Patent Publication Number: US-2021165175-A1

Title: Optical sub-assembly and telescopic-shaped core cylinder module thereof

Description:
RELATED APPLICATIONS 
     This application is a division of U.S. nonprovisional patent application Ser. No. 16/699,664, filed Dec. 1, 2019, the contents of which are incorporated herein by reference as if fully disclosed herein 
    
    
     TECHNICAL FIELD 
     Example embodiments relate generally to the field of optical communications and, more particularly, to optical sub-assemblies and a telescopic-shaped core cylinder module thereof. 
     BACKGROUND 
     Growing demand for higher performance and speed has led to the widespread use of optical fibres in communications. In optical communication systems, light is used to send data to a remote end via an optical fibre in the form of pulses of light, instead of electrical current. A fibre optic transceiver is a key component in the communication system and may be classified by fibre mode, transfer rate, transmission distance, wavelength, and connector type. One connector type transceiver is a bi-directional (BiDi) transceiver and a key component of the BOSA is a BOSA (bi-directional Optical Sub-Assembly). 
     A BOSA uses two independent wavelength channels, one to transmit and one to receive transmissions to and from interconnected devices, over a single fibre strand. The transmit wavelength at one connection end matches the receive wavelength at an opposing connection end and vice versa. The BOSA is capable of separating transmit (Tx) data and receiving (Rx) data at each end. 
     Generally, a BOSA is made up of an optical emitter having a light source, such as a laser diode, an optical receiver having a light receiving source, such as a photodiode, a wavelength filter, passing light at one wavelength while reflecting light at another wavelength, and an optical connector, outputting the emitted light and inputting the received light, surrounded by a housing. Tx data is transmitted by the optical emitter through the wavelength filter to an optical fibre in the optical connector. Rx data is transmitted via the optical fibre through the filter unit to the optical receiver. 
     While the wavelength filter is capable of separating the Tx data and Rx data, all laser applications are prone to surface reflections, whereby some of the emitted light launched by the laser source is reflected back into the interior of the housing and some of the light received or reflected back from the optical fibre passes through the wavelength filter and impinges on the laser diode. These surface reflections create problems for the BOSA, increasing noise therein or causing operational failure. One or more additional filters may be added to the BOSA, such as a blocking filter over the photodiode to block light of the laser diode&#39;s wavelength; however, as additional filters are added, costs and complexity increase and reliability and focusing stability of the emitted light onto the optical fibre may be degraded. 
     For the laser source, surface reflections off targeted surfaces back into the laser source decreases the stability and operating lifespan thereof through damage, unexpected laser problems, or overheating. One or more additional components may also be added to the BOSA, such as an isolator, which is an optical component that emits a circularly polarized beam and allows light to transmit in only a single direction; however, isolators have more parts and are larger than filters, which increases the costs and complexity of the BOSA even further. 
     SUMMARY 
     Optical sub-assemblies and telescopic-shaped core cylinder modules thereof are provided. 
     In an embodiment, an optical sub-assembly, comprising a filtering optical module, a light emitting module, at least a light receiving module, a fibre optic connector, a fibre optic cable, and a telescopic-shaped core cylinder module is provided. 
     The filtering optical module comprises a first filtering module end, a second filtering module end, at least a third filtering module end, and a mounting and pass-through structure. The second filtering module end is positioned opposite to the first filtering module end. The first and second filtering module ends include a first filtering module core and a second filtering module core, respectively. The first and second filtering module cores have a first central axis. The at least a third filtering module end includes at least a third filtering module core and at least a third central axis perpendicular to the first central axis of the first and second filtering module cores. The mounting and pass-through structure having a central pass-through opening, a flat backing portion, an angled mount structure having a mounting angle, and a flat mount structure, wherein the first central axis and at least a third central axis passes through the central pass-through opening. 
     The light emitting module includes a light emitting device, emitting light, fixedly positioned in the first filtering module core. The emitted light comprises a first optical signal. 
     The at least a light receiving module has a light receiving device, receiving light, fixedly positioned in the at least a third filtering module core. The received light comprises a second optical signal. 
     The fibre optic connector comprises a connector body. The fibre optic cable comprises a fibre optic. The fibre optic cable is fixedly positioned in the fibre optic connector outputting and inputting the first optical signal and the second optical signal. 
