Patent Publication Number: US-2023144154-A1

Title: Dense wavelength division multiplexing modulization system

Description:
PRIORITY APPLICATION 
     This application claims the benefit of priority of U.S. Provisional Application No. 63/277,723, filed on Nov. 10, 2021, the content of which is relied upon and incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The technology of the disclosure relates to dense wavelength division multiplexing provided in fiber optic apparatuses and equipment. 
     BACKGROUND OF THE DISCLOSURE 
     Benefits of optical fiber include extremely wide bandwidth and low noise operation. Because of these advantages, optical fiber is increasingly being used for a variety of applications, including but not limited to broadband voice, video, and data transmission. Fiber optic networks employing optical fiber are being developed and used to deliver voice, video, and data transmissions to subscribers over both private and public networks. These fiber optic networks often include separated connection points linking optical fibers to provide “live fiber” from one connection point to another connection point. In this regard, fiber optic equipment is located in data distribution centers or central offices to support interconnections. For example, the fiber optic equipment can support interconnections between servers, storage area networks (SANs), and other equipment at data centers. Interconnections may be supported by fiber optic patch panels or modules. 
     The transition to deep fiber architectures, such as Remoter Phy Distribution (RPD) or  5 G, significantly transforms the nature of traditional head ends into large scale  10 G switched network centers. Although similar to large scale datacenters—where large strand count fiber trunks are used to interconnect the massive amount of switch ports—the distribution of individual “ports” in neighborhood nodes dramatically drives up strand counts for outside plant (OSP) fiber trunks in the same manner. OSP fiber optic network typically employ wavelength division multiplexing (WDM) technology, and particularly dense wavelength division multiplexing (DWDM) to more efficiently transport traffic. However, the resulting large scale deployment of WDM and DWDM filtering introduces new challenges for space density, channelization efficiency, and cross connection methodology. 
     Wavelength division multiplexing (WDM) multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths of light. This technique enables bidirectional communications over one strand of fiber, as well as multiplication of capacity. WDM modules may utilize a plurality of optical filters, e.g. bandpass filters and channel filters, to isolate wavelengths for each channel. Some representative optical filters may include thin film filters (TTFs) and arrayed wave guide (AWG) filters. Dense wavelength division multiplexing (DWDM) increases the number of channels that can be transmitted over a single optical fiber by reducing the spacing between channels, such as 0.8/0.4 nm (100 GHz/50 GHz grid). However, when using filter methods for a DWDM deployment, an increase in the number of channels requires a corresponding increase in the number of filters. Each additional filter consumes additional space in a fiber optic assembly or module. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure relates to a fiber optic assembly that includes a body and a lid coupled to the body where the body and the lid each define a respective fiber routing plane. The fiber optic assembly also includes a plurality of ports on the body and a plurality of ports on the lid such that when the lid and the body are in a closed configuration, the ports of the body and the ports of the lid define a singular connection plane. 
     In one embodiment, a fiber optic assembly is provided. The fiber optic assembly comprising: a body defining a first fiber optic component routing plane; a cover configured to cover the body and the first fiber optic component routing plane; a first plurality of fiber optic components disposed in a front side of the body; and a plurality of optical filters disposed within the first fiber optic component routing plane, wherein the plurality of optical filters enable up to 450 DWDM channels; wherein the fiber optic assembly has a volume less than 10 8  mm 3 . 
     In another embodiment, the body comprises a base having at least one sidewall extending therefrom, wherein the base defines a first fiber optic component routing plane, and an interior side of the cover coupled to the body and configured to cover the body, the cover defining a second fiber optic component routing plane. In another embodiment, wherein the plurality of optical filters comprises a first plurality of optical filters and a second plurality of optical filters, and wherein the first plurality of optical filters is stacked on top of each other within the first fiber optic component routing plane and the second plurality of optical filters is stacked on top of each other within the second fiber optic component routing plane. In another embodiment, the fiber optic assembly further comprising a plurality of filter cradles disposed within the body, the plurality of filter cradles are each configured to retain some of the plurality of optical filters in two stacked rows. In another embodiment, the two stacked rows comprises a first row optical filters and a second row of optical filters, the second row of optical filters defines valleys between adjacent optical fibers in the second row of optical filters, and the first row of optical filters are disposed in the valleys defined by the second row of optical filters such that the first row of optical filters is offset from the second row of optical filters. In another embodiment, at least one optical fiber is routed from the first fiber optic component routing plane to the second fiber optic component routing plane. In another embodiment, the fiber optic assembly further comprising: a first plurality of splice protectors disposed in the first fiber optic component routing plane; and a second plurality of splice protectors in the second fiber optic component routing plane, wherein the first plurality of splice protectors are stacked on top of each other and the second plurality of splice protectors are stacked on top of each other. In another embodiment, the fiber optic assembly has a length between 250 mm and 650 mm. In another embodiment, the fiber optic assembly has a width between 250 mm and 650 mm. In another embodiment, the fiber optic assembly has a height between 5 mm and 25 mm. In another embodiment, the fiber optic assembly comprises of a single fiber optic assembly configured to fully occupy a width of a chassis. In another embodiment, the volume is less than 107 mm 3 . 
