly  105  shown in this exemplary embodiment includes a first connector  106  and a second connector  107 , each of which has a form factor commonly referred to in the art as an “LC” (originally an abbreviation for Lucent Connector) form factor. In accordance with the LC form factor, each of the first connector  106  and the second connector  107  has a generally square profile that is insertable into a first optical port  120  and a second optical port  125  respectively of the optical communications module  100 . Each of the first optical port  120  and the second optical port  125  of the optical communications module  100  has a corresponding square profile for receiving the first connector  106  and the second connector  107  respectively. 
     In accordance with the disclosure, a deformable constraining member (not shown) is used during assembly of the optical communications module  100  to ensure that each of the first optical receptacle  108  and the second optical receptacle  109  is precisely aligned with respect to the walls of the first optical port  120  and the second optical port  125  respectively. The deformable constraining member further constrains movement of the first optical receptacle  108  and the second optical receptacle  109  with respect to the walls of the first optical port  120  and the second optical port  125  respectively. As a result of this arrangement, precise optical alignment is automatically achieved between the two optical receptacles  108  and  109  of the optical communications module  100  and the two respective connectors  106  and  107  in the fiber optic cable assembly  105  when the fiber optic cable assembly  105  is coupled to the optical communications module  100 . These aspects will be described below in more detail using other figures. 
       FIG. 2  shows a perspective external view of the optical communications module  100 . In accordance with this illustrative embodiment, the optical communications module  100  includes a front housing portion  230  coupled to a rear housing portion  235 . The front housing portion  230  includes the first optical port  120  and the second optical port  125 . The first optical port  120  provides room for connecting the first connector  106  of the optical cable  105  to the first optical receptacle  108 . The second optical port  125  provides room for connecting the second connector  107  of the optical cable  105  to the second optical receptacle  109 . The optical communications module  100  further includes an upper housing portion  205  and a lower housing portion  210 . In one example implementation, each of the upper housing portion  205  and the lower housing portion  210  is made entirely, or in part, of a metal, although non-metallic materials may be used in other implementations. In a first exemplary embodiment, the upper housing portion  205  and the lower housing portion  210  can be provided in the form of a pivot and snap feature that allows the two portions to be mated with each together. In a second exemplary embodiment, the upper housing portion  205  and the lower housing portion  210  can be mated with each other using multiple screws (not shown). 
     A portion of each of the first optical receptacle  108  and the second optical receptacle  109  projects out via respective openings that have been provided for this purpose in the optical communications module  100 . Specifically, a cylindrical body portion  226  of the first optical receptacle  108  projects out through a first opening and a cylindrical body portion  227  of the second optical receptacle  109  projects out through a second opening in the optical communications module  100 . The first opening is formed by a combination of an alignment notch  233  that is provided in the front wall  232  of the upper housing portion  205  and a corresponding alignment notch (not shown) that is provided in a front wall  238  of the lower housing portion  210 . The second opening is formed by a combination of another alignment notch  234  that is provided in the front wall  232  of the upper housing portion  205  and another corresponding alignment notch (not shown) that is provided in the front wall  238  of the lower housing portion  210 . The various alignment notches will be described below in more detail with reference to other figures. 
       FIG. 3  shows an enlarged frontal view of the optical communications module  100  in accordance with one exemplary embodiment of the disclosure. This enlarged formal view corresponds to a preliminary condition wherein the front wall  232  of the upper housing portion  205  has not yet been mated with the front wall  238  of the lower housing portion  210  and prior to the start of an assembly procedure of the optical communications module  100 . In this exemplary embodiment, the front wall  232  of the upper housing portion  205  includes the alignment notch  233  and the alignment notch  234 . Each of the alignment notches  233  and  234  can have various shapes. In the exemplary embodiment shown in  FIG. 3 , each of the alignment notches  233  and  234  has a composite shape that combines a rectangular portion  251  with a curved portion  252 . The rectangular portion  251  is configured to accommodate a deformable constraining member  325  as will be described below in more detail. 