     The telescopic-shaped core cylinder module of an optical sub-assembly, comprising a first cylinder core end, a second cylinder core end, a cylinder core, and at least a gel coating layer is provided. The cylinder core has at least two tapered diameter core portions comprising a first and second core portion. A diameter of the first core portion is larger than a diameter of a second core portion and the shapes of the first and second core portions are conical. The first cylinder core end encompasses the first core portion and a portion of the second core portion and the second cylinder core end encompasses a portion of the second core portion not encompassed by the first cylinder core end. The at least a gel coating layer is over an inner surface of the telescopic-shaped core cylinder module. The telescopic-shaped core cylinder module is integrally formed and configured to perform isolation on optical signals via the tapered diameter core portions, taperedly shrinking the area for reflected light to impinge on the light emitting device, and the at least a gel coating layer, absorbing wavelengths of the optical signals reflected in and to the tapered diameter core portions. 
     In an embodiment, the optical sub-assembly further comprises at least one wavelength filter, a least one blocking filter, a connector collar, and a boot. The least one wavelength filter is fixedly positioned on the angled mount structure of the filtering optical module and separates the directed light paths of the first optical signal and second optical signal. The at least one blocking filter is fixedly positioned on the flat mount structure and flush with the flat backing portion, blocking the emitted light from passing therethrough. The connector collar includes an end portion having an annular protrusion, fixedly positioned on the second filtering module end, damping the connector body. The boot has an undercut and is fixedly positioned on the end portion of the connector collar, wherein the annular protrusion of the connector collar is snap-fit assembled to the undercut. 
     In some embodiments, the first optical signal of the light emitting device positioned along the first central axis is directed to the at least two tapered diameter core portions, the at least one wavelength filter, and onto the fibre optic. The second optical signal of the light receiving device positioned along the at least a third central axis perpendicular to the first central axis is received from the fibre optic and the least one wavelength filter. 
     In an embodiment, a telescopic-shaped core cylinder module of an optical sub-assembly, comprising a first cylinder core end, a second cylinder core end, a cylinder core, and at least a gel coating layer is provided. The cylinder core has at least two tapered diameter core portions comprising a first and second core portion. A diameter of the first core portion is larger than a diameter of a second core portion and the shapes of the first and second core portions are conical. The first cylinder core end encompasses the first core portion and a portion of the second core portion and the second cylinder core end encompasses a portion of the second core portion not encompassed by the first cylinder core end. The at least a gel coating layer is over an inner surface of the telescopic-shaped core cylinder module. The telescopic-shaped core cylinder module is integrally formed and configured to perform isolation on optical signals via the tapered diameter core portions, taperedly shrinking the area for reflected light to impinge on the light emitting device, and the at least a gel coating layer, absorbing wavelengths of the optical signals reflected in and to the tapered diameter core portions. 
     In some embodiments, the telescopic-shaped core cylinder module further comprises a first transitional core portion, a second transitional core portion, a first guiding core portion, a second guiding core portion, a first inner guiding core portion, and a second inner guiding core portion. The first transitional core portion has a cylindrical shape extending from a first end of the first core portion, wherein a diameter of the first transitional core portion is larger than the diameter of the first core portion. The difference in the size of the diameters of the first transitional core portion and first core portion is configured to contain excess gel from the at least a gel coating layer over the inner surface areas of the first core portion of the of the telescopic-shaped core cylinder module following application over an inner surface thereof. The second transitional core portion has a cylindrical shape extending from the second inner guiding core portion opposite to the second core portion, wherein a diameter of the second transitional core portion is smaller than the diameter of the second core portion. The first guiding core portion has a conical shape radially expanding outwardly from the first transitional core portion opposite to the first core portion. The second guiding core portion has a conical shape radially expanding outwardly from the second transitional core portion opposite to the second inner guiding core portion. The first inner guiding core portion has a conical shape and is positioned between the first and second core portions. The second inner guiding core portion has a conical shape radially expanding outwardly from the second core portion opposite to the first inner guiding core portion. 
     In some embodiments, the amount of the at least two tapered diameter core portions is three. In some embodiments, the amount of the at least two tapered diameter core portions is greater than three. 
     In some embodiments, the amount of the at least a gel coating layer of the telescopic-shaped core cylinder module is two coating layers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Unless specified otherwise, the accompanying drawings illustrate aspects of the innovative subject matter described herein. Referring to the drawings, wherein like reference numerals indicate similar parts throughout the several views, several examples of heatsink fins incorporating aspects of the presently disclosed principles are illustrated by way of example, and not by way of limitation. 
         FIG. 1A  is a schematic perspective view of an optical sub-assembly, according to an example embodiment. 
         FIG. 1B  is an exploded view of the optical sub-assembly of  FIG. 1A , according to an example embodiment. 
         FIG. 2A  is a schematic perspective view of the optical sub-assembly of  FIG. 1A  with line A-A, according to an example embodiment. 