     In one embodiment, a fiber optic assembly is provided. The fiber optic assembly comprising: a body defining a first fiber optic component, wherein the body comprises a base having at least one sidewall extending therefrom, wherein the base defines a first fiber optic component routing plane; a cover coupled to the body and configured to cover the body, the cover comprising an interior side of the cover coupled to the body, the cover defining a second fiber optic component routing plane; a first plurality of fiber optic ports disposed in a front side of the body; a first plurality of optical filters disposed within the first fiber optic component routing plane; a second plurality of fiber optic ports disposed in a front side of the cover; and a second plurality of optical filters disposed within the second fiber optic component routing plane. 
     In another embodiment, when the fiber optic assembly is in a closed position, the first plurality of fiber optic ports and the second plurality of fiber optic ports are in a single connection plane. In another embodiment, the first plurality of optical filters is stacked on top of each other within the first fiber optic component routing plane and the second plurality of optical filters is stacked on top of each other within the second fiber optic component routing plane. In another embodiment, the first plurality of optical filters and the second plurality of optical filters enable up to 450 DWDM channels. In another embodiment, at least one optical fiber is routed from the first fiber optic component routing plane to the second fiber optic component routing plane. In another embodiment, the fiber optic assembly, further including a first plurality of splice protectors disposed in the first fiber optic component routing plane and a second plurality of splice protectors in the second fiber optic component routing plane; wherein the first plurality of splice protectors are stacked on top of each other and the second plurality of splice protectors are stacked on top of each other. In another embodiment, the fiber optic component routing plane is less than 108 mm 3 . In another embodiment, when the fiber optic assembly is in an open position, the first plurality of fiber optic ports and the second plurality of fiber optic ports are in different planes. In another embodiment, the first plurality of optical filters are operably connected to the first plurality of fiber optic ports and the second plurality of optical filters are operably connected to the second plurality of fiber optic ports. 
     Additional features and advantages will be set out in the detailed description which follows, and in part will be readily apparent to those skilled in the technical field of optical connectivity. It is to be understood that the foregoing general description, the following detailed description, and the accompanying drawings are merely exemplary and intended to provide an overview or framework to understand the nature and character of the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments. Features and attributes associated with any of the embodiments shown or described may be applied to other embodiments shown, described, or appreciated based on this disclosure. 
         FIG.  1    is a perspective view of a conventional fiber optic equipment rack with an installed conventional 1-U size chassis supporting high-density fiber optic modules to provide a given fiber optic connection density and bandwidth capability; 
         FIG.  2    is a perspective view of a fiber optic module installed in the fiber optic equipment rack of  FIG.  1   ; 
         FIGS.  3 A and  3 B  are perspective views of a fiber optic assembly to be used with the equipment rack of  FIG.  1    in a closed and an open configuration, respectively; 
         FIG.  3 C  is a cross-sectional view of the fiber optic module of  FIG.  3 B  with optical fibers included, according to an example embodiment; 
         FIGS.  4 A and  4 B  are perspective views of another embodiment of a fiber optic assembly to be used with the equipment rack of  FIG.  1    in a closed and an open configuration, respectively; 
         FIGS.  5 A and  5 B  are perspective views of another embodiment of a fiber optic assembly to be used with the equipment rack of  FIG.  1    in a closed and an open configuration, respectively; 
         FIGS.  6  and  7    are schematic views of a forty eight (48) channel MUX and DeMUX DWDM fiber optic module, respectively; and 
         FIG.  8    illustrates the interaction of the MUX and DeMUX DWDM fiber optic modules shown in  FIGS.  6  and  7   , respectively, when paired. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments will be clarified by examples in the description below. In general, the present disclosure relates to a fiber optic assembly that includes a body and a lid coupled to the body where the body and the lid each define a respective fiber routing plane. The fiber optic assembly also includes a plurality of ports on the body and a plurality of ports on the lid such that when the lid and the body are in a closed configuration, the ports of the body and the ports of the lid define a singular connection plane. 
     Referring first to  FIG.  1   , a conventional fiber optic equipment  10  from a front perspective view is shown. The fiber optic equipment  10  supports high-density fiber optic assemblies that support a high fiber optic connection density and bandwidth in a 1-U space, as described below. The fiber optic equipment  10  may be provided, for example, at a data distribution center or central office, to support cable-to-cable fiber optic connections and to manage a plurality of fiber optic cable connections. In some embodiments, the fiber optic equipment  10  has one or more fiber optic equipment trays  20  that each support one or more fiber optic assemblies. Here, the fiber optic assemblies are substantially enclosed fiber optic modules  22 . Fiber optic modules  22  are used throughout the specification of illustrative purposes, however, fiber optic assemblies that are not substantially enclosed may also be used. In addition to the fiber optic modules  22 , the fiber optic equipment  10  could also be adapted to support one or more fiber optic patch panels, or other fiber optic equipment, that supports fiber optic components and connectivity. 