     The front wall  238  of the lower housing portion  210  includes a corresponding alignment notch  236  and an alignment notch  237 . In various exemplary implementations, each of the alignment notches  236  and  237  can have a U-shape, a V-shape, a semicircular shape, a composite shape, or a hybrid shape. These shapes will be described below in more detail using other figures. 
     When the front wall  232  of the upper housing portion  205  is mated with the front wall  238  of the lower housing portion  210 , a combination of the alignment notch  233  and the alignment notch  236  constitutes the first opening through which projects the cylindrical portion  226  of the optical receptacle  108 . Similarly, a combination of the semicircular alignment notch  234  and the alignment notch  237  constitutes the second opening through which projects the cylindrical portion  227  of the optical receptacle  109 . 
     Typically, each of the upper housing portion  205  and the lower housing portion  210  is fabricated using a molding process, whereby each of the alignment notches  233 ,  234 ,  236  and  237  is automatically aligned to a precision tolerance with respect to one or more surfaces of the first optical port  120  and the second optical port  125 . For example, the alignment notch  236  is automatically aligned with a sidewall  306  and a bottom surface  307  of the first optical port  120 , and the alignment notch  237  is automatically aligned with a sidewall  308  and a bottom surface  309  of the second optical port  125 . 
     The first deformable constraining member  325  can be accommodated in the rectangular portion  251  of the alignment notch  233  and in vertical alignment with a top surface of the cylindrical body portion  226  of the first optical receptacle  108 . Particulars pertaining to accommodating the first deformable constraining member  325  in the rectangular portion  251  are provided below with reference to other figures. A second deformable constraining member  330  can be similarly accommodated in the rectangular portion  251  of the alignment notch  234  and in vertical alignment with a top surface of the cylindrical body portion  227  of the second optical receptacle  109 . 
     When the upper housing portion  205  is mated with the lower housing portion  210 , such as, for example, by employing a pivot and snap feature when assembling the optical communications module  100 , the first deformable constraining member  325  is pressed downwards and makes contact with the top surface of the cylindrical body portion  226  of the first optical receptacle  108 . At the same time, the second deformable constraining member  330  makes contact with the top surface of the cylindrical body portion  227  of the second optical receptacle  109 . When pressure is further applied to secure the mating of the upper housing portion  205  with the lower housing portion  210 , such as, for example, by operating one or more screws (not shown) that are included in one or both of the upper housing portion  205  and the lower housing portion  210 , the rectangular portion  251  of the alignment notch  233  compresses the first deformable constraining member  325  causing it to deform and furthermore, to push the optical receptacle  108  into the alignment notch  236 . The rectangular portion  251  of the alignment notch  234  similarly compresses the second deformable constraining member  330  causing it to deform and furthermore, pushes the optical receptacle  109  into the alignment notch  237 . 
       FIG. 4  shows a profile drawing of a portion of the optical communications module  100  in accordance with another exemplary embodiment of the disclosure. Unlike the exemplary embodiment described above with reference to  FIG. 3  wherein each of the alignment notch  236  and the alignment notch  237  in the lower housing portion  210  is a substantially U-shaped, in this exemplary embodiment, the lower housing portion  210  includes a first V-shaped alignment notch  405  and a second V-shaped alignment notch  415 . 
     The V-shaped alignment notch  405  facilitates automatic alignment of the optical receptacle  108  with a first longitudinal optical axis  410  of the optical communications module  100 . It is highly desirable that the first longitudinal optical axis  410  of the optical communications module  100  be automatically and precisely aligned with a light propagating axis of the first connector  106  that is shown in  FIG. 1 . The V-shaped alignment notch  415  similarly facilitates automatic alignment of the optical receptacle  109  with a second longitudinal optical axis  420  of the optical communications module  100 . It is highly desirable that the second longitudinal optical axis  420  of the optical communications module  100  be automatically and precisely aligned with a light propagating axis of the second connector  107  that is shown in  FIG. 1 . 
