Abstract:
A hermetically sealed media converter apparatus configured to operate in harsh high-pressure differential environments, such as deep marine environments, and oil and gas. A hermetically sealed media converter apparatus is provided having a vessel forming an inner chamber that is hermitically sealed from surrounding ambient environment outside the vessel. Media conversion circuitry is contained within the inner chamber. At least one hermetic electrical feedthrough is mounted on the vessel enabling a transmit wire and a receive wire to pass therethrough and connect to the media conversion circuitry, while maintaining the hermetic seal of the inner chamber of the vessel from the surrounding ambient environment. Similarly, a hermetic optical feedthrough also is mounted on the vessel enabling an optical fiber to pass therethrough and connect to the media conversion circuitry, while maintaining the hermetic seal of the inner chamber of the vessel from the surrounding ambient environment.

Description:
REFERENCE TO RELATED APPLICATION 
       [0001]    This non-provisional patent application claims priority to U.S. provisional patent application entitled “Pressure Resistant Optical Module,” having application No. 61/345,323, and filed on May 17, 2010, the entire contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to media converters, and more particularly, to media converters designed to function in harsh ambient environments. 
         [0004]    2. Description of Related Art 
         [0005]    Media converters that commonly include optoelectronic transceivers generally include photo-detectors and lasers that convert data signals between optical and electronic transmission formats. Media converters transmit and receive digital optical signals in computers, servers, routers or switches, and are essential subassemblies in these communications systems. Media converters include numerous optical, electronic and optoelectronic components. These optoelectronic components enable media converters to transmit and receive digital or analog optical signals under electronic signal control by converting electronic signals into digital or analog optical signals for transmission over fiber optic cables and networks. Media converters also function by receiving and converting digital optical signals into electronic digital signals for use by the host computers, servers, routers or switches. Since the size of the components is very small in a media converter assembly and they are susceptible to humidity, dirt, dust and multiple other contaminants that can cause degradation, a controlled environment is mandatory for it components to be housed in order to operate efficiently and reliably. 
         [0006]    A transmit optical subassembly or TOSA typically comprises, at least, a minimum of a solid-state laser device and a light transmission conductor along with conventional data signal electronic control circuits. These circuits control and drive a solid-state laser in order to generate light pulses under an electronic control. The receive optical subassembly or ROSA, at a minimum, is similarly constituted of a photo-detector and a light transmission conductor together with electronic circuits necessary both to convert the output of a photo-detector into usable electronic data signals and to transmit and condition the output signals of a photo-detector. The photo-detector output signals are generated by light pulses that impinge upon the detection surface of a photo-detector by an associated light transmission conductor. 
         [0007]    Typically, optical data signal conductors are optical fibers. The digital light signals are conducted into and out of a transceiver assembly often by very small optical fibers, usually effective propagation elements in the order of 8-10 microns in diameter. Similarly, the exit or the light projection aperture of a solid-state laser is commensurately small. The photo-detector detection surface may be similarly small in high speed devices so that all of the light of the incoming digital signal impinging on the detection surface may be equally susceptible to environmental contaminants and environmental physical influences. With the diameter of the transmission core of an optical fiber being typically 8-10 microns, the placement of and quality of the pulses of light are critical. Light signals must not be attenuated or degraded by contaminants or other external hazards and physical influences on any of the optical fiber end faces, surfaces of lenses, surfaces of reflection suppressors, faces of the optoelectronic components, or in the atmospheric light path. 
         [0008]    Very significant efforts are made to create extremely accurate alignments of the optical elements of the system. In more enhanced systems, the digitized optical signal may be passed through one or more lenses and an anti-reflection isolator, and then may be reflected off angled surfaces on the end of an optical fiber to direct, control and position the light pulses properly relative to other optical elements of the system. 