     The fiber optic equipment  10  includes a fiber optic equipment chassis  12  (“chassis  12 ”). The chassis  12  is shown as being installed in a fiber optic equipment rack. The fiber optic equipment rack  14  contains two vertical rails  16 ,  18  that extend vertically and include a series of apertures for facilitating attachment of the chassis  12  inside the fiber optic equipment rack. In some example embodiments, the chassis  12  may include a housing surrounding at least a portion of the chassis  12 . The chassis  12  is attached and supported by the fiber optic equipment rack  14  in the form of shelves that are stacked on top of each other within the vertical rails  16 ,  18 . The fiber optic equipment rack may support 1-U-sized shelves, with “rack unit” or “U” equal to 1.75 inches in height and nineteen (19) inches in width, as specified in EIA-310-D; published by the Electronic Industries Alliance. In certain applications, the width of “U” may be twenty-three (23) inches. Also, the term fiber optic equipment rack  14  should be understood to include structures that are cabinets, as well. In this embodiment, the chassis  12  is 1-U in size; however, the chassis  12  could be provided in a size greater than 1-U as well, such as 2-U, 4-U, or the like. 
     The fiber optic equipment  10  includes one or more of fixed or extendable fiber optic equipment trays  20  that each carry one or more fiber optic assemblies or fiber optic modules  22 . Each fiber optic equipment tray  20  may include one or more module guides rails  24  configured to slidably receive the fiber optic modules  22 . In an example embodiment, the fiber optic modules may be installable from either the front of the fiber optic equipment trays  20  the rear of the fiber optic equipment trays, or both. The chassis  12  and fiber optic equipment trays  20  support fiber optic modules  22  that support high-density fiber optic connection density and/or high density WDM channel density in a given space, including in a 1-U space. 
       FIG.  1    shows exemplary fiber optic components  23  disposed in the fiber optic modules  22  that support fiber optic connections. For example, the fiber optic components  23  may be fiber optic adapters or fiber optic connectors. As discussed below, the fiber optic modules  22  in this embodiment can be provided such that the fiber optic components  23  can be disposed through at least about eighty-five percent (85%) of the width of the front side or face of the fiber optic module  22 , as an example. The fiber optic module  22  may include one or more fiber optic components  23 . For example, the fiber optic components  23  may include multi-fiber push-on/pull-off (MPO) connectors or adapters (e.g., according to IEC 61754-7). In some examples, the fiber optic components  23  include very-small form factor (VSFF) duplex connectors or adapters, such as MDC connectors or adapters (sometimes referred to as “mini duplex connectors”) offered by U.S. Conec, Ltd. (Hickory, N.C.), and SN connectors or adapters (sometimes referred to as a Senko Next-generation connectors) offered by Senko Advanced Components, Inc. (Marlborough, Mass.). Such VSFF connectors or adapters may be particularly useful in the structured optical fiber cable systems in this disclosure, and will be referred to generically as “dual-ferrule VSFF components” due to their common design characteristic of the connectors having two single-fiber ferrules within a common housing (and the adapters being configured to accept such connectors). As used herein duplex connectors include two optic fibers, one transmit optical fiber and one receive optical fiber. A multi-fiber fiber optic component, as used herein includes more than two optical fibers. 
     Referring now to  FIG.  2   , a conventional fiber optic module  22  is shown. Fiber optic module  22  configuration may provide a front opening  28  of approximately 85 millimeters (mm) or less wherein fiber optic components  23  can be disposed through the front opening  28  and at a fiber optic connection density of at least one fiber optic connection per approximately 2 mm of width or less of the front opening of the fiber optic modules  22  for dual-ferrule VSFF adapters, such as SN connector adapters or an MDC connector adapter or LC connector adapters or the like. Reference below to LC connectors and adapters and/or MDC connectors and adapters, is merely for illustrative purposes and other duplex fiber optic components, e.g. connectors and associated adapters, may also be used. In this example, eighteen (18) duplex fiber optic components may be installed in each fiber optic module  22 . The fiber optic equipment trays  20  ( FIG.  1   ) in this embodiment support up to four (4) of the fiber optic modules  22  in approximately the width of a 1-U space, and three (3) fiber optic equipment trays  20  in the height of a 1-U space for a total of twelve (12) fiber optic modules  22  in a 1-U space. Thus, for example, if eighteen (18) duplex fiber optic components were disposed in each of the twelve (12) fiber optic modules  22  installed in fiber optic equipment trays  20  of the chassis  12  as illustrated in  FIG.  1   , a total of four hundred thirty two (432) fiber optic connections, or two hundred sixteen (216) duplex channels (i.e., transmit and receive channels), would be supported by the chassis  12  in a 1-U space. 
     In the example depicted in  FIG.  1   , the fiber optic equipment trays  20  include module guide rails  24  disposed on each edge and three module guide rails  24  disposed at intermediate locations, between each of the fiber optic modules  22 . In other embodiments, one or more of the module guide rails  24  may be removed or may be selectively removable, such as by snap fit or fasteners. Removing one or more of the module guide rails  24  may enable a larger fiber optic module to be utilized which has a larger front side face than two smaller fiber optic modules. This larger front side face may accommodate additional fiber optic components  23  as described in U.S. Pat. No. 10,715,271, granted on Jul. 14, 2020, the disclosure of which is hereby incorporated by reference herein. 