         FIG. 2B  is a schematic cross-sectional view of the optical sub-assembly of  FIG. 1A  along line A-A in  FIG. 2A , according to an example embodiment. 
         FIG. 3A  is a schematic perspective side view of the interior of the filtering optical module of an optical sub-assembly, according to an example embodiment. 
         FIG. 3B  is a schematic perspective top view of the filtering optical module of  FIG. 3A , according to an example embodiment. 
         FIG. 3C  is a schematic perspective end view of the second filtering module end of the filtering optical module of  FIG. 3A , according to an example embodiment. 
         FIG. 3D  is a schematic perspective end view of the first filtering module end of the filtering optical module of  FIG. 3A , according to an example embodiment. 
         FIG. 4A  is a schematic perspective top view of an optical sub-assembly without a light emitting module, at least a light receiving module, connector collar, and booth, according to an example embodiment. 
         FIG. 4B  is a schematic perspective side view of the interior of the optical sub-assembly of  FIG. 4A , according to an example embodiment. 
         FIG. 4C  is an exploded view of the interior of the optical sub-assembly of  FIG. 4A , according to an example embodiment. 
         FIG. 5A  is a schematic perspective side view of an optical sub-assembly without a light emitting module and at least a light receiving module, according to an example embodiment. 
         FIG. 5B  is an exploded view of the interior of the optical sub-assembly of  FIG. 5A , according to an example embodiment. 
         FIG. 6  is a schematic perspective side view of the interior of the filtering optical module and telescopic-shaped core cylinder module of an optical sub-assembly, according to an example embodiment. 
         FIG. 7A  is a schematic perspective side view of the interior of the telescopic-shaped core cylinder module of an optical sub-assembly, according to an example embodiment. 
         FIG. 7B  is a schematic perspective end view of the second cylinder core end of the telescopic-shaped core cylinder module of  FIG. 7A , according to an example embodiment. 
         FIG. 7C  is a schematic perspective end view of the first cylinder core end of the telescopic-shaped core cylinder of  FIG. 7A , according to an example embodiment. 
         FIG. 8A  is a schematic perspective side view of the interior of the filtering optical module, light emitting module, and telescopic-shaped core cylinder module of an optical sub-assembly, according to an example embodiment. 
         FIG. 8B  is a schematic perspective top view of the interior of the filtering optical module, light emitting module, and telescopic-shaped core cylinder module of  FIG. 8A , according to an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following describes various principles related to optical communication systems by way of reference to specific examples of optical sub-assemblies, including arrangements and examples of filtering optical modules, light emitting modules, light receiving modules, fiber optic connectors and cables and telescopic-shaped core cylinder modules embodying innovative concepts. More particularly, but not exclusively, such innovative principles are described in relation to selected examples of filtering optical modules, light emitting modules, light receiving modules, fiber optic connectors and cables and telescopic-shaped core cylinder modules and well-known functions or constructions are be described in detail for purposes of succinctness and clarity. Nonetheless, one or more of the disclosed principles can be incorporated in various other embodiments of fiber optic connectors and adapters to achieve any of a variety of desired outcomes, characteristics, and/or performance criteria. 
     Thus, filtering optical modules, light emitting modules, light receiving modules, fiber optic connectors and cables and telescopic-shaped core cylinder modules having attributes that are different from those specific examples discussed herein can embody one or more of the innovative principles, and can be used in applications not described herein in detail. Accordingly, embodiments of filtering optical modules, light emitting modules, light receiving modules, fiber optic connectors and cables and telescopic-shaped core cylinder modules not described herein in detail also fall within the scope of this disclosure, as will be appreciated by those of ordinary skill in the relevant art following a review of this disclosure. 
     Example embodiments as disclosed herein are directed to optical sub-assemblies and telescopic-shaped core cylinder modules thereof. The optical sub-assemblies may be applicable to, as an example, optical line terminals (OLTs) installed in a central control station of a passive optical network (PON) system, which is a type of fiber-to-the-curb (FTTC), fiber-to-the-building (FTTB), or fiber-to-the-home (FTTH) system, employing point-to-multiple point network architecture, and devices and equipment on a remote users premises of the FTTC, FTTB, or FTTH system. In an embodiment, an optical sub-assembly comprising a filtering optical module, a light emitting module having a light emitting device and a light-emission-side lens, at least a light receiving module having a light-reception-side lens, at least one wavelength filter, a fibre optic connector, a fibre optic cable having a fiber optic, and a telescopic-shaped core cylinder module having tapered diameter core portions and at least a gel coating layer, is provided. A first optical signal of the light emitting device is directed to the light-emission-side lens, the tapered diameter core portions, the least one wavelength filter, and onto the fibre optic. The second optical signal of the light receiving device is received from the fibre optic, the least one wavelength filter, and the light-reception-side lens. The telescopic-shaped core cylinder module is configured to perform isolation on optical signals via the tapered diameter core portions, taperedly shrinking the area for reflected light to impinge on the light emitting device, and the at least a gel coating layer, absorbing wavelengths of the optical signals reflected in and to the tapered diameter core portions. 