         [0009]    Contaminants and other external hazards introduced into or allowed to enter the internal environment of a media converter module may include dust particles, water, water vapor or condensate, dust, fumes, smoke, and even varying ambient pressure changes. Such contaminants and pressure changes may reduce or alter the light signal transmission strength sufficiently to render the media converter unreliable in either or both the “transmit” or “receive” modes of operation. 
         [0010]    Even micron-sized particles of dust, debris or other contaminants that settle on or are attracted to the optical surfaces, which coat or block even a portion of the light path, will greatly diminish the optical strength of a signal passing to or from the optoelectronic element. Similarly, if there are lenses or other optical elements in the light path, each of these optical elements may collect dust, particulate contamination, moisture, or a film of contamination on any or all the optical surfaces thereof, and thus prevent the efficient passage of light therethrough. Lasers are very sensitive to moisture, and reflective coatings on facets of some types of lasers, such as a DFB (distributed feedback) laser, are sensitive to condensed moisture as the condensate acts to interfere with the passage of the laser signals therethrough. Similarly, changes in the ambient pressure can distort or disrupt the very sensitive configurations or alignments of these highly sensitive electrical and optical components of a media converter module. 
         [0011]    The use of media converter modules continues to expand into various fields, including harsh and hazardous environments. These harsh environments include oil, gas and water, such as with submarine deployments. These harsh environments are often challenged by the inability to protect the sensitive optical coupling elements, such as the interface of the laser and detector devices from the ingress of very high pressure fluids such as seawater or oil. Similarly, when it is necessity to join optical fibers at a connector interface of a media converter module in a marine environment, there can be great difficulties managing cleanliness and pressure differentials to provide reliable and repeatable optical connection performance. 
         [0012]    Accordingly, there is a need for a media converter module design that can reliably function and be connected to surrounding wire, electrical and optical connectors and cables in harsh environments, including environments experiencing high ambient pressure differentials. 
       SUMMARY OF THE INVENTION 
       [0013]    In accordance with the present invention, a hermetically sealed media converter apparatus is provided that is designed to operate in high pressure differential environments, such as deep marine environments. In addition to high-pressure differential environments, the hermetically sealed media converter apparatus of the present invention also is designed to operate in harsh ambient environments such as oil and gas. The hermetically sealed media converter apparatus of the present invention is specifically designed to protect its sensitive electrical and optical internal components in harsh ambient pressure differential environments. 
         [0014]    In accordance with the present invention, a hermetically sealed media converter apparatus is provided having a vessel forming an inner chamber that is hermitically sealed from the surrounding ambient environment outside the vessel. A media converter module is contained within the inner chamber having several elements, for example, an opto-detector, a laser transmitter, an electrical transmitter, and an electrical receiver. A hermetic wire or multiples or wire that may be part of a continuous wire cable or formed as a pin or pins such as those of a electrical connector are mounted as a hermetically sealed feedthrough located at a first position on the vessel enabling a transmit wire or wires and/or a receive wire or wires to pass through the first feedthrough of the vessel and connect to the electrical transmitter and/or electrical receiver within the vessel, respectfully, while maintaining the hermetic seal of the inner chamber of the vessel from the surrounding ambient environment. A hermetic optical fiber feedthrough is located at a second entry of the same vessel enabling an optical fiber or fibers also to pass through the vessel, while maintaining the hermetic seal of the inner chamber of the vessel from the surrounding ambient environment. Other wire elements such as those conducting power or monitoring data to and from the media converter within the vessel also may be provided for by supplementary hermetic feedthroughs at some other entry/exit points to the vessel. 
