Abstract:
An optical network includes a fiber optic link and one or more distributed block filter pairs. A given block filter pair includes a first block filter and a second block filter disposed at disparate locations along the fiber optic link. The first block filter of a respective pair is a bi-directional device that redirects optical carriers within a particular block wavelength range onto or off of the fiber optic link depending on a direction of the optical signals. The second block filter of a respective pair also is a bi-directional device that redirects carriers within the particular block wavelength range onto or off of the fiber optic link depending on a direction of the optical signal. The block filter pairs enable bi-directional communications over the fiber optic link between corresponding nodes disposed at different locations along the fiber optic link. Since the wavelength range in a block includes multiple carriers in both directions, the wavelength range in its entirety can be connected to a single subtended fiber and transmitted a significant distance before the carriers are separated and provided individual ports for connection to equipment. This feature thus provides multi-wavelength fiber conservation not only in the main fiber line as in conventional multi-wavelength systems, but in the subtended fiber lines as well.

Description:
BACKGROUND 
     Early cable networks supported one-way broadcasting of television programs to subscribers. This was sufficient in the early days of television. Eventually, however, because the Internet has become so popular, subscribers now desire the ability to transmit as well as receive data over their network connections. 
     To accommodate subscribers&#39; needs, conventional cable networks have evolved to enable subscribers to transmit more and more data in a reverse or upstream direction to a network. For example, via a device such as a cable modem, in addition to receiving data such as requested content for playback, a subscriber is now able to transmit data to remote locations over a network. 
     Because of inherent high bandwidth capability, fiber optic links are commonly used to convey data in both upstream and downstream directions. Expansion of fiber optic links and efficient use of such links can be challenging. In certain instances, bandwidth on installed conventional fiber optic links may be under-utilized. 
     BRIEF DESCRIPTION OF EMBODIMENTS 
     Embodiments herein deviate with respect to conventional techniques. For example, one embodiment herein is directed towards novel and more efficient use of optical resources in a shared network environment to facilitate distribution of data. 
     More specifically, as discussed herein, an optical network includes a fiber optic link and a so-called block filter pair. The block filter pair can be one of multiple block filter pairs in the optical network. 
     In one embodiment, the block filter pair includes a first block filter and a second block filter disposed at disparate locations along the fiber optic link. In general, the first block filter can be a bi-directional device that redirects optical carriers within a particular block wavelength range onto or off of the fiber optic link depending on a direction of the optical signal. That is, a group of optical communication carriers (each comprising an optical carrier (i.e., carrier signal) defined by its respective center wavelength) within an optical spectrum range assigned to the block filter can be separated into single carrier connections, after first being redirected off of the fiber optic link via the block filter. In a similar vein, the second block filter also can be a bi-directional device that redirects carriers (i.e., modulated carrier signals) within the particular block wavelength range onto or off of the fiber optic link depending on a direction of the optical carrier signal, for subsequent separation into individual optical carriers for reception and/or transmitter connection. 
     In one embodiment, there is a distinction between channels and so-called carriers. Channels refer to a spectrum “space” or “slot” of defined optical bandwidth; the channels exist without any light (i.e., optical carrier signal) being present. Carriers (i.e., modulated carrier signals) represent light energy of the information modulated onto a respective carrier wavelength present within the allocated channels. 
     Assume that the first block filter receives a first set of optical carriers within the particular wavelength range from a first multiplexer resource to which the first block filter is communicatively coupled. The first block filter inputs the first set of optical carriers received from the first multiplexer filter resource onto the fiber optic link downstream towards the second block filter. The second block filter receives the first set of optical carriers in the downstream direction on the fiber optic link. Because the first set of optical carriers falls within the particular block wavelength range assigned to the second block filter, the second block filter redirects the first set of carriers off the fiber optic link to a second multiplexer resource. 
     In an opposite direction, assume that the second block filter receives a second set of optical carriers within the particular wavelength range from the second multiplexer resource. The second block filter inputs the second set of optical carriers onto the fiber optic link upstream towards the first block filter. The first block filter receives the second set of optical carriers in the upstream direction. Because the second set of optical carriers resides within the particular block wavelength range assigned to the first block filter, the first block filter redirects the second set of optical carriers off the fiber optic link to the first multiplexer resource. 
     Redirecting multiple optical carriers within an assigned optical range is beneficial because a respective block filter (multiplexer) can support many service groups in a cable network environment. 
     Redirection of a block of spectrum (e.g., one or more modulated carrier signals) covering multiple channels is beneficial because the entire group of channels can then be connected across a single strand of fiber to a remote location where individual carriers are separated from each other so equipment can be connected. Prior techniques required a fiber for each channel from the main fiber to the remote equipment. This technique is of particular value as it conserves fiber resources in side-runs of fiber cable to equipment that only needs connection to the channels in the block. Other carriers not in the block are allowed to continue down the main fiber run to other equipment locations. 
     As further described herein, each of the first multiplexer resource and the second multiplexer resource includes a series connection of multiple optical filters and corresponding optical ports on which to individually receive the first set of optical carriers and individually output the second set of optical carriers. In accordance with further embodiments, another technique that could be used is the “prism-like” diffraction grating based device that separates channels all at once. 
     Note that any of one or more of the multiplexer resources as discussed herein can include: i) multiple optical input ports on which to receive a first set of optical carriers, ii) multiple optical output ports from which to output a second set of optical carriers, iii) at least one bi-directional optical port. Input and output ports are typically bidirectional, even if they are only used for carriers transmitted in one direction. 
     In one embodiment, the multiplexer filter resource can include a circulator resource. In such an instance, the circulator resource can be configured to receive carriers within a first set of optical channels from a multiplexer that combines light from multiple optical input ports. The circulator resource directs transmission of the first set of optical carriers out of the bi-directional optical port. The circulator resource can at the same time receive a second set of optical carriers as inputs to the bi-directional optical port. The circulator resource directs the second set of optical carriers to a connected multiplexer that separates the carriers into individual output ports of the multiplexer resource. In accordance with one embodiment, note that in the circulator configuration, the input and output multiplexers can be separate in optical terms, although they may physically packaged together. 
     An amplifier resource can be connected between the multiple optical input port multiplexer and the circulator resource. In such an instance, the optical amplifier resource amplifies the first set of carriers received on the multiple optical input ports. The circulator resource directs the amplified first set of carriers out of the bi-directional optical port to the first block filter disposed in series with the fiber optic link. Accordingly, signals received at optical input ports of the first multiplexer resource can be amplified and subsequently transmitted from the circulator resource to the first block filter and downstream on the fiber optic link. 