       FIGS.  3 A and  3 B  are perspective views of an exemplary fiber optic assembly of the present disclosure, particularly a substantially enclosed fiber optic module  122 . The fiber optic assembly may include a base or body  102  configured to support a fiber optic arrangement. The body  102  may define a fiber routing volume, which may be fully, or partially enclosed as described below, or may be generally unenclosed. For example, the fiber routing volume defined by the body  102  of the fiber optic assembly may be fully enclosed, or a hermetically sealed volume, or it can be a volume defined by sides of the fiber optic assembly that are not fully enclosed, such as a support base, or a support base with at least one wall, ledge, or ridge. 
     The depicted fiber optic module  122  is comprised of the body  102  with a cover  104  coupled to body  102  such that body  102  and cover  104  are detachable with each other. In some embodiments, body  102  and cover  104  are hingedly coupled to each other at rear sidewall  105  such that body  102  and cover  104  are detachable with each other. The fiber routing volume  106  is disposed inside the body  102  and the cover  104  has an interior surface  107  that is configured to cover the fiber routing volume  106  of the body  102 . The body  102  is disposed between a first side edge, an opposing second side edge, and a rear edge. In an example embodiment, a first sidewall  103 A is disposed at the first side edge, a second sidewall  103 B is disposed at the second side edge, and a rear sidewall  105  is disposed at the rear edge. The sidewalls  103 A,  103 B,  105  may be continuous or discontinuous. The cover  104  may engage one or more of the sidewalls  103 A,  103 B,  105  and at least partially enclose the fiber routing volume with the interior side of the cover  104 . For example, the sidewalls  103 A,  103 B,  105  and/or cover  104  may include one or more complementary tabs and recesses, may be interference fit, or the otherwise engage each other. 
     As shown in  FIGS.  3 A and  3 B , body  102  and cover  104  are configured to span a width W ( FIG.  1   ) of chassis  12 . Stated another way, fiber optic module  122  spans an entire width of chassis  12  ( FIG.  1   ). Such a configuration provides spatial advantages in that the module guide rails  24  are removed thereby providing additional space for fiber routing and optical fiber component management within the fiber optic module  122 . Stated another way, the surface area of body  102  is larger thereby providing greater internal space for corresponding optical components. Additionally, a singular fiber optic module  122  as shown provides the capability of including MUX and DeMUX applications within the same fiber optic module  122 . The width (W) of the fiber optic module  122  may be based on the configuration of the fiber optic components  23 . For example, the depicted fiber optic module  122  includes fiber optic components  23  configured to receive 72 duplex fiber connectors, specifically VSFF connectors. In this embodiment, the width (W) of the fiber optic module  22 , e.g. the lateral distance between sides, is about 430 mm. The length (L) or depth of the fiber optic module  22 , from the front side to a rear side, may be based on fiber routing and fiber management, such as minimizing bend loss by limiting or preventing sharp bends in the optical fibers. In some embodiments, a length (L) of fiber optic module  122  is about 405 mm. In some embodiments, a height (H) of fiber optic module  122  is about 12 mm.  FIG.  3 A  shows fiber optic module  122  in a closed configuration. In the closed configuration, fiber optic module  122  has a length L ranging between 250 mm and 650 mm, between 385 mm and 650 mm, or between 385 mm and 510 mm. In some embodiments, in the closed configuration, fiber optic module  122  has a width W ranging between 250 mm and 650 mm, between 385 mm and 650 mm, or between 385 mm and 510 mm. In some embodiments, in the closed configuration, fiber optic module  122  has a height H ranging or between 5 mm and 25 mm. In some embodiments, fiber optic module  122  has a volume of less than 10 8  mm 3 , or less than 10 7  mm 3 . 
     Fiber optic components  23  can be disposed through a front end  108  of the main body  102  and configured to receive fiber optic connectors connected to fiber optic cables. In this example, the fiber optic components  23  are duplex MDC fiber optic adapters that are configured to receive and support connections with duplex MDC fiber optic connectors. However, any fiber optic duplex connection type desired can be provided in the fiber optic module  22 . One or more module rails  110  are disposed on the first sidewall  103 A and/or second sidewall  103 B of the fiber optic module  122 . The module rails  110  are configured to be inserted within the module guide rails  24  in the fiber optic equipment tray  20 , as illustrated in  FIG.  1   . In this manner, when it is desired to install a fiber optic module  122  in the fiber optic equipment tray  20 , the front end  108  of the fiber optic module  122  can be inserted from either the front end or the rear end of the fiber optic equipment tray  20 . 
     In the depicted example, the fiber optic module  122  is configured to support a plurality of WDM channels, each WDM channel is defined by a particular optical wavelength. More particularly, the depicted fiber optic module  122  is configured to support ninety six (96) DWDM channels. The depicted fiber optic module  122  is merely for illustrative purposes and similar configurations may be utilized to support eight (8) DWDM channels, twelve (12) DWDM channels, thirty-six (36) DWDM channels, forty eight (48) DWDM channels, or other suitable DWDM channel densities. In some embodiments, the depicted fiber optic module  122  is configured to support up to 144 DWDM channels. 