         [0015]    The foregoing has outlined, rather broadly, the preferred features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the present invention and that such other structures do not depart from the spirit and scope of the invention in its broadest form. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIGS. 1   a  and  1   b  are perspective views of a hermetically sealed media converter apparatus configured in accordance with a preferred embodiment of the present invention; 
           [0017]      FIGS. 2   a - 2   d  provide additional views of the media converter apparatus shown in  FIGS. 1   a - 1   b;    
           [0018]      FIGS. 3   a - 3   c  illustrate internal components of the media converter apparatus shown in  FIGS. 1   a - 1   b  and  2   a - 2   d;    
           [0019]      FIGS. 4   a  and  4   b  illustrate more detailed views of hermetic feedthroughs shown in  FIGS. 1   a - 1   b ,  2   a - d , and  3   a - 3   c;    
           [0020]      FIGS. 5   a  and  5   b  illustrate detailed views of hermetic feedthroughs configured in accordance with another embodiment of the present invention; 
           [0021]      FIGS. 6   a  and  6   b  illustrate detailed views of hermetic feedthroughs configured in accordance with a further embodiment of the present invention; and 
           [0022]      FIG. 7  is a block diagram of circuitry used in a preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]    Referring now to the drawings,  FIGS. 1   a  and  1   b  are perspective views from different ends of a hermetically sealed media converter apparatus  10  configured in accordance with a preferred embodiment of the present invention.  FIGS. 1   a  and  1   b  illustrate a vessel or capsule  12  having a first end  14  and a second end  16 . The first and second ends  14 , 16  are formed into plates or flanges that are secure and hermetically sealed to opposing open ends of the vessel  12 . The vessel  12  is preferably cylindrical in configuration forming an internal chamber inside, but the vessel  12  can also have other configurations in other embodiments, such as a rectangle, square, circle, or even a globe. A cylindrical configuration is particularly suitable for high pressure environments, such as the deep sea. The vessel  12  is preferably constructed of a metal, but may be constructed of other materials, such as a polymer or a ceramic. 
         [0024]    The first end or flange  14  is preferably soldered, brazed, welded or glued to an open end of the vessel  12  to form a hermetic seal. The flange  14  also can be hermetically or fluid or liquid or gas tight sealed to an open end of the cylindrical vessel  12  by other known techniques, such as screws or bolts in combinations with rubber O-rings or C-rings. The second end, flange or plate  16  also is hermetically liquid or gas tight sealed to the opposing open end of the vessel  12 . The flange  16 , similar to flange  14 , is hermetically sealed to the other end of vessel  12  by a known technique, described above. Bolts  18  are shown as one of many examples securing the flange  16  to the end of the vessel  12  to form a hermetic seal. 
         [0025]      FIG. 1   a  illustrates hermetic electrical feedthroughs  20 , 22  for wires and/or metal pins that may form part of an electrical connector  24 , 26 , respectively. Feedthroughs  20 , 22  provide hermetic pass throughs for wires or metal pins  24 , 26 . In the illustrated embodiment, wires  24 , 26  preferably correspond to wire for transmitting signals (TX) and wires for receiving receiving (RX) signals, but not necessarily.  FIG. 1   b  illustrates hermetic optical feedthrough  28  for optical fibers  30 . Electrical feedthroughs  20 , 22  and optical feedthrough  28  are preferably constructed of metal and hermetically sealed to or within an opening in the flanges  14  and  16 , respectfully. The electrical feedthroughs  20 , 22  include apertures  31 , 33  which provide a passageway for electrical wires. The electrical wires  24 , 26  are hermetically sealed within the apertures  31 , 33  by ceramics or glass soldering/brazing, glue, or other known hermetically sealing technique. The wires  24 , 26  pass completely through the electrical feedthoughs  20 , 22  from the ambient environment outside the apparatus  10  to the inner chamber within the apparatus  10 . 
         [0026]      FIG. 1   b  illustrates a hermetic optical feedthrough  28  having an aperture  35  enabling optical fibers  30  to pass from the outside ambient environment to the inner chamber inside the media converter apparatus  10 . The optical fibers  30  are hermetically sealed within the aperture  35  using known techniques, such as glass soldering or glue. The optical fibers  35  can provide single, bi-directional, or even multiplexed signals on each fiber. The hermetic optical feedthrough  28  is preferably constructed of metal hermetically sealed to or within an opening in the flange  16 . 