     These and other more specific embodiments are disclosed in more detail below. 
     As discussed herein, techniques herein are well suited for use in network applications. However, it should be noted that embodiments herein are not limited to use in such applications and that the techniques discussed herein are well suited for other applications as well, etc. 
     Additionally, note that although each of the different features, techniques, configurations, etc., herein may be discussed in different places of this disclosure, it is intended, where suitable, that each of the concepts can optionally be executed independently of each other or in combination with each other. Accordingly, the one or more present inventions as described herein can be embodied and viewed in many different ways. 
     Also, note that this preliminary discussion of embodiments herein purposefully does not specify every embodiment and/or incrementally novel aspect of the present disclosure or one or more claimed invention(s). Instead, this brief description only presents general embodiments and corresponding points of novelty over conventional techniques. For additional details and/or possible perspectives (permutations) of the invention(s), the reader is directed to the Detailed Description section and corresponding figures of the present disclosure as further discussed below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an example diagram illustrating an optical network including a block filter pair and respective multiplexer filter resources according to embodiments herein. 
         FIG. 2  is an example diagram illustrating a configuration of multiplexer filter resources according to embodiments herein. 
         FIG. 3  is a diagram illustrating an example of assigned optical channel usage in a fiber network according to embodiments herein. 
         FIG. 4  is an example diagram illustrating initial installation of an optical network to include a single block filter according to embodiments herein. 
         FIGS. 5-9  are example diagrams illustrating expansion of an optical network to include multiple block filter pairs according to embodiments herein. 
         FIG. 10  is an example diagram illustrating a multiplexer filter resource including a circulator resource and/or amplifier according to embodiments herein. 
         FIG. 11  is an example diagram illustrating an optical network environment including multiple block filters according to embodiments herein. 
         FIG. 12  is an example diagram illustrating use of block filter pairs and related resources according to embodiments herein. 
         FIGS. 13 and 14  are example methods according to embodiments herein. 
     
    
    
     The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of preferred embodiments herein, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, with emphasis instead being placed upon illustrating the embodiments, principles, concepts, etc. 
     DETAILED DESCRIPTION 
       FIG. 1  is an example diagram of a network according to embodiments herein. 
     As shown by way of a non-limiting example, network  100  includes one or more interconnection of optical links  105 - 1 ,  105 - 2 ,  105 - 3 , etc. (collectively, optical link  105 ). Network  100  further includes block filter pair including block filter  120 - 1  and block filter  120 - 2 . The block filter  120 - 1  can be substantially identical to block filter  120 - 2 . 
     By way of a non-limiting example, the n  100  can be a passive optical network. 
     As shown, block filter  120 - 1  and block filter  120 - 2  are disposed at disparate locations along the optic link  105 . For example, block filter  120 - 1  is disposed at one terminal end of optical link  105 - 2 ; block filter  120 - 2  is disposed at the other terminal end of optical link  105 - 2 . Optical link  105 - 1  extends further upstream. Optical link  105 - 3  extends further downstream. 
     Each of the block filters  120  redirects optical carriers within a particular block wavelength range onto or off of the fiber optic link depending on a direction of the optical signal. 
     For example, the block filter  120 - 2  can receive multiple wavelengths (i.e., optical carriers) of light on port K of optical link  105 - 2  in an upstream direction. In one embodiment, the multiplexer filter resource  130 - 2  receives optical carriers  19 ,  20 ,  23 , and  25  on respective ports Z, Y, X, and W of multiplexer filter resource  130 - 2 . Multiplexer filter resource  130 - 2  outputs optical carriers in channels  19 ,  20 ,  23 , and  25  out of bi-directional port M over a communication link such as a fiber optic link to bi-directional port S of block filter  120 - 2 . Block filter  120 - 2  redirects the received optical carriers in channels  19 ,  20 ,  23 , and  25  out of port Q of block filter  120 - 2  upstream onto fiber optic link  105  towards block filter  120 - 1 . Block filter  120 - 2  and multiplexer filter resource  130 - 2  can be co-located or located at disparate locations with respect to each other. 
     The block filter  120 - 1  redirects wavelengths or optical carriers in channels  19 ,  20 ,  23 , and  25  that fall within a predetermined wavelength range off of the optical link  105 - 1  and out of bi-directional optical port L over a communication link such as a fiber optic link to bi-directional port M of multiplexer filter resource  130 - 1 . Block filter  120 - 1  and multiplexer filter resource  130 - 1  can be co-located or located at disparate locations with respect to each other. 
     In turn, multiplexer filter resource  130 - 1  redirects the received optical carriers in channels  19 ,  20 ,  23 , and  25  out of respective ports W, X, Y, and Z as shown. 
     In a reverse direction, the multiplexer filter resource  130 - 1  includes multiple optical input ports A, B, C, and D to receive respective optical carriers in channels  21 ,  22 ,  24 , and  26  as shown. The multiplexer filter resource  130 - 1  optically aggregates and directs the collection of optical carriers in channels  21 ,  22 ,  24 , and  26  out of bi-directional port M of multiplexer filter resource  130 - 1  over a communication link such as a fiber optic link and into port L of block filter  120 - 1 . 
     Block filter  120 - 1  optically redirects the optical carriers out of port K of the block filter  120 - 1  upstream on optical link  105 - 2  to block filter  120 - 2 . 
     The block filter  120 - 2  optically redirects the received wavelengths or optical carriers in channels  21 ,  22 ,  24 , and  26  from port Q off of the optical link  105 - 2  and out of bi-directional optical port S over a communication link such as a fiber optic link to bi-directional port M of multiplexer filter resource  130 - 2 . 
     In turn, multiplexer filter resource  130 - 2  redirects the received optical carriers  21 ,  22 ,  24 , and  26  out of respective ports D, C, B, and A as shown. 
     Thus, each of the first block filter  120 - 1  and the second block filter  120 - 2  can be a bi-directional filter device that redirects optical carriers within the particular block wavelength range onto or off of the fiber optic link depending on a direction of the optical signal. 
     Note that optical carriers that do not fall within a bandpass range (e.g., a range of wavelengths including optical channels  19 - 26 ) assigned to block filters  120  are not redirected off of the optical link  105 - 2  to optical multiplexer resources  130 , but are instead transmitted further upstream or downstream. 