       FIG. 1A  is a schematic perspective view of an optical sub-assembly, according to an example embodiment.  FIG. 1B  is an exploded view of the optical sub-assembly of  FIG. 1A , according to an example embodiment.  FIG. 2A  is a schematic perspective view of the optical sub-assembly of  FIG. 1A  with line A-A, according to an example embodiment.  FIG. 2B  is a schematic cross-sectional view of the optical sub-assembly of  FIG. 1A  along line A-A in  FIG. 2A , according to an example embodiment. Referring to  FIGS. 1A to 2B , in an embodiment, an optical sub-assembly  100 , comprising a filtering optical module  150 , a light emitting module  110 , at least a light receiving module  160 , a fibre optic connector  180 , a fibre optic cable  190 , and a telescopic-shaped core cylinder module  120  is provided. 
       FIG. 3A  is a schematic perspective side view of the interior of the filtering optical module of an optical sub-assembly, according to an example embodiment.  FIG. 3B  is a schematic perspective top view of the filtering optical module of  FIG. 3A , according to an example embodiment.  FIG. 3C  is a schematic perspective end view of the second filtering module end of the filtering optical module of  FIG. 3A , according to an example embodiment.  FIG. 3D  is a schematic perspective end view of the first filtering module end of the filtering optical module of  FIG. 3A , according to an example embodiment. Referring to  FIGS. 3A to 3B , and referring to  FIGS. 1A to 2B , the filtering optical module  150  comprises a first filtering module end  141 , a second filtering module end  159 , at least a third filtering module end  151 , and a mounting and pass-through structure  157 . The second filtering module end  159  is positioned opposite to the first filtering module end  141 . The first and second filtering module ends  141 ,  159  include a first filtering module core  145  and a second filtering module core  156 , respectively. The first and second filtering module cores  145 ,  156  have a first central axis  142 . The at least a third filtering module end  151  includes at least a third filtering module core  146  and at least a third central axis  147  perpendicular to the first central axis  142  of the first and second filtering module cores  145 ,  156 . The mounting and pass-through structure  157  having a central pass-through opening  155 , a flat backing portion  149 , an angled mount structure  153  having a mounting angle, and a flat mount structure  148 , wherein the first central axis  142  and at least a third central axis  147  passes through the central pass-through opening  155 . 
     In some embodiments, the optical sub-assembly  100  further comprises at least one wavelength filter  153   a  and at least one blocking filter  148   a . The at least one wavelength filter  153   a  is fixedly positioned on the angled mount structure  153  of the filtering optical module  150  and separates the directed light paths of the first optical signal and a second optical signal of at least a light receiving module  160  having a light receiving device, receiving light, fixedly positioned in the at least a third filtering module core  146 . The at least one blocking filter  148   a  is fixedly positioned on the flat mount structure  148  and flush with the flat backing portion  149 , blocking the emitted light from passing therethrough. Those of ordinary skill in the relevant art may readily appreciate that in some embodiments the optical sub-assembly  100  may comprises more than one light receiving module, wavelength filter and blocking filter and the embodiments are not limited thereto. The amount of light receiving modules, wavelength filters and blocking filters determines the amount of structures required in the filtering optical module  150  and the embodiments are not limited thereto. As long as the respective light paths of the optical signals of the light emitting module may be directed and the at least a light receiving module may be separated or blocked for operation of the optical sub-assembly  100 . 
       FIG. 4A  is a schematic perspective top view of an optical sub-assembly without a light emitting module, at least a light receiving module, connector collar, and booth, according to an example embodiment.  FIG. 4B  is a schematic perspective side view of the interior of the optical sub-assembly of  FIG. 4A , according to an example embodiment.  FIG. 4C  is an exploded view of the interior of the optical sub-assembly of  FIG. 4A , according to an example embodiment. Referring to  FIGS. 4A to 48 , and referring to  FIGS. 1A to 3D , in an embodiment, the fibre optic connector  180  comprises a connector body  188  and a ferrule  187 . The connector body  188 , includes a first connector body end  181   b  having a sloped ferrule core  185  and a second connector body end  189   b  having a buffer clamp core  186 . The ferrule  187  has a first ferrule end  181   a , a second ferrule end  189   a  and a ferrule core  182   a , wherein a side of the first ferrule end  181   a  is slanted at an angle in a same direction and of less than the mounting angle of the angled mount structure  153 . The slanted side of the first ferrule end  181   a  assists in mitigating reflected light to impinge on the light emitting device. 