     The description below is made with reference to the first deformable constraining member  325 . However, it should be understood that the description applies equally well to the second deformable constraining member  330 . 
     Attention is first drawn to a dashed line outline of the first deformable constraining member  325  that is indicative of a shape of the first deformable constraining member  325  during a preliminary condition wherein the front wall  232  of the upper housing portion  205  has not yet been mated with the front wall  238  of the lower housing portion  210 , (such as, for example, prior to using the pivot and snap feature for assembling the optical communications module  100 ). 
     A dashed line outline of the cylindrical body portion  226  of the first optical receptacle  108  is also shown to indicate one possible position in which the cylindrical body portion  226  can be located as a result of say, a manual placement action carried out upon the optical receptacle  108  during the start of the assembly procedure of the optical communications module  100 . 
     As mentioned above, the assembly procedure can be executed in various ways such as, for example, by employing a pivot and snap feature to mate the upper housing portion  205  with the lower housing portion  210  and/or by operating one or more screws (not shown) that leads to pressurized contact between the upper housing portion  205  and the lower housing portion  210 . During the assembly procedure, the rectangular portion  251  of the alignment notch  233  applies compression force upon the first deformable constraining member  325  (as indicated by the arrow  401 ). The first deformable constraining member  325  in turn makes contact with an upper surface of the cylindrical body portion  226  of the first optical receptacle  108  and pushes the first optical receptacle  108  downwards into the V-shaped alignment notch  405 . 
     During this process, an automatic alignment action occurs as a result of the sloping side  406  of the V-shaped alignment notch  405  causing the cylindrical body portion  226  to slide downwards such that the cylindrical body portion  226  eventually rests against two contact points  407  and  408  of the V-shaped alignment notch  405 . The dimensions and shape of the V-shaped alignment notch  405  is explicitly tailored with reference to a diameter of the cylindrical body portion  226  such that the cylindrical body portion  226  is automatically aligned with the optical axis  410 . 
     It should be understood that the dimensions and shapes of variously shaped alignment notches referred to elsewhere in this disclosure are also explicitly tailored with reference to the diameter of the cylindrical body portion  227  such that the cylindrical body portion  226  is automatically aligned with the optical axis  410  and eventually rests against two contact points that are similar to the two contact points  407  and  408  of the V-shaped alignment notch  405 . 
     Now referring back to the V-shaped alignment notch  405 , upon completion of the assembly procedure, the first optical receptacle  108  automatically becomes precisely aligned with respect to the various walls and surfaces of the first optical port  120  (shown in  FIG. 1 ). This precise alignment allows the square profile of the first connector  106  of the fiber optic cable assembly  105  (shown in  FIG. 1 ) to establish a snug fit inside the first optical port  120  and minimize, if not eliminate, wiggling of the first connector  106  in the first optical port  120 . 
     Attention is next drawn to the first deformable constraining member  325  in order to describe certain features of the first deformable constraining member  325 . It should be understood that this description is equally applicable to the second deformable constraining member  330 . Each of the first deformable constraining member  325  and the second deformable constraining member  330  is made of malleable material such as, for example, a malleable plastic or a soft metal alloy. The malleable material has certain properties pertaining to transitioning from an elastic regime to a plastic regime. Specifically, the malleable material selected for implementing the first deformable constraining member  325  and the second deformable constraining member  330  in accordance with the disclosure, transitions from an elastic regime to a plastic regime when subjected to a certain amount of compression force for effecting a deformation. A transition from an elastic regime to a plastic regime can be generally characterized by one of several parameters that is known in the art as Young&#39;s modulus. The malleable material in accordance with the disclosure has a Young&#39;s modulus that is higher than the Young&#39;s modulus of an “elastic” material such as rubber (0.01 to 0.1 GPa) and lower than the Young&#39;s modulus of a “stiff” material such as, for example, steel (180-200 GPa). Accordingly, in various embodiments in accordance with the disclosure, each of the first deformable constraining member  325  and the second deformable constraining member  330  can be made of a material that has a Young&#39;s modulus range extending from about 0.5 GPa to about 100 GPa, which includes various plastics as well as various soft metal alloys such as aluminum, for example. However, it will be pertinent to point out that this range explicitly precludes rubber. 