     For example, assume that block filter  120 - 2  receives a first group of one or more out-of-band optical carriers (e.g., any of one or more carriers outside the range of optical carriers  19 - 26 ) on port R as transmitted in an upstream direction from optical link  105 - 3 . Block filter  120 - 2  passes the received first group of out-of-band carriers out of port Q upstream on optical link  105 - 2 . Port K of block filter  120 - 1  receives the first group of out-of-band optical carriers from optical link  105 - 2  and, since the received first group of out-of-band optical carriers falls outside the range of wavelengths (e.g., optical channels  19 - 26 ) that are redirected to port L, passes the received first group of out-of-band carriers out of port J upstream on optical link  105 - 1 . 
     Assume as another example that block filter  120 - 1  receives a second group of one or more out-of-band optical carriers (e.g., any of one or more carriers outside the range of optical channels  19 - 26 ) on port J as transmitted in a downstream direction on optical link  105 - 1 . Block filter  120 - 1  passes the received second group of out-of-band carriers out of port K downstream on optical link  105 - 2 . Port Q of block filter  120 - 2  receives the second group of out-of-band optical carriers from optical link  105 - 2  and, since the received second group of out-of-band optical carriers falls outside the range of wavelengths that are redirected to port S, passes the received second group of out-of-band carriers out of port R downstream on optical link  105 - 3 . 
       FIG. 2  is an example diagram more particularly illustrating multiplexer filter resources and respective functionality according to embodiments herein. 
     As shown in this example embodiment, multiplexer filter resource  130 - 1  includes a series connection of multiple optical filter resources including optical filter resource  210 - 1 , optical filter resource  210 - 2 , optical filter resource  210 - 3 , and optical filter resource  210 - 4  (collectively, optical filter resources  210 ). As shown, the series connection in multiplexer filter resource  130 - 1  further includes optical filter resource  211 - 1 , optical filter resource  211 - 2 , optical filter resource  211 - 3 , and optical filter resource  211 - 4  (collectively, optical filter resources  211 ). 
     In this example embodiment, each of the optical filter resources includes a pass port (P), a common port (C), and a reflection port (R). During operation, the common port of each filter passes all wavelengths to a next filter resource or port in the sequence. The pass port passes an assigned band of one or more wavelengths. The reflection port stops pass port wavelengths but passes all others out to a next optical filter resource or port in the sequence. Dotted lines between optical ports and optical filter resources  210  represent fiber optical links. 
     In one embodiment, the ordering of optical filter resources in each of the multiplexer filter resources  130  can vary to balance losses. For example, optical losses occur in each optical filter resource. To reduce losses in the downstream direction, optical filter resources  210  and  220  are disposed nearest to respective bi-directional port M. To balance losses amongst the optical channels, as shown, the ordering of the optical channels is reversed. That is, as shown, the ordering of optical filter resources in multiplexer filter resource  130 - 1  is channel  21 ,  22 ,  24 , and  26  in the sequence of optical filters. The ordering in complementary multiplexer filter resource  130 - 2  is optical channel  26 ,  24 ,  22 , and  21 . 
     Downstream loss can be traded against upstream loss. That is, upstream optical filter resources  211  and  221  reside farthest from the port M. Thus, upstream optical channels  19 ,  20 ,  23 , and  25  experience losses from sequence of respective optical filter resources  210  and  220 . Downstream optical channels  21 ,  22 ,  24 , and  26  do not experience losses from passing through sequence of respective optical filter resources  211  and  221 . This is advantageous, as it can be used to better match the asymmetrical nature of real-world data traffic. Since the upstream links often carry less traffic, they can better tolerate higher losses for a given set of implementation trade-offs compared to the more heavily loaded downstream links. 
     Operation of Multiplexer Filter Resource  130 - 1   
     In this example embodiment, assume that bi-directional port M of multiplexer filter resource  130 - 1  receives, as input, a set of optical carriers in channels  19 ,  20 ,  23 , and  25  from block filter  120 - 1 . Recall that block filter  120 - 1  redirects the optical carriers in channels  19 ,  20 ,  23 , and  25  in the upstream direction off of optical link  105 - 2  to port M of multiplexer filter resource  130 - 1  because they (i.e., optical channels  19 ,  20 ,  23 , and  25 ) fall within the optical bandpass range assigned to block filter  120 - 1 . 
     In such an instance, port C of optical filter resource  210 - 1  receives the set of optical carriers in channels  19 ,  20 ,  23 , and  25 . Port R of optical filter resource  210 - 1  outputs all received optical carriers in channels  19 ,  20 ,  23 , and  25  because optical filter resource  210 - 1  is configured to pass only assigned optical carrier in channel  21  out of port P to optical port A. 
     Port C of optical filter resource  210 - 2  receives the set of optical carriers in channels  19 ,  20 ,  23 , and  25 . Port R of optical filter resource  210 - 2  outputs the set of carriers in channels  19 ,  20 ,  23 , and  25  to optical filter resource  210 - 3  because optical filter resource  210 - 2  is configured to pass only assigned optical carrier in channel  22  out of port P to optical port B. 
     Port C of optical filter resource  210 - 3  receives the set of optical carriers in channel  19 ,  20 ,  23 , and  25 . Port R of optical filter resource  210 - 3  outputs the set of carriers in channels  19 ,  20 ,  23 , and  25  to optical filter resource  210 - 4  because optical filter resource  210 - 3  is configured to pass only a carrier in assigned optical channel  24  out of port P to optical port C. 
     Port C of optical filter resource  210 - 4  receives the first set of optical carriers in channels  19 ,  20 ,  23 , and  25 . Port R of optical filter resource  210 - 4  outputs the set of carriers in channels  19 ,  20 ,  23 , and  25  to optical filter resource  211 - 1  because optical filter resource  210 - 4  is configured to pass only assigned optical carrier in channel  26  out of pass port P to optical port D. 
     Port C of optical filter resource  211 - 1  receives the set of optical carriers in channels  19 ,  20 ,  23 , and  25 . Port P of optical filter resource  211 - 1  passes the optical carrier in channel  19  to optical output port W. Port R of optical filter resource  211 - 1  redirects all other carriers in channels  20 ,  23 , and  25  to optical filter resource  211 - 2 . 
     Port C of optical filter resource  211 - 2  receives carriers in channels  20 ,  23 , and  25 . Port P of optical filter resource  211 - 2  passes carrier in channel  20  to optical output port X. Port R of optical filter resource  211 - 2  redirects all other received carriers in channels  23  and  25  to optical filter resource  211 - 3 . 