         [0027]      FIG. 2   a  is top view of the hermetically sealed media converter apparatus  10 . Shown are the flange  14  soldered to a first end of the vessel  12 , and flange  16  secured to the opposing end of the vessel  12  by bolts  18 . Hermetic electrical feedthroughs  20 , 22  are shown providing a passageway for wires  24 , 26  from the ambient environment to the inner chamber of the vessel  12 . Similarly, the hermetic optical feedthrough  28  is shown providing a passageway for the optical fibers  24  from the ambient environment into the inner chamber of the vessel  12 . 
         [0028]      FIG. 2   b  illustrates a side view of the hermetically sealed media converter apparatus  10  providing the vessel  12  and flanges  14 , 16  and sealing bolts  18 . Wires  26  passing through hermitic feedthrough  22  and optical fibers  24  passing through hermetic optical feedthrough  28  also are illustrated. 
         [0029]      FIG. 2   c  provides an end view of flange  16  being hermetically sealed to the vessel  12  by bolts  18 . Optical fibers  24  passing through hermetic optical feedthrough  28  also are illustrated. 
         [0030]      FIG. 2   d  is an end view of flange  14 . Hermetic electrical feedthroughs  20 , 22  are shown hermetically sealed to the flange  14 , and providing passageways for wires  24 , 26  to pass from the ambient environment into the inner chamber of the vessel  12 . 
         [0031]      FIGS. 3   a - 3   c  illustrates internal components of the hermetically sealed media converter apparatus  10 .  FIGS. 3   a - 3   c  illustrate media conversion circuitry  50  for use with an optoelectronic transceiver  58  utilizing, for example, VCSEL components coupled to the internal end of the hermetic optical feedthrough  28 . Wires  24  pass through the hermetic electrical feedthrough  20  and connect to the transmit media conversion circuitry board  51 . Similarly, wires  26  pass through the hermetic electrical feedthrough  22  and connect to the receive media conversion circuitry board  53 . Transmit (TX) wires  55  and receive wires (RX)  57  connect the transmit and receive media conversion circuit boards  51 , 53  to the optoelectronic transceiver  58 . The optoelectronic transceiver  58  is directly connected to the internal end of the hermetic optical feedthrough  28 . The optical fibers  24  pass through the hermetic optical feedthrough  28  and connect to the optoelectronic transceiver  58 . 
         [0032]      FIG. 4   a  illustrates an enlarged view of the media conversion circuitry  50  connected to the optoelectronic transceiver  58 , which is directly connected to the internal end of the hermetic optical feedthrough  28 .  FIG. 4   b  provides a further enlarged view of the optoelectronic transceiver  58  connected to wires  55 , 57 , which in turn are connected to the media conversion circuitry  50 . 
         [0033]      FIG. 5   a . illustrated an enlarged view of media conversion circuitry  60  to be located within the inner chamber of the vessel  12 . This media conversion circuitry  60  is configured in accordance with another embodiment of the present invention and utilizes an MT ferrule  62  connected to a hermetic optical feedthrough  64 . The media conversion circuitry  60  is connected to the MT ferrule  62  by optical pigtails  66 , 68 .  FIG. 5   b  provides a more detailed view of the MT ferrule  62  and optical pigtails  66 , 68 . 
         [0034]      FIG. 6   a  illustrates an enlarged view of media conversion circuitry  70  to be located within the inner chamber of the vessel  12 .  FIG. 6   b  provides a further enlarged view of the media conversion circuitry  70 . The media conversion circuitry  70  is configured in accordance with another embodiment of the present invention and utilizes a TOSA  72  and a ROSA  74  connected between a hermetic optical feedthrough  76  and electrical media conversion transmit circuitry  71  and electrical media conversion receive circuitry  73 . Optical fiber  75  passes from the ambient environment outside the vessel  12 , through the hermetic optical feedthrough  76  and to the TOSA  72  within the inner chamber of the vessel  12 . Electrical wires  78  connect the TOSA  72  to the electrical media conversion transmit circuitry  71 . Similarly, optical fiber  77  passes from the ambient environment outside the vessel  12 , through the hermetic optical feedthrough  76  and to the ROSA  74  within the inner chamber of the vessel  12 . Electrical wires  79  connect the ROSA  74  to the electrical media conversion receive circuitry  73 . 