     In an embodiment, the fibre optic cable  190  includes a fibre optic  195 , a fibre optic coating, and a buffer tube  198 . The fibre optic  195  has a first optic portion  194 , second optic portion  196  and a third optic portion  197 . The fibre optic cable  190  is fixedly positioned in the fibre optic connector  180 , wherein the third optic portion  197  is positioned in a central axis of the buffer clamp core  186  and the first and second optic portions  194 ,  196  are positioned in a stepped adjusted central axis of the sloped ferrule core  185 , respectively, outputting and inputting the first optical signal and the second optical signal. 
       FIG. 5A  is a schematic perspective side view of an optical sub-assembly without a light emitting module and least a light receiving module, according to an example embodiment.  FIG. 5B  is an exploded view of the interior of the optical sub-assembly of  FIG. 5A , according to an example embodiment. Referring to  FIGS. 5A and 5 , and referring to  FIGS. 1A to 4C , in an embodiment, the optical sub-assembly  100  further comprises a connector collar  176  and a boot  178 . The connector collar  176  includes an end portion having an annular protrusion, fixedly positioned on the second filtering module end  159 , clamping the connector body  188  and surrounding portions of the ferrule  187 , the sloped ferrule core  185 , and the buffer clamp core  186 . The boot  178  has an undercut and is fixedly positioned on the end portion of the connector collar  176  and surrounding the buffer clamp core  186  and a portion of the sloped ferrule core  185 , wherein the annular protrusion of the connector collar  176  is snap-fit assembled to the undercut. 
       FIG. 6  is a schematic perspective side view of the interior of the filtering optical module and telescopic-shaped core cylinder module of an optical sub-assembly, according to an example embodiment.  FIG. 7A  is a schematic perspective side view of the interior of the telescopic-shaped core cylinder module of an optical sub-assembly, according to an example embodiment.  FIG. 7B  is a schematic perspective end view of the second cylinder core end of the telescopic-shaped core cylinder module of  FIG. 7A , according to an example embodiment.  FIG. 7C  is a schematic perspective end view of the first cylinder core end of the telescopic-shaped core cylinder of  FIG. 7A , according to an example embodiment. Referring to  FIGS. 6 to 7C , and referring to  FIGS. 1A to 5B , in an embodiment, the telescopic-shaped core cylinder module  120  comprises a first cylinder core end  122  having a cylindrical shape, a second cylinder core end  129  having a conical shape, a cylinder core  122 , and at least a gel coating layer. The cylinder core  122  has at least two tapered diameter core portions, comprising a first and second core portion  125 ,  126 . The diameter of a first core portion  125  is larger than a diameter of a second core portion  126  and the shapes of the first and second core portions  125 ,  126  are conical. The first cylinder core end  122  encompasses the first core portion  125  and a portion of the second core portion  126  and the second cylinder core end  129  encompasses a portion of the second core portion  126  not encompassed by the first cylinder core end  122 . The at least a gel coating layer is over an inner surface of the telescopic-shaped core cylinder module  120 . The telescopic-shaped core cylinder module  120  is integrally formed and configured to perform isolation on optical signals via the tapered diameter core portions  125 ,  126 , taperedly shrinking the area for reflected light to impinge on the light emitting device, and the at least a gel coating layer, absorbing wavelengths of the optical signals reflected in and to the tapered diameter core portions  125 ,  126 . 
     In an embodiment, the at least a light receiving module  160  has a light receiving device, receiving light, and a protective casing having a light-reception-side lens, directing rays to the light receiving device, encompassing the light receiving device, fixedly positioned in the at least a third filtering module core  146 . Those of ordinary skill in the relevant art may readily appreciate that the at least a light receiving module  160  may comprise of less, more or substitute functioning elements known by those skilled in the relevant art and the embodiments are not limited thereto. The received light comprises a second optical signal. 
     In some embodiments, the light receiving device of the at least a light receiving module  160  is a 1.25 Gb/s to 100 Gb/s InGaAs PIN photodiode; however, the embodiments are not limited thereto. Those of ordinary skill in the relevant art may readily appreciate that other types of light receiving devices having other types of photodiodes may be employed depending upon application, as long as the second optical signal of the light receiving device positioned along the at least a third central axis  147  perpendicular to the first central axis  142 , can be received from the first optic portion  194  of the fibre optic  195 , the at least one wavelength filter  153   a , and the light-reception-side lens. 