     Port C of optical filter resource  211 - 3  receives carriers in channels  23  and  25 . Port P of optical filter resource  211 - 3  outputs carrier in channel  23  to optical output port Y. Port R of optical filter resource  211 - 3  outputs received carrier in channel  25  to optical filter resource  211 - 4 . 
     Port C of optical filter resource  211 - 4  receives carrier in channel  25 . Port P of optical filter resource  211 - 4  outputs carrier in channel  25  to optical output port Z. 
     In a reverse direction, the series connection of multiple optical filter resources  210  aggregates optical carriers in channels  21 ,  22 ,  24 , and  26  and outputs them to optical output port M of multiplexer filter resource  130 - 1 . 
     For example, port P of optical filter resource  210 - 4  receives optical carrier in channel  26  from optical input port D. Optical filter resource  210 - 4  passes the received optical carrier in channel  26  out of its port C (common) to port R (reflected) of optical filter resource  210 - 3 . As discussed herein, port C in the following non-limiting examples refers to a respective “common” port of a filter resource; port R in the following non-limiting examples refers to a respective “reflected” port of a filter resource. 
     By way of a non-limiting example, the optical filter resources can refer to the use of thin-film filter technology, where a “Common” wide spectrum connection is separated into two ports: 1) the block passband, and 2) all other spectrum regions in the device operating range. 
     Other filter technologies such as diffraction gratings may also be useable in this invention to produce optical filters. In this latter case, those would not have a port named “reflected” because they may not be based on reflection. 
     Port R of optical filter resource  210 - 3  receives optical carrier in channel  26  from optical filter resource  210 - 4 . Port P of optical filter resource  210 - 3  receives optical carrier in channel  24  from optical input port C. Optical filter resource  210 - 3  aggregates and then passes optical carriers in channels  26  and  24  out of port C of optical filter resource  210 - 3  to port R of optical filter resource  210 - 2 . 
     Port R of optical filter resource  210 - 2  receives optical carrier in channels  26  and  24  from optical filter resource  210 - 3 . Port P of optical filter resource  210 - 2  receives optical carrier in channel  22  from optical input port B. Optical filter resource  210 - 2  aggregates and then passes optical carriers in channels  26 ,  24 , and  22  out of port C of optical filter resource  210 - 2  to port R of optical filter resource  210 - 1 . 
     Port R of optical filter resource  210 - 1  receives optical carriers in channels  26 ,  24 , and  22  from optical filter resource  210 - 2 . Port P of optical filter resource  210 - 1  receives optical carrier in channel  21  from optical input port A. Optical filter resource  210 - 1  aggregates and passes optical carriers in channels  26 ,  24 ,  22 , and  21  out of port C of optical filter resource  210 - 1  to bi-directional port M of multiplexer filter resource  130 - 1 . 
     Operation of Multiplexer Filter Resource  130 - 2   
     The multiplexer filter resource  130 - 2  operates in a similar manner. 
     In this example embodiment, assume that port M of multiplexer filter resource  130 - 2  receives, as input, a set of optical carriers in channels  21 ,  22 ,  24 , and  26  from block filter  120 - 2 . Recall that block filter  120 - 2  redirects the optical carriers in channels  21 ,  22 ,  24 , and  26  in the downstream direction off of optical link  105 - 2  to port M of multiplexer filter resource  130 - 2  because they (i.e., optical channels  21 ,  22 ,  24 , and  26 ) fall within the optical bandpass range assigned to block filter  120 - 2 . 
     Port C of optical filter resource  220 - 1  receives the set of optical carriers in channels  21 ,  22 ,  24 , and  26  from bi-directional port M. Optical filter resource  220 - 2  is configured to pass only assigned optical carrier in channel  26  out of port P to optical port A of multiplexer filter resource  130 - 2  (which happens to be assigned as an output optical port in this case). Port R of optical filter resource  220 - 1  outputs the balance of carriers in channels  21 ,  22 , and  24  to port C of optical filter resource  220 - 2 . 
     Port C of optical filter resource  220 - 2  receives the set of optical carriers in channels  21 ,  22 , and  24  from optical filter resource  220 - 1 . Optical filter resource  220 - 2  is configured to pass only assigned optical carrier in channel  24  out of its respective port P to port B of multiplexer filter resource  130 - 2  (which happens to be assigned as an output in this case). Port R of optical filter resource  220 - 2  outputs the set of carriers in channels  21  and  22  to port C of optical filter resource  220 - 3 . 
     Port C of optical filter resource  220 - 3  receives the set of optical carriers in channels  21  and  22 . Optical filter resource  220 - 2  is configured to pass only assigned optical carrier in channel  22  out of its respective port P to port C of multiplexer filter resource  130 - 22  (which happens to be assigned as an output in this case). Port R of optical filter resource  220 - 3  outputs the carrier in channel  21  to port C of optical filter resource  220 - 4 . 
     Port C of optical filter resource  220 - 4  receives optical carrier in channel  21 . Optical filter resource  220 - 4  is configured to pass only assigned optical carrier in channel  21  out of its respective port P to port D of multiplexer filter resource  130 - 2  (which happens to be assigned as an output in this case). Because there are no more downstream channels left, port R of optical filter resource  220 - 4  does not output any optical carriers to port C of optical filter resource  221 - 1 . 
     In a reverse direction, the sequence of optical filter resources  221  aggregates and transmits upstream optical carriers in channels  19 ,  20 ,  23 , and  25  to sequence of optical filter resources  220 . Optical filter resources  220  convey the optical carriers to bi-directional port M of the multiplexer filter resource  130 - 2 . 
     More specifically, port Z of optical filter resource  221 - 4  is an optical input port that receives optical carrier in channel  19 . Port C of optical filter resource  221 - 4  outputs the received optical carrier in channel  19  to port R of optical filter resource  221 - 3 . 
     Port R of optical filter resource  221 - 3  receives optical carrier in channel  19  from optical filter resource  221 - 4 . Port P of optical filter resource  221 - 3  receives optical carrier in channel  20  from port Y of multiplexer filter resource  130 - 2 . Optical filter resource  221 - 3  combines and outputs optical carriers in channels  19  and  20  to port R of optical filter resource  221 - 2 . 
     Port R of optical filter resource  221 - 2  receives optical carriers in channels  19  and  20  from optical filter resource  221 - 3 . Port P of optical filter resource  221 - 2  receives optical carrier in channel  23  from port X of multiplexer filter resource  130 - 2 . Optical filter resource  221 - 2  aggregates and outputs a combination of optical carriers in channels  19 ,  20 , and  23  to port R of optical filter resource  221 - 1 . 