         [0035]    On the electrical side of the media conversion circuitry  70 , electrical wires  80  pass through the hermetic electrical feedthrough  81  and to the electrical transmit media conversion circuitry  71 , and electrical wires  82  pass through the hermetic electrical feedthrough  83  and connect to the electrical receive media conversion circuitry  73 . 
         [0036]      FIG. 7  illustrates a block diagram of a media converter apparatus  100  configured in accordance with the present invention. In order to achieve an aspect of the invention, the media converter apparatus  100  includes an airtight and watertight vessel  102  capable of protecting the media conversion circuitry  104  contained inside the vessel  102 . 
         [0037]    In accordance with a further important aspect of the present invention, the hermetically sealed vessel  102  maintains a consistent Pressure  2  (P 2 ) which is not affected by changes in the external ambient Pressure  1  (P 1 ). The internal Pressure  2  (P 2 ) can be close to a vacuum, pressure approximate at sea level, or a pressure exceeding sea level, whatever pressure is desired to be maintained by a user, which is independent of changes in the ambient pressure P 1 . 
         [0038]    Turning now to other components within the media converter apparatus  100 , a hermetic electrical feedthrough  108  and a hermetic optical feedthrough  110  are hermetically sealed on opposing open ends of the vessel  102  and in some embodiments could be the same end or penetration point of the vessel, which preferably has a cylindrical configuration. Electrical wires  111  pass through the hermetic electrical feedthrough  108  into the hermetically sealed inner chamber  103  of the vessel  102  and connect to the media conversion circuitry  104 . These wires could similarly be entering and exiting the vessel through the same hermetic penetration element as the optical fibers in some configurations. Similarly, optical fibers  112  pass through a hermetic optical feedthrough  110  from the ambient environment having pressure P 1  to the inner chamber  103  having pressure P 2 , and connect to the media conversion circuitry  104 . 
         [0039]    In accordance with an additional aspect of the present invention, a diagnostic circuit  106  is included within the inner chamber  103  to be connected to and monitor operation of the media conversion circuitry  104 . The diagnostic circuit is  106  is connected to a system controller via a communication wire  121  passing through the hermetic electrical feedthrough  108 . A temperature sensor or temperature transducer  107  is located within the inner chamber  103  to monitor the temperature within the inner chamber  103 . The temperature sensor  107  is connected to a system controller via a communication wire  122  passing through the hermetic electrical feedthrough  108 . A pressure sensor or pressure transducer  108  is located within the inner chamber  103  to monitor pressure within the inner chamber  103 . The pressure sensor  108  is connected to a system controller via a communication wire  123  passing through the hermetic electrical feedthrough  108 . 
         [0040]    A DC/DC transformer  114  receives power via the hermetic electrical feedthrough  111  and provides power to the media conversion circuitry  104 . On the electrical side of the media conversion circuitry  104 , electrical wires  111  are first received by isolation transformers  115 , 116 , which in turn are electrically connected to Ethernet chip sets  117 , 118 . Similarly, optical fibers  112  pass through the hermetic optical feedthrough  110  and connect to optoelectronic transceivers  119 , 120 , which are electrically connected to the Ethernet chip sets  117 , 118 . 
         [0041]    While specific embodiments have been shown and described to point out fundamental and novel features of the invention as applied to the preferred embodiments, it will be understood that various omissions and substitutions and changes of the form and details of the apparatus illustrated and in the operation may be done by those skilled in the art, without departing from the spirit of the invention.