       FIG. 8A  is a schematic perspective side view of the interior of the filtering optical module  150 , light emitting module, and telescopic-shaped core cylinder module of an optical sub-assembly, according to an example embodiment.  FIG. 8B  is a schematic perspective top view of the interior of the filtering optical module  150 , light emitting module, and telescopic-shaped core cylinder module of  FIG. 6A , according to an example embodiment. Referring to  FIGS. 8A to 8I , and referring to  FIGS. 1A to 7C , in an embodiment, the light emitting module  110  includes a light emitting device, emitting light, a light-emission-side lens  118 , refracting the emitted light, and a protective casing having a central window, encompassing the light emitting device and light-emission-side lens  118 , fixedly positioned in the first filtering module core  145 . Those of ordinary skill in the relevant art may readily appreciate that the light emitting module  110  may comprise of less, more or substitute functioning elements known by those skilled in the relevant art and the embodiments are not limited thereto. The emitted light comprises a first optical signal. 
     Those of ordinary skill in the relevant art may readily appreciate that the light emitting module  110  may further comprise additional elements, and the embodiments are not limited thereto. As long as the first optical signal of the light emitting device can be directed to the light-emission-side lens  118 , the tapered diameter core portions  125 ,  126 , the at least one wavelength filter  153   a , and onto the fibre optic  195 . 
     In some embodiments, the light emitting device of the light emitting module  110  is a 1.26-μm to 1.65-μm 1.25 Gb/s to 100 Gb/s TO-56-packaged distributed-feedback (DFB) laser diode; however, the embodiments are not limited thereto. Those of ordinary skill in the relevant art may readily appreciate that other types of light emitting devices may be employed depending upon application, as long as the first optical signal of the light emitting device can be directed to the light-emission-side lens  118 , the tapered diameter core portions  125 ,  126 , the at least one wavelength filter  153   a , and onto the fibre optic  195 . 
     In an embodiment, a telescopic-shaped core cylinder module  120  of an optical sub-assembly  100 , comprising a first cylinder core end  122  having a cylindrical shape, a second cylinder core end  129  having a conical shape, a cylinder core  122 , and at least a gel coating layer is provided. Referring to  FIGS. 7A to 7C , the cylinder core  122  has at least two tapered diameter core portions comprising a first and second core portion  125 ,  126 . The diameter of a first core portion  125  is larger than a diameter of a second core portion  126  and the shapes of the first and second core portions  125 ,  126  are conical. The first cylinder core end  122  encompasses the first core portion  125  and a portion of the second core portion  126  and the second cylinder core end  129  encompasses a portion of the second core portion  126  not encompassed by the first cylinder core end  122 . The at least a gel coating layer is over an inner surface of the telescopic-shaped core cylinder module  120 . The telescopic-shaped core cylinder module  120  is integrally formed and configured to perform isolation on optical signals via the tapered diameter core portions  125 ,  126 , taperedly shrinking the area for reflected light to impinge on the light emitting device, and the at least a gel coating layer, absorbing wavelengths of the optical signals reflected in and to the tapered diameter core portions  125 ,  126 . 
     In some embodiments, the amount of the at least two tapered diameter core portions is three. In some embodiments, the amount of the at least two tapered diameter core portions is greater than three. 
     In some embodiments, the amount of the at least a gel coating layer of the telescopic-shaped core cylinder module  120  is two coating layers. 
     In some embodiments, the telescopic-shaped core cylinder module  120  further comprises a first transitional core portion  124 , a second transitional core portion  127 , a first guiding core portion  123   a , a second guiding core portion  123   z , a first inner guiding core portion  123   b , and a second inner guiding core portion  123   c . The first transitional core portion  124  has a cylindrical shape extending from a first end of the first core portion  125 , wherein a diameter of the first transitional core portion  124  is larger than the diameter of the first core portion  125 . The difference in the size of the diameters of the first transitional core portion  124  and first core portion  125  is configured to contain excess gel from the at least a gel coating layer over the inner surface areas of the first core portion  125  of the of the telescopic-shaped core cylinder module  120  following application over an inner surface thereof. The second transitional core portion  127  has a cylindrical shape extending from the second inner guiding core portion  123   c  opposite to the second core portion  126 , wherein a diameter of the second transitional core portion  127  is smaller than the diameter of the second core portion  126 . The first guiding core portion  123   a  has a conical shape radially expanding outwardly from the first transitional core portion  124  opposite to the first core portion  125 . The second guiding core portion  123   z  has a conical shape radially expanding outwardly from the second transitional core portion  127  opposite to the second inner guiding core portion  123   c . The first inner guiding core portion  123   b  has a conical shape and is positioned between the first and second core portions  125 ,  126 . The second inner guiding core portion  123   c  has a conical shape radially expanding outwardly from the second core portion  126  opposite to the first inner guiding core portion  123   b.    