     Port R of optical filter resource  221 - 1  receives optical carriers in channels  19 ,  20  and  23  from optical filter resource  221 - 2 . Port P of optical filter resource  221 - 1  receives optical carrier in channel  25  from port W of multiplexer filter resource  130 - 2 . Optical filter resource  221 - 1  aggregates and outputs a combination of optical carriers in channels  19 ,  20 ,  23  and  25  to port R of optical filter resource  220 - 4 . 
     The series connection of multiple optical filter resources  220  then conveys the combination of optical carriers in channels  21 ,  22 ,  24 , and  26  to and out of port M of the multiplexer filter resource  130 - 2 . For example, port R of optical filter resource  220 - 4  receives the optical carriers in channels  19 ,  20 ,  23 , and  25  from optical filter resource  221 - 1 . Optical filter resource  220 - 4  outputs the combination of optical carriers in channels  19 ,  20 ,  23 , and  25  out of port C of optical filter resource  220 - 4  to optical filter resource  220 - 3 . 
     Port R of optical filter resource  220 - 3  receives the optical carriers in channels  19 ,  20 ,  23 , and  25  from port C of optical filter resource  220 - 4 . Optical filter resource  220 - 3  outputs the combination of optical carriers in channels  19 ,  20 ,  23 , and  25  out of port C of optical filter resource  220 - 3  to optical filter resource  220 - 2 . 
     Port R of optical filter resource  220 - 2  receives the optical carriers in channels  19 ,  20 ,  23 , and  25  from port C of optical filter resource  220 - 3 . Optical filter resource  220 - 2  outputs the combination of optical carriers in channels  19 ,  20 ,  23 , and  25  out of port C of optical filter resource  220 - 2  to optical filter resource  220 - 1 . 
     Port R of optical filter resource  220 - 1  receives the optical carriers in channels  19 ,  20 ,  23 , and  25  from port C of optical filter resource  220 - 2 . Optical filter resource  220 - 1  outputs the combination of optical carriers in channels  19 ,  20 ,  23 , and  25  out of port C of optical filter resource  220 - 1  to bi-directional port M of the multiplexer filter resource  130 - 2 . As previously discussed, block filter  120 - 2  receives the combination of optical carriers in channels  19 ,  20 ,  23 , and  25  from the bi-directional port M. 
       FIG. 3  is a diagram illustrating an example of assigned optical channel usage in a fiber network according to embodiments herein. In accordance with settings in  FIG. 3 ,  FIGS. 5-9  illustrate expansion of the cable network environment to include multiple pairings of block filters. 
     Embodiments herein can be implemented in a shared cable network environment in which the block filter and multiplexer filter resources are used to distribute content to one or more different services groups using a common fiber optic link. That is, an optical link  105  can be configured to include multiple block filter pairs. As discussed, each block filter pair enables shared use of an optical link  105 . 
     As shown in  FIG. 3 , the settings of respective block filter pairs can be spaced apart from each other. For example, the block filter pair including block filter  120 - 1  and block filter  120 - 2  support redirecting optical signals (such as carriers) in channels  19 - 26 . Optical channel  27  is unused and provides a spacing with respect to the next block filter pair including block filter  520 - 1  and block filter  520 - 2 . Optical channels  40 - 42  are unused and provide spacing with respect to the next block filter pair including block filter  620 - 1  and block filter  620 - 2 . Optical channels  55  and  56  are unused and provide a spacing with respect to the next block filter pair including block filter  820 - 1  and block filter  820 - 2 . 
     Further as shown, each optical channel can be assigned as an upstream channel or a downstream channel on the optical link  105 . In one embodiment, one or more of the upstream and downstream assigned optical channels are interleaved with respect to each other. For example, optical channel  23  can be allocated as an upstream optical channel interleaved between downstream optical channels  22  and  23 . Optical channel  24  can be allocated as a downstream optical channel interleaved between upstream optical channels  23  and  25 , and so on. 
     In one non-limiting example embodiment, use of the optical channels is deployed from longer wavelengths to shorter wavelengths. For example, the first pair of block filters installed in network  100  can be configured to support passing optical signals (i.e., carriers) in channels  19 - 26 ; the second pair of block filters installed in network  100  can be configured to support passing optical signals in channels  28 - 39 ; and so on. The following figures illustrate a more specific implementation of network  100  in accordance with allocation as specified by  FIG. 3 . 
       FIG. 4  is an example diagram illustrating initial installation of an optical network to include a single block filter according to embodiments herein. 
     As shown, block filter pair and corresponding multiplexer filter resources can be installed in cable network environment  400  to support upstream and downstream optical channels. As previously discussed, the block filter  120 - 1  can be disposed at one end of optical link  105 - 1 ; block filter  120 - 2  can be disposed at the other end of the optical link  105 - 2 . 
     Further as shown, block filter  120 - 1  can be disposed in a hub resource  410  of a cable network environment  400 . Optical channels  19 - 26  support bi-directional communication from the hub resource  410  to a first service area in cable network environment including one or more service areas. (Note that additional details of cable network environment  400  are shown and discussed with respect to  FIG. 12 .) 
     In one embodiment, a pair of upstream and downstream optical channels can be assigned for servicing a respective service area. For example, optical channels  25  and  26  can be assigned to receive and distribute data to a first service area; optical channels  23  and  24  can be assigned to receive and distribute data to a second service area; optical channels  20  and  22  can be assigned to receive and distribute data to a third service area; and so on. As mentioned, additional details are shown in  FIG. 12 . 
       FIGS. 5-9  are example diagrams illustrating expansion of an optical network to include multiple block filter pairs according to embodiments herein. 
     In accordance with example settings as discussed in  FIG. 3 ,  FIG. 5  is a diagram illustrating expansion of the cable network environment  400  to include an additional block filter pair including block filter  520 - 1  disposed in hub resource  410  and block filter  520 - 2  disposed downstream on optical link  105 . Note that the additional block filter pair can be added to network  400  without interrupting data transmission service with respect to block filter  120 - 1  and block filter  120 - 2 . 
     Block filter  120 - 1  and block filter  120 - 2  pass all carriers (upstream or downstream, as the case may be) along optical link  105  other than optical signals in channels  19 - 26 , which are in the redirection band. 