       FIG.  3 B  illustrates the fiber optic module  122  in an open configuration with the cover  104  of the fiber optic module  122  hinged about rear sidewall  105  to expose the fiber routing volume  106  and other internal components of the fiber optic module  122 . The fiber optic module  122  may include a plurality of optical filters  112  disposed within the fiber routing volume  106 . The optical filters  112  depicted enable at least twenty-four (24) DWDM channels, as described in further detail below. Some example optical filters  112  may include thin film filters (TFFs) and/or arrayed wave guide (AWG) filters. In a preferred embodiment, the optical filters  112  comprise TTF optical filters. In some embodiments, each of optical filters  112  comprises a single optical WDM filter. In some embodiments, optical filters  112  may be retained in a predetermined position within the fiber routing volume  106  by one or more filter cradles. The optical filters  112  may be arranged to provide a particularly small the depth or height H of the fiber optic module  22 . As such, the optical filters  112  may be arranged in channel groups, such as groups of at least eight (8) DWDM channels. The optical filters  112  for the DWDM channels may be disposed in offset rows (A, B, and C as shown in  FIG.  3 C  and discussed herein). In an example embodiment, the height of the fiber optic module  122  may be about 12 mm. In some embodiments, optical filters  112  are housed in filter cradles, and additional fiber optic components may be disposed in the filter cradles, such as couplers, bandpass filters, or the like. 
     In an example embodiment, the fiber optic module  122  may include on or more fiber optic splice connections disposed between the optical filters  112  and the fiber optic components  23 . For example, the one or more fiber optic splices may be fusion splices. The one or more fusion splices may be disposed in a splice protector sleeves  116  to prevent or limit damage to the fusion splices. The one or more splice protector sleeves  116  may also be disposed in one or more of the filter cradles. Alternatively, a thermoplastic layer may be used to protect the fusion slices. The thermoplastic layer may be similar to those described in U.S. Pat. No. 11,131,811, titled “FIBER OPTIC CABLE ASSEMBLY WITH THERMOPLASTICALLY OVERCOATED FUSION SPLICE, AND RELATED METHOD AND APPARATUS”, filed Sep. 17, 2019 the disclosure of which is fully incorporated by reference. The one or more splice protector sleeves  116  may also be disposed in one or more of the filter cradles. In some example embodiments, one or more fiber routing guides  118  may be disposed in the fiber routing volume  106 . The configuration of the fiber routing guides  118  and optical filters  112  within the fiber routing volume  106  may enable fiber routing without bend loss. For example, the optical fibers may be routed such that the optical fibers maintain a bend radii of greater that about 15 mm, e.g. are routed to limit or prevent sharp bends that may cause signal of fiber degradation. An example fiber routing pattern is described below in reference to  FIG.  3 B . 
     Referring now to  FIG.  3 C , a cross sectional view of the routing of optical fibers  130 A,  130 B is shown. As shown, optical fibers  130 A,  130 B are each arranged in an offset row configuration. In particular, rows A, B, and C of optical fibers  130 A,  130 B are oriented such that a center of an optical fiber of row B of optical fibers  130 A is between a pair of centers of optical fibers of row A of optical fibers  130 B, and a center of an optical fiber of row C of optical fibers  130 A is between a pair of centers of optical fibers of row B of optical fibers  130 B. 
     This configuration applies to optical filters  112  where optical filters  112  of row B are offset with optical filters of row A as described above with respect to rows A, B of each of optical fibers  130 A,  130 B. In some embodiments, filter cradles may be used to receive a portion of optical fibers  130 A,  130 B and optical filters  112 . Filter cradles and the corresponding configurations of optical fibers  130 A,  130 B within optical filters  112  are disclosed in U.S. Pat. No. 10,715,271, filed Dec. 2, 2019, the relevant disclosure of which is hereby incorporated by reference. 
     In some embodiments with filter cradles, the use of an epoxy is involved as described below. In this embodiment, an epoxy layer is first applied onto a surface of body  102  in a plane that is perpendicular to the orientation of filters  112 . This epoxy layer is parallel with the bottom layer of the cradle, and the epoxy layer adheres the cradle onto the surface of body  102 . 
     In embodiments without filter cradles, an epoxy is first applied onto a surface of body  102  in a plane that is perpendicular to the orientation of filters  112 . Then, the filters  112  are placed onto the epoxy layer, and a second layer of epoxy is applied onto the filters  112 . After the second layer of epoxy is applied onto the filters  112 , a second layer of filters  112  is applied onto the second layer of epoxy. Then, a third layer of epoxy is applied onto the second layer of filters  112 , and a final layer of filters  112  are applied. 
     In some embodiments, one or more fiber routing guides  118  may be disposed between the fiber optic components  23  and the filter  112  disposed at about one-third (⅓) the length of the fiber optic module  122 . In some example embodiments, one or more fiber routing guides  118  are disposed between the filter  112  disposed at about one-third (⅓) and the filter  112  disposed at two-thirds (⅔) the length of the fiber optic module  22 . Additionally or alternatively, in some embodiments, fiber routing guides  118  may be disposed between the rear sidewall  105  and the filter  112 . The fiber routing guides  118  may be formed of metal, molded plastic, or a flexible material, such as rubber. In an example embodiment, the fiber routing guides  118  may be substantially rectangular in shape, although other configurations are contemplated, such as cylindrical. In some embodiments, fiber routing guides  118  may include a fiber slot passing through a wall of the fiber routing guides  118 . The fiber slot may enable an optical fiber to be inserted or removed from the fiber routing guide  118 . In an example embodiment, the fiber slot may be formed at an angle relative to the direction of fiber routing, which may reduce inadvertent removal of a fiber from the fiber routing guide  118 . 