     Drawing attention back to  FIG. 4 , the dashed line outline of the first deformable constraining member  325  indicates a shape of the first deformable constraining member  325  prior to compression pressure being applied upon the first deformable constraining member  325  by the rectangular portion  251  of the alignment notch  233 . Upon application of compression pressure, the first deformable constraining member  325  deforms to an initial deformed shape that can be characterized by a bottom surface  326  of the first deformable constraining member  325  conforming to the shape of a portion of the upper surface of the cylindrical body portion  226  of the first optical receptacle  108 . At this time, a ceiling portion  451  of the rectangular portion  251  is in contact with, and pressing down upon, a top surface  327  of the first deformable constraining member  325 , thereby forcing the first deformable constraining member  325  to retain the initial deformed state. 
     The initial deformed state of the first deformable constraining member  325  automatically urges the first optical receptacle  108  to be seated in the V-shaped alignment notch  405  and prevents wiggling of the cylindrical portion  226  of the optical receptacle  108 , thereby constraining movement of some or all portions of the first optical receptacle  108  inside the optical communications module  100 . More particularly, the first deformable constraining member  325  prevents lateral movement (upwards, downwards, or sideways) of the cylindrical portion  226  of the optical receptacle  108 . The second deformable constraining member  330 , which has been deformed by the rectangular portion  251  of the alignment notch  234 , similarly prevents lateral movement (upwards, downwards, or sideways) of the cylindrical portion  227  of the optical receptacle  109 . 
     The initial deformed state of the first deformable constraining member  325  can be retained during normal use and operation of the optical communications module  100 . However, if it is desired to disassemble the optical communications module  100  at a later instant in time, such as, for example, by operating one or more screws to decouple the upper housing portion  205  from the lower housing portion  210 , the compression pressure applied upon the first deformable constraining member  325  by the rectangular portion  251  gets automatically removed as a result of the decoupling operation. When the compression force is removed, each of the first deformable constraining member  325  and the second deformable constraining member  330  is transformed to a free-standing deformed state. However, unlike a rubber compound, the material of the first deformable constraining member  325  is selected to explicitly prevent the first deformable constraining member  325 , when in the free-standing deformed state, from reverting to the original shape shown by the dashed line outline. 
     Furthermore, upon a partial removal of the compression pressure, for example, as a result of an intentional or accidental partial separation of the upper housing portion  205  from the lower housing portion  210 , the initial deformed state of the first deformable constraining member  325  changes to an intermediate deformed state. The intermediate deformed state is characterized by the top surface  327  of the first deformable constraining member  325  resiliently bulging upwards and maintaining pressurized contact with the ceiling portion  451  of the alignment notch  233 . The pressurized contact provided by the intermediate deformed state of the first deformable constraining member  325  thus restricts movement of some or all portions of the first optical receptacle  108  inside the optical communications module  100  even when the upper housing portion  205  is partially separated from the lower housing portion  210 . An intermediate deformed state of the second deformable constraining member  330  similarly restricts movement of some or all portions of the second optical receptacle  109  inside the optical communications module  100 . 