     The block filters  520  and multiplexer filter resources  530  operate in a similar manner as block filters  120  and multiplexer filter resources  130 ; however, as shown in  FIG. 3  settings, the block filters  520  and multiplexer filter resources  530  support a different optical redirection band (e.g., optical channels  28 - 39 ) and processing. 
     For example, as shown in  FIG. 5 , multiplexer filter resource  530 - 2  includes a series connection of optical filter resources to aggregate optical signals (i.e., modulated carrier signals) in channels  34 ,  35 ,  37 , and  38 . Multiplexer filter resource  530 - 2  outputs the aggregated set of optical signals to the block filter  520 - 2 . In an upstream direction, block filter  520 - 2  redirects optical signals in channels  34 ,  35 ,  37 , and  38  received from multiplexer filter resource  530 - 2  upstream on optical link  105  towards block filter  520 - 1 . 
     Upstream, block filter  120 - 1  passes received optical carriers in optical channels  34 ,  35 ,  37 , and  38  upstream to block filter  520 - 1 . Block filter  520 - 1  redirects optical carriers in channels  34 ,  35 ,  37 , and  38  off of the optical link  105  to multiplexer filter resource  530 - 1 . In a similar manner as previously discussed, multiplexer filter resource  530 - 1  includes a series connection of optical filter resources to redirect optical carriers in channels  34 ,  35 ,  37 , and  38  to respective optical output ports. 
     Multiplexer filter resource  530 - 1  includes a series connection of optical filter resources to aggregate inputted optical signals in channels  28 ,  33 ,  36 , and  39 . Multiplexer filter resource  530 - 1  outputs the aggregated set of optical carriers to the block filter  520 - 1 . Block filter  520 - 1  redirects optical signals in channels  28 ,  33 ,  36 , and  39  received from multiplexer filter resource  530 - 1  downstream on optical link  105  towards block filter  520 - 2 . 
     Downstream, block filter  520 - 2  redirects optical signals in channels  28 ,  33 ,  36 , and  39  off of the optical link  105  to multiplexer filter resource  530 - 2 . Multiplexer filter resource  530 - 2  includes a series connection of optical filter resources to separate and redirect signals in optical channels  28 ,  33 ,  36 , and  39  to respective optical output ports of the multiplexer filter resource  530 - 2 . 
       FIG. 6  is an example diagram illustrating a cable network environment according to embodiments herein. 
     In accordance with example settings as discussed in  FIG. 3 ,  FIG. 6  is a diagram illustrating expansion of the cable network environment  400  to include block filter pair including block filter  620 - 1  disposed in hub resource  410  and block filter  620 - 2  disposed downstream on optical link. Block filter  620 - 1 , block filter  620 - 2 , and related optical hardware resources can be installed without interrupting services associated with block filter  120 - 1 , block filter  120 - 2 , block filter  520 - 1 , and block filter  520 - 2 . 
     In this example embodiment, the block filters  620  and multiplexer filter resources  630  operate in a similar manner as block filters  120  and multiplexer filter resources  130 ; however, as shown in  FIG. 3  settings, the block filters  620  and multiplexer filter resources  630  support redirection of a different optical. For example, as shown in  FIG. 3 , block filters  620  are assigned to a redirection band of signals on channels  43 - 54 . 
     During operation, in an upstream direction, block filter  620 - 1  redirects optical signals in channels  49 ,  50 ,  51 , and  53  off of the optical link  105  to multiplexer filter resource  630 - 1 . Multiplexer filter resource  630 - 1  includes a series connection of optical filter resources to redirect optical signals in channels  49 ,  50 ,  51 , and  53  out of respective optical output ports. 
     Multiplexer filter resource  630 - 1  includes a series connection of optical filter resources to aggregate optical signals in channels  44 ,  48 ,  52 , and  54 . Block filter  620 - 1  redirects optical signals in channels  44 ,  48 ,  52 , and  54  received from multiplexer filter resource  630 - 1  downstream on optical link  105  towards block filter  620 - 2 . 
     Downstream, block filter  620 - 2  redirects optical signals in channels  44 ,  48 ,  52 , and  54  off of the optical link  105  to multiplexer filter resource  630 - 2 . Multiplexer filter resource  630 - 2  includes a series connection of optical filter resources to separate and redirect optical signals in channels  44 ,  48 ,  52 , and  54  to respective optical output ports. 
     Multiplexer filter resource  630 - 2  includes a series connection of optical filter resources to aggregate signals in optical channels  49 ,  50 ,  51 , and  53 . Block filter  620 - 2  redirects signals in optical channels  49 ,  50 ,  51 , and  53  received from multiplexer filter resource  630 - 2  upstream on optical link  105  towards block filter  620 - 1 . 
       FIG. 7  is an example diagram illustrating expansion of the cable network environment according to embodiments herein. As shown, multiplexer filter resource  730 - 1  and multiplexer filter resource  730 - 2  can reside at respective terminal ends of optical link  105 . In accordance with such an embodiment, there is no need for a respective block filter pair as the ends are terminated and the cable network environment cannot be expanded. 
       FIG. 8  is an example diagram illustrating expansion of the cable network environment according to embodiments herein. As an alternative to the configuration in  FIG. 7 , as shown in  FIG. 8 , the optical link  105  extends beyond block filter pair including block filter  820 - 1  and block filter  820 - 2 . In such an embodiment, the optical bandwidth on a pre-existing or new optical link can support pass-through transmission (as opposed to redirecting) of optical signals in channels other than channels  19 - 26 ,  28 - 39 ,  43 - 54 , and  57 - 64 . That is, the cable network environment  400  in  FIG. 8  does not include block filters to redirect optical signals in channels  1 - 18 ,  27 - 29 ,  40 - 42 ,  45 - 46 ,  55 - 56 ,  65 ,  66 , etc., off of the optical link. 
       FIG. 9  is an example diagram illustrating expansion of the cable network environment according to embodiments herein. As shown, the block filter pairs in cable network environment  400  can be implemented in any suitable order along the optical link  105 . 
       FIG. 10  is an example diagram illustrating a multiplexer filter resource including a circulator resource according to embodiments herein. 
     As mentioned, each of the multiplexer filter resources can include any suitable series connection of optical filters and corresponding optical ports on which to individually receive and output optical channels. 