     Referring back to  FIG.  3 B , two sets of optical fibers  130  are routed through fiber optic module  122 . As shown, each set of the optical fibers  130 A,  130 B may be routed in a half of the width W of fiber optic module  122 , through the fiber routing guides  118 , optical filters  112 , splice protector sleeves  116 , fiber guides  120 , and the like. The optical fibers  130  may be routed to minimize bend loss caused by sharp bending, such as by maintaining a bend radii of greater than about 15 mm. In an example embodiment, the length (L) of the fiber optic module may be about 216 mm or less. 
     Referring now to  FIGS.  4 A and  4 B , an alternate embodiment of a fiber optic module  222  is shown, in which like reference numbers refer to like features in the fiber optic module  122  illustrated in  FIGS.  3 A- 3 D  except as noted herein. Moreover, the features of fiber optic module  222  are the same as fiber optic module  122  except as described herein. 
     As shown, fiber optic module  322  includes a body  102  and a cover  104  that is coupled to body  102  at a rear sidewall  105  such that body  102  and cover  104  are detachable with each other. In some embodiments, body  102  and cover  104  are hingedly coupled to each other at rear sidewall  105  such that body  102  and cover  104  are detachable with each other. Cover  104  has an interior surface  107  that is configured to cover fiber routing volume  106  and configured to provide a surface for optical fiber components as discussed in greater detail below. As shown, interior surface  107  receives one set of the optical fibers  130 A,  130 B. In  FIG.  4 B , optical fibers  130 B are received in interior surface  107 . However, it is within the scope of the present disclosure that optical fibers  130 A could be received in interior surface  107 . Interior surface  107  also includes corresponding splice protector sleeves  116 , optical filters  112  with corresponding cradles  114  and configurations, and optical fiber routing guides  118  as described above with respect to  FIGS.  3 A- 3 D  except as noted below. As shown in  FIG.  4 B , both body  102  and interior surface  107  of cover  104  include splice protector sleeves  116 , optical filters  112  and corresponding cradles  114 . In some embodiments, body  102  and interior surface  107  include single layers of each of splice protector sleeves  116 , optical filters  112  and corresponding cradles  114  such that when fiber optic module  222  is in a closed configuration as shown in  FIG.  4 A , splice protector sleeves  116  and optical filters  112  are stacked onto each other. In some embodiments, like structures of body  102  and interior surface  107  are stacked upon each other. For example, splice protector sleeves  116  of interior surface  107  are stacked onto splice protector sleeves  116  of body  102 , and optical filters  112  of interior surface  107  are stacked onto optical filters  112  of body  102 . However, it is within the scope of the present disclosure that alternate stacking configurations may be used. Having single layers on both cover  104  and body  102  enables easy access to such structures and facilitates easy repair when needed. 
       FIG.  4 A  shows fiber optic module  222  in a closed configuration, and  FIG.  4 B  shows fiber optic module  122  in an open configuration. Referring to  FIG.  4 B , body  102  and cover  104  define connection planes P 1  (also known as a “first fiber optic component routing plane”) and P 2  (also known as a “second fiber optic component routing plane”) respectively when fiber optic module  222  is in the open configuration. As shown, body  102  includes a portion of fiber optic components  23 A and cover  104  includes a portion of fiber optic components  23 B within connection planes P 1 , P 2 , respectively. Advantageously, such a configuration maximizes the number of fiber optic components  23 A,  23 B that can be installed onto body  102  and cover  104 . In addition, such a configuration is malleable in that the number of fiber optic components  23 A,  23 B to be added (during manufacturing) onto body  102  and cover  104 , respectively, is adjustable depending on the application of fiber optic module  222  due to increased space along front end  108  of body  102  and cover  104 . Also, such a configuration is modular such that body  102  and cover  104  can be assembled separately and then coupled to each other after individual assembly. This may reduce manufacturing complexity and increase accessibility, thereby, increasing manufacturing speed and reducing manufacturing costs of fiber optic module  222 . Fiber optic components  23 A,  23 B are similar to those described above as fiber optic components  23 , and for the sake of brevity, description of the fiber optic components  23 A,  23 B is omitted. 
     When fiber optic module  222  is in a closed configuration shown in  FIG.  4 A  (e.g., transitioning from an open configuration of  FIG.  4 B  to a closed configuration of  FIG.  4 A ), body  102 , cover  104 , and fiber optic components  23 A,  23 B of fiber optic module  222  are in a single connection plane P 3  as shown. 
     Referring now to  FIGS.  5 A and  5 B , an alternate embodiment of a fiber optic module  322  is shown, in which like reference numbers refer to like features in the fiber optic module  122  illustrated in  FIGS.  3 A- 3 D  except as noted herein. Moreover, the features of fiber optic module  322  are the same as fiber optic module  122  except as described herein. 