     In some embodiments, the diameter of the second transitional core portion  127 , second core portion  126 , first core portion  125 , and first transitional core portion  124  is 0.7 mm, 1.2 mm, 1.6 mm, and 2 mm, respectively, having differences of 0.5 mm, 0.4 mm and 0.4 mm, respectively; however, the embodiments are not limited thereto. Those of ordinary skill in the relevant art may readily appreciate that the diameters may vary depending upon application and requirements, such as, the size of the optical sub-assembly  100 . Generally, the size of the diameters of the second transitional core portion  127 , second core portion  126 , first core portion  125 , and first transitional core portion  124  may range from 0.1 mm to 2 mm, 0.6 mm to 2.5 mm, 1 mm to 2.9 mm, and 1.4 mm to 3.3 mm, respectively. As long as isolation can be performed on optical signals via the tapered diameter core portions  125 ,  126 , taperedly shrinking the area for reflected light to impinge on the light emitting device, and the at least a gel coating layer, absorbing wavelengths of the optical signals reflected in and to the tapered diameter core portions  125 ,  126  and the difference in the size of the diameters of the first transitional core portion  124  and the first core portion  125  can contain excess gel from the at least a gel coating layer over the inner surface areas of the first core portion  125  of the of the telescopic-shaped core cylinder module  120  following application over an inner surface thereof. 
     In some embodiments, the at least a gel coating layer of the telescopic-shaped core cylinder module  120  can absorb a full range of wavelengths between 1260 and 1670 nm in various bands; however, the embodiments are not limited thereto. Those of ordinary skill in the relevant art may readily appreciate that as technology changes, so may the required wavelength ranges or bands. As long as the at least a gel coating layer, along with the tapered diameter core portions  125 ,  126 , can substantially reduce emitted light launched by the light emitting device, reflecting back into the interior of the filtering optical module  150  via the structures therein and light received or reflected back from the optical fibre  195 , passing through the least one wavelength filter  153   a  and impinging on the light emitting device. 
     In some embodiments, the at least a gel coating layer is made up of at least a metal oxide; however, the embodiments are not limited thereto. As long as the at least a gel coating layer can be applied over the inner surface areas of the telescopic-shaped core cylinder module  120 , absorbing a full range of wavelengths between 1260 and 1670 nm in various bands. 
     In some embodiments, the material of the filtering optical module  150 , fibre optic connector  180  and telescopic-shaped core cylinder module  120  is stainless steel; however, the embodiments are not limited thereto. Those of ordinary skill in the relevant art may readily appreciate that other materials may be employed, such as aluminum or high-temperature polymer, as long as the operation of the optical sub-assembly  100  is not hindered and the telescopic-shaped core cylinder module  120  can perform isolation on optical signals via the tapered diameter core portions  125 ,  126 , taperedly shrinking the area for reflected light to impinge on the light emitting device, and the at least a gel coating layer, can absorb wavelengths of the optical signals reflected in and to the tapered diameter core portions  125 ,  126 . 
     In some embodiments, the mounting angle of the angled mount structure  153  is around 45° degrees. However, those of ordinary skill in the relevant art may readily appreciate that adjustments may be made to the mounting angle depending upon design requirements and the embodiments are not limited thereto. As an example, and not to be limiting, for two angled mount structures, the mounting angle may be around 45° degrees in one direction and 45° degrees in an opposite direction and the embodiments are not limited thereto. As long as the first optical signal of the light emitting device positioned along the first central axis  142 , can be directed to the light-emission-side lens  118 , the tapered diameter core portions  125 ,  126 , the least one wavelength filter  153   a , and onto the first optic portion  194  of the fibre optic  195  and the optical signals of the light receiving devices positioned along the central axis&#39; perpendicular to the first central axis  142 , can be received from the first optic portion  194  of the fibre optic  195 , the wavelength filters, and the light-reception-side lenses. 