     As shown in  FIG. 10 , the multiplexer filter resource  1030 - 1  (e.g., a modified version of multiplexer filter resource  130 - 1 ) includes multiple optical input ports such as ports A, B, C, and D on which to individually receive respective optical signals in channels  21 ,  22 ,  24 , and  26 . Multiplexer filter resource  1030 - 1  further includes multiple optical output ports such as ports W, X, Y, and Z from which to individually output respective optical signals in channels  19 ,  20 ,  23 , and  25 . 
     Multiplexer filter resource  1030 - 1  further includes a bi-directional optical port M, circulator resource  1020 , and optical amplifier  1050 . 
     The optical filter resources  310  (e.g., optical filter resource  310 - 1 , optical filter resource  310 - 2 , optical filter resource  310 - 3 , etc.) aggregate the optical signals in channels  21 ,  22 ,  24 , and  26  in a similar manner as previously discussed. 
     For example, port P of optical filter resource  310 - 1  receives optical signal in channel  21  from optical input port A. Optical filter resource  310 - 1  passes optical signal in channel  21  out of port C of optical filter resource  310 - 1  to port R of optical filter resource  310 - 2 . 
     Port R of optical filter resource  310 - 2  receives optical signal in channel  21  from optical filter resource  310 - 1 . Port P of optical filter resource  310 - 2  receives optical signal in channel  22  from optical input port B. Optical filter resource  310 - 2  aggregates and then outputs optical signals in channels  21  and  22  out of port C of optical filter resource  310 - 2  to port R of optical filter resource  310 - 3 . 
     Port R of optical filter resource  310 - 3  receives signals in optical channels  21  and  22  from optical filter resource  310 - 2 . Port P of optical filter resource  310 - 3  receives optical signal in channel  24  from optical input port C. Optical filter resource  310 - 3  aggregates and then passes optical signals in channels  21 ,  22 , and  24  out of port C of optical filter resource  310 - 3  to port R of optical filter resource  310 - 4 . 
     Port R of optical filter resource  310 - 4  receives optical signals in channels  21 ,  22 , and  24  from optical filter resource  310 - 3 . Port P of optical filter resource  310 - 4  receives optical signals in channel  26  from optical input port D. Optical filter resource  310 - 4  aggregates and then passes optical signals in channels  21 ,  22 ,  24 , and  26  out of port C of optical filter resource  310 - 4  to the input of optical amplifier  1050 . 
     As its name suggests, the optical amplifier  1050  amplifies one or more of the received optical signals in channels  21 ,  22 ,  24 , and  26 . Circulator resource  1020  receives the amplified optical signals in channels  21 ,  22 ,  24 , and  26  and redirects the amplified optical signals out of bi-directional port M of multiplexer filter resource  1030 - 1 . Circulator resource  1020  provides isolation of optical filter resources  310  and corresponding optical channels with respect to optical filter resources  311  and corresponding optical channels. 
     In a reverse direction, the circulator resource  1020  receives a second set of optical signals in channels  19 ,  20 ,  23 , and  25  as inputs to the bi-directional optical port M from the block filter  120 - 1 . These are inputted optical signals and data from a remote network node. 
     The multiplexer filter resource  1030 - 1  directs the second set of optical signals in channels  19 ,  20 ,  23 , and  25  to respective optical output ports. More specifically, as mentioned, assume that the circulator resource  1020  receives optical signals in channels  19 ,  20 ,  23 , and  25  from bi-directional port M. Circulator resource  1020  redirects the inputted optical signals in channels  19 ,  20 ,  23 , and  25  to port C of the optical filter resource  311 - 1 . 
     The optical filter resource  311 - 1  is configured to pass optical channel  19  from port P of optical filter resource  311 - 1  to optical output port W. Optical filter resource  311 - 1  is further configured to redirect received optical signals in channels  20 ,  23 , and  25  out of port R of the optical filter resource  311 - 1  to input port C of optical filter resource  311 - 2 . 
     Port C of optical filter resource  311 - 2  receives optical signals in channels  20 ,  23 , and  25 . The optical filter resource  311 - 2  is configured to pass optical signal in channel  20  out of port P of optical filter resource  311 - 2  to optical output port X. Optical filter resource  311 - 2  is further configured to redirect received optical signals in channels  23  and  25  to input port C of optical filter resource  311 - 3 . 
     Port C of optical filter resource  311 - 3  receives optical signals in channels  23  and  25 . The optical filter resource  311 - 3  is configured to pass the signal in optical channel  23  out of port P of optical filter resource  311 - 3  to optical output port Y. Optical filter resource  311 - 3  is further configured to redirect received optical signal in channel  25  to input port C of optical filter resource  311 - 4 . 
     Port C of optical filter resource  311 - 4  receives an optical signal in channel  25 . The optical filter resource  311 - 4  is configured to pass optical signal in channel  25  out of port P of optical filter resource  311 - 4  to optical output port Z. 
     This configuration of the multiplexer filter resource is useful because upstream optical signals in channels  19 ,  20 ,  23 , and  25  are not needlessly attenuated via passing through optical filter resources  310 . 
       FIG. 11  is an example diagram illustrating an implementation of a cable network environment according to embodiments herein. 
     As shown, the cable network environment  1100  can include block filter pairs as well as corresponding multiplexer filter resources. However, the multiplexer filter resource  130 - 1  has been replaced with multiplexer filter resource  1030 - 1 , which includes the optical amplifier  1050  and circulator resource  1020  as previously discussed. As mentioned, multiplexer filter resource  1030 - 1  is useful because it amplifies the optical signals prior to transmission to block filter  120 - 1  and downstream on optical link  105 . 
     As further mentioned, the circulator resource  1020  in multiplexer filter resource  1030 - 1  provides isolation. Received optical signals on channels  19 ,  20 ,  23 , and  25  do not need to pass through a series connection of filters including optical filter resources  310  because circulator resource  1020  inputs the signals directly into string of optical filter resources  311 . The received optical signals in channels  19 ,  20 ,  23 , and  25  do not pass through the sequence of optical filter resources  310  and are therefore not attenuated by optical filter resources  311 . 
       FIG. 12  is an example diagram illustrating a cable network environment including block filter pairs and multiplexer filter resources according to embodiments herein. 
     As shown, cable network environment  1200  includes hub resource  410 . Hub resource  410  includes one or more block filters such as block filter  120 - 1 , block filter  520 - 1 , etc. Hub resource  410  can be a building at a headend of a cable network in which the block filters reside. 