     As shown and similar to fiber optic module  222  of  FIGS.  4 A- 4 B , fiber optic module  322  includes a body  102  and a cover  104  that is coupled to body  102  at a rear sidewall  105  such that body  102  and cover  104  are detachable with each other. In some embodiments, body  102  and cover  104  are hingedly coupled to each other at rear sidewall  105  such that body  102  and cover  104  are detachable with each other. Cover  104  has an interior surface  107  that is configured to cover fiber routing volume  106  and configured to provide a surface for optical fiber components as discussed in greater detail below. As shown, interior surface  107  receives one set of the optical fibers  130 A,  130 B. In  FIG.  5 B , optical fibers  130 B are received in interior surface  107 . However, it is within the scope of the present disclosure that optical fibers  130 A could be received in interior surface  107 . Interior surface  107  also includes corresponding splice protector sleeves  116 , optical filters  112  with corresponding cradles  114  and configurations, and optical fiber routing guides  118  as described above with respect to  FIGS.  3 A- 3 D  except as noted below. As shown in  FIG.  5 B , both body  102  and interior surface  107  of cover  104  include splice protector sleeves  116 , optical filters  112  and corresponding cradles  114 . In some embodiments, body  102  and interior surface  107  include single layers of each of splice protector sleeves  116 , optical filters  112  and corresponding cradles  114  such that when fiber optic module  222  is in a closed configuration as shown in  FIG.  5 A , splice protector sleeves  116  and optical filters  112  are stacked onto each other. In some embodiments, like structures of body  102  and interior surface  107  are stacked upon each other. For example, splice protector sleeves  116  of interior surface  107  are stacked onto splice protector sleeves  116  of body  102 , and optical filters  112  of interior surface  107  are stacked onto optical filters  112  of body  102 . However, it is within the scope of the present disclosure that alternate stacking configurations may be used. Having single layers on both cover  104  and body  102  enables easy access to such structures and facilitates easy repair when needed. 
       FIG.  5 A  shows fiber optic module  122  in a closed configuration, and  FIG.  5 B  shows fiber optic module  122  in an open configuration. Referring to  FIG.  5 B , body  102  and cover  104  define connection planes P 1  and P 2  respectively when fiber optic module  122  is in the open configuration. As shown, body  102  includes a portion of fiber optic components  23 A and cover  104  includes a portion of fiber optic components  23 B within connection planes P 1 , P 2 , respectively. Advantageously, such a configuration maximizes the number of fiber optic components  23 A,  23 B that can be installed onto body  102  and cover  104 . In addition, such a configuration is malleable in that the number of fiber optic components  23 A,  23 B to be added (during manufacturing) onto body  102  and cover  104 , respectively, is adjustable depending on the application of fiber optic module  222  due to increased space along front end  108  of body  102  and cover  104 . Also, such a configuration is modular such that body  102  and cover  104  can be assembled separately and then coupled to each other after individual assembly. This can increase manufacturing speed of fiber optic module  222 . Fiber optic components  23 A,  23 B are similar to those described above as fiber optic components  23 , and for the sake of brevity, description of the fiber optic components  23 A,  23 B is omitted. 
     Similar to  FIG.  4 A , when fiber optic module  322  is in a closed configuration shown in  FIG.  5 A  (e.g., transitioning from an open configuration of  FIG.  5 B  to a closed configuration of  FIG.  5 A ), body  102 , cover  104 , and fiber optic components  23 A,  23 B of fiber optic module  322  are in a single connection plane P 3  as shown. 
     Moreover, fiber optic module  322  has a width W that is smaller than width W of fiber optic module  122 . In particular, in some embodiments, fiber optic module  322  has a width W ranging between 80 mm and 90 mm, between 80 mm and 85 mm, or between 84 mm and 85 mm. In some embodiments, width W of fiber optic module  322  is about 84.5 mm. In some embodiments, width W of fiber optic module  322  enable three (3) fiber optic modules  322  to be seated within fiber optic equipment tray  20 . In some embodiments, fiber optic module  322  has a length L and a height H that is different than fiber optic modules  122 ,  222 . In particular, in some embodiments, fiber optic module  322  has a height H ranging between 10 mm and 15 mm, between 12 mm and 15 mm, or between 12 mm and 13 mm. In some embodiments, height H of fiber optic module  322  is about 84.5 mm. In some embodiments, fiber optic module  322  has a length L ranging between 200 mm and 205 mm, between 202 mm and 205 mm, or between 203 mm and 204 mm. In some embodiments, length L of fiber optic module  322  is about 203 mm. Fiber optic module  322  has a fiber routing volume  106  ranging between 160,000 mm 3  and 280,000 mm 3  or between 225,000 mm 3  and 280,000 mm 3 . In some embodiments, fiber optic module  122  has a volume of less than 10 8  mm 3 , or less than 10 7  mm 3 . 