     In the exemplary embodiment shown in  FIG. 4 , each of the two alignment notches  405  and  415  provided in the front wall  238  of the lower housing portion  210  has a V-shape. However, in other embodiments, a hybrid V-shape that incorporates a linear portion can be used. To elaborate upon this aspect, attention is drawn to the V-shaped alignment notch  415 , which further shows a dashed line outline of a hybrid notch  416  having segments that are indicated by reference designators  416   a  through  416   e . The segments  416   a ,  416   c , and  416   e  correspond to segments of a U shape, while the segments  416   b  and  416   d  are linear segments. The location of the linear segment  416   b  is explicitly selected to encompass the contact point  407  where the cylindrical body portion  227  of the second optical receptacle  109  makes contact with the hybrid notch  416  and the location of the linear segment  416   d  is explicitly selected to encompass the contact point  408  where the cylindrical body portion  227  of the second optical receptacle  109  makes another contact with the hybrid notch  416 . 
     The segments  416   a ,  416   c , and  416   e  of the U-shape can provide benefits such as, for example, minimizing emission of electromagnetic energy from inside the optical communications module  100 . It will be understood that the first V-shaped alignment notch  405  can be similarly replaced by a hybrid notch that is similar to the hybrid notch  416 . 
     Attention is now drawn to  FIG. 5 , which shows a perspective view of various exemplary components mounted in the lower housing portion  210  of the optical communications module  100 . The various exemplary components include an electronic circuit assembly  505 , a first optoelectronic sub-assembly  506 , and a second optoelectronic sub-assembly  207 . The electronic circuit assembly  505  includes various components that operate upon electrical signals that can be provided to, or received from, one or both of the first optoelectronic sub-assembly  506  and the second optoelectronic sub-assembly  207 . 
     Each of the first optoelectronic sub-assembly  506  and the second optoelectronic sub-assembly  507  performs operations that include signal conversion between the optical domain and the electrical domain. For example, when the optical communications module  100  is configured to transmit optical signals out of the first optical receptacle  108 , the first optoelectronic sub-assembly  506  can convert electrical signals received from the electronic circuit assembly  505  into optical signals that are propagated out of the first optical receptacle  108 . On the other hand, when the optical communications module  100  is configured to receive an optical signal via the first optical receptacle  108 , the first optoelectronic sub-assembly  506  can convert the received optical signals into electrical signals that are then provided to the electronic circuit assembly  505 . 
     In this exemplary embodiment, the various components of the electronic circuit assembly  505  are mounted on a printed circuit board (PCB)  525 . The PCB  525  can be a multilayer PCB and include a ground layer. The ground layer is connected to a set of ground contacts that are a part of an edge connector  520 . The edge connector  520  has other contacts that are connected to various other components of the electronic circuit assembly  505  for purposes of conducting various electrical signals that are operated upon by the electronic circuit assembly  505 . Such signals include power signals that are used to power the various components of the electronic circuit assembly  505 . 
     When the optical communications module  100  is inserted into a host device (not shown) such as a router or a communications switch, the edge connector  520  mates with a corresponding connector in the host device. Each of the contacts in the edge connector  520  makes contact with a matching set of contacts in the corresponding connector of the host device. 
     Each of the first optoelectronic sub-assembly  506  and the second optoelectronic sub-assembly  507  is typically implemented in the form of a metal enclosure. The first optical receptacle  108  and the second optical receptacle  109  are each mounted on a respective wall of the first optoelectronic sub-assembly  506  and the second optoelectronic sub-assembly  507 . Thus, the cylindrical body portion of each of the first optical receptacle  108  and the second optical receptacle  109  project into the first optical port  120  and the second optical port  125  respectively of the communications module  100 . The first deformable constraining element  325  is mounted on the cylindrical body portion of the first optical receptacle  108  and the second deformable constraining element  330  is mounted on the cylindrical body portion of the second optical receptacle  109  in accordance with the disclosure. 
       FIG. 6  shows a close-up perspective view of a portion of the optical communications module  100  that incorporates the first deformable constraining element  325  placed in contact with the cylindrical body portion  226  of the first optical receptacle  108  and the second deformable constraining element  330  placed in contact with the cylindrical body portion  227  of the second optical receptacle  109  in accordance with the disclosure. The placement of each of the first deformable constraining element  325  and the second deformable constraining element  330  can be executed in various ways. 