     In this example embodiment, the content manager  140 - 1  is communicatively coupled to respective ports A, B, C, D, W, X, Y, and Z of multiplexer filter resource  130 - 1 . In a manner as previously discussed, the content manager  140 - 1  receives data on optical signals in channels  19 ,  20 ,  23 , and  25  in an upstream direction from distribution node  140 - 2 . Content manager  140 - 1  transmits data over respective optical signals in channels  21 ,  22 ,  24 , and  26  downstream to distribution node  140 - 2 . 
     In this example embodiment, the distribution node  140 - 2  is coupled to respective ports A, B, C, D, W, X, Y, and Z of multiplexer filter resource  130 - 2 . In a manner as previously discussed, the distribution node  140 - 2  receives data in the downstream direction on optical signals in channels  21 ,  22 ,  24 , and  26 . Distribution node  140 - 2  transmits data over respective optical signals in channels  19 ,  20 ,  23 , and  25  in an upstream direction to content manager  140 - 1  in hub resource  410 . 
     The optical channels associated with a respective block filter pair can be allocated in any suitable manner to provide access to one or more service groups in cable network environment  1200 . 
     For example, the pair of optical channels including upstream optical signal in channel  19  and downstream optical signal in channel  21  can be allocated to support communications over communication link  650 - 1  (such as a coaxial cable, fiber link, etc.) between distribution node  140 - 2  and network  600 - 1  (e.g., a first service group of multiple subscribers that share use of the communication link  650 - 1 ). That is, the distribution node  140 - 2  can be configured to receive data from one or more subscribers over communication link  650 - 1  and transmit such data upstream over optical channel  19  to content manager  140 - 1 . The distribution node  140 - 2  can be configured to receive data from the content manager  140 - 1  on an optical signal in channel  21 . Distribution node  140 - 2  initiates transmission of the received data over communication link  650 - 1  to the one or more subscribers in network  600 - 1 . 
     The pair of optical channels including upstream optical signal in channel  20  and downstream optical signal in channel  22  can be allocated to support communications over communication link  650 - 2 . For example, the distribution node  140 - 2  can be configured to receive data from one or more subscribers in network  600 - 2  (e.g., a second service group of multiple subscribers that share use of the communication link  650 - 2 ) over communication link  650 - 2 . The distribution node  140 - 2  transmits the received data upstream on an optical signal in channel  20  to content manager  140 - 1 . The distribution node  140 - 2  can be configured to receive data from the content manager  140 - 1  on an optical signal in channel  22 . In such an instance, distribution node  140 - 2  initiates transmission of the received data over communication link  650 - 2  to the one or more subscribers in a respective service group. 
     In a similar manner, a first pair of optical channels such as optical channels  28  and  34  can support communications between content manager  540 - 1  and network  600 - 2  through optical link  105  and the distribution node  540 - 2 . A second pair of optical channels such as optical channels  33  and  35  can support communications between content manager  540 - 1  and network  601 - 2  through a portion of optical link  105  and distribution node  540 - 2 ; and so on. 
     In this manner, the non-limiting example configuration as discussed herein can support communications up to sixteen service groups using a single optical fiber optic link. 
     Thus, each content manager  140 - 1 ,  540 - 1 , etc., in hub resource  410  can be a centralized resource configured to communicate (e.g., receive and transmit data) with multiple service groups of subscribers in disparately located networks  600  (e.g., network  600 - 1 , network  600 - 2 , . . . ),  601  (e.g., network  601 - 1 , network  601 - 2 , . . . ), etc. 
     Functionality supported by the different resources will now be discussed via flowcharts in  FIGS. 13-14 . Note that the steps in the flowcharts below can be executed in any suitable order. 
       FIG. 13  is an example diagram illustrating an optical network environment including multiple block filters according to embodiments herein. 
     In processing block  1310 , first block filter  120 - 1  disposed in cable network environment  400  inputs a first set of optical channels of signals onto a fiber optic link downstream towards a second block filter  120 - 2  in the cable network environment  400 . The first block filter and second block filter are substantially matched; that is, the first block filter and second block filter redirect a substantially same band of optical channels of signals on and off the fiber optic link. 
     In processing block  1320 , the second block filter  120 - 2  inputs a second set of optical channels of signals onto the fiber optic link upstream towards the first block filter  120 - 1 . 
     In processing block  1330 , the first block filter  120 - 1  receives and redirects the received second set of upstream optical channels of signals off of the fiber optic link to multiplexer filter resource  130 - 1 . 
     In processing block  1340 , the second block filter  120 - 2  receives and redirects the first set of downstream optical channels of signals off of the fiber optic link to multiplexer filter resource  130 - 2 . 
       FIG. 14  is an example diagram illustrating use of block filter pairs and related resources according to embodiments herein. 
     In processing block  1410 , the multiplexer filter resource  1030 - 1  aggregates a first set of optical signals on channels (e.g.,  21 ,  22 ,  24 , and  26 ) received on multiple optical input ports (e.g., ports D, C, B, and A). 
     In processing block  1420 , the multiplexer filter resource  1030 - 1  utilizes a circulator resource  1020  in the multiplexer filter resource  1030 - 1  to redirect transmission of the aggregated first set of optical signals in channels (e.g., channels  21 ,  22 ,  24 , and  26 ) out of a bi-directional optical port M of the optical multiplexer resource  1030 - 1  to a respective fiber optic link such as optical link  105 . Amplifier  1050  can be used to amplify optical signals in channels  21 ,  22 ,  24 , and  26  prior to transmission out of port M. 
     In processing block  1430 , the multiplexer filter resource  1030 - 1  receives a second set of optical signals in channels (e.g.,  19 ,  20 ,  23 , and  25 ) as inputs to the bi-directional optical port M of the optical multiplexer resource  1030 - 1 . 
     In processing block  1440 , the circulator resource  1020  redirects the second set of optical signals in channels (e.g.,  19 ,  20 ,  23 , and  25 ) for distribution to a series connection of multiple optical filter resources and distribution from optical output ports W, X, Y, and Z. 
     Note again that techniques herein are well suited for expanding use of a optical links in a cable network environment. However, it should be noted that embodiments herein are not limited to use in such applications and that the techniques discussed herein are well suited for other applications as well. 
     Based on the description set forth herein, numerous specific details have been set forth to provide a thorough understanding of claimed subject matter. However, it will be understood by those skilled in the art that claimed subject matter may be practiced without these specific details. 
     While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present application as defined by the appended claims. Such variations are intended to be covered by the scope of this present application. As such, the foregoing description of embodiments of the present application is not intended to be limiting. Rather, any limitations to the invention are presented in the following claims.