     In some embodiments, the mechanical fixing means of the optical sub-assemblies comprise adhesion or welding, such as laser welding; however, the embodiments are not limited thereto. Those of ordinary skill in the relevant art may readily appreciate that other fixing means may be used for the optical sub-assemblies of the embodiments, as long as the operation of the optical sub-assembly  100  is not hindered and the telescopic-shaped core cylinder module  120  can perform isolation on optical signals via the tapered diameter core portions  125 ,  126 , taperedly shrinking the area for reflected light to impinge on the light emitting device, and the at least a gel coating layer, absorbing wavelengths of the optical signals reflected in and to the tapered diameter core portions  125 ,  126 . 
     In the embodiments, optical sub-assemblies and telescopic-shaped core cylinder modules thereof are provided. The optical sub-assembly  100  comprises a light emitting module  110  having a light emitting device, such as a laser diode, a least a light receiving module  160  having a light receiving device, such as a photodiode, and a light-reception-side lens, at least one wavelength filter  153   a , passing light at one wavelength while reflecting light at another wavelength, a fibre optic connector  180 , a fibre optic cable  190  having a fiber optic  195 , assembled and fixedly secured in the fibre optic connector  180 , a filtering optical module  150 , and an integrally formed telescopic-shaped core cylinder module  120  having tapered diameter core portions  125 ,  126  and at least a gel coating layer. 
     Tx data of a first optical signal of the light emitting device is directed to the light-emission-side lens  118 , the tapered diameter core portions  125 ,  126 , the at least one wavelength filter  153   a , and onto a fibre optic  195 . Rx data of a second optical signal of the light receiving device is received from the fibre optic  195 , the least one wavelength filter  153   a , and the light-reception-side lens. 
     The problems of surface reflection for an optical sub-assembly, increasing noise therein or causing operational failure are mitigated via the integrally formed telescopic-shaped core cylinder module  120  and at least a gel coating layer. The telescopic-shaped core cylinder module  120  is configured to perform isolation on optical signals via the tapered diameter core portions  125 ,  126 , taperedly shrinking the area for reflected light to impinge on the light emitting device, and the at least a gel coating layer, absorbing wavelengths of the optical signals reflected in and to the tapered diameter core portions  125 ,  126 . Thus, emitted light launched by the light emitting device, reflecting back into the interior of the filtering optical module  150  via the structures therein and light received or reflected back from the optical fibre  195 , passing through the least one wavelength filter  153   a  and impinging on the light emitting device are substantially reduced. At least one blocking filter  148   a  is employed over the photodiode to block light of the laser diode&#39;s wavelength along with the least one wavelength filter  153   a . Reliability and focusing stability of the emitted light onto the optical fibre are held without additional costs and complexity. For the light emitting device, surface reflections off targeted surfaces back into the light emitting device decreases the stability and operating lifespan thereof through damage, unexpected laser problems, or overheating. Isolation is performed via the integrally formed telescopic-shaped core cylinder module  120  and at least a gel coating layer. Thus, an isolator is not required, and the additional costs and complexity of employing the isolator is avoided. 
     The presently disclosed inventive concepts are not intended to be limited to the embodiments shown herein, but are to be accorded their full scope consistent with the principles underlying the disclosed concepts herein. Directions and references to an element, such as “up,” “down,”, “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,” and the like, do not imply absolute relationships, positions, and/or orientations. Terms of an element, such as “first” and “second” are not literal, but, distinguishing terms. As used herein, terms “comprises” or “comprising” encompass the notions of “including” and “having” and specify the presence of elements, operations, and/or groups or combinations thereof and do not imply preclusion of the presence or addition of one or more other elements, operations and/or groups or combinations thereof. Sequence of operations do not imply absoluteness unless specifically so stated. Reference to an element in the singular, such as by use of the article “a” or “an”, is not intended to mean “one and only one” unless specifically so stated, but rather “one or more”. As used herein, “and/or” means “and” or “or”, as well as “and” and “or.” As used herein, ranges and subranges mean all ranges including whole and/or fractional values therein and language which defines or modifies ranges and subranges, such as “at least,” “greater than,” “less than,” “no more than,” and the like, mean subranges and/or an upper or lower limit. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are known or later come to be known to those of ordinary skill in the relevant art are intended to be encompassed by the features described and claimed herein. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure may ultimately explicitly be recited in the claims. No element or concept disclosed herein or hereafter presented shall be construed under the provisions of 35 USC 112(f) unless the element or concept is expressly recited using the phrase “means for” or “step for”. 
     In view of the many possible embodiments to which the disclosed principles can be applied, we reserve the right to claim any and all combinations of features and acts described herein, including the right to claim all that comes within the scope and spirit of the foregoing description, as well as the combinations recited, literally and equivalently, in the following claims and any claims presented anytime throughout prosecution of this application or any application claiming benefit of or priority from this application.