     In one exemplary implementation, each of the first deformable constraining element  325  and the second deformable constraining element  330  can be manually placed upon the respective the cylindrical body portions  226  and  227  prior to mating of the upper housing portion  205  with the lower housing portion  210 . 
     However, another exemplary implementation is illustrated in  FIG. 7 , which shows an inside view of an exemplary upper housing portion  205  configured to anchor each of a first deformable constraining element  725  and a second deformable constraining element  730  in accordance with the disclosure. More particularly, in this exemplary implementation, the first deformable constraining element  725  is anchored inside a first recess  705  and the second deformable constraining element  730  is anchored inside a second recess  710 . The first recess  705  and the second recess  710  can be located in a bottom edge of a front wall  735  of the upper housing portion  205 . 
     The anchoring of the first deformable constraining element  725  inside the first recess  705  and the second deformable constraining element  730  inside the second recess  710  can be executed in various alternative ways, such as, for example, by using one or more clasps; by using one or more protrusions or indentations in each recess; by using one or more tabs or recesses in each deformable constraining element; by using surface roughness that provides frictional contact; or by using epoxy to hold the deformable element in place. 
       FIG. 8  shows an exemplary embodiment of the deformable constraining element  725  incorporating anchoring elements for anchoring the deformable constraining element inside a recess in accordance with the disclosure. The features indicated with respect to the first deformable constraining element  725  can be identical to features that are provided in the second deformable constraining element  730  as well. 
     Viewing  FIG. 8  in conjunction with  FIG. 7 , it can be understood that the first deformable constraining element  725  is a rectangular element having a longer side aligned substantially parallel to the front wall  735  of the upper housing portion  205 . Because the front wall  735  of the upper housing portion  205  is coplanar to the front wall  238  of the lower housing portion  210  (shown in  FIG. 2 ), the longer side of the first deformable constraining element  725  is also aligned substantially parallel to the front wall  238  of the lower housing portion  210 . 
     The exemplary first deformable constraining element  725  includes a first protrusion  726  and an adjacent second protrusion  726  on a side surface of the first deformable constraining element  725 . In this exemplary implementation, each of the first protrusion  726  and the second protrusion  726  is provided in the form of a tab. A similar (or identical) pair of protrusions  728  can be provided on an opposing side surface of the first deformable constraining element  725 . Each protrusion provides a friction fit when the first deformable constraining element  725  is press-fitted into the first recess  705  of the upper housing portion  205  because the protrusions  726  and  727  can plastically deform to fill the available width of the recess and provide the requisite friction fit. The first recess  705  can also incorporate other features that provide a retention force upon the first deformable constraining element  725 . 
     The friction fit advantageously allows the internal portion of the upper housing portion  205  to face downwards during mating with the lower housing portion  210 , without having the first deformable constraining element  725  (and the second deformable constraining element  730 ) fall out of their respective recesses. The first recess  705  and the second recess  710  are aligned with respect to the lower housing portion  210  such that the first deformable constraining element  725  automatically comes in contact with the upper surface of the cylindrical body portion  226  of the first optical receptacle  108 , and the second deformable constraining element  730  automatically comes in contact with the upper surface of the cylindrical body portion  227  of the first optical receptacle  109 , when the upper housing portion  205  is mated with the lower housing portion  210 . 
     In alternative embodiments, a single protrusion can be used in place of multiple protrusions; one or more protrusions can be located on various surfaces other than, or in addition to, the side surfaces of the first deformable constraining element  725 ; and various shapes can be used for the protrusions such as, for example, a bulb shape, a strip shape, or a cylinder shape. 
     In summary, it should be noted that the invention has been described with reference to a few illustrative embodiments for the purpose of demonstrating the principles and concepts of the invention. It will be understood by persons of skill in the art, in view of the description provided herein, that the invention is not limited to these illustrative embodiments. Persons of skill in the art will understand that many such variations can be made to the illustrative embodiments without deviating from the scope of the invention.