     Referring now to  FIGS.  6 - 8   ,  FIG.  6    illustrates a schematic view of an example of a forty eight (48) channel MUX DWDM fiber optic modules  122 ,  222 , or  322 ,  FIG.  7    illustrates an example fiber optic connection arrangement for the forty eight (48) channel DWDM fiber optic modules  122 ,  222 , or  322  of  FIG.  6   , and  FIG.  8    illustrates the interaction of the MUX and DeMUX DWDM fiber optic modules shown in  FIGS.  6  and  7   , respectively, when paired. As used in this disclosure, optical components being “connected to” each other refers to an optical path being established between the components. With brief reference to  FIG.  7   , an input fiber may be connected to a common port  401 , e.g. “COM” or “CM”. The input fiber may be configured to carry up to forty-eight DWDM channel signals  450  (hereinafter referred to as “optical signals  450 ”). The common port  401  may be in communication with one or more splitters  402 , such as a 98/2 splitter  402 A and a 50/50 splitter  402 B that divide the optical power into two paths according to the power splitting ratio. The  50 / 50  splitter  402 B may receive an input from both the input and output of the  98 / 2  splitter  402 A and output the received signals to test ports  403 A,  403 B “T 1 , T 2 ”. In some embodiments, a bandpass filter may be provided between the common port  401  and the splitter  402 A,  402 B and/or the test port  403 A,  403 B. The bandpass filter may pass an optical signal used for optical time domain reflectometer (OTDR) device testing of the fiber optic modules  122 ,  222 , or  322 . In an example embodiment an isolator, such as a 1550 nm isolator, may be disposed between the  50 / 50  splitter  402 B and a test port, such as test port  403 B. While two test ports  403 A,  403 B are shown in  FIGS.  6 - 8   , it is within the scope of the present disclosure that in some embodiments, an alternate number of test ports  403  may be used or no test ports  403  may be used depending on the application of fiber optic modules  122 ,  222 ,  322 . 
     An output of the  98 / 2  splitter  402 A, may be in communication with an express bandpass filter  404 . The express bandpass filter  404  may be configured to pass a signal to an express port  405  and a plurality of DWDM channels to the DWDM filters  406 . Similar to test ports  403 A,  403 B, while one express port  405  is shown in  FIGS.  6 - 8   , it is within the scope of the present disclosure that in some embodiments, an alternate number of express ports  405  may be used or no express ports  405  may be used depending on the application of fiber optic modules  122 ,  222 ,  322 . The DWDM filters  406  may include a plurality of group bandpass filters  407  configured to pass the signal for eight (8) or more adjacent DWDM channels. In some embodiments, the group bandpass filter  407  may be an eight-skip-zero (8s0) filter. Such filters can perform the function of separating a plurality of adjacent DWDM channel wavelengths, e.g. eight DWDM channels, from the optical signal. It is within the scope of the present disclosure that alternate group bandpass filters  407  may be used, such as ten-skip zero, six-skip zero, four-skip zero, and the like, for example. Moreover, it is within the scope of the present disclosure that an alternate number of group bandpass filters  407  may be used depending on the application of the fiber optic modules  122 ,  222 ,  322 . The output of the group bandpass filter  407  may be in communication with a plurality of DWDM channel filters  408 . Each of the DWDM channel filters  408  may be a bandpass filter configured to pass a specific DWDM channel signal. The DWDM channel filters  408  may be in communication with an output channel connection  410 . In the depicted embodiment, the fiber optic modules  122 ,  222 ,  322  include output channels  14 - 61  corresponding to forty eight (48) DWDM channels. It is within the scope of the present disclosure that an alternate number of DWDM channel filters  408  may be used in the modules of the present disclosure depending on the application of the fiber optic modules  122 ,  222 ,  322 . 
     In an example embodiment, the output of the last group bandpass filter  407  may also be in communication with an upgrade “Upg” port  411 . The Upgrade port  411  may enable the signal for additional DWDM channels to be passed to a downstream fiber optic module. The upgrade port  411  is connected in parallel with group band pass filter  407  and the DWDM channel filter  408 . Similar to test ports  403  and express ports  405 , while an upgrade port  411  is shown in  FIGS.  6 - 8   , it is within the scope of the present disclosure that in some embodiments, an alternate number of upgrade ports  411  may be used or no upgrade ports  411  may be used depending on the application of fiber optic modules  122 ,  222 ,  322 . In other embodiment, a group bandpass filter  407  may be disposed to pass the third group of DWDM channel signals and the remaining signal is passed to the upgrade port  211 , as depicted in  FIGS.  6  and  7   . While the above description of the components of the fiber optic modules  122 ,  222 ,  322  has been directed to  FIG.  7   , the component descriptions are the same for the MUX application of  FIG.  6    and will be further described below with respect to the interaction between a pairing of the MUX and DeMUX applications ( FIG.  8   ). 
     As mentioned previously,  FIG.  8    illustrates the interaction of the MUX and DeMUX DWDM fiber optic modules shown in  FIGS.  6  and  7   , respectively, when paired. As shown, MUX module combines the input signals from DWDM filters  406  and outputs optical signals  450  from the COM port  401  of the MUX module, and optical signals  450  are inputted into the COM port  401  of the DeMUX module. The optical signals  450  are then passed through the DeMUX module (through band pass filters, etc.) to the DWDM filters of the DeMUX module, and the output signals are outputted from the DeMUX module and to the end user application through the output channel connection  410 . 
     There are many other alternatives and variations that will be appreciated by persons skilled in optical connectivity without departing from the spirit or scope of this disclosure. For at least this reason, the invention should be construed to include everything within the scope of the appended claims and their equivalents.